In this study, shear‐induced crystallization of short carbon fiber (SCF)‐reinforced isotactic polypropylene (iPP) composite was investigated using polarized optical microscopy (POM) and rheometry. Although the SCF exhibited no nucleation ability to iPP in the quiescent melt under the chosen conditions, different interfacial morphologies were observed after shear was applied. The POM results revealed that the crystallite morphologies along the SCF strongly depended on the shear rate ( $\dot{\gamma }$) and shear duration. A nucleation kinetics model was proposed to determine how shear affects the fraction of SCF covered with transcrystalline. The nucleation rate on the SCF was proportional to ${\dot{\gamma }}^n$. The dependence of the nucleation rate corresponded well with the change in the shear‐induced free energy of the melt, indicating that the interactions between SCF and iPP were insignificant. The rheological results demonstrated that conformational ordering directly affected the nucleation rate. The helical content near the SCF increased rapidly owing to the enhancement of shear. Therefore, the nucleation kinetics on the SCF surface accelerated significantly.

中文翻译：

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剪切对碳纤维增强聚合物复合材料成核的影响：实验和模型

在这项研究中，使用偏光光学显微镜（POM）和流变法研究了短碳纤维（SCF）增强的全同立构聚丙烯（iPP）复合材料的剪切诱导结晶。尽管在选择的条件下，SCF在静态熔体中对iPP没有显示出成核能力，但在施加剪切后观察到了不同的界面形态。POM结果表明，沿SCF的微晶形态强烈依赖于剪切速率（$\dot{\gamma }$）和剪切持续时间。提出了一种成核动力学模型，以确定剪切如何影响被跨晶覆盖的SCF的分数。SCF的成核速率与${\dot{\gamma }}^{ñ}$。成核速率的依赖性与熔体剪切诱导的自由能的变化非常吻合，表明SCF和iPP之间的相互作用微不足道。流变学结果表明，构象有序直接影响成核速率。由于剪切力的增加，SCF附近的螺旋含量迅速增加。因此，SCF表面的成核动力学显着加快。