摘要:

AbstractThe pyrolysis of nylon 6 has been shown to proceed by a first‐order process to yield ε‐caprolactam as the primary product. This degradation has an energy of activation of approximately 46 kcal/mole which would seem to indicate the involvement of a homolytic process. Inclusion of organobromine compounds such as hexabromobiphenyl and dodecabromopentacyclo [5·3·0·02,6·03,9·04,8]decane catalyzed the pyrolysis but did not significantly alter the nature of the degradation products. Because of this, simple organobromine compounds are not good candidates for utilization as flame retardants fo

ISSN:0021-8995    

DOI:10.1002/app.1974.070180701

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

年代:1974

数据来源: WILEY

摘要:

AbstractTri‐n‐butylstannyl fluoride exhibited 75% drag reduction in a capillary rheometer at 25,000 Reynolds number in hexane at 0.1% concentration. There was no loss of drag reduction from shear degradation after 300 cycles at 17,000 Reynolds number. Tri‐n‐butylstannyl chloride showed no drag reduction under these same conditions. Polyisobutylene, similarly examined, gave 72% and 69% drag reduction at 0.01 and 0.1% concentrations, respectively; but after 300 cycles at 17,000 Reynolds number, the drag reduction fell to 45% for the 0.1% solution and to 40% after only 100 cycles for the 0.01% solution. The effectiveness of tri‐n‐butylstannyl fluoride is explained by the formation of a linear polymer SnF‐ ‐ ‐Sn—F‐ ‐ ‐ in which pentacoordinate tin is linked through fluorine bridges. The relative viscosity of tri‐n‐butylstannyl fluoride in hexane increased more rapidly with increased concentration and decreased more rapidly with increased temperature than similar solutions of polyisobutylene. This result is probably due to a shift in the average molecular weight

ISSN:0021-8995    

DOI:10.1002/app.1974.070180702

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

年代:1974

数据来源: WILEY

摘要:

AbstractGel permeation chromatography of polyoxymethylene has been studied using N,N‐dimethylformamide as the solvent. Polyoxymethylene samples used here are a copolymer of tetraoxane with 1,3‐dioxolane and a commercial polyoxymethylene whose molecular weight distributions are moderately broad. Their intrinsic viscosities [η] range from 1.4 to 2.8 dl/g. Factors affecting chromatograms are discussed, and the operating conditions were determined by using the analytical scale GPC. On the basis of these operating conditions, the molecular weight fractionation of polyoxymethylene was carried out by using the preparative scale GPC. It was found that polyoxymethylene can be effectively fractionated to give seven to ten fractions each of them containing the fractionated polymer ranging in weight from 0.2 to 8 mg when 40 mg polymer sample was used for a run of the measurement. The fractionated polymers were also found to have a narrow molecular weight distribution within a single peak, and theirMw/Mnvalues decrease with increasing molecular we

ISSN:0021-8995    

DOI:10.1002/app.1974.070180703

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

年代:1974

数据来源: WILEY

摘要:

AbstractIn studying macromolecular properties of lignins, gel permeation chromatography (GPC) is a convenient method for the determination of lignin molecular weights and their distribution. A GPC analytical column was calibrated by preparing narrow molecular weight lignin fractions, then applying the method of Goring and co‐workers to obtain molecular weights from the ultracentrifuge at zero concentration and zero field force. Diffusion and other curve‐broadening effects in the GPC analytical column were taken into account by applying the correction method of Hamielec and co‐workers to derive the coefficients of the calibration curve. The molecular weight of a lignosulfonate sample determined on the GPC was found to coincide closely with that obtained by ultracentrifug

ISSN:0021-8995    

DOI:10.1002/app.1974.070180704

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

年代:1974

数据来源: WILEY

摘要:

AbstractOn complete hydrazinolysis of poly(ethylene terephthalate), terephthalomonohydrazide is formed from carboxyl‐end terephthaloyl residues in a quantity equivalent to the content of carboxyl endgroups in the polymer. The compound is separated from the reaction mixture by ion exchange and determined photometrically [epsiv;240in 0.1NHCl = 16,700 (1000 cm2/mole)]. A COOH determination carried out in this way is endgroup specific and, unlike titration, is not subject to interference by ionogenic fiber additives. Aromatic comonomers with acidic substituents (e.g., 5‐sulfoisophthalic acid) in chemically modified, cationically dyeable poly(ethylene terephthalate) are determined simultaneously with the carboxyl endgroups by the same analytical method. In this case, the terephthalamonohydrazide and 5‐sulfoisophthalodihydrazide are separated by ion exchange, and the difference in their spectral behavior is used for quantitative determination with the aid of a two‐component analysis:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} c_1 {\rm = (6}{\rm .21 }D_{240} {\rm - 1}{\rm .04 }D_{212} ){\rm } \times {\rm 10}^{{\rm - 5}} {\rm mole/l}{\rm .} \\ c_2 {\rm = (2}{\rm .62 }D_{212} {\rm - 0}{\rm .51 }D_{240} ){\rm } \times {\rm 10}^{{\rm - 5}} {\rm mole/l} \\ \end{array} $$\end{document}wherec1c2= concentration of terephthalomonohydrazide and 5‐sulfoisophthalodihydrazide, respectively; and D240D212= optical density at 240 and 212 nm, respectively. The content of carboxyl endgroups in polyether esters poly(p‐(2‐ethyleneoxy)‐benzoate), is determined on the basis of thep‐(β‐hydroxyethoxy)benzoic acid [epsiv;258in 0.1NHCl = 16,100 (1000 cm2/mole)] liberated from carboxyl‐end monomer units by hydrazinolysis. For copolyether esters withp‐(β‐hydroxyethoxy)benzoic acid as a comonomer, the contents of carboxyl‐end terephthalic acid and p‐(β‐hydroxyethoxy)benzoic acid are determined simultaneously with the acid of a spectrophotometric twocomponent analysis:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} c_1 {\rm = (7}{\rm .65 }D_{240} {\rm - 3}{\rm .27 }D_{258} ){\rm } \times {\rm 10}^{{\rm - 5}} {\rm mole/l}{\rm .} \\ c_2 {\rm = (7}{\rm .91 }D_{258} {\rm - 3}{\rm .49 }D_{240} ){\rm } \times {\rm 10}^{{\rm - 5}} {\rm mole/l.} \\ \end{array} $$\end{document}wherec2,c2= concentration of terephthalomonohydrazide and p‐(β‐hydroxyethoxy)‐benzoic acid, respectively; and D240, D258= optica

ISSN:0021-8995    

DOI:10.1002/app.1974.070180705

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

年代:1974

数据来源: WILEY

摘要:

AbstractSoluble chloromethylated polystyrene and its copolymers with vinylidene chloride as well as poly(phenyl oxides) brominated in the side chains and in the ring were synthesized and characterized in detail by NMR. The halogenated polymers were phosphonylated with alkyl phosphites. Uncrosslinked polymers with pendent phosphonate groups were prepared in the presence of etheral solvents, which solvate the ionic intermediates of the Arbuzov reaction. These polyphosphonates are highly hygroscopic and are soluble in a variety of solvents. TheirTg's are in the range of 50–175°C. Their thermal behavior was analyzed on the basis of thermogravimetric measurements combined with mass‐spectrometric analysis. Poly(styrene phosphonate) seems to be the most stable, and its thermal decomposition starts at ∼330°C. The polymeric phosphonates are compatible with an unusually large number of polymeric systems and seem to form “true” polymeric alloys with acet

ISSN:0021-8995    

DOI:10.1002/app.1974.070180706

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

年代:1974

数据来源: WILEY

摘要:

AbstractBlends of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared by mixing the polymers in the melt and in the absence of a solvent. PMMA was the major constituent of the blend. Traces of gel permeation chromatograms showed that the starting materials retain their polymeric character after Brabender processing. Data obtained from notched Izod impact strength tests at 23°C showed that blends may exhibit values ranging from about 0.3 to 0.9 ft‐lb/in. notch. Differences in mix conditions afford blends which, from a phenomenologic viewpoint, consist of a mixture of two glassy polymers or of a rubbery polymer dispersed in a glassy matrix. Micrographs of a crack pattern in companion blends consisting of PMMA/PVAc 85/15 are consistent with impact strength test resul

ISSN:0021-8995    

DOI:10.1002/app.1974.070180707

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

年代:1974

数据来源: WILEY

摘要:

AbstractBlends of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared by mixing the polymers in the melt and in the absence of a solvent. PMMA was the major constituent of the blend. The polymer blends were tested, using various methods, to determine if they are compatible as solids. Data obtained from dynamic mechanical and DSC measurements show that, when they are mixed under given Brabender mix conditions, the blends exhibit properties characteristic of polymer pairs compatible as solids. If the mix conditions are altered, a two‐phase system is evidenced. Using micrographs obtained by light microscopy in phase contrast as criteria, two companion blends containing PMMA/PVAc 80/20 would be classified as incompatible as solids because of the differences in refractive index of PMMA and PVAc. The micrographs also show that, in the system that would otherwise be listed as compatible, the PVAc domains appear to be relatively uniform in size and distribution through the PMMA matrix. In its companion blend, large, irregularly shaped particles of PVAc which are poorly dispersed in the PMMA matrix are eviden

ISSN:0021-8995    

DOI:10.1002/app.1974.070180708

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe photosensitivities and the rates of photocrosslinking of poly(vinyl α‐cyanocinamate) and poly(vinyl α‐cyanocinnamoxyacetate) were investigated. The photocrosslinkings of these polymers proceeded mainly through radical addition, and these polymers showed higher photosensitivities than poly(vinyl cinnamate) and poly(vinyl cinnamoxyacetate), in spite of lower rates of photocrosslinking of the former pol

ISSN:0021-8995    

DOI:10.1002/app.1974.070180709

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

年代:1974

数据来源: WILEY

摘要:

AbstractBismaleimides polymerize at elevated temperatures, forming highly crosslinked, high temperature‐resistant polymers. From the decrease of the ν(HC) band at 3100 cm−1, rate constants and activation energies of the polymerization of four homologous aliphatic bismaleimides were determined. Up to a 20–30% conversion, the polymerization is pseudofirst order. An almost linear correlation between the activation energy and the number of methylene groups in the sequence between the maleimide residues

ISSN:0021-8995    

DOI:10.1002/app.1974.070180710

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

年代:1974

数据来源: WILEY