摘要
针对超声外场对聚合物制件内部凝聚态结构以及力学性能影响的问题,选用等规聚丙烯(iPP)材料,设计制造了带有标准拉伸试样的壳体制件超声辅助注塑模具并进行成型实验,借助X射线衍射、偏光显微镜观测及拉伸实验等方法,研究了不同超声功率及超声作用时间,对制件凝聚态结构与力学性能的影响。结果表明:在填充与保压阶段增大超声功率,有助于激发流动熔体的分子运动活性,促进分子的取向排列,使试样的结晶度增大,屈服强度提高。而将超声作用时间由填充保压延长至冷却阶段时,增大超声功率虽仍可促进试样结晶度增大,但其屈服强度却随试样中β晶含量的增加而明显降低。可见试样的力学性能,不仅取决于其内部分子形成结晶结构的多少,还取决于分子所能形成的晶体结构形态。不同晶型的凝聚态结构,其力学性能明显不同。
Aiming at the influence of ultrasonic field on the internal condensation structure and mechanical properties of polymer parts,an ultrasonic-assisted injection mould for shell parts with standard tensile specimens was designed and manufactured using isotactic polypropylene(iPP)material.By means of X-ray diffraction,polarizing microscope observation and tensile test,the effects of different ultrasonic power and time on the condensed state structure and mechanical properties of the parts were studied.The results show that increasing the ultrasonic power during the filling and holding stages is helpful to stimulate the molecule movement activity of the flowing melt,promote the orientation arrangement of the molecule,increase the crystallinity and yield strength of the sample.When the time of ultrasonic action is prolonged from filling holding pressure to cooling stage,the yield strength decreases obviously with the increase of the content of beta crystal in the sample,although the crystallinity of the sample increases with the increase of ultrasonic power.It can be seen that the mechanical properties of specimens depend not only on the number of crystalline structures formed by the internal molecules,but also on the morphology of crystalline structures formed by the molecules.The mechanical properties of condensed structure with different crystal forms are obviously different.
作者
刘莹
毕杰
顾硕
于同敏
Liu Ying;Bi Jie;Gu Shuo;Yu Tongmin(Engineering Research Center for Molding Product of Ministry of Education,Dalian University of Technology,Dalian 116023,China)
出处
《塑料科技》
CAS
北大核心
2019年第10期46-50,共5页
Plastics Science and Technology
基金
国家自然科学基金项目(51575080)
关键词
注塑成型
超声振动
凝聚态结构
微观检测
力学性能
Injection molding
Ultrasound vibration
Condensed state structure
Microscopic testing
Mechanical properties
