We directly observed the polymerization and crystallization of polyamide 6 (PA6) via anionic polymerization with a combination of in situ wide-angle X-ray scattering (WAXS), temperature measurements, and real-time visualization. In situ WAXS discriminated polymerization and the crystallization of PA6. The peak temperatures produced by exothermic polymerization and crystallization were identified during the temperature measurements. Visual observations were consistent with the WAXS spectral changes. The WAXS results indicated that the molding process consisted of three stages: (1) polymerization induction, (2) polymerization, and (3) crystallization. We compared the polymerization rate, crystallization rate, and crystallinity at each molding temperature. Both polymerization and crystallization were slow at temperatures below 127 °C. Polymerization was fast at temperatures exceeding 166 °C, but PA6 was gelated, and the crystallization rate and crystallinity were low. In contrast, polymerization was fast at 139, 148, and 155 °C, and crystallization was faster at 148 and 155 °C than at 139 °C. Therefore, the total molding time of PA6 was shorter at 148 and 155 °C than at other temperatures. The crystallinity of PA6 decreased with increasing temperature due to increasing molecular weights. We concluded that molding temperatures between 148 and 155 °C were suitable for providing PA6 with high productivities and good properties. The polymerization and crystallization of polyamide 6 (PA6) via anionic polymerization was observed using a combination of in situ wide-angle X-ray scattering (WAXS), temperature measurement, and real-time visualization at 119–182 °C. In-situ WAXS discriminated between polymerization and the crystallization of PA6. The WAXS results indicated that polymerization was fast at 139–155 °C, and crystallization was fast at 148–155 °C. The crystallinity of PA6 decreased with increasing temperature. We concluded that molding temperatures between 148 and 155 °C were suitable for high productivities of PA6 with good properties.

中文翻译：

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等温过程中ε-己内酰胺阴离子聚合和聚酰胺6结晶的原位WAXS同时研究

我们结合原位广角 X 射线散射 (WAXS)、温度测量和实时可视化，通过阴离子聚合直接观察了聚酰胺 6 (PA6) 的聚合和结晶。原位 WAXS 区分聚合和 PA6 的结晶。在温度测量过程中确定了由放热聚合和结晶产生的峰值温度。目视观察与 WAXS 光谱变化一致。WAXS 结果表明成型过程包括三个阶段：(1) 聚合诱导，(2) 聚合和 (3) 结晶。我们比较了每个成型温度下的聚合速率、结晶速率和结晶度。在低于 127 °C 的温度下，聚合和结晶都很慢。超过166℃时聚合速度快，但PA6凝胶化，结晶速率和结晶度低。相比之下，聚合在 139、148 和 155 °C 下快速，结晶在 148 和 155 °C 下比在 139 °C 下更快。因此，PA6 的总成型时间在 148 和 155 °C 时比在其他温度下更短。由于分子量增加，PA6 的结晶度随温度升高而降低。我们得出结论，148 至 155 °C 的成型温度适合为 PA6 提供高生产率和良好性能。使用原位广角 X 射线散射 (WAXS)、温度测量和 119–182 °C 实时可视化的组合，观察了聚酰胺 6 (PA6) 通过阴离子聚合的聚合和结晶。原位 WAXS 区分聚合和 PA6 的结晶。WAXS 结果表明聚合在 139-155°C 下快速，结晶在 148-155°C 下快速。PA6 的结晶度随温度升高而降低。我们得出的结论是，148 至 155 °C 的成型温度适合具有良好性能的 PA6 的高生产率。