Mikhail John P, Rutledge Gregory C
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA 02139, USA.
Polymers (Basel). 2023 Oct 30;15(21):4262. doi: 10.3390/polym15214262.
Semicrystalline polymers are lightweight, multiphase materials that exhibit attractive shock dissipation characteristics and have potential applications as protective armor for people and equipment. For shocks of 10 GPa or less, we analyzed various mechanisms for the storage and dissipation of shock wave energy in a realistic, united atom (UA) model of semicrystalline polyethylene. Systems characterized by different levels of crystallinity were simulated using equilibrium molecular dynamics with a Hugoniostat to ensure that the resulting states conform to the Rankine-Hugoniot conditions. To determine the role of structural rearrangements, order parameters and configuration time series were collected during the course of the shock simulations. We conclude that the major mechanisms responsible for the storage and dissipation of shock energy in semicrystalline polyethylene are those associated with plastic deformation and melting of the crystalline domain. For this UA model, plastic deformation occurs primarily through fine crystallographic slip and the formation of kink bands, whose long period decreases with increasing shock pressure.
半结晶聚合物是轻质的多相材料，具有吸引人的减震特性，并且作为人和设备的防护装甲具有潜在应用。对于10 GPa及以下的冲击，我们在半结晶聚乙烯的真实联合原子（UA）模型中分析了冲击波能量存储和耗散的各种机制。使用带有定容装置的平衡分子动力学模拟了具有不同结晶度水平的系统，以确保所得状态符合兰金-于戈尼奥条件。为了确定结构重排的作用，在冲击模拟过程中收集了序参量和构型时间序列。我们得出结论，半结晶聚乙烯中负责冲击能量存储和耗散的主要机制是那些与晶域的塑性变形和熔化相关的机制。对于这个UA模型，塑性变形主要通过精细的晶体滑移和扭折带的形成而发生，扭折带的长周期随冲击压力的增加而减小。
