Chen Kang, Schweizer Kenneth S
Department of Materials Science, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801, USA.
Phys Rev Lett. 2009 Jan 23;102(3):038301. doi: 10.1103/PhysRevLett.102.038301. Epub 2009 Jan 20.
A nanometer scale dynamical theory is proposed for the large amplitude strain hardening phenomenon in polymer glasses. The new physical picture is that external deformation induces anisotropic chain conformations, which modifies interchain packing, resulting in density fluctuation suppression and intensification of localizing dynamical constraints and activation barriers. The resulting stresses are of intermolecular origin and arise primarily from prolongation of segmental relaxation, not single chain entropic rubber elasticity. Theoretical predictions for the magnitude, temperature, and deformation rate dependence of the hardening modulus are consistent with experiments and simulations.
针对聚合物玻璃中的大振幅应变硬化现象，提出了一种纳米尺度动力学理论。新的物理图像是，外部变形会诱导各向异性的链构象，这会改变链间堆积，从而抑制密度涨落，并强化局部动力学约束和活化能垒。由此产生的应力源自分子间作用，主要是由链段弛豫的延长引起的，而非单链熵弹性橡胶弹性。关于硬化模量大小、温度和变形速率依赖性的理论预测与实验和模拟结果一致。
