Increase The Compatibility Of PA66 And PCT With Epoxy Type Chain Extender And Epoxy Modified Nano-SiO₂

The demand for heat-resistant nylon increases as electronic components become smaller,thinner,lighter,more functional,more precise,quieter,and more heat-resistant.However,at present,the heat-resistant nylon is controlled by foreign manufacturers.PA66 has excellent mechanical properties,but the heat-resistance of PA66 is poor.As a new member of polyester family,PCT has excellent heat-resistance.In order to improve the heat-resistance of PA66,reaction extrusion was used to prepare PA66/PCT blends.At first,commercial chain extender ADR 4468 was used as the compatibilizer of PA66 and PCT.Scanning electron microscope(SEM),differential scanning calorimetry apparatus(DSC),tensile test,impact test,HDT test were used to study the microstructure,crystallization behavior,mechanical properties,heat-resistance of the PA66/PCT blends and determined the best filling amount of ADR-4468.The results showed that the PA66/PCT blend with 0.5 phr ADR had the best comprehensive performance.After annealing for 4 h,the HDT of the PA66/PCT blend was 18.1 ^oC higher than the PA66 annealed at the same condition.Then,the surface modification of nano Si O₂was performed with KH560(3-glycidyloxypropyltrimethoxysilane)and KH832(n-octyltriethoxysilane),and the modified nano-Si O₂was filled into PCTmeltto evaluate itseffect of viscosifying PCT.Then improve the method,KH560(3-Glycidyloxypropyltrimethoxysilane)and nano-Si O₂particles are filled into PET or PCT melt by extrusion process to increase the melt viscosity of the PET or PCT.When the KH560 and the nano-Si O₂particles are both filled at 2.5 phr,the melt viscosity-increasing effect is the best.Transmission electron microscopy imaging showed that the dispersion of nano-Si O₂in PET was well.The reaction mechanism between KH560,nano-Si O₂and PET was confirmed by FTIR.The grafting of PET molecules to Si O₂nanoparticles was analyzed by TGA.Finally,“KH560 and nano-Si O₂combination”was added into PA66 and PCT melt as a compatibilizer to produce PA66/PCTblends,and the microstructure,crystallization behavior,processing properties,mechanical properties and heat resistance of the composite were studied.When the addition amount of nano Si O₂and KH560 is both 0.5phr,the comprehensive performance of PA66/PCT blend is the best.After annealing at 100 ^oC for 4 h,HDT was 17? higher than PA66 annealed at the same condition.