Polgmeric Foaming and its Process Development

通过模拟和基础实验研究了溶解气体浓度、压力释放速率和操作温度等工艺变量对气泡生长动力学、成核速率和最终气泡尺寸的影响。在聚烯烃发泡过程中，基础实验表明，气泡尺寸随着压力释放速率的减小而增大，而随着操作温度的降低而减小。此外，较高浓度的溶解气体导致较小的气泡尺寸。这些结果得到了本项目新开发的数值模拟的证实。该模拟器是基于Shafs成核和气泡生长模型开发的。模拟和实验结果均表明，在聚合物发泡过程中，压力释放速率、溶解气体浓度和操作温度是控制气泡尺寸和发泡密度的主要因素。模具的优化设计一直是未解决的问题之一。

The effect of processing variables such as concentration of dissolved gas, release rate of pressure and operation temperature on bubble growth dynamics, nucleation rate and final bubble size was examined by both simulation and fundamental experiments. In the polyolefin foaming process, fundamental experiments showed that bubble size increased when the release rate of pressure decreased, whereas bubble size decreased when the operating temperature decreased. Furthermore, a higher concentration of dissolved gas resulted in smaller bubble size. These results were confirmed by numerical simulation that was newly developed in this project. The simulator was developed based on Shafs nucleation and bubble growth models. Both simulation and experimental results elucidated that release rate of pressure, concentration of dissolved gas and operating temperature are the principal factors which control bubble size and foaming density in the polymeric foaming process. Optimal design of die remained as one of the unsolved problems.