This paper aims at elucidating which factors are effective in terms of influencing the die swell of unvulcanized rubber upon extrusion. To that end, compression, viscosity, and extrusion tests were performed on two types of ethylene–propylene–diene rubbers, while additional compression tests were performed on natural rubber. First, all three testing modalities were assessed separately, revealing that for the tested materials the compressibility is pressure-dependent; the viscosity is velocity-dependent; and the die swell is influenced by several, partly intertwined factors. In order to better understand the collected experimental data, we have employed the theoretical tool of dimensional analysis, showing that the compressibility of unvulcanized rubber is of great importance for the die swell. Surprisingly, the temperature dependence of the die swell turns out to be much less prominent than standardly assumed. Further key factors influencing the die swell concern the geometries of the die and of the canal.

本文旨在阐明哪些因素对影响未硫化橡胶挤出时的模头膨胀是有效的。为此，对两种乙烯-丙烯-二烯橡胶进行了压缩、粘度和挤出测试，同时对天然橡胶进行了额外的压缩测试。首先，对所有三种测试方式分别进行了评估，表明测试材料的可压缩性与压力有关；粘度与速度有关；冲模膨胀受几个相互交织的因素影响。为了更好地理解收集到的实验数据，我们采用了尺寸分析的理论工具，表明未硫化橡胶的压缩性对模具膨胀非常重要。出奇，结果证明，芯片膨胀的温度依赖性不如标准假设的那么突出。影响模具膨胀的其他关键因素涉及模具和管道的几何形状。