Abstract We used the reactive extrusion method to modify virgin polyamides 6 (PA6) for melt foaming. The reactive extrusion was performed with a Haake melt mixer, and the following modifiers were used: 1,1′-isophthaloyl-bis-caprolactam (IBC), 2,2′-bis(2-oxazoline) (BOZ) and an epoxy-type chain extender KL-E4370 (EP) as well as an IBC and BOZ combination. The chain extender’s effects on the reactive modification were characterized through the PA6 chain’s rheological properties, including the storage modulus, the loss modulus, and the dynamic complex viscosity. The EP-modified PA6 was shown to have the highest viscoelasticity; that is, the highest melt strength. The PA6′s melting and crystallization properties were also investigated. A high-pressure differential scanning calorimeter (DSC) under compressed CO2 was used to evaluate the foaming temperature windows. Finally, the foamability of the modified PA6 was verified by our batch melt foaming experiments, where supercritical CO2 was used as the blowing agent. The EP-modified PA6 with the highest melt strength had the widest foaming window and the biggest expansion ratio.

中文翻译：

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使用多功能扩链剂和反应挤出进行熔融发泡的聚酰胺 6 扩链

摘要 我们使用反应挤出法对用于熔融发泡的原生聚酰胺 6 (PA6) 进行改性。使用 Haake 熔体混合器进行反应挤出，并使用以下改性剂：1,1'-间苯二甲酰-双-己内酰胺 (IBC)、2,2'-双(2-恶唑啉) (BOZ) 和环氧-型扩链剂 KL-E4370 (EP) 以及 IBC 和 BOZ 组合。扩链剂对反应性改性的影响通过 PA6 链的流变特性表征，包括储能模量、损耗模量和动态复数粘度。EP 改性的 PA6 具有最高的粘弹性；即最高的熔体强度。还研究了 PA6 的熔化和结晶性能。在压缩 CO2 下的高压差示扫描量热仪 (DSC) 用于评估发泡温度窗口。最后，改性 PA6 的发泡性通过我们的间歇熔融发泡实验得到验证，其中超临界 CO2 用作发泡剂。具有最高熔体强度的EP改性PA6具有最宽的发泡窗口和最大的膨胀比。