Extraction and Usage of Starch from Banana Pseudostem to Develop Biodegradable Polymer Composites

Abstract

Polymer products have become an integral part in our daily life as a basic need. It producedon a massive scale worldwide and its production crosses the 150 million tonnes per yearglobally. Polymers have broad range of applications in films, wrapping materials, shoppingand garbage bags, fluid containers, clothing, toys, household and industrial products andbuilding materials. Polymer materials play a dominate role in the packaging applicationstoday. Most of packaging materials are based on petroleum based by-products. Theseproducts may remain for centuries in our surrounding environment after the usage causinglots of environmental issues. Biodegradable polymers are the one of the options available toprotect the environment. Most biodegradable polymers can be engineered to be compostedsafely in a properly managed, municipal composting environment and breakdown occurs in acombination of water and microbial activity. Most of natural polymers are biodegradable innature. Increasing interest in applying polymers based on natural materials such as starch hasbeen observed. Starch is a bio-material and one of the most abundant and inexpensivepolysaccharide sources which has the unique characteristic of biodegradability and easilydissolve in water. Blends of synthetic polymers and starches can be prepared so they arebiodegradable. The objective of this research is to develop biodegradable composite materialsusing starch and Low Density Polyethylene (LDPE).

Banana is a very popular fruit in Sri Lanka. It is cultivating in most of the areas of thecountry. The banana pseudostem was selected as a fruit waste to extract starch. Starch wasextracted from different varieties banana pseudostems such as Rathkesel, Puwalu, Suwadel,Ambul kesel, Alukesel and Ratahondral. The maximum starch amount (5 wt%) was given byPuwalu pseudostem. Fourier Transform Infrared (FTIR) Spectroscopy was used tocharacterize the extracted starch. Experimental results showed that all characteristic peaksrelated to starch were present in the extracted FTIR spectra. FTIR spectra further showed thatstarch composition was almost same in all the banana plants. Laboratory scale internal mixerat 150 0C temperature and speed of 60 rpm was used to prepare the LDPE – starch polymermixture by varying 1wt% to 5wt% starch. LDPE - starch biodegradable polymer compositewas prepared with the help of a hydraulic press. Tensile properties, soil burial test and waterabsorption tests were carried out to measure the degradability of the developed product.There was a significant weight lost in starch containing composite samples during the soilburial test. Tensile test results were also showed that considerable property changes in starchcontaining samples with compared to pure LDPE. LDPE - starch composites are exciting anduseful materials to protect the environment.