Determination of Gel Content (C-C Crosslink) in Polybutadiene Rubber by Differential Scanning Calorimetry

Document Type : Research Paper

Authors

1 Department of Applied Chemistry, Faculty of Chemistry, Tehran North Branch, Islamic Azad University, P.O. Box: 15875-5981, Tehran, Iran

2 Department of Chemistry, Faculty of Basic Science, Ahar Branch, Islamic Azad University, Poata Code: 5451116714, Ahar, Iran

Abstract

Due to the gel formation in polybutadiene and some of the problems raised in rubber industry such as groove cracking in products, quantification of the gel content and identification of the microstructure of butadiene elastomer is extremely important. In this paper, the gel content in polybutadiene rubber was identified by differential scanning calorimetry. The thermal decomposition of the polybutadiene rubber was studied by thermal analysis methods in 0-650°C. The thermal decomposition, in the same temperature range, of the polymer with different gel contents under the similar conditions showed that the oxidation and decomposition of the samples occur in three steps. The thermal analysis curves showed that the cis-trans isomerization occurs by increases in the gel content at lower temperatures of a wider thermal range with rising trans isomer and decreases in cis isomer contents, respectively. Also, with the increase in the gel content there is a tendency in lowering double bond density and there is higher energy release in oxidation and decomposition regions due to the breakage in crosslink density of polymer networks. According to the values resulting from enthalpy and heat flow rate, the thermal index was obtained for samples at two maximum temperatures related to two processes of cis-trans isomerization and the cyclization reaction. The gel content (C-C crosslink) in polybutadiene rubber is determined by the interconnection between the ratio of heat flow index and gel content from the differential scanning calorimetry curves.

Keywords

Iranian Journal of Polymer Science and Technology
Volume 27, Issue 3 - Serial Number 3
July and August 2014
Pages 211-203

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