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• Chemical Engineering  (282)
• Documentation  (7)
• Wiley-Blackwell  (289)
• Nature Publishing Company
• 1990-1994
• 1970-1974  (289)
• 1965-1969
• 1970  (289)
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• Wiley-Blackwell  (289)
• Nature Publishing Company
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• 1990-1994
• 1970-1974  (289)
• 1965-1969
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• 1
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 163-169
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The unusual physical properties of polybutylene are ascribed to details of morphology and a unique crystalline transformation. Inherent properties important for industrial film uses include toughness, low creep, relatively high temperature resistance, stress crack resistance and flexibilty. Four types of packaging applications are described for a new polybutylene resin based on butene-1 monomer. These include industrial film, easy opening tear packages, shrink film, and rotationally molded tanks.A polybutylene shrink film is described having a combination of optical and shrink properties similar to vinyl shrink film, but with mechanical properties typical of polyolefin shrink films.Rotationally molded parts exhibit an unusual degree of toughness, stress crack resistance, and low crystallization stresses in thick parts.
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• 2
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 228-234
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: When plastics are used for outdoor applications, they often deteriorate fairly rapidly. Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as well. This theory is satisfactory for many polymers, but does not explain the instability of some polymers which are transparent to ultraviolet, nor the stability of some polymers which contain ultraviolet-absorbing and/or unstable groups. Plastics are often stabiliized by addition of ultraviolet reflectors, absorbers, or deactivators, increasing stability sufficiently for outdoor use; theoretical explanation of their protective action is satisfactory when they work, but does not explain their specificity or their failures.
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• 3
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 4
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 247-250
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A new quantitative thermal analysis technique was attempted on ABS and Noryl-type polyblends. A particular component within a polyblend was identified by its glass transition temperature and the amount of the component was determined from the increase in specific heat at the glass transition temperature.Two commercial Noryl resins were determined to be blends of high impact polystyrene and polyphenylene oxide in 47-47 and 69-17 proportions by weight, respectively. Polystyrene appears to be cosoluble with polyphenylene oxide without the formation of any complex. The PS-PPO polyblends yield single sharp glass transitions which are a function of concentration.
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• 5
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 209-214
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: This paper illustrates a numerical simulation of polymer flow as applied to the injection molding fill process. The simulation model considers heat conduction and viscous heat generation along with the temperature dependence of the flow parameters to predict fill lengths and fill times of thin constant crossection cavities. This simulation is designed for molding situations where fill is difficult, such as thin cavity sections, long flow length requirements, or difficult-to-process materials. The simulation sensitivity is explored by performing experimental molding trials with two different cavity thicknesses. The thinner cavity illustrated a short shot in all cases with the thick cavity completely filling. The simulation accurately distinguishes between the short shot and fill conditions, although significant error is noted for the length prediction of the short shot and the time-to-fill of the full shot condition.
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• 6
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 222-224
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The solubility parameter of polyisobutylene has been determined from intrinsic viscosity measurements in a single solvent as a function of temperature. The change in solubility parameter of the solvent as a function of temperature was calculated form the equation \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{d{\rm}ln \delta s}}{{d{\rm}ln Vs}} = - \frac{{n + 1}}{2}$\end{document} where Vs, the molal volume, changes with temperature. The vlaue for the solubility parameter thus obtained compares well with values reported in the literature for intrinsic viscosity measurements in a series of solvents. Similar measurements were made with an ethylenepropylene copolymer. The solubility parameter of 87 mole % C2 ethylene-propylene copolymer was determined to be 8.1-8.6 in either toluene or methylcyclohexane.
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• 7
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 235-240
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A phenomenological treatment has been developed for correlations between melt flow properties of high-density polyethylenes and the processability of bottles. Defining two parameters for the flow properties, it was found experimentally that linear relationships hold satisfactorily between these flow parameters for the raw materials and those of corresponding extrudates. Several kinds of defects in high-density polyethylene bottles can be represented in terms of the flow parameters. These parameters may provide useful measures in predicting good appearance of bottles blow-molded with high-density polyethylene.
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• 8
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 293-299
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The dynamic elastic moduli were measured on macroscopic models simulating two-phase microstructures where the second phase was present as a continuous, isotropic network. Using open-pore polymer foams with higher-moduli, infiltrating matrices, the composite moduli were found to be linear with volume fraction of the network phase. Variations of network cell size or surface area indicated that the moduli increased with increasing interfacial area, but only when interphase wetting was present and matrix contraction upon solidification occurred. Metallic foams with a lower moduli matrix produced moduli that were compatible with existing bounding theories for composites.
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• 9
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 102-107
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A description of tensile failure of polymeric materials under multiaxial loading has been formulated, based on a combination of ideas and implications derived from Smith's work on uniaxial tensile failure envelopes and the author's earlier theoretical work. Some simplification of the formal expressions was achieved by imposing restrictions that would assure that the uniaxial failure envelope is recovered under uniaxial tensile stress conditions and that the progression toward failure is monotonically increasing under monotonically increasing loads. The final result emerges as an extension of the uniaxial failure envelope applied to failure under multiaxial loads. Subsequently, the result is capable of describing rate effects to the same extent as can be described by the uniaxial failure envelope. This is an added capability over many of the existing multiaxial failure descriptions. Unfortunately, the result applied at best, only to those materials for which the uniaxial failure envelope applies; thus the generality is restricted. Some preliminary verification is presented for LX-04-1, a high-explosive material composed of 85% HMX and 15% Viton by weight, using Peterman's results from 68°F biaxial tests. Further experimental work is underway.
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• 10
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 130-130
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 11
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 12
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 122-130
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The dynamic mechanical properties of low-density polyethylene melts were measured as a function of frequency and temperature using the Orthogonal Rheometer. These results were expressed in terms of the components G′ and G″ of the dynamic modulus and the components η′ and η″ of the dynamic viscosity. The functions J′, J″, η*, and G* were also calculated from the results.The method of reduced variables or time-temperature superpositions was attempted on the results. The classical method was found to require modification to be applied to these low-density polyethylenes. From this modified form of the reduced variables technique, the temperature dependence of the elastic and viscous parts of the response could be separated.The experimentally determined temperature dependence of the elastic part of the response was found not to be in accord with the accepted theory of rubber elasticity.The temperature dependence of the viscous part of the response is discussed in terms of the concept of flow activation energy, and clarification of this term is explored. It is concluded that the temperature dependent properties of polymer melts are best compared at equivalent time scales of response in the non-Newtonian region. In order to do this the temperature dependence of the elastic part of the response must be included explicitly in the reduction scheme.
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• 13
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 133-138
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. The weight fractions of PPO in the mixtures were 0.25, 0.50 and 0.75. The dynamic mechanical measurements indicate that partial mixing took place but that two distinct phases, one rich in PS and the other in PPO, exist in all the mixtures studied. Each phase exhibits a characteristic relaxation peak associated with the glass transition of that phase. DSC measurements, on the other hand, reveal only a single glass transition apparently characteristic of the PS rich phase in each case. The results indicate that a given type of experiment will indicate compatibility or incompatibility depending upon the size of the molecular process it represents.
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• 14
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Documentation ; Computers for literature searches ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: In mechanized systems used for searching in literature stores there is a steadily growing necessity not only to be able to formulate concepts as a search condition but also the characteristic connections under which these concepts appear in the inquiry. In this way the precision of the mechanized literature search is considerably increased. TOSAR has been developed in order to improve computerized literature searching in this respect.
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• 15
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Dokumentationsring der chemisch-pharmazeutischen Industrie ; Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The members of the Documentation Ring have chosen the “punched picture” method for coding of chemical and pharmaceutical literature. Chemical, biochemical, and medical facts gleaned from a publication are broken down into basic concepts, each of which is allocated a certain position on the punched card. This system has proved to be reliable over a period of twelve years.
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• 16
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The documentation system operated by the IDC Internationale Dokumentationsgesellschaft für Chemie mbH uses electronic data processing methods. It allows the storage and retrieval of structures, reactions, and nonstructural keyword information. Structures and reactions are coded as terms of a faceted classification, while keywords are stored in clear text. 900000 formulas from patent and journal publications, including many Markush formulas, have now been stored on magnetic tape. Searches in this store are carried out with IDC programs, which require an average computer time of less than 1 minute per inquiry (CPU time). The structure terms can be produced by computer from topological records. The field covered at present is low molecular weight organic chemistry, though extension to macromolecular chemistry is feasible, and is in fact planned.
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• 17
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The principles of the topological encoding of formulas and machine searching are briefly described. These methods have been developed to the point where it is now possible to carry out a computer search for a given structural fragment without the risk of false drops. It is also possible to carry out searches whose requirements, while well-defined and readily used by chemists, cannot be represented exclusively by element symbols and chemical bonds.
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• 18
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Information services ; Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The definition of information services derives from the demarcation between documentation and information. The main criteria for information services are up-to-dateness, clarity, manageability, relevance, and flexibility. In addition to the printed information media (tables of contents, lists of titles, abstract journals) services have been offered in recent years which are prepared with the aid of data processing machines and which operate on the basis of data tapes (SDI, profile searches).
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• 19
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The Documentation Ring of the chemical and pharmaceutical industries uses a punched card system to record chemical reactions. The starting materials and the end products are encoded with a fragmentation code, and the bonds that change during the reaction are recorded in the same way. Reaction modifiers and physical data can also be stored. In the case of multistage reactions, both the individual stages and various groups of stages are recorded.
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• 20
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Weinheim : Wiley-Blackwell
ISSN: 0570-0833
Keywords: Documentation ; Chemistry ; General Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: A computer-based system for the documentation of company research results in drug research is described. The system stores the numerous results of standardized biological tests and processes chemical formulas by topological techniques. The stored material is processed to provide computer-printed card indexes and lists on chemical and/or biological topics. The programs enable searches to be made for any desired substructure and for pharmacophoric groups, thus providing highly effective assistance in the search for structure-activity relationships.
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• 21
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 177-184
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Increases in modulus, tensile strength, and swelling caused by reinforcing silicone rubber with silica filler were correlated with the thermoelastic parameter, fe/f. A new semiempirical equation of state, containing a generalized front factor, was derived to explain the experimental results. While the retractive force in pure gum elastomers is largely entropic in origin, reinforcement in silicone rubber-silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic modes.
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• 22
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 193-203
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The capillary flow instability resulting in extrudate distortion has been studied for ethylene polymer melts using a molecular structure approach. It is found that the instability initiates at a critical value of elastic strain energy independent of (average) molecular weight for linear polyethylene. Once the flow breaks down, a slip interface within the melt is formed near the capillary wall, causing an abrupt increase in volumetric throughput. The velocity gradient within the melt remains continuous through the instability, however. Low molecular weight species present in the molecular weight distribution of linear polyethylene tend to suppress slip. Blends of linear and branched polyethylene exhibit instability behavior characteristic of both components throughout the entire range of composition. Results are discussed in terms of specific molecular mechanisms.
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• 23
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 225-227
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The thermal stability of elastomers containing siloxane linkages has been compared using the technique of chemical stress relaxation in an inert environement. Enhancement of the already high stability of the basic poly (dimethyl siloxane) silicone rubber by the substitution of hetero groups in and on the main chain was proved, with the exception of the pendent trifluoroporopyl group. Particulary dramatic was the effect of the mcarborane moiety in the SiB-2 elastomers which elevated the stability of the siloxane chain by more than 100°C relative to silicone rubber.
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• 24
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Stamford, Conn. [u.a.] : Wiley-Blackwell
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 25
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 185-192
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero-structural, airfoil, or blade components.
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• 26
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 204-208
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Dynamic mill stability tests of PVC powder blends at the equiviscous temperatures were correlated with the clarity and color obtained in extrusion and blow molding of bottles. Copolymers of vinyl chloride with alkyl vinyl ether and propylene in a calcium-zinc stabilizer, impact modified formulation had better processability than a homopolymer and produced bottles having lower values of absorbance and yellowness index. Product imperfections which were evident in blow molding of dry blends, but not during milling or capillary rheometer extrusion, were found to be related to the particle size distribution and volatile content of the resin.
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• 27
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 215-221
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A new method of treating torque rheometer test data has been developed. First, it involves converting the torque values measured over a range of temperatures to torques corresponding to a constant reference temperature. Then the log of the calculated torques is plotted against time. The method has been applied to several polypropylene grades, and the effects of numerous test variables have been explored. Correlations have been developed between torque rheometer data and fundamental polymer properties of viscosity and molecular weight. The method should also be applicable to polymers other than polypropylene.
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• 28
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 279-288
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted-average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
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• 29
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 268-278
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The extursion melting model of Tadmor et al. (1967) has been modified to include the effects of screw channel curvature and melt leakage through the screw flight-barrel clearance. An alternate coordinate system was used in modifying the model to simplify the addition of curvature corrections. Also proposed is an improved method of computing solid bed velocity. A substantial number of typographical errors and truncations appeared in the original data published by Tadmor et al., and verification of their computations with corrected data was successful in all cases. Channel curvature corrections and the improved method of computing solid bed velocity increased the predicted rate of solid bed width decrease by approximately 14% during the initial stages of melting. Addition of leakage flow to the model tended to offset this effect completely or in part. Leakage flow effects always predominated during the later stages of melting, however. These effects may interact differently for other extruder sizes or screw designs; therefore, the modified melting model should be a more accurate model for use in the design of extruder screws and in studies of extruder performance.
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• 30
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 289-292
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The dynamic mechanical properties of blends of polymer melts were measured using the orthogonal rheometer. Two-phase blends, polyethylene-polystyrene, polyethylene-poly-(methylmethacrylate), and polystyrene-polymethylmethacrylate, were studied. The in-phase and out-of-phase moduli were measured over the range of composition and at frequencies between 10-4 and 10 revolutions/sec.The out-of-phase modulus increases in a monotonic manner with composition. The in-phase modulus, however, shows a maximum with composition in two cases. Examination of the relaxation spectra of these blends shows that when no maximum occurs it can be written as an additive function of the spectra of the components. In the case where a maximum is observed in the modulus the measured spectrum of the blend is shifted in frequency relative to the calculated one. This is tentatively attributed to slight interpretation and solubility of one phase in the other in these cases.
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• 31
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 300-304
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of polymer-swelling and dissolution in liquids. Results for a variety of polymer-swelling agent systems demonstrate that information usually requiring more sophisticated experimental techniques can be readily obtained with the TMA. In particular rates of swelling and penetrant diffusion coefficients can be determined for selected systems. Dissolution measurements, exemplified here for polystyrene in three different solvents, can be utilized to obtain steady state rates of solvent penetration and rough estimates of the interdiffusion coefficient for a system. The experimental limitations involved in both types of measurement are discussed.
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• 32
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 305-308
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of penetration of a hemispherically-tipped probe into a material sample. Two amorphous copolymers were studied at various temperatures above their softening points. Kinetics of penetration are compared with tensile creep measurements for these viscoelastic materials. A simple semi-empirical relationship between creep and penetration at small strains is applied and found to yield approximate although not exact agreement with experiment. It is thus possible that for homogeneous materials of this type creep data might be easily predicted with a fair degree of accuracy from penetration data and vice versa. Experimental problems involved in the TMA penetration technique are discussed.
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• 33
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Stamford, Conn. [u.a.] : Wiley-Blackwell
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 34
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 309-313
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A statistical study was conducted to determine the significance of the sources of variability in the laboratory (carbon arc) weathering of a light-stabilized polyester resin system. Color fastness of the resin was evaluated in terms of changes in total color, lightness, and chromaticity. Factors that significantly influenced the results were variability within castings and between batches of resin, location of the specimen within the exposure apparatus, and the storage time prior to testing. The carbon arc instrument provided a relatively insensitive test for evaluating a light-stabilized polymer system, chiefly because, with a stable polymer, small random variations in response become almost equal to the small change in color developed on exposure.
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• 35
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 317-319
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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• 36
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 320-326
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: In this study, a linearly viscoelastic polyurethane film was subjected to continuous, sinusoidal deformation in a new isothermal deformation calorimeter, whose design details were recently reported (1). Internal energy and entropy of the polymer at each state in the deformation cycle were computed from heat rate and work rate data. This was made possible by using linear viscoelasticity theory to predict the irreversible entropy production. Thermal data were corrected for instrument time lag.
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• 37
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 327-331
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Interpenetrating polymer networks of polyacrylate (A) and poly (urethane-urea) (U) were prepared by mixing lattices of self-curing polyacrylate and urethane-urea prepolymer followed by subsequent curing of each network. The structures of the mixtures were analyzed by the dynamic viscoelasticity and the electron microscopy. It was found that a phase inversion occurred from the “U-phase particles in A-phase matrix” to the “A-phase in U-phase matrix” at A/U ≑ 30/70 as the U-phase content increases.With increasing A-phase content, tensile strength started to increase and elongation-to-break becomes almost constant after the A-phase formed a continuous phase. This implies that the tensile properties are closely related to the morphological features.
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• 38
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 332-339
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A precise method of oven-aging polypropylene monofilament has been developed employing a tubular oven in which temperature and air velocity within each tube are accurately controlled. The monofilaments are suspended within each tube by means of specially construced heat stabilized polypropylene holders (no metal contact), which facilitate handling and record keeping. Each filament is held in an attitude perpendicular to the air flow. Failures almost invariably occur in the middle of each filament. Oxidative stabilities of filaments aged in the tubular oven at a constant temperature and air flow were found to be dependent upon (a) distance of the filaments from the incoming air side and (b) whether the exposure was continuous or intermittent. If these parameters are kept constant, relatively good precision can be obtained. The 95% confidence level for a single observed value was found to be on the order of ±10% of the average oven stability within the whole oven and ±7% within a single tube. Precisions of about ±2.5% can be obtained by employing averages of 10 replicates exposed on the same specimen holder.
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• 39
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 340-344
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The cross-linked, ladderlike structure of cured pyrrones is not susceptible to forming at ordinary temperatures and pressures. At unusually high processing temperatures, of the order of 500°C, these intractable materials are observed to undergo transient flow sufficient to allow molding of the material. This observation, supported by analytical information, suggests that the flow occurs because of the breakage of covalent organic bonds and subsequent structural rearrangement of the cross-linked polymer network. This is in accord with a number of isolated reports of the pyrolytic behavior of several polymers.
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• 40
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 349-357
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A detailed study of the physical properties of alternating block copolymers of polydimethyl siloxane and bisphenol-A polycarbonate is presented. The results suggest that the mechanical and optical properties of such materials are dependent upon the presence of associated regions as well as the nature of the chain between such regions. Dielectric, infrared, and DSC data as well as the stress and birefringence strain behavior are presented.
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• 41
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 358-363
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: When a thin-walled rubber tube containing an incompressible fluid is compressed between two parallel plates the internal pressure rise depends on the restraints in the contact regions. When there is no friction in the contact zone the pressure rise is lower than when slip is prevented, so that the tube, regarded as a spring, has a compression stiffness which depends on the frictional conditions. The same considerations apply to the inflation of a tube between fixed parallel plates. In this case unstable inflation sets in at a critical pressure when the interfaces are frictionless; the tube develops a pronounced bulge when this pressure is approached. Simple theoretical relations are derived for the internal pressure and compressive force for both these deformations, and for both boundary conditions, assuming that the rubber is Neo-Hookean in elastic behavior. Experimental measurements on tubes of different dimensions are shown to be in reasonably good quantitative agreement with these theoretical predictions in all cases.
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• 42
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 364-368
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate). Diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh. The activation energy is 30 Kcal/g mole. In polymerizing powders (20-200 mesh), the crystallinity of prepolymer and its changes during the polymerization affect the diffusivity and thus the polymerization rate. The diffusivity was found to be linearly proportional to the mass fraction of the amorphous phase in PET polymer.
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• 43
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 369-375
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A torsion pendulum study of boron fiber-epoxy resin composites has shown marked deviations, at elevated temperatures, from the predicted behavior. A new damping peak at approximately 180°C as measured at 5 Hz is present which appears to be independent of the type of epoxy resin present in the matrix. This peak is attributed to interfacial effects between the boron fibers and the matrix resin. A linear model is tentatively proposed to explain this effect.
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• 44
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 345-348
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The need for low-pressure molding of electronic assemblies and devices has long been realized by customers and plastic processors throughout the military, space, and commercial industry. Probably the single, greatest advance in this area to date has been the introduction of liquid resin molding or, as sometimes called, liquid transfer molding and liquid injection molding. This paper briefly discusses the studies being conducted in the area of material developments, applications, and tooling considerations and cites several case histories comparing the advantages of liquid resin molding vs powder molding. This paper also includes the relatively new efforts being investigated for economical mass production of solid state light-emitting diodes and solid state optical numerical readouts.
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• 45
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 383-387
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The object of measurement was the diffusion of elemental sulphur labelled with the radioisotope S35 in typical representatives for various types of rubber. The highest values of diffusion coefficient have been found in cis 1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol-1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.
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• 46
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 57-65
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The flow behaviors of a series of polyvinylchloride (PVC) resins covering a broad range of molecular weight have been examined at several temperatures. It has been shown that the influence of temperature on viscosity depends on the temperature range. That is, the flow activation energy is not constant but can be approximated by two values, one applicable to low temperatures, the other to high temperatures.The flow activation energy based on viscosities at constant shear rate decreases as the molecular weight increases. In contrast, the flow activation energy from viscosities at constant shear stress increases with molecular weight.The fact that the activation energy is dual valued does not seem to be associated with the polymer type. Both emulsion and suspension resins exhibit this behavior. Addition of certain modifiers appears to alter the activation energy at lower temperatures. These observations indicate that the shift in the activation energy in the low temperature range is due to a change in the flow mechanism.
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• 47
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 70-78
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The non-Newtonian viscosity of concentrated solutions of a styrene-butadiene-styrene, SBS, block copolymer was measured with a novel capillary viscometer. Polymer concentrations ranged from 0.165 to 0.306 g/cc. Apparent shear rates ranged from 1 to 105 sec-1. Five different solvents were employed. All of the flow curves can be reduced to a single master curve with the same shape exhibited by monodisperse polystyrenes and the Graessley theory. The shift factor for the shear rate axis, τ0, approximately parallels the Rouse relaxation time, τR, but shows a residual concentration and solvent dependence not predicted by the Rouse form. For different solvents at the same concentration, better solvents show a minimum relative zero shear viscosity, η0/ηs, and a maximum ratio τR/τ0. It is concluded that all solvent effects are not adequately incorporated into the zero shear viscosity for the purposes of constructing master plots; however, the shape of the master plot is not affected by the solvent or the polymer block structure.
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• 48
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 1-3
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: An empirical equation is presented which describes polymer solution viscosity, η, over the entire concentration range from a knowledge of intrinsic viscosity, [η], Huggins constant, k′, and bulk flow viscosity of polymer, η0. The equation is: \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{\eta _{sp}}}{{C[\eta]}} = \exp \left\{{\frac{{{\rm k'[}\eta {\rm]C}}}{{1 - bC}}} \right\}$\end{document} where solution viscosity, η, is contained in ηsp. No arbitrary parameters are invoked since b can be evaluated at bulk polymer (C = polymer density) where everything else is known. The equation accurately portrays the viscosity of polypropylene oxide (PPG 2025) from infinite dilution to bulk polymer in a very good solvent (benzene) and in a somewhat poorer (∼ θ) solvent (methylcyclohexane). The hydrodynamic consequences of the thermodynamic interactions between polymer and solvent are reflected in the constants. This equation should be applicable to other polymer/solvent systems, and thus be immediately useful to those working with concentrated polymer solutions.
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• 49
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 241-246
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The results of a study to determine the biological stability of clear, colorless, biocide-treated PVC film are presented. With the exception of a resistant control, all the PVC film samples tested contained a plasticizer susceptible to biological deterioration. Biocide-treated and control PVC film samples were subjected to biological attack in soil burial. Portions of each sample were exposed to leaching and to weathering in a weatherometer followed by soil burial to test the stability of each biocide to loss by water and weathering exposure. Of the 32 biocide preparations tested only 2, N-(trichloromethylthio) phthalimide and copper 8-quinolinolate, a known effective reference compound, were found to provide good protection for treated film in direct soil burial and in soil burial following leaching and weatherometer exposure. Natural weathering outdoors confirmed the results found with weatherometer exposed samples. The N-(trichloromethylthio) phthalimide was less effective than the reference compound in suppressing surface growth. In addition, N-(trichloromethylthio) phthalimide may not be compatible with all PVC formulations.
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• 50
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 253-260
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Notched Charpy impact strengths of a series of plasticrubber two-phase polymer systems were measured over a wide range of temperatures. Blends of polyvinylchloride and rubbers with varying chemical structures, and several ABS polymers were investigated.In all systems, Charpy impact strength began to increase near the Tg of the rubber component followed by a logarithmic increase with increasing temperature. The trend is expressed by the following empirical relation: \documentclass{article}\pagestyle{empty}\begin{document}$$I{\rm = }A{\rm exp(- }B/T{\rm)}$$\end{document} where I is Charpy impact strength, A and B are constants, and T is the absolute temperature. This equation is applicable between the Tg's of the plastic and the rubber components. The increasing tendency of impact strength, i.e. the B value of the above equation, is depressed mainly by the decrease of the compatibility and/or the interfacial adhesive force between the two phases. Toughening mechanism and the ways of increasing toughness are discussed based on the craze formation mechanism.
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• 51
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 261-267
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Yield stress (σY) and elongation to break (εb) were measured over a wide range of temperature under three different strain rates (\documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document}) for a series of polyvinylchloride-rubber blends, ABS polymer and high-impact polystyrene. It was found that a temperature-strain rate reduction was possible for σY and the composite curve obtained by the superposition was expressed by the following relation: \documentclass{article}\pagestyle{empty}\begin{document}$$\sigma _{\rm Y} = K_1 + K_2 \log \dot \varepsilon A_T$$\end{document} where K1 and K2 are the material constants, and AT is the shift factor.As for εb, a new maximum was found at around room temperature in addition to the known maximum at around the glass transition temperature of the matrix phase. The results are discussed in terms of the craze theory for rubber toughening of plastics.
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• 52
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 148-153
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A method for determining the melt elasticity is developed. The method requires the measurement of axial pressure distribution in a capillary and makes use of the extrapolated value of the pressure at the exit of a capillary, the so-called “residual pressure.” The same measurement also provides data for determining the flow curve. Measurements were taken with polyethylene and polypropylene. The results are presented and discussed with particular emphasis on the application of the method to various ways of processing polymers.
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• 53
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 139-147
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: This paper discusses the influence of fiber-glass reinforcement content on the physical properties of four theroplastic injection molded materials. In addition, the effects of binder difference (i.e., thermoplastic vs. thermosetting), associated with the reinforcement, are described.Several properties that were expected to show response to glass content and binder differences have been examined. Among these are short- and long-term tensile strength, flexural properties, compressive resistance, impact strength, deflection temperature under load (DTL), and environmental stress cracking.This work has demonstrated that fiber-glass reinforcement of the particular thermoplastics described in this paper has led to substantial improvements in both the stiffness and strength characteristics of the base resins. The responses to binder chemistry difference was found to be slight in many instances for the resins, as reflected by the tests described herein. However, the long-term tensile, impact, DTL, and stress-cracking tests have shown considerable sensitivity to binder change in some cases, especially with respect to the polypropylene, SAN and polyamide plastics. The particular response to a given binder system, however, appears to vary both with the material under test and the property used to detect such response.
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• 54
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 154-158
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: In injection molding certain polymers, fracture of the polymer stream sometimes occurs at the mold surface. This phenomenon has been found to be a tearing apart of the polymer surface layer accompanied by downstream slip of the flowing melt at the polymer/mold interface. Fracture occurs early in mold filling and is initiated usually at the gate to the mold cavity. Analysis of the fracture mechanism indicates that fracture is caused by: (1) high shearing stress in the melt as it fills the mold; (2) poor polymer/mold adhesion; and (3) low polymer surface cohesive strength.
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• 55
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 159-162
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The thermal instability of polybutadiene-based rubber used to improve the impact strength of vinyl-type polymers often presents processing problems. Rubber manufacturers have attempted to alleviate this situation by incorporating various types of stabilizers. However, this is not always successful. One of the consequences of using a rubber that is not sufficiently stable in the production of modified vinyl-type polymers is the formation of insoluble gel particles during processing. In an attempt to prevent this from occurring, a test was developed that can differentiate between rubbers of acceptable and non-acceptable thermal stability. In principle, the test consists of exposing the rubber in question to a controlled thermal abuse of such intensity and duration as to approximate the thermal abuse to which the rubber will be subjected in a normal processing sequence. (The extent of abuse will vary for different processes and must be empirically established for each system.) Following this controlled exposure, the rubber is tested for gel-particle content by filtration of a specific solution, much the same way that the rubber manufacturer tests for initial gel-particle content. Sufficient data have been compiled to statistically describe the validity of the test.
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• 56
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 170-176
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Versamid cured-epoxy specimens were loaded in tension, compression, and flexure at different strain rates and temperatures to determine the yield stress and strain, and tangent, secant, and relaxation moduli. A torsion pendulum was used to measure the dynamic properties as a function of temperature and frequency. The time-temperature superposition principle was used to reduce this data to master curves. It was concluded that the time-temperature shift factors for secant moduli up to the yield point, for stress relaxation and for dynamic moduli were identical and were independent of the mode of loading. It was also shown that the presence of fillers or reinforcing agents likewise had no effect on the shift factors.
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• 57
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 13-18
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Earlier work reported the superposition of flow curves for plasticized compounds of vinyl chloride homopolymer with corresponding curves for unplasticized resin. Viscosity shift factors for three plasticizer systems plotted against temperature define an apparent fusion temperature for the bulk polymer. A Brabender Plasticorder, used as a temperature-scanning rheometer, determined fusion temperatures for various plasticized PVC compounds. These data confirm a fusion temperature for bulk polymer near 205°C, and permit calculation of Flory-Huggins χ parameters over substantial ranges of composition and temperature. The thermodynamic parameter correlates well with viscosity shift factors for compounds with polymer volume fractions below 0.6. The possibility is therefore raised of calculating flow characteristics for plasticized PVC compounds from knowledge of χ only. The temperature and composition dependence of χ, estimated for the system PVC-diiso-octyl phthalate, is similar to reported variations in simpler polymer-diluent systems. Thus, PVC-plasticizer systems may follow analogous thermodynamic rules.
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• 58
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 19-23
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: The kinetics of the molecular vaporization process of 21 plasticizers were investigated in detail. By both isothermal and nonisothermal kinetic methods, it was evident that 11 were quite pure single compounds, while 10 were clearly mixtures of compounds. For the single component species internal energies for vaporization and rates of volatilization are listed. The internal energies of vaporization are about one-half or less of values one can estimate from the additive factor method of Small. Thus, solubility parameters based on our experimental values are low by about 30 percent. From this and previous work on linear alkanes, it is concluded that in the molecular vaporization process, the large organic molecules studied evaporate approximately as spheres and hence low values for the energy of vaporization are obtained. Consequently, the difference between our experimental energy and that estimated from solubility parameters is the energy for extending the molecule in a vacuum environment.
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• 59
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 32-37
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: A method is described for measuring the rate of water vapor transmission through thick sections of polyethylene used as insulation on electrical conductors of pure sodium metal. The technique could be generally useful for materials which do not react with sodium, and for cylindrical samples which can be filled with molten sodium in a dry box. For samples with uniform dimensions the results are extremely precise because sensitive electrical measurements are used. Specimens of products in final form can be employed to determine the effects of variations in processing.
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• 60
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 24-31
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Flow at the entrance of a tube or channel is of interest in many polymer processes. Except for mathematical treatments at high Reynolds numbers and in creeping Newtonian flow, one must turn to empirical correlating equations and qualitative observations. These are discussed in two parts, one on pressure drop and the other on flow patterns. The discussion of pressure drop is largely a review, dealing with inertial, viscous, and elastic contributions to the pressure drop in tapered and sharp-edged entrances; also presented are new data for a viscoelastic polymer solution in tapered cone entrances. In the section on flow patterns, stress birefringent data for a very elastic solution flowing into a channel entrance show an unusual effect: stress discontinuities, not unlike “shock waves,” upstream and downstream of the entrances. This is in contrast to Newtonian and less elastic materials in which the stress patterns change gradually between the developed flow region and the entrance region.
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• 61
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Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 43-47
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: In this paper the results of both the theoretical and experimental stress analyses of composite materials reinforced with ribbons are presented. The reinforcing materials for such composites are characterized as two-dimensional elements which are isotropic in planes parallel to the faces. The theoretical work is based on the finite element method. Experimentally, the photoelastic technique is employed to determine the stresses around the glass ribbons embedded in an epoxy matrix. The specimens, containing a number of aligned ribbons, were loaded in tension parallel to the ribbon width. The variation of shearing stress at the ribbon-matrix interface as well as the pertubation effect on both the ribbon normal stress and interfacial shear due to the discontinuity of the neighboring ribbons are discussed.
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• 62
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
Polymer Engineering and Science 10 (1970), S. 38-42
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
Notes: Studies have been made of the heat and light induced oxidation of ether linked commercial thermoplastics using a variety of analytical methods. Our studies on polyoxymethylene, polyphenylene oxide, and its blends with polystyrene are discussed here. Comparisons of heat and light stability are made with thermoplastics previously reported.Heat aging of polyoxymethylene causes a decrease in elongation and weight as well as volatile product formation and changes in the infrared spectrum indicative of chain scission. Exposure to ultraviolet light accelerates the oxidative reaction. Polyoxymethylene copolymer is more thermally stable but both polymers are rapidly degraded during light aging.Investigation of the heat and light induced oxidation of polyphenylene oxide shows that oxidation, in either case, leads to a crosslinking reaction resulting in embrittlement of the polymer. The process is difficult to retard. However, oxygen uptake results indicate that blends of polyphenylene oxide and polystyrene can be suitably stabilized against thermal oxidation. Preliminary results indicate that oxidation of these blends proceeds by a chain scission mechanism.
Type of Medium: Electronic Resource
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• 63
Electronic Resource
Stamford, Conn. [u.a.] : Wiley-Blackwell
ISSN: 0032-3888
Keywords: Chemistry ; Chemical Engineering
Source: Wiley InterScience Backfile Collection 1832-2000