摘要:

AbstractThe radiation‐induced copolymerization of vinylene carbonate (M1) with isobutyl vinyl ether (M2) has been investigated over the temperature range of 40–80°C. The monomer reactivity ratiosr1andr2were determined to be 0.118 and 0.148, respectively, and an activation energy of 7.6 kcal/mole (31.8 kJ/mole) was calculated for the copolymerization pro

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140501

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

Abstract2,4,6‐Tri‐tert‐butylphenoxyl (TBP) is dissolved and reacted with hydroperoxide groups of polyethylene and polypropylene in the amorphous phase. The reaction is not limited by diffusion, and unlike the case in the liquid phase, the concentration of TBP is not zero at the end of the reaction time, even though hydroperoxide groups are in excess. The biomolecular rate constant is smaller in the solid than it is in the liquid phase and depends on molecular motion. A linear relationship between the rate constant and frequency of rotation of radicals in polymers is obs

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140502

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractIonic species in poly(methyl methacrylate) (PMMA) have been studied by optical absorption and ESR spectrometry. γ‐Irradiation of PMMA containing aromatic solutes gave rise to the absorption spectra of corresponding cation radicals. TheGvalue for the formation of cation radicals was determined to be 1.5. Anionic radicals of the solutes were not detected for the aromatic solutes studied. Anionic species of pure PMMA were identified by both absorption spectra and ESR spectra. It has an absorption maximum at 440 nm. A sharp singlet with a line width of about 5 G which was found by ESR spectrometry was tentatively assigned to the trapped electron of PMMA. The results show that a large number of electron traps in PMMA may exist on the ester side chain themselv

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140503

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe glass transition temperatures of polypropylene, poly‐1‐butene, polyisobutylene, and an ethylene‐propylene (EP) copolymer have been determined by inverse gas chromatography. The results are consistent with those determined by other procedures. When applied to low‐, medium‐ and high‐density polyethylene, values of −35, −25, and −18°C, respectively, were obtained. Because of the fact that the chromatographic technique involves essentially a sensitive detection of free volume in a polymer, it is suggested that these values representTgif it is defined as an iso‐free volume state of the amorphous phase

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140504

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe cleavage of poly(vinyl alcohol) in dimethyl sulfoxide at 42°C has been measured viscometrically in the presence oftert‐butyl hydroperoxide and metal complexes. Phthalocyanine complexes of copper(II), iron(III), cobalt(II), and vanadium as VO(II) as well as hemin, hematin, chlorophyllin, and cytochrome c were used. The rates of decomposition oftert‐butyl hydroperoxide in the presence of these metal complexes were measured idometrically. These data are compared to results obtained with other metal complexes in similar react

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140505

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractTo investigate the nature of the propagating species in cationic polymerization ofpara‐substituted styrenes,p‐chlorostyrene (pCIS),p‐methylstyrene (pMS), andp‐methoxystyrene (pMOS), were polymerized with acetyl perchlorate or iodine in various solvents at 0°C, and the molecular weight distribution (MWD) of the polymers was measured by means of gel‐permeation chromatography. When ClO4−was a counterion, poly(pCIS) having a bimodal MWD was produced, while polymers of pMOS and pMS possessed a unimodal MWD, regardless of the solvent polarity. When more nucleophilic I−(or I3−) was a counterion, however, polymers having a bimodal MWD were produced from pMOS and pMS. These results showed that either dissociated or nondissociated propagating species existed in the cationic polymerization of styrene derivatives with acetyl perchlorate or iodine, and that the type of MWD was strongly dependent on the stability of the growing cation and the nucleophilicity o

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140506

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractAn interesting effect of pyridine on the anionic polymerization of styrene in THF is described. Pyridine forms a complex with living polystyrene and greatly slows the polymerization rate without changing the degree of polymerization. From kinetic and spectroscopic studies, it was clear that there exist two active species in this system and the complex between living polystyrene and pyridine was of the 1:1 type, which itself had a weak ability to grow. The formation constant of the complexKwas found to be about 4 × 105l./mole. The effect of substituted pyridine was also studied and the nature of the complex was discussed

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140507

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractN‐Methyl‐N‐allylmethacrylamide (MAMA) was synthesized and polymerized with radical initiators, and the structure of poly‐MAMA was studied, in order to establish the concept that difunctional monomers having monofunctional counterparts which do not polymerize are likely to give rise to highly cyclized polymer, if the cyclized polymer is in a lower free‐energy level than the monomer. The cyclopolymerizability of MAMA was considerably higher than that ofN‐allylmethacrylamide, which was previously reported, and its monofunctional counterpart can be polymerized. The extent of cyclization of poly‐MAMA was about 93%, even in the polymer obtained by bulk polymerization. The repeating units of poly‐MAMA consist mainly of five‐membered rings; six‐membered rings and pendent methacryl groups were detected in addition as minor repeating components. The monofunctional counterparts of MAMA, i.e.,N‐methyl‐N‐n‐propylmethacrylamide (MPMA) andN‐methyl‐N‐allylisobutyramide (MAIA), were also synthesized. Neither MPMA nor MAIA showed any tendency toward polymerization under the same experimental conditions as used for MAMA. The results thus obtained all su

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140508

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

Abstract(R)‐(+)‐2‐Methyl‐2‐ethyl‐3‐propiothiolactone was synthesized by debenzylation and cyclization of (−)‐2‐methyl‐2‐ethyl‐3‐benzylmercaptopropionyl chloride under the conditions of Friedel‐Crafts synthesis, and by dehydration of (R)‐(+)‐2‐methyl‐2‐ethyl‐3‐mercaptopropionic acid with dicyclohexyl carbodiimide. The configuration of the (+)‐propiothiolactone was determined by chemical interconversion with (−)‐2‐methyl‐2‐ethylsuccinic acid, the absolute configuration of which is known to be (R). The polymerization of (R)‐(+)‐2‐methyl‐2‐ethyl‐3‐propiothiolactone was performed in bulk with tetrabutylammonium versatate as catalyst. The specific rotation of the polymer ([α]D+151.7°) compared with the rotation of the low molecular weight model compound (R)‐(+)‐2‐methyl‐2‐ethyl‐3‐acetylmercapto‐thiolpropionic acid methyl ester ([α]D+55.0°) shows a significant enhancement

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140509

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractNovel oxime‐containing polyamides have been prepared by the ring‐opening polyaddition of combinations of two benzobis[1,2]oxazinediones, 4,6‐diphenylbenzo[1,2‐d:5,4‐d′]bis[1,2]oxazine‐1,9‐dione and 4,9‐diphenylbenzo[1,2‐d:4,5‐d′]bis[1,2]oxazine‐1,6‐dione, with two aliphatic diamines in a polar aprotic solvent such asN‐methyl‐2‐pyrrolidone. The polymerization was almost completed within a day at room temperature. These polymers had inherent viscosities in the range of 0.12–0.38 and were soluble in a wide range of solvents, including formic acid and hotm‐cresol, as well as a number of polar aprotic solvents. All the polymers softened at a temperature ranging from 165 to 185°C. Thermal characterization of the polyamides by TGA and DTA showed polymer decomposit

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140510

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY