Preparation Of PE/MMT Nanocomposites

This work first prepare Ziegler-Natta catalyst loading on MMT, then preparePE/MMT nanocomposites by in situ polymerization, and research the properties of thenanocomposites.Analyze the effects of alcohol content, the type of alcohol, MMT content onpolymerization activity and the products bulk density. The results show that whenalcohol is isooctanol/butanol mixed alcohol, MgCl₂/alcohol molar ration equals2.6,ester is tetraethyl orthosilicate（TEOS）, TEOS/MgCl₂molar ration equals0.5,MMT/MgCl₂mass ratio equals4, Al/Ti molar ratio equals10～40, the bulk density ofnanocomposites is highest.Morphology of catalyst and PE/MMT nanocomposites are characterized by SEMand XRD. The results show that the displace of MMT slices are up to1.30nm from1.10nm, the morphology of catalyst is copied from MMT carrier, the diffraction o fMMT in the nanocomposites are disappeared indicated that the structure of PE/MMTnanocomposites are exfoliated. The dispersion of MMT in the PE matrix ischaracterized by TEM, the result shows that when MMT content is less than1.2%,MMT disperses in PE matrix without orientation, while when MMT content is morethan1.2%, part of MMT slices Present partial order phenomenon. These indicate thatthe structure of PE/MMT nanocomposites transfers from exfoliated to interclated.Crystalline form is characterized by PLM, the result show that with the increase ofMMT content, the nucleation density of the nanocomposites decreases while the crystalnucleus size increases.Melting temperature and crystallization is studied by DSC. The result show thatwith the increase of MMT content, the melting temperature of the nanocompositesincreases while the crystallization temperature nearly remain unchanged. Thecrystallization behavior of the nanocomposites confers to Avarmi equation, thecrystallization rate of1.2%MMT content nanocomposites greater than5.7%MMTcontent. Thermal property is researched by the TG. The result shows that at the sameheating temperature the thermal beginning degradation temperature of PE5increasesabout22than PE1which indicates that the addition of MMT can improve the thermalstability of the nanocomposites. When the heating rate increases from5/min to20/min, the theramal ending temperature increases50, the thermal degradationrange increases from69.6to105.3which indicates that the increase of the heatingrate is in favor of the thermal stability.Mechanical properties of the nanocomposites are characterized. The results showthat with the increase of MMT addition, both tensile strength and the elongation of thenanocomposites first increase then decrease, when the MMT content is2.6%, thecomprehensive performance of the nanocomposites is best, the tensile strength is39.7Mpa, the elongation at break is103%.