Recently, carbon fiber reinforced thermoplastics (CFRTP) have been widely used for various applications instead of carbon fiber reinforced thermosetting plastics (CFRP). Some matrix resins of CFRTP are crystalline polymers such as polyamide (PA), polyetheretherketone (PEEK), and polyimide. In this study, carbon fiber reinforced polyamide 6 was used, and the effect of crystal state of PA6 on the mechanical properties of CFRTP was investigated. To understand the crystal state of PA6, Differential scanning calorimetry (DSC) analysis was carried out, and an increase in the heat treatment time increased the crystallinity of PA6. The results of bending tests showed that there was a relationship between bending strength and crystallinity, however, longer heat treatment time decreased Young’s modulus. The results of acoustic emission (AE) analysis and fractography showed that 30-h heat treatment made the matrix resin of CFRTP more brittle. To investigate the reason for this behavior, the DSC analysis of CFRTP was carried out. After the 30-h heat treatment, the crystal state was different compared to that of other materials. Therefore, bending properties are affected by the crystal state. Consequently, the crystal state must be considered to create CFRTP with desired properties.

近年来，碳纤维增强热塑性塑料（CFRTP）代替碳纤维增强热固性塑料（CFRP）已广泛用于各种应用。CFRTP的某些基体树脂是结晶聚合物，例如聚酰胺（PA），聚醚醚酮（PEEK）和聚酰亚胺。在这项研究中，使用碳纤维增强聚酰胺6，并研究了PA6的晶态对CFRTP力学性能的影响。为了理解PA6的晶体状态，进行了差示扫描量热法（DSC）分析，并且热处理时间的增加增加了PA6的结晶度。弯曲试验的结果表明，弯曲强度与结晶度之间存在关系，但是，较长的热处理时间降低了杨氏模量。声发射（AE）分析和分形分析的结果表明，30小时的热处理使CFRTP的基体树脂更脆。为了调查此行为的原因，对CFRTP进行了DSC分析。经过30小时的热处理后，其晶体状态与其他材料相比有所不同。因此，弯曲性能受晶体状态的影响。因此，必须考虑晶态以产生具有所需性质的CFRTP。