蛋白酶解产物对天然橡胶硫化特性和物理机械性能的影响

Effect of enzymolytic product on the curing characteristics and physico-mechanical properties of natural rubber

采用离心法制备不同蛋白质含量的天然胶乳,再通过碱性蛋白酶酶解橡胶粒子表面蛋白质,研究了蛋白质酶解产物对天然橡胶硫化特性和动态行为的影响。结果表明,随着离心次数的增加,天然橡胶中氮质量分数由0.27%降至0.13%,生胶复数黏度降低,混炼胶硫化速率变慢,硫化胶交联密度降低,力学性能下降,储能模量在应变和频率扫描下不断降低;由于蛋白质分解产物的作用,天然胶乳经离心加酶处理后,复数黏度高于单纯离心处理的,而且硫化速率加快,力学性能、储能模量均得到提升,尤其是二次离心加酶天然橡胶的硫化速率可达17.8 min^(-1),拉伸强度可达23.73 MPa,明显高于二次离心天然橡胶的9.59 min^(-1)和20.52 MPa。

The natural latexes with different protein contents were prepared by centrifugation and then treated by alkaline protease to hydrolyze protein on the rubber particle surface,and the effects of protein hydrolysates on curing characteristics and dynamic behavior of natural rubber were stu-died.The results showed that with the increment of centrifugation times nitrogen mass fraction decreased from 0.27%to 0.13%,complex viscosity of raw rubber and curing rate of compound decreased,cross-linking density and mechanical properties of natural rubber vulcanizates declined,and storage modulus reduced under strain and frequency sweep.However,complex viscosity,curing rate,mechanical properties and storage modulus of natural rubber treated by multi-centrifugation and enzyme increased compared with those of natural rubber treated by only multi-centrifugation,due to the role of protein hydrolysates,and especially for the natural rubber treated by twice centrifugation and enzyme,curing rate could reach 17.8 min^(-1) and tensile strength could reach 23.73 MPa,which were significantly higher than curing rate of 9.59 min^(-1) and tensile strength of 20.52 MPa of natural rubber treated by only twice centrifugation,respectively.