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尼龙1010样品在初始应变为1%、2.8%和5.1%的条件下,在不同的恒温环境中分别进行不少于10 h的应力松弛实验,得到20~80℃范围的应力松弛曲线.研究了不同应力、温度下的应力松弛速率、松弛过程的残余应力、活化体积以及相关参数的数学关系.结果表明,尼龙样品在松弛过程中存在一定的形变残余应力,体系存在恒定的长时模量.不同初始应变的尼龙样品松弛过程表现出相似的规律,当松弛速率-d(σ/σ0)/dlnt达到最大值后,在一段时间内聚合物内部活化单元发生松弛,-dσ/dt与作用于样品的有效应力σ*为指数关系.随着松弛过程的进行,应力减小到一定程度后,活化体积V逐渐增加,此时独立的活化单元运动受到限制,聚合物内部依靠多个活化单元的协同运动将内应力逐渐松弛,应力辅助功Vσ*为常数,-dσ/dt与σ*满足幂律关系,幂指数为σ*V/(k T).
Nylon 1010 samples were subjected to stress relaxation tests of not less than 10 h under different initial temperature conditions under the conditions of initial strain of 1%, 2.8% and 5.1%, respectively, and stress relaxation curves in the range of 20 to 80 ° C were obtained. The stress relaxation rate at different temperatures, the residual stress of the relaxation process, the activation volume and the related parameters were studied.The results show that there exists some residual stress in the relaxation process of nylon samples, and the system has a constant long-term modulus. The relaxation process of nylon samples with different initial strains shows a similar rule. When the relaxation rate -d (σ / σ0) / dlnt reaches the maximum value, the activation elements in the polymer relaxes within a certain period of time, and -dσ / The effective stress σ * of the sample is exponential. As the relaxation process proceeds, the activation volume V gradually increases after the stress is reduced to a certain extent. At this time, the movement of the independent activation unit is limited. The internal activation of the polymer depends on multiple activation units The internal stress gradually relaxes with the coordinated motion. The stress auxiliary Vσ * is constant, -dσ / dt and σ * satisfy the power law and the power exponent is σ * V / (k T).