有机硅涂层对聚碳酸酯透明件耐溶剂-应力开裂性能的影响

研究表面涂覆有机硅涂层的聚碳酸酯( Polycarbonate, PC)透明件在乙醇中的溶剂-应力开裂( Environ-mental stress cracking, ESC)行为,利用自制的环境力学测试装置考察PC/涂层体系在溶剂与应力共同作用下的应力松弛行为和表面裂纹形貌。结果表明：有机硅涂层在一定程度上改善了透明件的耐溶剂-应力开裂性能,带涂层试样在乙醇环境中的应力松弛比纯PC明显减慢,并且表面裂纹数量减少；有机硅涂层对乙醇与试样表面层的接触及扩散吸收起到有效阻隔,进而可降低溶剂对 PC 的塑化作用；涂层与 PC 基体力学性质较为匹配,在承载条件下涂层不易发生脱落开裂,在溶剂-应力共同作用过程中仍然能对 PC基体起到一定保护作用。

Effect of Surface Silicone Coating on Environmental Stress Cracking Resistance of Transparent Polycarbonate Parts

Environmental stress cracking( ESC) behavior of silicone coated polycarbonate ( PC) in ethanol was studied. Stress relaxa-tion of PC and PC/silicone coating under a combined action of ethanol and stress was measured by self-made three point bending equip-ment. After stress relaxation testing, crack morphology was observed by polarizing microscope. The results indicate that silicone coating is able to improve the stress cracking resistance of PC parts in ethanol. The coated PC shows slower stress relaxation rate and less num-ber of cracks than pristine PC. It is mainly attributed to that the silicone coating can provide barrier effect to the absorption and diffu-sion of ethanol in PC substrate. Furthermore, the mechanical properties of flexible silicone coating matched fairly well with that of PC, so that the coating is uneasy to peel off from PC substrate during the ESC testing. The silicone coating has a favorable effect to protect PC substrate from ESC under the combined action of solvent and stress.