Properties of polylactic aicd/polycaprolactone/montmorillonite (PLA/PCL/MMT) nanocomposites

Abstract

Polylactid acid/Polycaprolactone (PLA/PCL) nanocomosites consisting of organically modified montmorillonite (organoclay) toughened with Metallocene catalysed Linear Low Density Polyethylene (mLLDPE) was prepared PLA/PLC of composition 70/30 with fixed mLLDPE content of 10 phr while MMT in 1, 2, 4 phr was produced. Correspond toughened nanocomposites were prepared by using a twin screw extruder then injected into typical speciments using an injection molding machine. The effects of mLLDPE and MMT on mechanical, thermal and thermomechanical properties of the PLA/PCL blend were investigated. The mechanical properties of the nanocomposites were studied through tensile, flexural and impact test. The thermal properties were characterized by using differential scanning calorimeter (DSC) and thermogravimetry analysis (TGA). The dynamic mechanical analysis (DMA) was used to investigate the effects of dynamic forces at various temperatures. mLLDPE toughened nanocomposites showed relatively lower tensile strength and flexural modulus compared to PLA/PCL nanocomposites and it was concluded from mechanical test that MMT increased tensile strength and flexural modulus of all nanocomposites at lower contents. On the other hand, impact strength and elongation at break of the mLLDPE toughened nanocomposites was higher than that of PLA/PCL nanocomposites and MMT loadings exhibited a reductive effect on impact strength of nanocomposites. The crystallization temperature and melting temperature of the nanocomposites did not change siginificantly while the thermal stability of the nanocomposites improved with incorporation of MMT. Storage modulus of nanocomposites below glass transition temperature increased with increasing MMT content.