摘要:

AbstractIn this study copolymerization of Turkish tall oil specimens with technical grade indene–coumarone fraction of coal‐tar oils (bp 150–230°C) was investigated. The effects of temperature, the reaction time and reactant ratio on the reaction rate, and the composition of the resulting copolymer were determined. Based on these studies the optimal reaction conditions were established. Some main characteristics of these new type of tall oil/indene–coumarone copolymers determi

ISSN:0021-8995    

DOI:10.1002/app.1991.070431101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractTwo varieties of tall oil were copolymerized with indene–coumarone and subsequently esterified with ethylene glycol, glycerol, and pentaerythritol in addition to these esters, Urethanes were also obtained by reacting pentaerythritol esters of copolymers with toluene diisocyanate (TDI). These resultant products were evaluated as varnish vehicles and their film properties were compared with some standard formulation of tall‐oil‐ and vegetable‐oil‐based varnishes. The effect of indene–coumarone content of copolymer on the film properties of final products were additionally studied. Film evaluation showed that these copolymer‐based varnish vehicles could be used in the field of organic su

ISSN:0021-8995    

DOI:10.1002/app.1991.070431102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe gas permeability and permselectivity of a series of halogen‐containing polycarbonates are discussed in terms of the fundamental solubility and diffusivity factors. These materials have structural features that hinder interchain packing and intrachain rotational mobility. Both diffusion and solubility coefficients are higher in materials with higher fractional free volumes. Diffusivity selectivities tend to increase with increasing restriction of intrachain torsional mobility. The materials with four bromine atoms substituted on the phenyl rings ortho to the carbonate linkages display a significantly increased diffusivity selectivity relative to conventional polycarbonate. This improvement in the ability of the polymer matrix to discriminate between gas molecules of different sizes is due to a reduction in intrachain torsional mobility. The reduction in chain mobility is indicated by higher glass transition and higher sub‐Tgtransition temperatures in the bromine‐substituted materials. The materials with hexafluoroisopropylidene moieties have high fractional free volumes and exhibit a very significant increase in permeability relative to conventional bisphenol‐A polycarbonate. The material with both the hexafluoro and the tetrabromo substitutions displays significantsimultaneousincreases in permeability and permselectivity relative to conventional polyca

ISSN:0021-8995    

DOI:10.1002/app.1991.070431103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA preparative‐scale, aqueous size‐exclusion chromatography system was constructed for fractionation of large molecular weight polymers. Calibration of molecular weight to elution volume was accomplished without polymer standards by using an eluent viscosity detector in series with a refractometer. The system was found to have a hydrodynamic size‐separation resolution that ranged from 500 to 3

ISSN:0021-8995    

DOI:10.1002/app.1991.070431104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA study of the interaction of solvent in a urethane/urea/ether copolymer belonging to the spandex family of materials is presented. Sorption and desorption isotherm data forN,N‐dimethylacetamide (DMAc) in spandex solutions are used to determine thermodynamic parameters of solvent/polymer interaction. Isosteric enthalpies for sorption of DMAc tend to approach the heat of evaporation of DMAc at high sorbed concentrations. A qualitative mechanism for assemblage of hard‐segment domains in the polymer during desorption is presented and interpreted in terms of the sorption isotherms and isosteric enthalpy data. The study provides useful insights into the influence of particulate additives, such as titanium dioxide (TiO2) in the solut

ISSN:0021-8995    

DOI:10.1002/app.1991.070431105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWood–polymer composites (WPC) of Geronggang (GE;Cratoxylon arborescens), a light tropical hardwood, impregnated with methyl methacrylate (MMA) and styrene‐co‐acrylonitrile (3 : 2; STAN), were prepared byin situpolymerization using γ radiation or catalystheat treatment. The dynamic flexural storage modulus,E′, for oven‐dried GE, moist GE, and GE–MMA and GE–STAN composites decreased with increasing temperature. The percentage decreases for GE with 10 and 16.5% moisture contents were 74.5 and 98.2%, respectively, which were higher than those for GE and GE composites, which ranged between 40 and 50%. The impregnated polymers were not as effective as water in acting as plasticizers, due to their nonpolar nature and much higher molecular weights. The α‐transition peaks for moist GE and GE composites were more distinct and were shifted to lower temperatures than those for oven‐dried GE. The values ranged between 75 and 150°C for moist GE and between 102 and 170°C for the GE composites. The α‐transitions of the catalyst–heat‐treated GE composites were lower than that of the radiation‐induced counterparts. GE–STAN composites were also observed to have lower α‐transition temperatures than those for GE–MMA for the respective treatment process, which seems to suggest that STAN interacted to a greater extent w

ISSN:0021-8995    

DOI:10.1002/app.1991.070431106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA membrane was designed for the separation of a water–alcohol mixture by pervaporation on the basis of the difference in hydrogen‐bonding interaction between two components of the membrane. Two kinds of poly(vinyl alcohol)‐g‐maleic anhydride/methyl methacrylate membrane were prepared by different methods: (1) A homogeneous membrane was formed by casting from dimethyl sulfoxide solution after purification. (2) A porous membrane was obtained directly by casting from the reaction solution, and then was purified. It is found that water was permeated through a homogeneous membrane preferentially in all ranges of feed compositions. Moreover, the flux was found to decrease with increasing PVA content in the membrane. The porous membrane after heat treatment has selective permeability for methanol. Pervaporation of water was investigated with respect to the feed concentration and also to the operating conditions. The effect of the molecular size of the permeating species on both permeation and separation is also di

ISSN:0021-8995    

DOI:10.1002/app.1991.070431107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe mechanism for the occurrence of internal stress in the curing cycle of four‐functional epoxide resins was investigated in detail. The internal stress in this system was generated at the vitrification point in the course of curing, because the modulus of samples was rapidly increased at this point. After the vitrification point, the internal stress was increased with an increase of the shrinkage in the curing and cooling processes.Moreover, the magnitude of the internal stress in the four‐functional resin systems depended on the chemical structure of aromatic diamines used as curing agents. This was explained by the difference of curing shrinkage after vitrification in each sys

ISSN:0021-8995    

DOI:10.1002/app.1991.070431108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractMembranes obtained from polymers, quaternized poly[3‐(N′,N′‐dimethyl) aminopropylacrylamide‐co‐acrylonitrile]s, showed selective separation of water from aqueous ethanol solution by pervaporation. The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. Differential scanning calorimetric melting endotherms of the water‐swollen membranes were studied to clarify the state of water in the membranes. The results suggested that there are two states of water in the membrane: bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was wa

ISSN:0021-8995    

DOI:10.1002/app.1991.070431109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe Iosipescu shear test method, adapted for adhesives, was used to evaluate shear stress–strain properties of five epoxy‐based film adhesives. The shear strength of some adhesives, determined by this technique, was found to differ greatly from that determined by either lap shear and/or thick adherend tests. Accurate measurements of the adhesive bond‐line deformation enabled evaluation of the adhesive elastic and plastic properties as well as the calculation of shear modulus. A high‐speed video camera was employed to augment observation on the joint defo

ISSN:0021-8995    

DOI:10.1002/app.1991.070431110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY