Synthesis of Biodegradable Polyolefins Based Polymer Composites Using Degradable Natural Materials

Abstract

Polymers are high molecular mass compounds and their structure is composed of a largenumber of repeating units. These days, polymer materials are so important in our daily lifethat survival of human life depends on these polymers. Polymer materials have wide range ofproperties that canbe used in different applications. There has been increasing public concernover the harmful effects of petrolium-based polymer packaging materials speciallypolyolefins in the environment after the usage. These pectrolium – based polymers createsignificant amount of waste after the usage and that generates the critical environmentalissues.Recycling, recovery and disposal of plastic waste are some of the options available.These methods have certain disadvantages and not hundred percent practical. An importantalternative to minimize the polymer waste is the introduction of biodegradable polymers,which can be degraded through the action of naturally occurring microorganisms.

The objective of this research was to produce biodegradable composite material with the helpof Low Density Polyethylene (LDPE), cellulose - hemi cellulose and natural enzymes.Cellulose and hemi cellulose are two types of biodegradable natural polymers. Cellulose -hemi cellulose mixtures were extracted using rice straw which is highly available in SriLanka as an agricultural waste. Approximately 33% of cellulose - hemi cellulose mixture wasextracted using rice straw. The biodegradability impartedby cellulose - hemi cellulose can befurther enhanced by introducing natural enzymes. Radish peroxidase is one of the naturalenzymes that were used to enhance the biodegradability of cellulose - hemi cellulose. Radishperoxidase was extracted by using radish roots.The extracted cellulose - hemi cellulose andradish peroxidase were analysed and characterized using Fourier Transform Infrared (FTIR)Spectroscopy. Main Functional groups related to cellulose - hemi cellulose and radishperoxidase were available in the extracted FTIR spectra. LDPE - cellulose - hemi cellulose -radish peroxidase polymer blend was prepared using laboratory scale internal mixture byusing 1wt% cellulose - hemi cellulose and varying 0.5wt% to 2.5wt% radish peroxidase. Themixing temperature and screw speed were 150 0C and 60 rpm respectively. Hydraulic presswas used to prepare the biodegradable polymer composite material. The degree ofbiodegradability was evaluated by measuring time dependent weight loss, water absorptionand tensile properties of the developed composite. Soil burial test was used to measure thetime dependent weight loss. Pure LDPE samples showed the high strength and constantweight during the soil burial test without degradation. Samples containing cellulose - hemicellulose – radish peroxidase showed a significant degradation during the testing period.According to the experimental results, this composite material can be used for variousapplications and their development is a good option for reducing the consumption ofpetroleum resources and environmental pollution issues.