Study On The Effect Of Isocyanate Terminated Silicone Resin On Diatomite /PBT And ABS/PBT Composites

In this thesis, diatomite/PBT, isocyanate terminated silicone resin/diatomite/ PBT, ABS/PBT and isocyanate terminated silicone resin/ABS/PBT composites were prepared by melt blending method, and using isocyanate terminated silicone resin as compatibilizer. The chemical structure, micro morphology crystallization properties, and thermal stability of composites were observed by FTIR, SEM, DSC, and TGA. The mechanical and thermal properties were tested, the influence of isocyanate terminated silicone resin on diatomite/PBT, ABS/PBT composites was discussed, and the compatibilization mechanism was analyzed.The FTIR showed that the isocyanate group in the compatibilizer react with hydroxyl of PBT, hydrolyzed methoxy group react with hydroxyl group on the surface of diatomite in isocyanate terminated silicone resin/diatomite/PBT composite; hydrolyzed cyano group of ABS react with the hydrolyzed methoxy of the compatibilizer in isocyanate terminated silicone resin/ABS/PBT composites and the compatibility of composites is improved.The SEM showed that the two-phase connection of diatomite/PBT and ABS/PBT composites are improved by the addition of isocyanate terminated silicone resin; the size of dispersed phase is reduced and evenly distributed, the interfacial adhesion force is enhanced.The result of DSC indicated that isocyanate terminated silicone resin/diatomite /PBT, isocyanate terminated silicone resin/ABS/PBT composites and PBT has the same crystal type, with the adding of compatibilizer, the movement of PBT molecular chain is hindered, the crystallization behavior of composite is hysteretic, and the crystallinity is decreased.The TGA showed that the initial decomposition temperature of PBT,isocyanate terminated silicone resin/diatomite/PBT and isocyanate terminated silicone resin /ABS/PBT composites is 359.49 oC, 369.96 oC and 368.41 oC, the residues of 480 oC is 5.92%, 16.11% and 8.53%, the thermal stability of the composites is improved.Performance analysis revealed that addition of isocyanate terminated silicone resin greatly improve the performance of diatomite/ PBT and ABS/PBT; when the mass ratio of isocyanate terminated silicone resin/diatomite/PBT is 6/10/90, the comprehensive performance is the best. The impact strength,bending strength, tensile strength, heat distortion temperature and vicat softening point is 8.92KJ/m2, 90.63 MPa, 65.53 MPa, 53.78 oC and 194.4oC, increase 73.8%, 46.86%, 32.41%, 2.01% and 9.34%.When the mass ratio of isocyanate terminated silicone resin /ABS/PBT is 3/40/60, the impact strength, bending strength, tensile strength and heat distortion temperature is 10.36KJ/m2, 92.21 MPa, 53.35 MPa and 86.20 oC, increase 101.95%, 49.42%, 7.80% and 63.51% respectively, vicat softening point is 149.10 oC, decrease 16.14%.Comparison of performance among PBT, diatomite/PBT, isocyanate terminated silicone resin/diatomite/PBT, ABS/PBT and isocyanate terminated silicone resin/ PBT/ABS composites showed that isocyanate terminated silicone resin and diatomite greatly improve the tensile strength and vicat softening point of composites; isocyanate terminated silicone resin and ABS greatly improve the impact strength and heat distortion temperature of composites.The reactivity of isocyanate group is released under high temperature, and react with the hydroxyl of PBT and generate urethane group, the hydrolyzed methoxy react with the hydroxyl groups on the surface of diatomite and the hydrolyzed cyano group of ABS. Isocyanate terminated silicone resin reduce the interfacial tension of the two-phase between diatomite/PBT and ABS/PBT composite, the compatibility is improved. Capacity of isocyanate terminated silicone resin have good effect on diatomite /PBT and ABS/PBT composites.