Development of Biodegradable Bioplastic Films from Taro Starch Reinforced with Bentonite

Abstract

Bioplastics are biodegradable plastics made from renewable natural sources like plants, animals and microbes. The synthetic plastics currently in use possess threat to the environment as it is non-biodegradable and is obtained from petrochemical sources which are non-renewable as well. Out of all the plastics used, the single use plastics are of great concern as they cannot be efficiently recycled. To encounter this problem, synthetic plastics can be replaced with bioplastics. Starch from Colocasia esculenta (Taro) is one of the best options available to develop such plastics as the granules sizes of them are smaller compared to Solanum tuberosum (potato) starch. The difference in size and shape of the granule will have an influence on the physicochemical properties of the starch and thus on the bioplastic film generated. Suitable fillers such as bentonite clay can be used to improve the mechanical property of the film. Apart from mechanical property, Bentonite was found to reduce starch matrix retrogradation by influencing B-type crystallinity. In this study, bioplastic films were developed using Taro starch (Colocasia esculenta) with glycerol as plasticizer and varying the bentonite concentration (0 to 2.5% w/w) as a filler material. The bioplastic films thus generated was characterised by instrumental techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), universal testing machine and differential scanning calorimetry (DSC). The films were also subjected to swelling test, chemical tests, wettability test and soil degradation studies. The SEM and FTIR results showed that the films formed were homogeneous without any agglomeration and ascertains that all the films are solely made from starch as they have similar wave number. The gelation temperature was predicted as 85°C using DSC. The tensile strength was also found to increase with increase in the concentration of bentonite. The swelling and soil degradation tests confirmed that the films formed were biodegradable and the rate of degradation was influenced by the bentonite concentration. The chemical tests show that the bioplastic films with bentonite showed increased resistance to acids and salts. Based on the results obtained, it can be concluded that the bioplastic films generated from taro starch were biodegradable with good mechanical properties which can replace synthetic plastics.