Anionic polyamide 6 (aPA6), synthesized via the ring-opening polymerization of ε-caprolactam, has emerged as a promising matrix for high-performance thermoplastic composites, offering advantages over conventional thermoplastics and thermosets. However, optimizing the microstructure and mechanical properties of aPA6 requires a comprehensive understanding of how processing conditions influence polymerization kinetics and resulting material characteristics. This work systematically investigates the interplay between two critical processing parameters, i.e., the mold temperature and catalysts concentration, on the microstructural and thermomechanical properties of aPA6, via a combined experimental and statistical approach. Increasing the mold temperature from 145 °C to 175 °C and the catalysts concentration led to a reduction in crystallinity, due to the promotion of polymerization over crystallization. Higher temperatures and concentrations also slightly anticipated thermal degradation onset from 388 °C to 327 °C. The elastic modulus decreased from 3.4 GPa to 2.7 GPa as temperature increased, primarily governed by the diminishing crystallinity. Similarly, the ultimate tensile strength declined from 80 MPa to 68 MPa with rising temperature. Interestingly, the strain at break exhibited a complex dependence, peaking at 48 % for an intermediate temperature of 165 °C and lower catalysts concentration, suggesting an optimal balance of crystallinity, branching, and high molecular weight. Statistical empirical models captured these relationships, enabling prediction and tailoring of aPA6 properties by tuning processing conditions. These insights pave the way for optimized manufacturing of high-performance aPA6 composites via techniques like thermoplastic resin transfer molding and expand potential applications to thermally sensitive reinforcements like natural fibers.

中文翻译：

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解读模具温度和催化剂浓度对阴离子聚酰胺 6 结晶度和机械性能的相互作用：实验和统计相结合的方法


通过 ε-己内酰胺开环聚合合成的阴离子聚酰胺 6 (aPA6) 已成为高性能热塑性复合材料的一种有前途的基体，与传统热塑性塑料和热固性塑料相比具有优势。然而，优化 aPA6 的微观结构和机械性能需要全面了解加工条件如何影响聚合动力学和所得材料特性。这项工作通过实验和统计相结合的方法，系统地研究了两个关键加工参数（即模具温度和催化剂浓度）之间对 aPA6 微观结构和热机械性能的相互作用。将模具温度从 145 °C 提高到 175 °C 和催化剂浓度会导致结晶度降低，因为聚合作用超过结晶作用。较高的温度和浓度也略微预示着从 388 °C 到 327 °C 的热降解开始。随着温度升高，弹性模量从 3.4 GPa 降低至 2.7 GPa，这主要是由结晶度降低决定的。同样，随着温度的升高，极限拉伸强度从 80 MPa 下降到 68 MPa。有趣的是，断裂应变表现出复杂的依赖性，在 165 °C 的中间温度和较低的催化剂浓度下达到 48% 的峰值，表明结晶度、支化和高分子量的最佳平衡。统计经验模型捕捉了这些关系，通过调整加工条件来预测和定制 aPA6 特性。 这些见解为通过热塑性树脂传递模塑等技术优化高性能 aPA6 复合材料的制造铺平了道路，并将潜在应用扩展到天然纤维等热敏增强材料。