摘要:

AbstractSolvent barrier studies for fluorinated polyethylene have shown that the fluorinated surfaces reduce the rate of permeation for many solvents. The barrier property has been related to physical and chemical properties of the solvent. For instance, solvents having a dielectric constant between 7 and 10 were not retained as well as solvents with a dielectric constant less than 7.

ISSN:0021-8995    

DOI:10.1002/app.1979.070230701

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

年代:1979

数据来源: WILEY

摘要:

AbstractThis paper reports the results of an investigation of pyropolycarboranes, nondeformable thermally stable cross‐linked polymeric materials obtained by pyrolysis of carborane‐containing polymers. Carborane‐containing polyamides and polyesters were heated in air under pressure and analyzed by thermomechanical and thermogravimetric methods. Moreover, the friction properties of the filled materials have been investigated. The effect of hydrogen liberation on the friction of filled pyropolycarboranes at elevated temperatures was used in developing self‐lubricating materials with friction coefficients at 30

ISSN:0021-8995    

DOI:10.1002/app.1979.070230702

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

年代:1979

数据来源: WILEY

摘要:

AbstractPolymerization of MMA was done in aqueous media and in a bulk (nonaqueous) system employing a H2O2‐TU redox initiator system. Kinetic features differ significantly depending on the nature of the reaction media. The redox system is much more efficient as a chain initiator in aqueous media than in bulk MMA, where conversion to polymer, thermally and even under photoactivated conditions, is very slow and sluggish. In the bulk media, pronounced inhibition and retardation effects appear to be due to formation of unstable reaction intermediate presumably through dimerization of Ṡ(:NH)·NH2radical generated in the primary redox reac

ISSN:0021-8995    

DOI:10.1002/app.1979.070230703

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe antiplasticizing effect of ester derivatives of bisphenol A: 1,1‐bis(4‐hydroxyphenyl)‐2,2‐propane diacetate (DAPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane diacetate (DACPP), 1,1‐bis(4‐hydroxy‐3,5‐dibromophenyl)‐2,2‐propane diacetate (DABPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane dibenzoate (DBCPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane di‐2,4‐dichlorobenzoate (DCBCPP) on polycarbonate was investigated. Obtained results indicate that antiplasticizing abilities of these compounds depend on the number of polar groups in the molecule, as well as on the possibility of tight filling the fre

ISSN:0021-8995    

DOI:10.1002/app.1979.070230704

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

年代:1979

数据来源: WILEY

摘要:

AbstractCellulose‐polyacrylonitrile (PAN) blends have been prepared by the regeneration of 2% concentration solutions in dimethylformamide–NO2solvent. The blends are transparent when containing between 0 and 50% by weight of PAN. Dynamic mechanical measurements indicate a shift in glass transition temperatureTgof PAN for the blends, suggesting partial miscibility between cellulose and PAN. Experimental density values larger than those predicted theoretically are also in agreement with this conclus

ISSN:0021-8995    

DOI:10.1002/app.1979.070230705

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe hydroxyl group content in 1‐chlorobutadiene–butadiene rubber prepared by emulsion polymerization (CB–BR) was determined by UV spectroscopy. CB–BR was allowed to react with phenyl isocyanate at room temperature, and the resulting N‐phenyl carbamate was assayed by UV measurement. The present method allowed the determination of a very small amount of hydroxyl groups contained in a high molecular weight hydrocarbon polymer. The hydroxyl group content in the hydroxyl‐terminated liquid polybutadiene was also determined. The value agreed closely with that obtained by the usual titration method. Hydroxyl groups in CB–BR are presumed to be produced by the hydrolysis of the active chlorine contained in CB–BR. This hydrolysis is dependent on the work‐up conditions of CB–BR, and the quantitative results were discussed with reference to the microstructure of the 1‐chlorobu

ISSN:0021-8995    

DOI:10.1002/app.1979.070230706

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe hydroxyl group content in 1‐chlorobutadiene–butadiene rubber (CB–BR) was increased by the following two methods: (1) heating of the CB–BR latex to hydrolyze the unstable chlorine in CB–BR and (2) introduction of hydroxyl by the Menschutkin‐type reaction between 2‐dimethylaminoethanol (DMAE) and the chlorine in CB–BR. By heating the latex at 70°C for 12 hr, 55% chlorine was hydrolyzed to result in a marked increase in hydroxyl group content in CB–BR, i.e., at least 55% chlorine is situated in the CB units of the 1,4‐configuration. Heat‐treated CB–BR was found to contain a small amount of conjugated triene structure by UV spectroscopy, which indicates that elimination of some unstable chlorine as hydrogen chloride occurs during latex heating. By reaction with DMAE, 44% chlorine was converted into hydroxyl in toluene at 27°C. CB–BR compounded with DMAE does not suffer from gelation by milling on an open roll. Thus, by these methods, high molecular weight butadiene rubber having various concentrations of

ISSN:0021-8995    

DOI:10.1002/app.1979.070230707

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

年代:1979

数据来源: WILEY

摘要:

AbstractComparisons were made of differential scanning‐calorimetric (DSC) thermograms of both liquid and powdered commercial phenol–formaldehyde resins. By a combination of the results from analyses under a variety of conditions, such as ambient pressure, high pressure, using freeze‐dried samples, and also by direct observation of the resin‐curing process in wood‐veneer assemblies, the curing reactions of phenol–formaldehyde resins were found to differ for resol and novolac systems. At a heating rate of 10°C/min, the resol resin showed endothermic curing reactions at temperatures of about 150°C, while the novolac‐type resin showed an exothermic peak maximum at about 160°C. Results are presented to show how DSC can be used to differentiate between a resol an

ISSN:0021-8995    

DOI:10.1002/app.1979.070230708

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

年代:1979

数据来源: WILEY

摘要:

AbstractA group of natural materials having anhydroglucose units linked by glycosidic bonds, as well as other related compounds, were irradiated with plasmas generated by a radio frequency field (13.56 MHz). Reactive sites created were characterized by electron spin resonance, chemiluminescence, infrared, and x‐ray photoelectron spectroscopy. The free radicals are related to the number of glycosidic bonds, and their decays result in chemiluminescence. In the absence of moisture and oxygen, however, the radicals are stable. During plasma irradiation, carbonyl groups as well as free radicals are formed on surfaces, and the atom ratio of oxygen to carbon on surfaces increases. Within the reactor, thin films of polymers can be deposited on cotton fabrics by allowing the monomer to enter the reactor above the fabric that is in a horizontal position downstream from the external electrode

ISSN:0021-8995    

DOI:10.1002/app.1979.070230709

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

年代:1979

数据来源: WILEY

摘要:

AbstractSamples of poly(vinylchloride) containing polyene sequences were made by partial dehydrochlorination by alkali in tetrahydrofuran solution, by alkali in dioxane, and thermally in dimethyl‐formamide. The reactions of polyene PVC were followed by UV spectrophotometry. Dienophiles were found to have relative reactivities similar to those found in reactions with low molecular‐weight dienes. The reaction with maleic anhydride yielded polymers which after hydrolysis contained carboxyl groups. Hydroxylation was made with osmium tetraoxide and performic acid. With the latter reagent the reaction proceeded to complete disappearance of the UV‐absorption peaks from trienes and higher polyenes: Gel permeation chromatography analysis showed that hydroxylation could be made with only minor changes in molecular‐weight distribution. The formation of gel upon thermal dehydrochlorination in DMF was shown to be due to physical cross linking probably arising by crystallization of polyene segments. The adhesion of the hydroxylated and carboxylated polymers to glass and stainless‐steel surfaces was investigated. Films adhered stronger as the degree of dehydrochlorination of the polyene PVC used to make the derivative increased. Samples with long sequences adhered much stronger than those containing short sequences of corresponding degrees of total sub

ISSN:0021-8995    

DOI:10.1002/app.1979.070230710

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

年代:1979

数据来源: WILEY