Graphite fluoride reinforced PA6 composites: Crystallization and mechanical properties

Abstract

Graphite fluoride (GrF) platelets were directly incorporated into polyamide 6 (PA6) by simple melt processing without using any surfactant. Due to the hydrogen bonding interaction between the filler and the matrix, GrF at a low loading shows good dispersion and partial exfoliation in PA6, as illustrated by scanning electron microscope and X-ray diffraction (XRD) measurements. The XRD results also reveal that the dominant γ-crystal in the neat PA6 converts to a relatively high content of α-crystal in the composites. Moreover, GrF has been found to be able to promote the mobility of the PA6 molecular chains, then favors the formation of α-crystal. Differential scanning calorimetry analysis demonstrates that GrF can act as heterogeneous nucleation agents to improve the onset of the crystallization temperature of PA6. Furthermore, tensile tests show that PA6 with 0.5 wt% GrF has an optimal improvement in elastic modulus and tensile strength by about 21.4% and 9.8%, respectively. Our current studies illustrate that good dispersion and partial exfoliation of GrF platelets in PA6, good adhesion between GrF and PA6, and more stable α-crystal formed in the matrix together contribute to the high-performance of the PA6/GrF composites at a low filler loading.