Influence of accelerated weathering on the thermo-mechanical, antibacterial, and rheological properties of polylactic acid incorporated with porous silica-containing varying amount of capsicum oleoresin

The polylactic acid is modified with porous silica-containing varying amount of capsicum oleoresin. The effect of accelerated weathering on the polymer degradation, thermomechanical, antibacterial, and rheological properties was studied. The accelerated weathering test was performed for 260 and 520h. The prepared composites show antimicrobial activity against gram-positive and gram-negative bacteria. The tensile strength, modulus, and percentage crystallinity of the composites increased by 17, 7, and 33% respectively with the addition of 1.54 wt% of capsicum oleoresin impregnated porous silica. On the other hand, the incorporation of capsicum oleoresin impregnated porous silica reduced shear modulus and shear viscosity of the composite films. The accelerated weathering, reduced tensile properties, thermal stability, and rheological properties; however, the percentage crystallinity was increased due to the chain scission of the polymer chains. The combination of ultraviolet irradiation, temperature, and humidity caused by the weathering test marginally reduced the antibacterial properties of the polymer films.