聚合转化率对硫调型氯丁胶结构与性能的影响

EFFECT OF MONOMER CONVERSION ON STRUCTURE AND PROPERTIES OF SULFUR—MODIFIED NEOPRENE

研究了硫调型氯丁橡胶乳液聚合中转化率对产晶结构与性能的影响.结果表明,随单体转化率的提高,聚合物的凝胶量及其交联密度增大,致使断链速度减慢,所得断链胶的门尼粘度上升,残存凝胶量增加,分子支化程度增大,分子量分布变宽,焦烧时间缩短。而相应硫化胶的拉伸强度、撕裂强度、冲击弹性和硬度等提高,扯断伸长率和永久变形下降。这些变化一般在转化率为80——85％时有明显转折.综合考虑产量与质量,聚合转化率控制在82±2％较为适宜。

The effects of monomer conversion on the structure and properties of the products in emulsion polymerization of sulfur modified neoprene were investigated. The results showed that with the rising of monomer conversion the gel content and crossolinking degree of the polymer inreased greatly, therefore the speed of peptization reaction slowed down and the mooney viscosity, the remnant gel, the molecular weight distribution and the molecular branching degree of the products increased, but the scorching time shortened. Furthermore,the tensile strength, the tear strength,the impact elasticity and the hardness of the corresponding vulcanized rubber increased but the elongation and the permanent set decreased with the rising of monomer conversion: In general, these changes of the structure and properties were most obvious at 80—85% of monomer conversion. In synthetic consideration of quantity and quality of the products, the optimal range of conversion should be about 82±2%.