Influence of Carbon Nanofiber Addition on Mechanical Properties and Crystallization Behavior of Polypropylene

Carbon nanofiber (CNF)-reinforced polypropylene (CNF/PP) composites with different CNF contents were preparedby melt mixing, and the mechanical properties and crystallization behavior of the CNF/PP composites obtained wereinvestigated. It was found that the tensile modulus of the composites was increased with the addition of CNFs, buttheir elongation at break and fracture strain energy were decreased, while the tensile strength of the composites wasfirstly increased and then decreased due to the agglomeration of CNFs at higher loading. Nonisothermal crystallizationanalysis showed that the CNFs played a role as nucleating agent in PP matrix, which led to increment in thecrystallization rate and the degree of crystallinity of PP. Moreover, X-ray diffraction studies showed that the CNFsincorporated in the PP matrix favored the growth of (040)-oriented PP crystals. With the increase in the CNFcontent, the nucleating and orientation roles of the CNFs were obviously enhanced.