Highly efficient load transfer in polypropylene/vapor grown carbon fiber nanocomposites

The alignment of fillers and the filler-matrix interfacial adhesion are crucial factors for improving the mechanical properties of nanocomposites. This study focuses on these effects in the melt-spun vapor grown carbon fibers and polypropylene (VGCFs/PP) composite fibers. By using different draw ratio, the alignment of VGCFs and the interfacial crystalline structure in the as-spun fibers can be easily controlled. Tensile testing showed that remarkable enhancements in tensile strength and modulus were achieved at high draw ratio. Topographic analysis of the fractured surfaces indicated that the enhancements were directly related to the strong interfacial adhesion and effective stress-transferring effect during the tensile test. Further analysis showed that the strong interfacial adhesion might be the result of stretching-induced transcrystalline structure. Our study sets a good example to realize a remarkable reinforcement in semicrystalline polymer composites by controlling the interfacial adhesion and filler alignment in a simple but efficient way.