Effect of Nano Fillers on the Production and Properties of LLDPE Using In-Situ Polymerization

Abstract

Linear low density polyethylene (LLDPE) was synthesized using in-situ polymerization of ethylene with various alpha olefins (comonomers). Zirconocene/MAO was used as catalyst/cocatalyst complex. The comonomers used under study were 1-hexene, 1-octene, and 1-decene. In this study, the effect of comonomers on the catalytic activity, melting temperature (Tm), degree of crystallinity (DOC), melt crystallization behavior and lamellar thickness distribution (LTD) were evaluated. A higher catalytic activity was recorded in the presence comonomers. Further, the comonomers have added more short chain branching (SCB) to the copolymers, which corresponds to lower DOC and Tm. The Mo crystallization model perfectly explained the crystallization behavior of the copolymers for all cooling rates under study. The modified Gibbs-Thomson equation was utilized to observe the melting behaviors and LTD of the copolymers. Moreover, the activation energies (EA) were calculated using Kissinger method. The 1-hexene comonomer exhibited the lowest EA. Overall, crystallization was found, to be more effected by the degree of branching rather than the comonomer type. In another study, LLDPE nanocomposites were synthesized in the presence of nano titania doped with 1 % (TiO2/Mn), used as a drop-in nanofiller. The comonomer selected for this study was 1-hexene, based on our previous findings. The nanofiller added more SCB to the polymer backbone and as result decreased the DOC and Tm. The nonisothermal crystallization behavior of the synthesized polymer nanocomposites were studied by Ozawa and Mo models. Additionally, the EA of the nanocomposites were calculated using Kissinger method. An increased EA profiles were observed, confirming a slower crystallization process in the presence of nano filler. Further, graphene/layered double hydroxides (G/LDHs) hybrid nanofillers were synthesized by co-precipitation technique and were successfully characterized using different characterization techniques. The hybrid G/LDHs based ethylene-co-1-hexene nanocomposites were synthesized using in-situ polymerization. The activity of the zirconocene catalyst was boosted in the presence of hybrid nanofillers. Moreover, the synthesized polymer nanocomposites have shown improved thermal stability. EA for the synthesized polymer nanocomposites were calculated using Friedman iso-conversional method. The G/LDHs based polymer nanocomposites have shown higher EA (more thermal stability) compared to bare LDHs based nanocomposites, because of the superior thermal properties inherited by these hybrid nanofillers.