线型低密度聚乙烯-氢氧化镁复合阻燃材料的改性

Modification of Linear Low Density Polyethylene-Magnesium Hydroxide Flame Retardant Composites

以一种商业化的Mg(OH)2为阻燃剂,以线型低密度聚乙烯(LLDPE)为高分子基材,采用两步法制备了LLDPE-Mg(OH)2复合阻燃材料(简称复合阻燃材料),考察了5种硅烷偶联剂对复合阻燃材料的改性效果,并从硅烷偶联剂的分子结构出发讨论了硅烷偶联剂对复合阻燃材料性能的影响。实验结果表明,Mg(OH)2粒子经5种硅烷偶联剂改性后粒径及其分布均有不同程度的增大和变宽;经KH-560(γ-缩水甘油醚氧丙基三甲氧基硅烷)偶联剂改性的复合阻燃材料的机械性能和热稳定性较好,因为KH-560分子中长有机疏水链上的活性环氧基团有效改善了Mg(OH)2粒子与LLDPE间的相容性;SEM表征结果进一步证实,经KH-560偶联剂改性的复合阻燃材料中Mg(OH)2与LLDPE的相容性及Mg(OH)2粒子在LLDPE基体中的分散性最好。

Linear low density polyethylene （LLDPE）-Mg （OH）2 composites were prepared by a two-step method, in which a kind of commercial Mg （OH） 2 was used as flame retardant and LLDPE as polymer matrix. Effects of five different silane coupling agents on properties of the composites were investigated according to molecular structures of the surface modifiers. The experimental results indicated that both particle sizes and their distribution of Mg（OH） 2 increased after being modified with various silane coupling agents. However, composites modified by KH-560 （ 3＇-（ 2,3-epoxypropoxy ） propyl trimethoxysilane） coupling agent possessed the best mechanical properties and thermal stability, which was ascribed to that the epoxy groups on long hydrophobic chains in KH-560 coupling agent molecules efficiently enhanced the compatibility between the Mg （OH）2 and the polymer matrix. Furthermore, investigation of the composite morphology by means of SEM confirmed that the composites modified by KH-560 coupling agent showed the best compatibility and the best dispersibility of Mg （OH） 2 in LLDPE.