Npmi-st Copolymers Pa6 And Heat-resistant Copolymer Compatibility

The copolymers of maleimide are excellent heat-resistant modifiers, because they can improve heat resistance of materials without influencing their other properties. In this work, N-phenylmaleimide(NPMI) and styrene(St) were selected to be copolymerized. NPMI was used as heat-resistant monomer and St to improve the melt flowability of the copolymer. NPMI-co-St random copolymers were synthesized by semi-batch solution polymerization with benzoyl peroxide as initiator and cyclohexanone as solvent. The contents of NPMI in copolymers were in the range from 17%～55% by varying the feed ratios of monomers. The contents of components in copolymers were measured by elemental analysis and the relationship between NPMI monomer feeding fractions and its contents in copolymers can be obtained. It can be found that the contents of NPMI in copolymers are higher than its feeding contents in monomer mixture because NPMI monomer is more active than St monomer in copolymerization. The chemical compositions and structures of the copolymers were characterized by FTIR and 13C NMR respectively. It was proved that the copolymers have random chain structure and the feature of the copolymers can improve the compatibility with the resins which need to be modified. The glass transition temperatures of copolymers were determined by DSC and the relationship between NPMI contents in copolymers and heat resistance of copolymers can be obtained. The glass transition temperature of copolymer became higher with the larger NPMI content in copolymer. When NPMI feeding fractions was 18 wt%, its content in copolymer was 40 wt%, and the glass transition temperature of copolymer reached 191℃. The copolymers with NPMI contents more than 40 wt% can be synthesized by increasing NPMI feeding ratios, but their glass transition temperature were not improved by a wide margin. The copolymers all have one glass transition temperature, and this result shows that the copolymers are homogeneous in chemical compositions. The copolymers were investigated TGA and the heat stability of the copolymers were improved obviously with the increasing contents of NPMI in the copolymers. The initial thermo decomposition temperatures of all copolymers were higher than 316℃, and this results show that the heat-resistant copolymers can meet the demand of plastic process.Besides the study on synthesizing of NPMI-co-St random copolymers, the work on blending of N-phenylmaleimide-styrene-maleic anhydride heat-resistant copolymers has been done.Three kinds of blends with different chemical components were prepared by melt blending:styrene-acrylonitrile random copolymer(SAN)/polyamide 6(PA6), N-phenylmaleimide-styrene-maleic anhydride(NSMA)/PA6, (NSMA/SAN)/PA6. SAN is the major component of acrylonitrile-butadiene-styrene (ABS), than SAN/PA6 blend can be regarded as the simple edition of ABS/PA6 blend. The aim of study on SAN/PA6 blend is to investigate the compatibility of ABS/PA6 alloy. The NSMA/PA6 blend can reflect the interaction between NSMA and PA6 and The (NSMA/SAN)/PA6 blend can represent simple edition of NSMA/ABS/PA6. The molecular chains of NSMA not only have heat resistant unit—NPMI, but also have maleic anhydride(MAH) functional groups which can react with amine groups of PA6. Therefore, the heat resistant modifier can be used as reactive compatiblizer in the blends.The three different composition blends were characterized by FTIR. The results showed that there were NSMA-PA6 graft copolymers in the blends of NSMA/PA6 and (NSMA/SAN)/PA6 because of in-situ reaction. There was not formed graft copolymers in blend of SAN/PA6. The morphologies of blends were observed by SEM. Because of the effective compatibilization of these formed NSMA-PA6 graft copolymers at the interface, finer dispersed phase morphologies were obtained in blends of NSMA/PA6 and (NSMA/SAN)/PA6. With the finest phase morphologies, the sizes of dispersed particles were small and the uniform dispersion can be obtained in (NSMA/SAN)/PA6. The thermal and rheological properties of these blends also were investigated. The relationship between propertis of blends and their structures can be found out.