Satoh Hiroki, Morita Ayumu, Arao Yoshihiko
Department of Applied Mechanics and Aerospace Engineering, School of Fundamental Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26, Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan.
Materials (Basel). 2025 Feb 20;18(5):926. doi: 10.3390/ma18050926.
Short fiber-reinforced thermoplastic composites (SFRTPs) have excellent recyclability and processability, but their mechanical properties are weak compared to continuous fiber products. Various studies have reported that the addition of GNPs improves the mechanical properties of SFRTPs, but it is unclear what effect different types of reinforcing fibers have on a hybrid composite system. In this study, the effect of adding a small amount (1 wt%) of graphene nanoplatelets (GNPs) to fiber-reinforced polypropylene composites on their mechanical properties was investigated from a crystallinity perspective. GNPs were mixed with polypropylene (PP)/carbon fiber (CF) or PP/glass fiber (GF) using a melt blending process, and composites were molded by injection molding. The results of mechanical property characterization showed no significant effect when GNPs were added to PP/CF, but when GNPs were added to PP/GF, this increased the composite's tensile strength and Young's modulus by approximately 20% and 10%, respectively. The interfacial shear strength (IFSS) predicted using the modified Kelly-Tyson equation did not change much before and after the addition of GNPs to PP/CF. On the other hand, the IFSS increased from 10.8 MPa to 19.2 MPa with the addition of GNPs to PP/GF. The increase in IFSS led to an increase in the tensile strength of PP/GF with the incorporation of GNPs. Differential scanning calorimetry (DSC) indicated that GNPs accelerated the crystallization rate, and the X-ray diffraction (XRD) results confirmed that GNPs acted as a crystal nucleating agent. However, CF was also shown to be a nucleating agent, limiting the effect of GNP addition. In other words, it can be said that the addition of GNPs to PP/GF is more effective than their addition to PP/CF due to the differential crystallization effects of each fiber.
短纤维增强热塑性复合材料（SFRTPs）具有出色的可回收性和加工性能，但其机械性能与连续纤维产品相比仍较弱。各种研究报告称，添加石墨烯纳米片（GNPs）可改善SFRTPs的机械性能，但不同类型的增强纤维对混合复合体系有何影响尚不清楚。在本研究中，从结晶度角度研究了向纤维增强聚丙烯复合材料中添加少量（1 wt%）石墨烯纳米片（GNPs）对其机械性能的影响。使用熔融共混工艺将GNPs与聚丙烯（PP）/碳纤维（CF）或PP/玻璃纤维（GF）混合，并通过注塑成型制备复合材料。机械性能表征结果表明，向PP/CF中添加GNPs时没有显著影响，但向PP/GF中添加GNPs时，复合材料的拉伸强度和杨氏模量分别提高了约20%和10%。使用修正的凯利-泰森方程预测的界面剪切强度（IFSS）在向PP/CF中添加GNPs前后变化不大。另一方面，向PP/GF中添加GNPs后，IFSS从10.8 MPa增加到19.2 MPa。IFSS的增加导致PP/GF在加入GNPs后拉伸强度增加。差示扫描量热法（DSC）表明GNPs加速了结晶速率，X射线衍射（XRD）结果证实GNPs起到了晶核剂的作用。然而，CF也被证明是一种成核剂，限制了添加GNPs的效果。换句话说，可以说由于每种纤维的结晶差异效应，向PP/GF中添加GNPs比向PP/CF中添加更有效。
