In this work, the effect of cellulose filaments (CFs) dispersion on the relaxation behavior of thermoplastics matrices was studied. The dispersion state of polystyrene/CF composites produced by two different processing methods, leading to two different dispersion qualities, was assessed using scanning electron microscopy (SEM), transmission electron microscopy, and small amplitude oscillatory shear (SAOS). Instead of the generally used plateau value of G′, the melt yield stress of the modified Carreau–Yasuda model was used to find an accurate value of the percolation threshold concentration. It was concluded that in this case, the process involving a solution mixing step led to a better dispersion than the process involving only melt mixing. Then, using the weighted relaxation spectra calculated using the Honerkamp and Weese method on SAOS results, it was shown that the better the dispersion, the more delayed the relaxation process of the polymer matrix. Finally, by studying the relaxation spectra as well as the melt yield stress of polypropylene/CF composites, it was possible to understand the evolution of their morphology upon CF concentration. It was shown that below 5 wt. %, a well dispersed network of CF was obtained, whereas from 5 to 15 wt. % CFs were agglomerating, then leading to a network of agglomerated fibers for concentrations above 15 wt. %. Those assessments done using SAOS results were confirmed by SEM.

中文翻译：

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添加纤维素长丝对热塑性塑料松弛行为的影响

在这项工作中，研究了纤维素长丝 (CFs) 分散体对热塑性塑料基质松弛行为的影响。使用扫描电子显微镜 (SEM)、透射电子显微镜和小振幅振荡剪切 (SAOS) 评估通过两种不同加工方法生产的聚苯乙烯/CF 复合材料的分散状态，导致两种不同的分散质量。代替一般使用的G 的高原值'，使用改进的 Carreau-Yasuda 模型的熔体屈服应力来找到渗透阈值浓度的准确值。得出的结论是，在这种情况下，涉及溶液混合步骤的过程比仅涉及熔体混合的过程导致更好的分散。然后，使用 Honerkamp 和 Weese 方法对 SAOS 结果计算的加权弛豫谱表明，分散越好，聚合物基体的弛豫过程越延迟。最后，通过研究聚丙烯/CF 复合材料的弛豫光谱以及熔体屈服应力，可以了解它们的形态随 CF 浓度的演变。结果表明，低于 5 wt. ％，获得了良好分散的 CF 网络，而 5 至 15 重量％。% CF 结块，然后导致浓度高于 15 重量％的附聚纤维网络。%。SEM 确认了使用 SAOS 结果进行的评估。