Effect of silane concentration on the properties of crosslinked linear low density polyethylene-montmorillonite nanocomposite

摘要

In this study, linear low density polyethylene (LLDPE) was grafted and crosslinked by reactive extrusion melt compounding using different silane concentration with and without the presence of montmorillonite (MMT) nanoclay. The effects of different silane concentration and the addition of nanoclay filler on the degree of crosslinking, mechanical, thermal, rheological, and morphological properties were investigated and reported. Gel content results for all crosslinked samples were found to increase with increasing silane concentration. Tensile strength and Young's modulus of crosslinked LLDPE samples increased with increasing silane concentration compared to neat LLDPE; while the crosslinked LLDPE samples containing nanoclay have achieved higher tensile strength and Young's modulus, indicating strong interfacial interaction between silane grafted LLDPE matrix and nanoclay. However, the decrease of elongation at break for all crosslinked samples were observed compared to neat LLDPE. A reduction in the degree of crystallinity for crosslinked samples, particularly crosslinked samples containing nanoclay, was shown by thermal analysis results; whereas the melting temperature did not change significantly with increased silane concentration and subsequent addition of nanoclay. Thermogravimetric analysis results have revealed significant thermal stability improvement for neat LLDPE with increased silane concentration. Furthermore, crosslinked samples containing nanoclay have achieved better thermal stability compared to crosslinked samples without nanoclay. At lower frequency, it was found that viscosity, and storage modulus of neat LLDPE increased with increased silane concentration due to crosslinking and further addition of nanoclay into crosslinked LLDPE. The transmission electron microscopy results confirmed the intercalated structure of the nanocomposite for the crosslinked samples containing nanoclay.