可瓷化交联乙烯-醋酸乙烯共聚物复合材料的制备与性能

Preparation and Properties of Ceramifiable Ethylene-Vinyl Acetate Copolymer Composites with Three Dimensional Cross-Linking Structures

采用过氧化二异丙基苯(BIPB)作为交联剂对乙烯-醋酸乙烯共聚物(EVA)进行交联改性。红外光谱和凝胶质量分数测试证明改性后的EVA形成了一种交联结构,其凝胶含量约为99.3%。进一步研究了EVA/硅酸盐玻璃粉(SGF)/聚磷酸铵(APP)复合体系中基体的交联程度,其值为98.8%,表明填料的添加对基体的交联反应几乎没有影响。动态流变分析表明,交联改性EVA复合材料比未改性的具有更高的剪切黏度和熔体强度。热重分析表明,交联改性能够提升复合材料的热稳定性,质量损失为5%时的温度为329℃,高于未改性的311℃。耐火性能测试表明,交联改性复合材料的烧蚀残余物弯曲强度随烧蚀温度的升高而增大,在1000℃时的弯曲强度是未改性样品的1.94倍,并且在烧蚀过程中能够很好地支撑其残渣质量,扫描电镜图片也显示其陶瓷体的结构更致密、表面裂纹相对更少。因此,基体的交联改性改善了材料的耐火性能。

The ceramifiable ethylene-vinyl acetate copolymer(EVA)composite with three dimensional cross linking structures was prepared by using bis(tertbutylperoxy)diisopropyl benzene(BIPB)as cross-linking agent.The FT-IR spectra and the value of gel content as 99.3%prove that the cross-linking structures are formed.The cross linking degree in the EVA matrix with silicate glass frits(SGF)and ammonium polyphosphate(APP)as additives was studied.The value of gel content as 98.8%suggests that the SGF and APP show no effect on the cross-linking reaction.Dynamic rheological analysis show that the cross-linked EVA composite has the higher shear viscosity and melt strength than the unmodified EVA composite.Thermogravimetric analysis(TGA)results indicate that the cross linking modification can improve the thermal stability of the composite.The cross-linked EVA composite exhibits a higher T_(5%)(T_(5%)=329℃)than the unmodified EVA composite(T_(5%)=311℃).The fire resistance test show that the flexural strength of ceramics residues of the cross-linked EVA composite increases with the increase of ablation temperature,the flexural strength is 1.94 times that of the unmodified sample at 1000℃,and can well support the mass of the residues in the ablation process,which is also shown by SEM that the surface structures of the residues of the cross-linked EVA composite are more continuous and compact at corresponding temperatures than unmodified sample.Therefore,the cross-linking structures in the matrix improve the fire resistance of the material.