Enhanced thermal-conductive and anti-dripping properties of polyamide composites by 3D graphene structures at low filler content

In this work, 3D graphene structures constructed by graphene foam (GF) were introduced into polyamide-6 (PA6) matrix for the purpose of enhancing the thermal-conductive and anti-dripping properties of PA6 composites. The GF were prepared by one-step hydrothermal method. The PA6 composites were synthesized by in-situ thermal polycondensation method to realize PA6 chains covalently grafted onto the graphene sheets. The 3D interconnected graphene structure favored the formation of the consecutive thermal conductive paths or networks even at relatively low graphene loadings. As a result, the thermal conductivity was improved by 300% to 0.847 W·m⁻¹·K⁻¹ of PA6 composites at 2.0 wt% graphene loading from 0.210 W·m⁻¹·K⁻¹ of pure PA6 matrix. The presence of self-supported 3D structure alone with the covalently-grafted PA6 chains endowed the PA6 composites good anti-dripping properties.     

抗滴落剂对PC/KSS阻燃材料性能的影响

以聚四氟乙烯(PTFE)和苯乙烯-丙烯腈包覆改性聚四氟乙烯(简称MPTFE)为抗滴落剂,研究了抗滴落剂对聚碳酸酯(PC)/二苯基砜磺酸钾(KSS)阻燃体系的阻燃性能、透明性能和热稳定性的影响,并探讨了其阻燃机理。结果表明:加入抗滴落剂对PC/KSS阻燃体系具有防滴落的作用,但阻燃体系的透光率略有降低,雾度有所增加,其中MPTFE阻燃效果更好,对PC/KSS阻燃体系的透明性影响较小;当MPTFE为0.5份时,PC/KSS阻燃体系的阻燃等级由UL94V—1级提高到UL94V—0级。     

A flame-retardant-free and thermo-cross-linkable copolyester: Flame-retardant and anti-dripping mode of action

Flame-retardant-free and thermo-cross-linkable copolyesters have been synthesized, and their flame retardation and anti-dripping behavior as a consequence of cross-linking during combustion were investigated in detail. TG-DSC simultaneous thermal analysis, rheological analysis, and TGA established the extent and rate of the cross-linking reaction. The extent of cross-linking depends on the content of cross-linkable monomer, PEPE, and the higher the extent of the cross-linking, the better the flame retardance and anti-dripping performance of copolyesters. The large melt viscosity caused by cross-linked networks at high temperature played the most important role in anti-dripping of copolyesters. TG-FTIR results confirmed that the flame-retardant activity of copolyesters mainly took effect in the condensed phase, and XPS results indicated that the carbonization process was aromatization-dominant. SEM and Raman analysis suggested that the char layers were constituted mainly of polyaromatic species with small and uniform microstructures at the surface. Consequently, both the large melt viscosity and the formation of an especially compact char with fine microstructure resulting from cross-linking were considered as the key to the flame retardance and anti-dripping performance of the polymer when subjected to the flame.