Thermally expandable microcapsules (MCs) are applicable to the foam processing of polypropylene (PP). The purpose of this study is to clarify the influence of processing conditions, such as temperature, shear rate and resin selection, on the behavior of thermally expandable MCs in PP. In this study, MC was added to several types of PP and extrusion foaming was performed. The average diameter of the MCs after processing was calculated to characterize the expansion of PP including MCs. Two types of molecular architecture, homo‐ and impact‐PP, were examined in this study. The expansion behavior could be summarized by the shear viscosity at the extrusion die. Irrespective of the molecular architecture, data were summarized on one curve on a plane that expressed the relation between the shear viscosity and average MC diameter. Shear viscosity is thus an effective parameter to examine base resin selection for MC foaming. POLYM. ENG. SCI., 60:558–562, 2020. © 2020 Society of Plastics Engineers

中文翻译：

---

基础聚合物的粘弹性对热膨胀性微胶囊挤出发泡的影响

可热膨胀的微囊（MCs）适用于聚丙烯（PP）的泡沫加工。这项研究的目的是阐明加工条件（例如温度，剪切速率和树脂选择）对PP中热膨胀MC行为的影响。在这项研究中，MC被添加到几种类型的PP中，并进行了挤出发泡。计算出加工后MC的平均直径以表征包括MC的PP的膨胀。在这项研究中，研究了两种类型的分子结构，均聚和影响PP。膨胀行为可以通过挤出模头处的剪切粘度来概括。不论分子结构如何，数据都在平面上的一条曲线上汇总，该曲线表示剪切粘度与平均MC直径之间的关系。因此，剪切粘度是检查用于MC发泡的基础树脂选择的有效参数。POLYM。ENG。SCI。，60：558–562，2020.©2020塑料工程师协会