Preparation And Properties Of Organic Silicon Blocked Polyurethane/epoxy Acrylates IPN

Due to the unique molecular structure of polyurethane, the products of PU has properties of abrasion resistance, cohesiveness, solvent resistance and excellent processability. Polyether-urethane has good low temperature flexibility, hydrolysis resistance and excellent processability but poor mechanical property and heat resistance limits its application. In this paper, the PU was modified by silicone and epoxy acrylic resin. Based on the two systems of modified PU(PUS) and the epoxy acrylate(EA), the PUS/EA IPN which has good mechanical property and high heat resistance were prepared.(1) Polyether polyurethane pre polymers modified by the hydroxyl silicone oil were synthesized. And then we synthesized the epoxy acrylate and the modified epoxy acrylate by using the KH570. In this paper, the chemical structure and thermal performance were studied by FTIR, SEM, DSC, TG and universal testing machine. When the content of hydroxyl silicone oil was 5%, the PUS has excellent performance. Its tensile strength was 1.56MPa, breaking elongation was 425%, its glass transition temperature was in the range of-48.3 ～-30.2 ℃ and the thermal decomposition temperature was 356.9 ℃. The SEM pictures showed that there was microscopic phase separation structure insist which affects the PUS’mechanical properties. The result of ultraviolet aging properties analysis indicate that the PUS has better environmental resistance than the PU.(2) In this paper, the EA was synthesized by using the low viscosity epoxy resin and acrylic acid at 110℃with four butyl bromide as catalyst and 2.6-di-tert-butyl-para-cresol as the polymerization inhibitor. And the EA was modified with KH570 which capends the hydroxies on EA and introduces double bonds. The thermal properties of EA and EAS were analyzed and their structures were performed by FTIR.(3) In this paper, the PUS/EA grafted IPN and the PUS/EA IPN were synthesized by bulk polymerization. The result of mechanical property test showed that the tensile strength of grafted IPN increased with the increasing of EA, however, it begun to reduce when the EAS content was 30%. It can be seen that the tensile strength of the grafted IPN was 7.5MPa when the content of EA was 20%, and the breaking elongation was 280%. The tensile strength of the IPN was 8.19MPa when the content of EAS was 30%, and the breaking elongation was 400%.(4) The thermal analysis showed that the grafted IPN and IPN has single Tg. The glass transition temperature of grafted IPN was in the range of-49.1 ℃ ～-36.4 ℃, the IPN was-40.5 ℃～-18.8 ℃. The thermal decomposition temperature of grafted IPN was 359.9 ℃ and the IPN was 359.0 ℃. Both of them were higher than the thermal decomposition temperature of PUS which was 356.9 ℃. And the thermal decomposition temperature increased with the increasing of the content of EAS.(5) The morphological structure and phase separation were studied by the SEM. The result indicated that the net-work structure formed in the grafted IPN and the IPN. It has microscopic phase separation structure between PUS and EA(s). And the microscopic phase separation structure could improve the performance of materials within limits.