engleski

EFFECT OF UV IRRADIATION ON THERMAL AND MECHANICAL PROPERTIES OF MATERIALS

Due to environmental concern and environmental protection a great attention has been developed for degradable polymers, especially in packaging industries that is greatly responsible for large accumulation of polymer waste. A possible solution to reduce the considerable amount of polymer waste while maintaining low prices and good quality of the products is to induce a certain level of biodegradability by blending synthetic polymers with biodegradable polymers such as starch. So, on the other hand it is very important to accelerate and enhancement their biodegradability. One of the well-known and simple methods is UV irradiation or heat treatment that leads to the formation of functional groups in hydrophobic polymer chains making them sensitive to further microbial attack thus accelerating their biodegradability. The objective of this work is to investigate the effects of UV irradiation on the properties of biodegradable blends of low-density polyethylene, LDPE, and thermoplastic starch, TPS. The thermoplastic starch was prepared by melting with glycerol as a plasticizer in a single screw Brabender extruder, while the biodegradable blends, LDPE/TPS, were prepared using a Brabender kneading chamber and compression molded in a hydraulic press. The prepared biodegradable blends with a different proportion of individual components were submitted to treatment with UV irradiation (wavelength 290 nm) for 30 days. The changes in mechanical properties, such as tensile strength and elongation at break have been investigated. Also, thermal changes of the biodegradable blends have been measured using the differential scanning calorimetry and the thermogravimetric analysis. UV irradiation causes photooxidative degradation mainly in the amorphous regions of the blends due to the direct absorption of photons on the surface of the polymer chain which results in breaking of the polymer chains, branching, networking, producing free radicals and reducing the molecular weight, causing deterioration of thermal and mechanical properties.

biodegradable blends, UV irradiation, thermal properties, mechanical properties

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