DICHLOROBUTYL BRANCH FORMATION AND THE QUESTION OF DIFFUSION-CONTROLLED PROPAGATION IN THE POLYMERIZATION OF VINYL-CHLORIDE

被引:20
作者
STARNES, WH
WOJCIECHOWSKI, BJ
CHUNG, HS
BENEDIKT, GM
PARK, GS
SAREMI, AH
机构
[1] COLL WILLIAM & MARY,DEPT CHEM,WILLIAMSBURG,VA 23187
[2] BF GOODRICH CO,CTR RES & DEV,BRECKSVILLE,OH 44141
[3] UNIV WALES COLL CARDIFF,SCH CHEM & APPL CHEM,CARDIFF CF1 3TB,S GLAM,WALES
关键词
D O I
10.1021/ma00108a023
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Previously published concentrations ((rho)over bar>(BB)'s) of the 2,4-dichloro-n-butyl branches in poly-(vinyl chloride) (PVC) have been used to develop a simple theory that predicts <(rho)over bar>(BB) values as a function of monomer concentration and temperature during polymerization. The experimental values of <(rho)over bar>(BB) are shown to be consistent, quantitatively, with the well-known ''back-biting'' mechanism for dichlorobutyl branch formation. They also indicate that the activation energy for back-biting is greater than that for normal chain propagation by 4.4 kcal/mol. In monomer-swollen PVC at 45-80 degrees C, back-biting:propagation rate-constant ratios (k(b)/k(p)'s) are invariant with monomer conversion up to total conversions of 83-91%, at least, and at 40 degrees C the value of k(b)/k(p) does not change significantly when the polymerization is carried out in 1,2-dichloroethane solution instead of in monomer-swollen polymer. These results are shown to provide strong evidence against diffusion control of the rate of chain propagation.
引用
收藏
页码:945 / 949
页数:5
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