National Engineering Research Center for Advanced Polymer Processing Technology, Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education, Zhengzhou University, Zhengzhou 450002, China.
Rev Sci Instrum. 2023 Jan 1;94(1):015102. doi: 10.1063/5.0130699.
A combined melt-stretching and quenching setup is designed and developed to allow experimental investigations of polymer crystallization under the complex flow-temperature environments comparable to those encountered in the actual industrial processing. The melt-stretching proceeds by two drums rotating in the opposite directions with simultaneous recording of a stress-strain curve, where the Hencky strain and strain rate (≤233 s) are adjustable over a large range. After stretching, liquid N is used as a cooling medium to quench the free-standing melt, which is sprayed directly to the deformed melt driven by an electric pump. To ensure a high cooling efficiency, a three-way solenoid valve is employed to execute a sequential control of the liquid N flow direction to reduce the boil-off of liquid N before entering the sample chamber. The melt cooling rate depends on the liquid N flow rate controlled by a flow valve, which is up to 221 °C/s when quenching the isotactic polypropylene (iPP) melt with a thickness of 0.28 mm at 150 °C. Two independent temperature control modules are designed to meet the requirements of different stages of melt-stretching and quenching. To verify the capability of the setup, we have performed the melt-stretching and quenching experiments on iPP samples. The setup is demonstrated to be a valuable new tool to study polymer crystallization under coupled flow-cooling fields.
设计和开发了一种组合的熔融拉伸和淬火装置，以允许在与实际工业加工中遇到的复杂流动-温度环境相当的条件下对聚合物结晶进行实验研究。熔融拉伸通过两个反向旋转的滚筒进行，同时记录应力-应变曲线，其中亨奇应变和应变速率（≤233 s）可以在很大范围内进行调节。拉伸后，液氮用作冷却介质来淬火自由站立的熔体，熔体由电动泵直接喷射到变形的熔体上。为了确保高冷却效率，采用三通电磁阀执行液氮流动方向的顺序控制，以减少进入样品室之前液氮的蒸发。熔体冷却速率取决于流量阀控制的液氮流量，当在 150°C 下以 0.28mm 的厚度淬火等规聚丙烯（iPP）熔体时，冷却速率高达 221°C/s。设计了两个独立的温度控制模块，以满足熔融拉伸和淬火不同阶段的要求。为了验证该装置的能力，我们在 iPP 样品上进行了熔融拉伸和淬火实验。该装置被证明是研究聚合物在耦合流-冷场下结晶的一种有价值的新工具。
