DOPO改性环氧化聚丁二烯的制备及其在PLA阻燃改性中的应用

Preparation of Epoxidized Polybutadiene Modified by DOPO and Its Application in Flame Retardant Modification of PLA

通过两步反应制备含9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)的大分子阻燃剂:第一步,对聚丁二烯的双键进行部分环氧化(环氧化程度分别为20%和30%),得到环氧化聚丁二烯(EPB);第二步,DOPO与EPB反应得到两种阻燃剂EPB20%–DOPO与EPB30%–DOPO。利用核磁共振氢谱与傅里叶变换红外光谱确定阻燃剂的化学结构,通过热重分析得到EPB20%–DOPO与EPB30%–DOPO的初始热分解温度分别为309.6℃和193.1℃。将两种阻燃剂与PLA复合制备PLA阻燃复合材料,测试了其热稳定性、流变行为、阻燃性能以及拉伸性能。结果表明,与纯PLA相比,复合材料的初始热分解温度有所降低,但高温热稳定性得到提高,EPB–DOPO的加入减小了复合材料的黏度。添加质量分数为10%和15%的EPB30%–DOPO后,复合材料的极限氧指数由纯PLA的21.0%分别提升至28.0%和28.5%,垂直燃烧阻燃等级均达到V–0级。添加EPB20%–DOPO后,复合材料的断裂伸长较纯PLA变大,而添加EPB30%–DOPO时,断裂伸长率减小,两种阻燃剂均使复合材料的拉伸强度降低。

The macromolecular flame retardants were prepared by two steps:first,the double bonds of polybutadiene were partially epoxidated (the epoxy degree was set to 20% and 30%) to obtain epoxidated polybutadiene (EPB),and second,the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was reacted with EPB to obtain two products with different epoxy degrees,EPB20%–DOPO and EPB30%–DOPO.The chemical structure of the product was determined with ~1H–NMR and FTIR.TG test results show that the initial thermal decomposition temperatures of EPB20%–DOPO and EPB30%–DOPO are 309.6℃ and 193.1℃,respectively.Then,the poly(lactic acid) (PLA) flame-retardant composites were prepared by blending PLA with EPB20%–DOPO and EPB30%–DOPO as macromolecular flame retardants,and the thermal stability,rheological behavior,flame retardant properties and tensile properties of the composites were characterized.The results show that,compared with pure PLA,the initial thermal decomposition temperatures of the composites decrease,but the thermal stability at high temperature increases,and the addition of EPB-DOPO reduces the viscosity of the system.When 10 wt% and 15 wt% EPB30%–DOPO were added,the limiting oxygen index of PLA flame retardant composite increases from 21.0% of pure PLA to 28.0% and 28.5% respectively,and V–0 flame retardant level of vertical combustion can be achieved.When EPB20%–DOPO is added,the elongation at break of the composite is larger than that of pure PLA,while when EPB30%–DOPO is added,the elongation at break decreases,and both of them reduce the tensile strength of the PLA flame retardant composite.