Studies on Preparation, Characterization and Biodegradation Behavior of Hdpe Natural Polymers Blends

Abstract

Polyethylene (HDPE) is widely used in various applications due to its chemical, physical. and biological inertness but its durability presents a great challenge when it is released in the environment. To reduce its adverse effect on environment, currently various efforts are being made to modify its properties using naturally occurring biodegradable polymers but still these modifications found to be costly and required biodegradability in polyethylene is not yet achieved. Therefore, an attempt has been made to deveop biodegradable polyethylene blends using naturally occurring polymers. In this connection biodegradable high density polyethylene (HDPE) blends were prepared by thermally blending 2.0, 5.0 and 10.0 wt % amount of naturally occurring polymers such as; chitosan (CH), cellulose(CE), starch (ST), alginate (AL), pectin (PE), shellac (SH) and xanthan (XA). The observed biodegradabilility in HDPE blends might be due to the presence of hydrolysable linkages and stereo-favourable orientations of blended natural polymers. The added polymers have played a significant role in increasing the hydrophilicity in blended HDPE and acted as a bioassimilative nutrients for seeded microorganisms. The biodegradability of HDPE-polymer blends was evaluated in presence of various fungi such as; aspergillus niger, aspergillus terreus, fusarium solani, tricoderma hariziauum and tricoderrma viride. The disinfected films of pristine HDPE and polymer blened HDPE were inoculated with these fungi and the extend of biodegrdation was evaluated after a incubation period of three months at 28 ± 1˚C. The biodegradability of HDPE-polymer blends was compared with pristine HDPE by evaluating their molecular weights, and weight percent loss in samples incubated for three months along with selected fungus. The biodegrdation in pristine HDPE and its polymer blends was confirmed by comparing their FT-IR spectra and also by evaluating the variations in their mechanical and thermal properties. A significant variation in their morphologies in prsence of fungi has confirmed biodegradation in HDPE-polymer blends in comparison to pristine HDPE films. These studies have provided sufficient evidnces to confirm the role of added natural polymers in developing a biodegradable HDPE by blending various polymers such as chitosan (CH), cellulose(CE), starch (ST), alginate (AL), pectin (PE), shellac (SH) and xanthan (XA). Out of these polymers, the chitosan is found to be quite effective as it is acted better bioassimilative nutrient for microorganisms to cause biodegrdation of HPEF in comparison to other polymers.