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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 16 (1976), S. 314-317 
    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: Addition polyirnide oligomers with nadimide end groups (I) have been synthesized from 4,4′-oxydiphthalic anhydride and 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride with several isomeric diamines and, nadic anhydride. The low molecular weight amic acid? and corresponding imides were isolated and characterized. Solubility and melt-flow properties of the imide prepolymers were studied to determine the applicability of the resins as adhesives and composite matrices. Thermomechanical transitions of the polymers were obtained by torsional braid analysis. Properties were compared with a similar addition polymer, P13N.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 9-14 
    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: Addition polyimide oligomers have been synthesized from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 3,3′-methylenedianiline using a variety of latent crosslinking groups as end-caps. The nominal 1300 molecular weight imide prepolymers were isolated and characterized for solubility in amide, chlorinated and ether solvents, melt-flow and cure properties, glass transition temperature, and thermal stability on heating in an air atmosphere. Adhesive strengths of the polyimides were obtained both at ambient and elevated temperatures before and after aging at 232°C. Properties of the novel addition polyimides were compared to a known nadic end-capped adhesive, LARC-13.
    Additional Material: 6 Ill.
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  • 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: A series of polyimides based on 4.,4′-isophthaloyldiphthalic anhydride (IDPA) was prepared and characterized by inherent viscosity, differential scanning calorimetry (DSC), solubility, wide-angle X-ray scattering (WAXS), and isothermal thermogravimetric analysis (ITGA). Film forming, tough, insoluble polyimides were obtained with most of the 11 diamines used for evaluation. Two materials were semicrystalline. Several compositions showed excellent thermooxidative stability by ITGA at 300 and 350°C in air, as compared to Kapton-H (Du Pont) film. The IDPA-m-phenylenediamine (m-PDA) composition, for example, gave a flexible, amorphous film having a Tg of 259°C (identical with LARC-TPI) and insoluble in a wide range of solvents. It is based on a potentially low-cost dianhydride (IDPA) and, unlike LARC-TPI, a low-cost, domestically available diamine which gives a negative Ames test.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1098-1105 
    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: Isothermal radial growth rates (G) of isotactic polypropylene (iPP) spherulites in immiscible blends with a polyethylene based ionomer (1) partially neutralized with Zn+2, (2) completely acidified, and (3) completely esterified have been determined at crystallization temperatures between 118 and 124°C by time-lapse photomicroscopy. In these blends iPP spherulites grow with increased G as compared to that of pure iPP. This behavior is attributed to increases in the rate of transport, due to limited miscibility induced by mechanical mixing. However, subtle differences in the melting behavior suggest that changes in Spherulite morphology may also be a contributing factor.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A knowledge of liquid-film flow rates is important for design purposes when accurate predictions are required of the conditions under which dryout heat flux occurs in nuclear reactors and boilers. Liquid-film flow rates were measured for a steam-water mixture in cocurrent, upward annular flow in a tube at a pressure of 1,000 lb./sq.in.abs. Sinters located at the test section exit were used to extract the liquid film after the method of the Harwell group. Sinter lengths of 2, 1, and 1/2 in. were employed to investigate the effect of length on the extracted liquid flow rates. The test section was a stainless steel pipe of inside diameter 0.493 in., approximately 200 diam. in length. The total mass flux ranged from 0.2 to 0.7 × 106 lb.m/hr.sq.ft. and the quality varied from 0.3 to 0.92.The experimental film flow rates were found to increase with decreasing quality. In the range of parameters investigated, the curves of film flow rate at constant quality vs. mass flux showed a maximum at a fixed value of steam velocity. At the same total mass flux and quality the film flow from the 1/2 in. sinter was lowest, suggesting that the crests of high amplitude roll waves overshot the sinter. Film flow rates were consistently higher than the theoretical predictions using Levy/s model. About one-third of the measured flow rates were twice as high as predicted.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 698-700 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 456-461 
    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 shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow-cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow-cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond strength.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1123-1126 
    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: Poly([4-(methacryloyloxy) butyl]pentamethyldisiloxane), PMBPD, has been prepared for the first time. At the weight average molecular weight of 55,900, it is a clear, viscous liquid with a glass transition temperature, Tg, of 236K. Copolymers with methylmethacrylate have also been prepared. The homo-and copolymers, all of which have methacrylate backbones with pendant siloxane groups, were blended with poly(methyl-methacrylate), PMMA. Using the existence of a single Tg as a definition of miscibility, it was found that blends of either PMMA or PMBPD with random copolymers are miscible. However, in spite of a clear appearance, the blend of the two horriopolymers were found to have two distinct Tgs.
    Additional Material: 1 Ill.
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  • 10
    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: Conditions are described for preparing blends of cellulose with nylon 6 (Ny6) and poly(ε-caprolactone) (PCL) from solutions in N,N-dimethylacetamide (DMAc)- lithium chloride (LiCl) by coagulation in a non-solvent. The binary blend films of both series, obtained over a wide composition range (10/90-90/10) from mixed polymer solutions, were characterized by wide-angle x-ray diffraction (WAXD), differential scanning calorimetry (DSC), and dynamic mechanical measurements. In the two series of cellulose blends the other component (Ny6 or PCL) was crystalline at every composition, but there was some degree of disproportional reduction of the crystallinity with an increase in cellulose content. From the dynamic Mechanical testing, the cellulose/Ny6 blends were found to be almost immiscible, although the possibility of a certain level of partial miscibility in the non-crystalline regions was admitted at high cellulose concentrations (〉80 wt%). For the cellulose/PCL blends, it was found that there was evidently an amorphous phase where a limited amount of cellulose could be well mixed with PCL. A relatively large shift of the midpoint in the PCL glass transition region to the higher temperature side was noted at the compositions containing 20 and 30 wt% cellulose. This effect is discussed in relation to the requirement of an optimum balance in the density of the interacting hydroxyl and ester groups, for obtaining true miscibility of cellulosics with PCL at the molecular level.
    Additional Material: 13 Ill.
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