摘要:

AbstractThermal antioxidants were incorporated into polyethylene as solutions in the silane coupling agent N‐β‐(aminoethyl)‐γ‐aminopropyltrimethoxysilane. Substantial improvements in retained concentration and induction time were observed for commercial phenolic and amine‐type antioxidants on prolonged oven aging in thin polyethylene films. As an alternative to solution formation, a stabilizer was bonded directly to silicon as the organic functional group in a silane coupling agent, resulting in improved dispersion and induction time. Improvements in antioxidant retention and induction time appear to correlate with compatibility of the silane–polyet

ISSN:0021-8995    

DOI:10.1002/app.1974.070180301

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

年代:1974

数据来源: WILEY

摘要:

AbstractGrafting of chain‐growth polymerizable monomers onto cellulose has been a thoroughly investigated area. Introduction of polymerizable monomeric species chemically bound to cellulose has been less fruitful. Crotonate esters, methacrylate esters, and allyl and vinyl derivatives are examples where subsequent polymerization to crosslinked species has been described. Reported are the reactions of vinylbenzyl chloride with causticized cotton fabric to give a series of vinylbenzylated celluloses with degrees of substitution from 0.05 to 0.26. Homopolymerization of these or copolymerization with maleic anhydride or dimethyl maleate gave little or no crosslinking under the conditions employed. Vinylbenzyl cellulose acetate proved to be a polymerizable “prepolymer” with diethyl ma

ISSN:0021-8995    

DOI:10.1002/app.1974.070180302

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

年代:1974

数据来源: WILEY

摘要:

AbstractBased on the known composition equation of copolycondensation product, an equation was derived to describe the kinetics of the copolycondensation process. On the basis of the equation derived, a theoretical curve describing the course of the process was found. A satisfying agreement between the theoretical and experimental curves was observed.

ISSN:0021-8995    

DOI:10.1002/app.1974.070180303

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

年代:1974

数据来源: WILEY

摘要:

AbstractAssuming the applicability of the Arrhenius equation to the polycondensation processes, two‐by‐two homopolycondensation processes proceeding with one of the monomers—the same in both cases—were examined. It was considered whether there is a temperature at which the reactivity of the two different monomers becomes the same. The isokinetic temperatures for four different systems were determined experimentally, and it was found that they are within an accessible experimenta

ISSN:0021-8995    

DOI:10.1002/app.1974.070180304

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe binding of mercuric chloride and other metal salts to bark, activated sludge (Milorganite), chitosan, poly(p‐aminostyrene), and other natural and synthetic materials was investigated by specific atomic absorption and x‐ray fluorescence spectroscopy. The synthetic poly(aminostyrene) was included for comparison with the natural polyamine chitosan. Our results show that a wide range of natural materials are potentially useful for the removal of toxic and precious metals that may be present in industrial effluents, mine waters, or other water supply. Such metal salts include those of mercury, lead, zinc, cadmium, copper, nickel, cobalt, iron, manganese, silver, platinum, palladium, and g

ISSN:0021-8995    

DOI:10.1002/app.1974.070180305

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

年代:1974

数据来源: WILEY

摘要:

AbstractTwo‐component interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) were prepared from two different polyurethanes (a polyester type and a polyether type) and a polyacrylate of two different crosslink densities. The linear polymers and prepolymers were combined in solution, together with crosslinking agents and catalysts, films cast, and subsequently chain extended and crosslinked in situ. In all cases, maxima in tensile strengths significantly higher than the tensile strengths of component networks occurred. This was explained by an increase in crosslink density due to interpenetratio

ISSN:0021-8995    

DOI:10.1002/app.1974.070180306

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

年代:1974

数据来源: WILEY

摘要:

AbstractTwo‐component interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) were prepared from three different polyurethanes and two epoxies. The linear prepolymers were combined in solution, together with crosslinking agents and catalysts, films cast, and subsequently chain extended and crosslinked in situ. Two of the IPN's showed significant improvement in thermal resistance, as measured by thermogravimetric analysis (TGA). All of the IPN's showed maxima in tensile strength significantly higher than the tensile strengths of the component networks at 25% polyurethane and minima at 75% polyurethane. The minima were explained by an initial dilution of the strong polyurethane hydrogen bonds by the epoxies, and the maxima, by an increase in crosslink density due to interpenetratio

ISSN:0021-8995    

DOI:10.1002/app.1974.070180307

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe diffusion coefficient of a solvating liquid or vapor in a semicrystalline membrane can be measured in a number of ways. In a previous paper, we discussed methods based on permeation rates. Here, we consider sorption–desorption kinetics at near‐ambient temperatures. Anomalies are identified and possible causes discussed in the light of new experiments, mostly involvingp‐xylene and polyeth

ISSN:0021-8995    

DOI:10.1002/app.1974.070180308

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe radiation‐induced polymerization of methyl methacrylate was investigated with radiation sources of cobalt 60 and accelerated electrons at dose rates up to 3 Mrads/sec. Extrapolation of previous rates of polymerization at dose rates of 0.01–200 rads/sec coincided with the present results, the rates being approximately proportional to the square root of the dose rate throughout the entire set of dose rates measured. The molecular weights seemed to be independent of dose rate at the highest dose rates investigated. A combination of high polymer with a much higher molecular weight than expected was formed, together with a substantial portion of low molecular weight polymer. The reason for this behavior is not clear at this time. TheG(M·) calculated from the molecular weights and fraction of polymer and resin was 6.0, which approaches that reported in previous investigations at low dose rates. There was no significant effect of air on the polymerization kinetics of methyl methacrylate at above 1 Mrad/sec. Nitrogen also did not influence the measured rates. Conversions to polymer were not substantially reduced by the presence of inhibitor at above 1.26 × 105rads/sec. Water did not influence the rates of polymerization, except at the highest temperature (50°C) investigated. A large posteffect was observed in sealed degassed ampoules after 25% conversion to polymer. Only 3.4% additional polymer was formed in 24 hr after irradiation in the presence of air. The activation energy for the electron beam polymerization of methyl methacrylate was about 7.0 kcal/mole. This value, considering the complications in technique such as beam heating, did not differ from literature data enough to suggest any mechanistic difference in the polymerization at high dose

ISSN:0021-8995    

DOI:10.1002/app.1974.070180309

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

年代:1974

数据来源: WILEY

摘要:

AbstractPermeability coefficients have been measured for normal butane, isobutane, isobutylene, and butene‐1 in Zendel Copolymer‐I at temperatures between 30° and 70°C and at penetrant pressuresp1up to 5.5 atm. The permeability coefficients of these organic vapors show behavior analogous to that observed for C3and C2hydrocarbons as detailed in our earlier work; i.e., near the condensation point of the penetrant,Pincreases as the temperature is decreased. Isothermal plots of logPversusp1in that region are generally linear and can be represented by empirical relations of the form\documentclass{article}\pagestyle{empty}\begin{document}$$ P = P_0 \exp \left( {ap_1 } \right) $$\end{document}whereP0is a constant. The slope a is a function of temperature:\documentclass{article}\pagestyle{empty}\begin{document}$$ a = a_0 \exp \left( {bt} \right) $$\end{document}wherea0is a constant andbhas the same value for the four hydrocarbons investi

ISSN:0021-8995    

DOI:10.1002/app.1974.070180310

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

年代:1974

数据来源: WILEY