摘要:

AbstractPreviously it was proposed that the solvent power of a pure or mixed organic liquid for a given polymer can be characterized by two parameters δhand χH. Using these two parameters, a two‐dimensional (2D) solubility diagram can be constructed to predict solubility or insolubility. In the investigation only the polymers, poly(methyl methacrylate), polystyrene, and poly(vinyl acetate), were used to demonstrate the applicability of the 2D method. In this note, applicability of the 2D method to the 33 polymers investigated in Hansen's works is presen

ISSN:0021-8995    

DOI:10.1002/app.1979.070230201

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

年代:1979

数据来源: WILEY

摘要:

AbstractA mixture of two organic liquids, each of which is a solvent for a given polymer, may become a nonsolvent mixture, if there is strong acid‐base interaction between the two solvents. Experimental results of such cases are presented for five polymers. These results are then correlated with the proposed modified form of the two‐dimensional approach. In the modification, an additional term for taking into account the acid‐base interaction is added to the expression for the hydrogen‐bonding solubility parameter of the liquid mixture; the dispersion forces and polar interactions are assumed to be undisturbed by the occurrence of the acid‐base in

ISSN:0021-8995    

DOI:10.1002/app.1979.070230202

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

年代:1979

数据来源: WILEY

摘要:

AbstractA high load‐bearing shock‐mitigating phenolic foam was developed to meet specific compression‐deflection and gas permeability requirements. It was required that the foam display an almost constant compressive stress within the limits of 50–68 psi at strains ranging from 10% to 60%. Furthermore, the foam had to possess a highly open‐celled structure so that its resistance to gas flow would be minimal. These properties were obtained from a chemical formulation utilizing a combination of two phenolic resins, a phosphoric‐sulfuric acid catalyst system, a surfactant combination that included both a hydrophilic and a lipophilic surfactant, and a fluorocarbon bl

ISSN:0021-8995    

DOI:10.1002/app.1979.070230203

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe effects of reaction rate and density on the properties of the phenolic foam described in the first paper were studied. Process and formulation variables were examined through altering the basic chemical composition described below, in which all parts are by weight; phenolic resin two component intermediate, 200 parts; hydrophilic surfactant, 0.25 parts; lipophilic surfactant, 0.50 parts; fluorocarbon blowing agent, 12 parts; 47.5 wt % sulfuric acid, 25 parts; and 80 wt % phosphoric acid, 15 parts. Compressive stress values at 20% deflection were utilized for comparing the effects of the studied parameters on the load bearing cabability of the foam. Pressure drop of air flowing through the foam was employed as a measure of the permeability or breathability. Permeability load bearing functions were identified as a potential means for optimizing the relationship between breathability and compression‐deflection characteristics. The overall effects of cell structure on the relationship between load bearing and density have been related in a qualitative manne

ISSN:0021-8995    

DOI:10.1002/app.1979.070230204

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe effects of variations in the chemical composition and processing conditions of the series of phenolic foams described in the two previous papers were studied. Compressive stiffness and density increased with increasing concentrations of the acid catalysts, the slower reacting phenolic resin component, water, the lipophilic component of the surfactant system, and age of the phenolic resins. These properties decreased with increasing concentration of the fluorocarbon blowing agent and process temperature. The compressive stiffness and density increased to a maximum and then decreased with increasing concentrations of the hydrophilic surfactant. Permeability or “breathability” of the foam decreased with the hydrophilic surfactant at low concentrations and then became essentially independent of further increases of this component. Increasing concentrations of the lipophilic surfactant gave foam having greater breathability. In all other cases the permeability of the foam decreased as its density increased. Effects of the variations in processing and composition on the dependency of load bearing upon density, on relationships between permeability and density and permeability and compressive stiffness, and upon cell structures are also descri

ISSN:0021-8995    

DOI:10.1002/app.1979.070230205

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

年代:1979

数据来源: WILEY

摘要:

AbstractA series of prepolymers containing terminal blocked isocyanate groups was prepared by reaction of isocyanate‐terminated prepolymers [derived from a poly(propylene oxide) diol (MW = 2000) or a triol (MW = 3000) and different diisocyanates] with various blocking agents. Their curing rates with a polyepoxide crosslinking agent were measured to assess their suitability for a delayed‐cure durable‐press treatment for wool. The curing rates varied over a wide range, but commonly used blocking groups such as phenols, caprolactam, β‐diketones, and alcohols were not sufficiently reactive for the intended application, although others, e.g., oximes and certain blocking agents containing a basic center such as N,N‐diethylhydroxylamine, hydroxypyridines, and hydroxyquinolines, had the required reactivity. Blocking by 1,3‐dipolar cycloaddition of nitrones was examined, but the reactivities were too low. Prepolymers containing blocked aromatic isocyanates were more reactive than those containing blocked aliphatic isocyanates. Difunctional butanone oxime‐blocked pre‐polymers cured slightly more slowly than analogous trifuncti

ISSN:0021-8995    

DOI:10.1002/app.1979.070230206

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

年代:1979

数据来源: WILEY

摘要:

AbstractSpectroscopic studies of weathered flame retardant cotton fabrics were conducted. The weathering conditions included combined and independent exposure to xenon arc light and low concentrations of SO2, NO2, and O3gases. Multiple internal reflectance infrared analysis of weathered Pyrovatex 3805‐treated fabric showed that the finish removed after 150 hr of weathering exposure had the same structure as the original finish. Interferometer spectra of Pyrovatex 3805 and THPOH‐NH3finishes on the fabric indicated no significant changes in the structure for both finishes after exposure to the various weathering conditi

ISSN:0021-8995    

DOI:10.1002/app.1979.070230207

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

年代:1979

数据来源: WILEY

摘要:

AbstractFormation of open‐pore urea/formaldehyde structures from nonetherified urea/formaldehyde resins involves reaction of one or more methylol groups with other methylol or amino groups. The structure formation proceeds through particle formation and growth until all the resin is consumed. A strong acid is preferred for achieving a porous structure in urea/formaldehyde resins; weakly ionized acids produce structures with low yield. Colloidal instability is an asset in porous structure formation. An 80:20 polyethylene oxide/polypropylene oxide block copolymer of approximate molecular weight 8500 has been found to be an entropic‐type destabilizer in the formation of porous structu

ISSN:0021-8995    

DOI:10.1002/app.1979.070230208

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe water vapor sorption‐desorption isotherms of graft copolymers of methyl methacrylate with natural and chemically modified wool (i.e., oxidized, reduced, methylated, and crosslinked) has been investigated. As a result of graft copolymerization a reduction in water absorption was observed. The results have also been analysed in the light of Hailwood–Horrobin equati

ISSN:0021-8995    

DOI:10.1002/app.1979.070230209

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

年代:1979

数据来源: WILEY

摘要:

AbstractA theoretical investigation of the emulsion polymerization of vinyl acetate in a continuous stirred tank reactor operating under conditions of sustained oscillations is reported here. Models of two levels of sophistication are developed: a comprehensive model that solves for the age distribution function of polymer particles and a simplified model that assumes discrete nucleation periods. The latter model should find use in adaptive control of latex reactors. These models adequately simulate experimental data after Greene et al.2for the emulsion polymerization of vinyl acetate under conditions of sustained oscillations.

ISSN:0021-8995    

DOI:10.1002/app.1979.070230210

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

年代:1979

数据来源: WILEY