Preparation of Thermoplastic Blends Filled with Polysaccharide and Study of Their Properties Before and After Ageing

Modification of the processability and functional properties of polymeric materials is widely used in polymer processing. The work deals with blends preparation of low-density polyethylene (LDPE) filled with carboxymethyl starch (CMS) with degree of substitution DS = 0.3 in four different amounts (5, 10, 15 and 20 wt%), and examination of their properties before and after ageing in variation of climatic conditions and heat light ageing. The effect of light, heat and variation of climatic conditions on the appearance, mechanical properties, structure and overall degradation of the material was observed through infrared spectroscopy (IR), determination of Vicat softening temperature (VST), colorimetry and scanning electron microscopy (SEM). The samples after heat light ageing and ageing in variation of climatic cycles showed a change in color, which was measured using a spectrophotometer and evaluated using a greyscale. As the CMS content in blends increased, the Vicat softening temperature decreased. Slight increase of VST of all blends occurred after ageing in variation of climatic conditions. After heat light ageing moderately significant decrease of VST was determined. This is indicating that the mechanical properties of blends were affected mainly by the exposure to light in the environment with elevated temperature. Comparison of IR spectra and SEM imaging of structure of LDPE/CMS blends before and after ageing confirmed expected influence of ageing on structure, appearance and overall quality of polymer blends with polysaccharide filler.