Weng Can, Li Jiangwei, Lai Jun, Liu Jiangwen, Wang Hao
College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China.
College of Mechanical and Electrical Engineering, Guangdong University of Technology, Guangzhou 510000, China.
Polymers (Basel). 2020 Oct 19;12(10):2409. doi: 10.3390/polym12102409.
Micro-injection molding has attracted a wide range of research interests to fabricate polymer products with nanostructures for its advantages of cheap and fast production. The heat transfer between the polymer and the mold insert is important to the performance of products. In this study, the interface thermal resistance (ITR) between the polypropylene (PP) layer and the nickel (Ni) mold insert layer in micro-injection molding was studied by using the method of non-equilibrium molecular dynamics (NEMD) simulation. The relationships among the ITR, the temperature, the packing pressure, the interface morphology, and the interface interaction were investigated. The simulation results showed that the ITR decreased obviously with the increase of the temperature, the packing pressure and the interface interaction. Both rectangle and triangle interface morphologies could enhance the heat transfer compared with the smooth interface. Moreover, the ITR of triangle interface was higher than that of rectangle interface. Based on the analysis of phonon density of states (DOS) for PP-Ni system, it was found that the mismatch between the phonon DOS of the PP atoms and Ni atoms was the main cause of the interface resistance. The frequency distribution of phonon DOS also affected the interface resistance.
微注塑成型因其具有成本低、生产速度快的优点，在制造具有纳米结构的聚合物产品方面引起了广泛的研究兴趣。聚合物与模具镶件之间的热传递对产品性能至关重要。在本研究中，采用非平衡分子动力学（NEMD）模拟方法研究了微注塑成型中聚丙烯（PP）层与镍（Ni）模具镶件层之间的界面热阻（ITR）。研究了ITR与温度、保压压力、界面形态和界面相互作用之间的关系。模拟结果表明，ITR随温度、保压压力和界面相互作用的增加而明显降低。与光滑界面相比，矩形和三角形界面形态均能增强热传递。此外，三角形界面的ITR高于矩形界面。基于对PP-Ni体系声子态密度（DOS）的分析，发现PP原子和Ni原子的声子DOS不匹配是界面电阻的主要原因。声子DOS的频率分布也影响界面电阻。
