一种无卤阻燃乙烯-醋酸乙烯酯共聚物的热分解动力学研究

Kinetics of Thermal Degradation of Halogen-free Flame-retarded Ethylene-Co-Vinyl Acetate

通过极限氧指数法(LOI)和垂直燃烧(UL-94)测试考察了一种无卤阻燃乙烯-醋酸乙烯酯共聚物(EVA)的阻燃性能;利用热重分析法(TG)研究了纯EVA及阻燃EVA在不同升温速率下的热稳定性及热分解动力学,并采用Kissinger及Flynn-Wall-Ozawa方法计算了纯EVA和阻燃EVA的热分解表观活化能。结果表明,添加40%复合膨胀阻燃剂的EVA复合材料,极限氧指数达到28.6%,UL-94测试达到V-0级,残炭量相对纯EVA明显提高;随着升温速率增大,EVA和阻燃EVA的起始失重温度和各阶段的失重峰温均向高温方向移动;二者在第一阶段的热分解活化能均低于第二阶段,阻燃剂的添加使EVA的最大失重速率明显降低,热分解表观活化能提高,增强了材料的热稳定性和阻燃性。

The flame retardant property of a halogen-free flame-retarded ethylene-co-vinyl acetate（FR-EVA） was studied by limiting oxygen index（LOI） and vertical burning（UL-94） test.The thermal stability of neat EVA and FR-EVA were investigated by dynamic thermogravimetric analysis（TGA） at different heating rates.Kissinger and Flynn-Wall-Ozawa equations were used to compute the weight loss data and calculate the thermal degradation activation energies of neat EVA and FR-EVA.Results show that,when 40 wt% flame retardant are added,the LOI value for FR-EVA improves from 19.0 % to 28.6 % for EVA,the burning grading reaches to UL-94 V-0 rating,and the amount of residues increase significantly.The onset decomposition temperature and the weight loss peak temperature of neat EVA and FR-EVA increase with the increase of the heating rate.The apparent activation energies of thermal decomposition of EVA and FR-EVA in the first stage are both lower than that of the second stage.The reduction of maximum weight loss rate and the increasing of thermal degradation activation energy indicate that the flame retardant property and thermal stability of EVA is improved by flame retardant.