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Titolo:
COMPUTER-SIMULATIONS OF MICROSTRUCTURE CHANGES RESULTING FROM THE THERMAL-DEGRADATION OF PVC
Autore:
RADIOTIS T; BROWN GR;
Indirizzi:
PULP & PAPER RES INST CANADA,570 ST JOHNS BLVD POINTE CLAIRE PQ H9R 3J9 CANADA MCGILL UNIV,DEPT CHEM MONTREAL PQ H3A 2K6 CANADA
Titolo Testata:
Journal of macromolecular science. Pure and applied chemistry
fascicolo: 5, volume: A34, anno: 1997,
pagine: 743 - 757
SICI:
1060-1325(1997)A34:5<743:COMCRF>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
POLYENE SEQUENCE DISTRIBUTION; ANOMALOUS STRUCTURES; CHEMICAL MODIFICATION; POLY(VINYL CHLORIDE); TACTICITY; POLYVINYL-CHLORIDE); STABILITY; POLYMER; DEHYDROCHLORINATION; SUBSTITUTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
T. Radiotis e G.R. Brown, "COMPUTER-SIMULATIONS OF MICROSTRUCTURE CHANGES RESULTING FROM THE THERMAL-DEGRADATION OF PVC", Journal of macromolecular science. Pure and applied chemistry, A34(5), 1997, pp. 743-757

Abstract

Recent studies of the dehydrochlorination of PVC in the solid state offer convincing evidence in support of a mechanism that involves initiation at gttg(-) conformations in isotactic stereosequences generally considered to be normal units. Attempts have been made to verify such a mechanism by direct measurements, using solution C-13 NMR, Of the changes in tacticity that result from the degradation. In this paper, computer simulations are reported that use Monte Carlo methods to simulate preferential degradation at isotactic sequences of various minimum sequence lengths. The results indicate that at the levels of degradation accessible to experimental verification by solution NMR (<2%), the predicted changes in triad probabilities are close to the limits of experimental error and are not a sensitive indicator of the mechanism. The simulations also indicate that for the degradation to result in polyene sequence lengths that correspond to experimentally determined values requires that the dehydrochlorination include some atactic and syndiotactic sequences which, in turn, reduces the changes in P-mm. On the other hand, there are some indications that more specific indications can be obtained from the changes in the probabilities for pentads and longer sequences, provided that appropriate NMR data can be generated.

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Documento generato il 09/07/20 alle ore 19:43:10