Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom.
U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 20783, USA.
Phys Rev E. 2017 Sep;96(3-1):030501. doi: 10.1103/PhysRevE.96.030501. Epub 2017 Sep 13.
We investigate the mechanical properties of amorphous polymers by means of coarse-grained simulations and nonaffine lattice dynamics theory. A small increase of polymer chain bending stiffness leads first to softening of the material, while hardening happens only upon further strengthening of the backbones. This nonmonotonic variation of the storage modulus G^{'} with bending stiffness is caused by a competition between additional resistance to deformation offered by stiffer backbones and decreased density of the material due to a necessary decrease in monomer-monomer coordination. This counterintuitive finding suggests that the strength of polymer glasses may in some circumstances be enhanced by softening the bending of constituent chains.
我们通过粗粒化模拟和非仿射晶格动力学理论研究了无定形聚合物的力学性能。聚合物链弯曲刚度的微小增加首先导致材料软化，而只有进一步增强骨架时才会发生硬化。存储模量 G^{'} 随弯曲刚度的这种非单调变化是由更硬的骨架提供的额外变形阻力与由于单体-单体配位的必然减少而导致的材料密度降低之间的竞争引起的。这种违反直觉的发现表明，在某些情况下，通过软化组成链的弯曲，可以增强聚合物玻璃的强度。
