Development and Characterisation of Waste Kibisu Silk Reinforced Biodegradable Polymer Composite

Abstract

In India’s current plastic management policy, single-use plastics are the most significant contributor to littered waste. Millions of plastic waste end up in the environment vis-a-vis soil, water bodies, watercourses, etc. It takes an average of one thousand years to decompose plastics completely. In India, the Plastic Waste (Management and Handling) Rules, 2011 included plastic waste management as its priority to address the issue of scientific plastic waste management. The Government has announced the Plastic Waste Management Rules, 2016, in suppression of the earlier Plastic Waste (Management and Handling) Rules, 2011, focusing on developing alternative biodegradable plastic with a faster degradation rate. An eco-friendly product, a complete substitute for plastic in all uses, has not been found to date. In the absence of a suitable alternative, it is impractical and undesirable to impose a blanket ban on the use of plastic all over the country. The real challenge is to improve plastic waste management systems or develop a feasible alternative to plastic disposables. So, the dire need of the hour is to furbish a viable low-cost alternative to plastic with zero or minimised carbon footprint. The current work aims to develop a hundred percent biodegradable composite by reinforcing waste Kibisu silk into wheat gluten as a possible replacement for plastic disposables. The fibre used here is waste Kibisu silk (bombyx Mori), an industrial waste available in abundance in silk-textile industries of India. To bind the fibres, organic wheat gluten was used as a biopolymer, a byproduct of wheat flour. After optimising among different parameters, castor oil is used as an effective natural plasticiser for plasticising wheat gluten. The natural lemon extract was used instead of synthetic citric acid for crosslinking. For better dispersion of wheat gluten into the water, sodium hydroxide (NaOH) was used. The prepared composites showed outstanding physio-chemical properties, which can be used to prepare mouldable sheets to produce biodegradable seedling pots, hospital trays, egg trays, nursery sampling pots, table tops and ceiling tiles etc. Based on the findings of this study, it can be concluded that waste Kibisu silk and wheat gluten with natural plasticisers and crosslinkers can make easily mouldable composite sheets which can be used for different purposes to reduce the usage of disposable plastics. The final result shows composite prepared with 50:50 six-hour treated waste Kibisu silk and wheat gluten with 10% castor oil, 2.5% NaOH, and 2.5% lemon extract gives the most promising properties in terms of mechanical strength and thermal stability. The bio-coating of aloe vera-gelatine is proven to be best suited for effectively coating the developed composites to prevent moisture absorption and water resistance.