THE COMPOSITIONAL HETEROGENEITY OF BUTADIENE-STYRENE COPOLYMERS SYNTHESIZED AT −18°C. IN EMULSION

1951 ◽  
Vol 29 (3) ◽  
pp. 270-283 ◽  
Author(s):  
R. J. Orr ◽  
H. Leverne Williams
Keyword(s):  
Transfer Reaction ◽  
Chain Transfer ◽  
Polymerization Temperature ◽  
Viscosity Data ◽  
Compositional Heterogeneity ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Chain Transfer Reaction ◽  
Molecular Weight Heterogeneity ◽  
Butadiene Styrene

A study has been made of butadiene-styrene copolymers formed at −18°C. From analyses for bound styrene in the product for various conversions and initial butadiene-styrene ratios the reactivity ratios were calculated to be r1 = 1.37 and r2 = 0.38 compared with 1.8 and 0.6 at 45°C. Q and e for butadiene were 1.38 and 0.008 relative to styrene at 1 and −0.8. Increment bound styrene curves calculated for each stage of the reaction indicated that the polymers were remarkably homogeneous at low conversions. The chain transfer reaction using mixed tertiary mercaptans as the modifier was studied. Regulating indices were found to have decreased with polymerization temperature. Number average [Formula: see text] and viscosity average [Formula: see text] molecular weights were calculated from mercaptan disappearance and vistex intrinsic viscosity data respectively. The molecular weight heterogeneity increased with increasing conversion and initial mercaptan content. The increment number average molecular weights were found to diminish with conversions, whereas the increment viscosity average increased at higher conversions as conversion increased.

THE POLYMERIZATION OF ISOPRENE AND 2, 3-DIMETHYLBUTADIENE AND COPOLYMERIZATION WITH STYRENE AT −18 °C. IN EMULSION

1952 ◽  
Vol 30 (2) ◽  
pp. 108-123 ◽  
Author(s):  
R. J. Orr ◽  
H. Leverne Williams
Keyword(s):  
Transfer Reaction ◽  
Chain Transfer ◽  
Price Equation ◽  
Side Reactions ◽  
Polymerization Temperature ◽  
Reactivity Ratios ◽  
Molecular Weights ◽  
Rate Of Polymerization ◽  
Chain Transfer Reaction ◽  
Cyclic Compounds

The rate of polymerization increased with purification of the monomers. It was possible that the dienes formed cyclic compounds or dimers in side reactions. The 1,2 addition of the monomer decreased with decreasing polymerization temperature. A study was made of the copolymerization of isoprene and dimethylbutadiene with styrene at −18° C. From analyses of bound diene in the product at various conversions and initial diene to styrene ratios the reactivity ratios for these diene-styrene systems were calculated to be r1 = 1.30 ± 0.02 and r2 = 0.48 ± 0.01 for isoprene and styrene and r1 = 0.92 ± 0.02, r2 = 0.42 ± 0.02 for dimethylbutadiene and styrene (styrene always being considered monomer 2). Q and e values from the Alfrey-Price equation were calculated as Q = 119 and e = −0.112 for isoprene and Q = 1.09 and e = −0.181 for dimethylbutadiene relative to Q = 1.0 and e = −0.8 for styrene. Fom these and the values previously determined for butadiene, reactivity ratios for all combinations of the three dienes were calculated. The chain transfer reaction between dienyl radicals and mixed tertiary mercaptans was studied and it was found that isoprenyl and dimethylbutadienyl radicals were much more reactive than butadienyl. The effect of this was illustrated by number and viscosity average molecular weights. Intrinsic viscosities of homo- and copolymers formed in a mercaptan-free recipe were measured and compared.

COMPOSITIONAL HETEROGENEITY OF BUTADIENE–ACRYLONITRILE COPOLYMERS PREPARED IN EMULSION AT 5°C

1951 ◽  
Vol 29 (3) ◽  
pp. 253-269 ◽  
Author(s):  
W. H. Embree ◽  
J. M. Mitchell ◽  
H. Leverne Williams
Keyword(s):  
Molecular Weight ◽  
Weight Distribution ◽  
Viscosity Data ◽  
Reactivity Ratios ◽  
Compositional Heterogeneity ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Conventional Solution ◽  
Acrylonitrile Copolymers ◽  
Butadiene Styrene

The copolymerization of butadiene and acrylonitrile is very similar to the copolymerization of butadiene and styrene. Polymers predominantly butadiene may be studied by conventional solution techniques but the study of polymers rich in acrylonitrile requires improved solvents for these materials. Polymerization rates are greatest for monomer ratios approximating equal proportions. The mercaptan modifier disappears much more slowly than in the butadiene–styrene system, the regulating index approximating unity. The number average molecular weights calculated from the mercaptan disappearance curves indicate uniform polymer molecular weights to relatively high conversions after which there is a decrease. The viscosity data indicate a rise in viscosity with conversion, which effect is overcome for charges rich in acrylonitrile by the lessening of branching, the more rapid disappearance of mercaptan at high conversion, and the tendency of polymers containing over 50% acrylonitrile to show very low dilute solution viscosities in the solvents tested. Viscosity molecular weights have been calculated and estimates of the molecular weight distribution made. These distributions appear to be quite narrow and the usual broadening at higher conversions is prevented by the increased modifier consumption and increased vinyl content of the polymer prepared with 50 parts acrylonitrile in the charge. The bound acrylonitrile has been determined at various conversions and the reactivity ratios have been found to be r1 = 0.28 and r2 = 0.02 for emulsions and r1 = 0.18 and r2 = 0.03 for oil phase portion only. Q is 0.74 and e is 1.47 as calculated by the Alfrey–Price equations.

LABORATORY STUDY OF LOW RATIO BUTADIENE–STYRENE COPOLYMERS

1949 ◽  
Vol 27f (2) ◽  
pp. 35-46 ◽  
Author(s):  
J. M. Mitchell ◽  
H. Leverne Williams
Keyword(s):  
Induction Period ◽  
Chain Transfer ◽  
Viscosity Data ◽  
Reactivity Ratios ◽  
Styrene Copolymers ◽  
Rate Of Reaction ◽  
Styrene Content ◽  
Mass Basis ◽  
Dodecyl Mercaptan ◽  
Butadiene Styrene

The copolymerization of styrene and butadiene in ratios in which the styrene equals or predominates over the butadiene on a mass basis is essentially similar to copolymerization in the presence of a predominance of butadiene. However, the rate of reaction and the length of the induction period is increased. Increasing the amount of the dodecyl mercaptan regulator results in a slight increase in rate and diminution of the induction period. The dodecyl mercaptan reacts at a lower rate than during the production of GR–S. The regulating index as defined by the ratio of the logarithm of the residual mercaptan over the conversion is 1.53. The bound styrene and increment styrene curves seem to be normal and indicate reactivity ratios r1 (butadiene) equal to 1.4 to 2.2, r2 equal to 0.5 to 0.7. If these reactivity ratios are corrected for the bifunctional nature of butadiene then the constants for butadiene monomer are Q equal to 0.9 and e equal to − 1. Likewise the gel–viscosity data are similar to those observed with GR–S except that the pre-gel rise in viscosity, the formation of gel, and the slope of the viscosity conversion curves diminish with increasing styrene in the charge. The chain transfer action of styrene is increasingly evident with increasing styrene content in the charge but in all cases the regulating effect of dodecyl mercaptan is still apparent.

scholarly journals Cationic Copolymerization of Isobutylene with 4-Vinylbenzenecyclobutylene: Characteristics and Mechanisms

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 201 ◽  
Author(s):  
Zhifei Chen ◽  
Shuxin Li ◽  
Yuwei Shang ◽  
Shan Huang ◽  
Kangda Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Cationic Polymerization ◽  
Transfer Reaction ◽  
Chain Transfer ◽  
Solid Phase ◽  
Random Copolymer ◽  
Glass Transition Temperatures ◽  
Cationic Copolymerization ◽  
Chain Transfer Reaction

A random copolymer of isobutylene (IB) and 4-vinylbenzenecyclobutylene (4-VBCB) was synthesized by cationic polymerization at −80 °C using 2-chloro-2,4,4-trimethylpentane (TMPCl) as initiator. The laws of copolymerization were investigated by changing the feed quantities of 4-VBCB. The molecular weight of the copolymer decreased, and its molecular weight distribution (MWD) increased with increasing 4-VBCB content. We proposed a possible copolymerization mechanism behind the increase in the chain transfer reaction to 4-VBCB with increasing of feed quantities of 4-VBCB. The thermal properties of the copolymers were studied by solid-phase heating and crosslinking. After crosslinking, the decomposition and glass transition temperatures (Tg) of the copolymer increased, the network structure that formed did not break when reheated, and the mechanical properties remarkably improved.

scholarly journals The Estimation of the Reactivity of the Growing Ion by Chain Transfer Reaction in Cationic Polymerization

1963 ◽  
Vol 20 (213) ◽  
pp. 49-57 ◽  
Author(s):  
Yukio Imanishi ◽  
Atsunobu Mizote ◽  
Toshinobu Higashimura ◽  
Seizo Okamura
Keyword(s):  
Cationic Polymerization ◽  
Transfer Reaction ◽  
Chain Transfer ◽  
Chain Transfer Reaction

scholarly journals Emulsion Polymerization of Chloroprene: Study of Branching and Chain Transfer Reaction by Kinetic Analysis of Gelation.

1991 ◽  
Vol 48 (12) ◽  
pp. 743-749
Author(s):  
Kenji ITOYAMA ◽  
Yasuaki DENDA ◽  
Nobuhiro HIRASHIMA ◽  
Shiro MATSUNAGA
Keyword(s):  
Kinetic Analysis ◽  
Emulsion Polymerization ◽  
Transfer Reaction ◽  
Chain Transfer ◽  
Chain Transfer Reaction
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