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Effect of mastication on molecular weight and molecular weight distribution of EPDM polymer and SBR
Author(s) -
Baranwal Krishna,
Jacobs Howard L.
Publication year - 1969
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1969.070130418
Subject(s) - mastication , molar mass distribution , degradation (telecommunications) , gel permeation chromatography , polymer , materials science , size exclusion chromatography , composite material , mooney viscosity , molecular mass , chemistry , polymer chemistry , chemical engineering , organic chemistry , copolymer , dentistry , medicine , telecommunications , computer science , enzyme , engineering
Abstract EPDM and SBR were masticated on an open mill. The temperature range of mastication for EPDM was 68–480°F. SBR was milled at 170–200°F. The gel‐permeation chromatography analyses were made on the masticated samples. For EPDM at 68°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is nonrandom. At constant mastication time between 182 and 315°F, there is little change in molecular weight. Mastication for 18 min at 480°F broadens the molecular weight distribution; the degradation is random. For SBR at 170–200°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is also nonrandom. Nonrandom degradation for both EPDM and SBR results in a narrowing of the molecular weight distribution, without build‐up of low molecular weight molecules, and without a shift in the peak molecular weight. This is contrary to nonrandom degradation of natural rubber where a shift in the peak molecular weight occurs with mastication time.