Study of the processing conditions of PCL/clay nanocomposites: molecular weight degradation, thermal and mechanical properties

LEANDRO LUDUEÑA; VERA ALVAREZ; JOSÉ KENNY; ANALÍA VAZQUEZ

Ascona

Congreso; 10th International conference on flow processes in composite materials (FPCM10; 2010

Packaging is the biggest industry of polymer processing. Food industry is its principal customer. Despite environmental problems, polymer packaging European market is increasing in about millions of tons per year. Foreseeing future laws about reducing the weight and volume of these products, cheap and biodegradable polymeric products are receiving growing attention. Polycaprolactone (PCL) belongs to this class of synthetic biodegradable polymers. PCL is linear, hydrophobic and partially crystalline polyester that can be slowly consumed by micro-organisms. The performance of PCL can be greatly enhanced by the dispersion of nanometer-size particles. From previous works it was found that 5 wt. % of montmorillonite modified with dimethyl, dehydrogenated tallow, quaternary ammonium (C20A) leads to the best dispersion degree of the reinforcement inside the PCL matrix. In this work the effect of processing conditions on the morphology, molecular weight and mechanical and thermal properties of the pure matrix and PCL/C20A nanocomposites was studied. For this porpoise the resident time (2, 3 and 4 minutes), the temperature profile along the compounder barrel ([60,80,100]°C; [60,90,120]°C; [70,100,130]°C) and the screw rotation speed (50, 100 and 150 rpm) were changed from the reference processing condition (2 min;[60,90,120]°C;100rpm). The as extruded materials were characterized by transmission electron microscopy in order to analyze the clay morphology, gas permeation chromatography to study the possibility of polymer molecular weight degradation by severe processing conditions and differential scanning calorimetry to find differences in the crystallinity of the matrix. Then, films 0.5mm thick were prepared by compression molded to be mechanically characterized by static tensile tests.