PP微孔发泡试样泡孔结构与拉伸性能的变化关系研究

Change Relationship between Cell Structure and Tensile Properties of PP Microcellular Foaming Plastic

通过仿真分析得到超临界N2注射成型聚丙烯(PP)微孔发泡试样的泡孔结构与拉伸性能之间的关联机制,即泡孔尺寸与拉伸性能成反比关系;然后利用控制变量法进行PP微孔发泡试样的超临界N2注射成型实验,研究注气时间、注射温度、注射速率对试样泡孔结构和拉伸性能的影响规律,揭示在不同工艺参数下试样泡孔结构与拉伸性能之间的变化关系。结果表明,注气时间和注射温度下泡孔尺寸与拉伸性能的变化关系总体上符合由仿真分析得到的关联机制;随注气时间增加,泡孔结构和拉伸性能总体上劣化;注射速率对泡孔结构和拉伸性能的影响相对较小,但较高的注射速率有利于减小泡孔尺寸;与其它两种工艺参数相比,不同注射温度下泡孔结构和拉伸性能之间的变化关系比较稳定。在保持较短的注气时间和较高的注射速率下,通过调整注射温度可获得泡孔尺寸小、密度高且拉伸性能好的PP微孔发泡试样。

Simulation method was used to explore the associated mechanism between cell structure and tensile properties of the polypropylene（PP） microcellular foaming specimens with supercritical N2 injection molding, which is that the cell size is inversely proportional to the tensile properties. Controlling variable method was used to do the supercritical N2 injection molding experiments for the PP microcellular foaming specimens, and the influences of gas injection time, injection temperature and rate on the cell strueture and tensile properties of the specimens were studied, revealing the change relationship between cell structure and tensile properties under different process parameters. The results show that under the conditions of gas injection time and injection temperature, by and large, the change relationship conforms to the the associated mechanism gained from the simulation. With the increase of the gas injection time, the cells tructure and tensile properties are deteriorated in general. The effects of the injection rate is relatively small, but the high injection rate is conducive to reduce the cell size. Compared with the other two kinds of process parameters, under different injection temperature, the change relationship between the cell structure and tensile properties is stable. While maintaining shorter gas injection time and high injection rate, the PP microcellular foaming specimen with small cell size, high cell density and tensile properties can be obtained by adjusting the injection temperature.