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Differential thermal analysis using high frequency dielectric heating II. Curing kinetics studies
Author(s) -
Wald S. A.,
Winding C. C.
Publication year - 1971
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760110111
Subject(s) - curing (chemistry) , polybutadiene , materials science , natural rubber , order of reaction , activation energy , kinetics , thermal decomposition , dielectric , peroxide , chemical kinetics , reaction mechanism , styrene butadiene , reaction rate , reaction rate constant , polymer chemistry , styrene , composite material , chemistry , copolymer , catalysis , organic chemistry , polymer , quantum mechanics , physics , optoelectronics
A previous paper described the theory and equipment of Differential Thermal Analysis using High Frequency Dielectric Heating, DTA/HF. Curing studies using DTA/HF on cis‐1,4‐polyisoprene rubber filled with 50 phr of CaCO 3 and containing from 1.5 to 4.5 phr of dicumyl peroxide (DCP) curative indicated that below about 185°C, the curing reaction was first order with respect to DCP; the mean activation energy was 32.6 kcal/mole; and the heat of reaction ranged from 60 to 80 kcal/mole DCP. These results are in agreement with published results. Above 185°C both thermodynamic and kinetic evidence implied that the reaction mechanism changed; the first order peroxide decomposition no longer controlled the overall rate of reaction. The curing of both stereo styrene‐butadiene rubber (SBR) and cis‐1,4‐polybutadiene rubber (BR) containing 50 phr of CaCO 3 and 0.5 phr of DCP was found to follow first order kinetics as expected. The magnitude of the heat of curing was used to determine the frequency of a vinyl propagation‐type cross‐linking reaction. Eight to 36 crosslinks per molecule of DCP were obtained. This reaction became more extensive at high temperature, in agreement with published results.