Mechanical and barrier properties of copolyester-nanoclay composites

This paper examines the influence of nanoclay on the structure, thermal and mechanical and gas barrier properties of a polyethylene terephthalate (PET)-based copolyester using a new modified formula. The copolyester considered in this work consists of partially replaced acid and diol monomers in main chain PET polymers, namely, polyethylene glycol (PEG) and isophthalic acid monomers, i.e., PET-IP. Nanoclays were filled from 0-3 wt% in PET-IP using the melt mixing method. The structural examination of composites tested by X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the distribution of nanolayers of clay particles in polymeric matrix. Up to 1 wt% nanoclay in PET-IP, an exfoliated structure resulted and above 1 wt% nanoclay an intercalated structure resulted. It was observed that 0.5 wt% nanoclay filled PET-IP resulted in improved nucleation characteristics and above 0.5 wt% nanoclay dramatically increased the gas transport (CO2, O-2, N-2 and water vapor), thermal and mechanical properties. The results also showed that the distribution of nanoclays affected the gas barrier properties of the polymer and can be controlled by processing parameters.