聚硼硅氧烷阻燃剂的合成工艺及其在聚碳酸酯中的应用

采用二步合成法制备了聚硼硅氧烷阻燃剂(PB),通过改变硼酸/硅烷比、缩合温度、水解时间优化了PB的合成工艺。同时研究了PB对聚碳酸酯(PC)阻燃性能和物理性能的影响。结果表明:严格控制硼酸/硅烷比和缩合温度是制备高效阻燃PB的关键,当硼酸/硅烷比(摩尔比)为1:1、缩合温度为100℃时所制备的PB的阻燃性能最好,在PC中添加5%(质量分数)该PB阻燃剂,PC的极限氧指数(LOI)从26%提高到39.4%。在热降解过程中,PB使PC的起始降解温度降低,但可使PC的热降解速率降低,高温残炭量增加,从而提高了PC的阻燃性能。添加PB可以基本保持PC优良的力学性能。另外,PB可保持PC原有的透明性,PC/PB阻燃材料仍旧呈透明状态。

Synthesis of polyborosiloxane flame retardant and its application to polycarbonate

Polyborosiloxane(PB)was synthesized through two-step reaction by using alkoxysilanes and boric acid as raw materials and synthesis optimization was studied through adjusting boric acid /silane molar ratio,condensation temperature and hydrolysis time.The effect of PB on flame retardancy and physical properties of polycarbonate(PC)was investigated.The results showed that strict control of boric acid/silane molar ratio and condensation temperature was the key to preparation of high efficiency flame retardant PB.When boric acid /silane molar ratio was 1:1,and condensation temperature was 100℃,PB had the best flame retardancy on PC.After adding 5%(mass)of PB,LOI of PC could increase from 26% to 39.4%.Addition of PB could decrease thermal degradation onset temperature of PC.However PB decreased mass loss rate of PC and increased degradation residue of PC at 800℃.PB could promote the formation of char residue which could serve as a good insulating barrier to reduce the radiant heat of flame and lower decomposition rate of PC.Addition of PB increased tensile strength and flexural strength of PC,but decreased impact strength of PC.In addition,PB had little effect on optical properties of PC,and the PC/PB composites were still transparent.