摘要:

AbstractThe polymerization of styrene in bulk at pressures up to 273 MPa and temperatures between 3 and 49°C with the use of γ‐radiation as the initiator has been studied. The polymerization rate and the molecular weight of the polymer increased with increasing pressure; the molecular weight increased at a slightly faster rate. The difference in the rate is a theoretical expectation which has not previously been observed because chain‐transfer reactions obscure the effect in chemically initiated systems. A small but significant retardation of the initiation reaction occurs as the pressure is increased. The results of previous workers are critically reviewed. Chain transfer at 25°C for pressures below 220 MPa is negligible when γ‐radiation is the initiator. The activation energy for bulk polymerization decreased with increasing pressure from 28.1 kJ/mole at 0.1013 MPa to 22.3 kJ/mole at 203 MPa. Volumes of activation at 25°C for 0.1013

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150601

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

Abstract2‐Sulfoterephthalic acid (STA) and disulfoisophthalic acid (DSIA) were synthesized through the sulfonation and the oxidation ofm‐ andp‐xylene. The polycondensation reactions of STA and DSIA with aromatic tetraamines gave polybenzimidazoles which contained one or two sulfonic acid groups for each repeating unit. The polymer obtained was soluble in sulfuric acid, some organic solvents, and aqueous strong alkaline solution. The polymers were stable up to 400°C, but they gave polybenzimidazoles above 400°C by eliminating sulfonic acid groups, instead of ring

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150602

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe fixation of histamine [2‐(4‐imidazolyl)ethylamine] along or at the end of the chain of a low molecular weight 1,4‐polyisoprene prepared by an anionic process has been studied, and the structure of the resulting polymers determined in comparison with those of organic model molecules similarly obt

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150603

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe hydrodynamic volume changes of the polyester‐based polyurethanes, as dimethylformamide solutions with and without lithium bromide, were studied. Gel‐permeation chromatographic (GPC) and intrinsic viscosity techniques were employed as methods for characterization. Decreases in intrinsic viscosity as well as dramatic changes in the GPC chromatograms were observed. These observations are explained by the polarity of these polyester‐based polyurethane molecules and the resulting characteristics of molecular expansion, association, and polymer–column interaction normally associated with polyelect

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150604

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractCrosslinked poly(styrenesulfonic acid) beads in contact with AlCl3vapors at 115°C reacted to give HCl and a complex incorporating S, Al, and Cl in the ratio 2:1:2. Electron microprobe x‐ray analysis showed that the complexes were distributed uniformly throughout the polymer structure, which consisted of 200 Å microspheres surrounded by a labyrinth of pores. The polymer is a very strong proton donor, comparable to the superacid solution SbF5+ FSO3H. Its structural and acidic properties are inferred to be similar to those of the complex formed from AlCl3and H2

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150605

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractPhenylphosphonyl‐N,N′‐biscaprolactam (I) and phenylphosphonyl‐N,N′‐bis(3,5‐dimethylpyrazole) (II) were synthesized and found to be very efficient activators for the anionic polymerization of caprolactam when used in combination with strong bases such as sodium caprolactam. Polymers obtained in the presence of I and II had generally higher molecular weights and were less sensitive to thermal degradation upon molding than those whose preparation entailed the use ofN‐acetyl‐caprolactam (III) as an activator. Thermal behavior and tensile properties indicated that the structure of these polyamides differs from that encountered in nylon 6 prepared with conventional anionic

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150606

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractAn ESR method was used to investigate the formation of free radicals during rubber mastication and filling of rubber with various carbon blacks. The ESR spectra of natural rubber and styrenebutadiene rubber with various carbon blacks are of a complex character. A narrow component line is superimposed on the much broader signal line of carbon black. The changes in this narrow spectral line with plasticization time and with carbon black content in the rubber–filler system result from interactions between the rubber macromolecules and filler particle

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150607

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractPolymers containing theN‐(4‐hydroxy‐3‐nitrophenyl)succinimide residue were designed in order to achieve acyl activation of a reacting carboxylic acid in the solid phase. These polymers were prepared through the following three routes: (a) styrene was allowed to copolymerize withN‐(4‐hydroxy‐3‐nitrophenyl)‐ orN‐(4‐acetoxy‐3‐nitrophenyl)maleimide, (b) styrene was copolymerized withN‐(4‐acetoxyphenyl)maleimide in the presence of divinylbenzene (DVB), and the copolymer obtained was hydrolyzed and nitrated, (c) a copolymer of maleic anhydride and styrene was reacted withp‐aminophenol, followed by nitration. The polymers prepared by routes b and c were converted to the activated polymer esters ofN‐blocked amino acids and peptides by using dicyclohexylcarbodiimide (DCC). The acylated polymers thus obtained were treated with amino acid esters and found to give peptides qu

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150608

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThree14C‐labeled benzoin methyl ether (α‐methoxy‐α‐phenylacetophenone) derivatives were utilized as photoinitiators in the polymerization of methyl methacrylate (MMA) and methyl acrylate (MA). The results of polymer end‐group analysis are in accord with a mechanism of benzoin ether photocleavage into initiator radicals and dispute earlier labeling studies which were interpreted as evidence for copolymerization of excited‐state benzoin ethers with reactive monomers. In MMA polymerization, the results indicate a preference for termination by disproportionation (∼60%) and provide evidence for primary radical termination at 0.041Mphotoinitiator (optically dense solutions) in neat MMA. Evidence for chain branching by initiator radical hydrogen abstraction from poly(methyl acrylate) (PMA) is also presented. The benzoyl and α‐methoxybenzyl radicals, produced on photolysis of benzoin methyl ether, appear to be equally effective in both initiation and hydrogen‐abstraction processes. Quantum yields at 366 and 313 nm indicate the absence of

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150609

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of normal alkanes and linear poly(α‐olefins) was found to occur predominately by random scissions, followed by volatilization into an open system. To show these processes the fragment distribution from high molecular weight linear polyethylene (fragments to C55),n‐alkanes, polypropylene, and polyisobutylene (fragments to C60) are reported and discussed in depth. Based on the results, a mechanism of random scissions followed by volatilization is postulated for polyethylene andn‐alkanes as well as for polyisobutylene and polypropylene. Polystyrene is shown not to follow the same mechanism, for little evidence for fragments above trimers was found. In addition, temperature rise–time measurements at the pyrolyzer probe are reported and e

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150610

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY