原位聚合制备聚乙烯/蒙脱土(MMT)纳米复合材料的研究

利用MgCl₂在醇中溶解和蒙脱土(MMT)在醇中层间膨胀的特性,制备了MgCl₂/TiC_l4负载于MMT层间的MMT/MgCl₂/TiC_l4催化剂,并通过原位聚合合成了聚乙烯/蒙脱土纳米复合材料.经广角X射线衍射(WAXD)和透射电子显微镜(TEM)分析表明,蒙脱土片层在乙烯聚合过程中发生了层间剥离,以单片层或几片层共存的形式无规地分散于聚乙烯基质中.与分子量相近的纯聚乙烯相比,极低的蒙脱土含量(质量分数<1%)能使复合材料的屈服强度、拉伸强度和拉伸模量有很大提高.复合材料中蒙脱土片层以纳米尺寸在聚乙烯基质中的良好分布和对聚乙烯分子链运动的限制作用是力学性能提高的主要因素.

Preparation of Polyethylene/Montmorillonite(MMT) Nanocomposite by in situ Polymerization

Polyethylene(PE)/montmorillonite(MMT) nanocomposites were prepared by in situ coordination polymerization by using a MMT MgCl 2 TiCl 4 catalyst activated by Al(Et) 3. The catalyst was prepared by firstly diffusing MgCl 2 into the swollen MMT layers, followed by loading TiCl 4 on the inner/outer layer surfaces of MMT where MgCl 2 already deposited on. The intercalation of MMT layers by MgCl 2 and TiCl 4 was demonstrated by the enlarged spacing between neighboring layers measured from WAXD patterns. The nano scale dispersion of MMT layers in the polyethylene matrix was characterized by WAXD and TEM observation. As consequence, tensile strength and tensile modulus of the nanocomposite materials were significantly improved as compared to virgin polyethylene of comparable molecular weight. The strong interaction between the uniformly dispersed nano dispersed montmorillonite layers and the resin matrix was thought to account for the remarkably enhancement in tensile properties.