不同温度下杜仲胶/天然橡胶共混硫化胶的拉伸性能及应力松弛

Tensile properties and stress relaxation of EUG/NR vulcanizates at different temperatures

将杜仲胶(EUG)与天然橡胶(NR)进行共混硫化,考察了不同EUG含量以及温度对硫化胶的拉伸性能和应力松弛的影响。结果表明,室温下EUG质量分数超过20%会形成结晶,随EUG质量分数逐渐增加到50%,硫化胶的断裂伸长率和拉伸强度均有不同程度下降;随温度升高,EUG晶区熔融,硫化胶抵抗形变能力降低,形变能力增强。在较高温度下,随EUG含量增加,硫化胶应力松弛的初始模量以及松弛到平衡值时的模量增大;随温度升高,应力松弛的初始模量以及松弛到平衡值时的模量减小。应用分数阶导数Kelvin模型对应力松弛曲线进行拟合,发现随温度升高,硫化胶体系中弹性部分减少而黏性部分增加,松弛时间缩短。

The effects of EUG contents and temperatures on tensile property and stress relaxation of EUG/NR vulcanizates are investigated.The results demonstrate that the elongation at break and the tensile strength of vulcanizates are decreased by the increase of EUG content at room temperature for the crystallization of EUG.With temperature increasing,the crystal of EUG is melting,and the deformation resistance of vulcanizates is weakened and the deformation ability of vulcanizates is enhanced.At relatively high temperature,the initial relaxation modulus and the equilibrium relaxation modulus of vulcanizates are both increased with increasing EUG content,and decreased as temperature increased.The stress relaxation curves are fitted by fractional derivative Kelvin model to evaluate the contributions from separate viscoelastic elements.The fitting results indicates the viscous part gets stronger and the elastic part gets weaker as temperature increases.As a result,the relaxation time is reduced.