Preparation and characterization of alkylphosphonium modified montmorillonite and linear low density polyethylene composites

Abstract

Thermally stable organo-montmorillonites (OMMTs) were successfully synthesized as filler for linear low density polyethylene (LLDPE) composites. By applying cation exchange method, naturally occurring Na+ cation in the interlayer of sodium montmorillonite (Na+-MMT) was replaced by four different alkylphosphonium ions which were trihexyltetra decylphosphonium (THTDP), triisobutyl methylphosphonium (TIBMP), tributylmethylphosphonium (TBMP) and tetrabutylphosphonium (TBP). The insertion of alkylphosphonium ions into montmorillonite (MMT) interlayer was meant to change the hydrophilic nature of Na+-MMT to organophilic. This thus enhanced the compatibility between LLDPE matrix and MMT. The OMMTs were then characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The LLDPE/OMMT composites were prepared via melt intercalation technique using an internal mixer at temperature 180oC, 80 rpm speed and 20 minutes residence time. The effect of OMMTs addition on the tensile, impact and thermal properties of LLDPE composites were evaluated. The morphologies of LLDPE/ OMMTs composites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) to characterize the nanoscale dispersion of the layered silicate.