Controlled preparation of grafted starch modified with Ni nanoparticles for biodegradable polymer nanocomposites and its application in food packaging.

Abstract

Grafting of starch with methyl methacrylate was carried out using a free radical mechanism. Free radicals were generated by the thermal disintegration of potassium persulphate at the temperature of 60°C. A variety of experimental methods were investigated to check the effect of different parameters such as (temperature, amount of starch, quantity of monomer) for efficient grafting. The optimum temperature found for good grafting was 60°C. The initial amount of starch was taken as 0.75 g. Keeping the amount of starch constant, the quantity of monomer was reduced gradually from 10 to 2ml in portions of 5 and 3ml. The controlled biodegradability of the grafted product was obtained by using a 3ml monomer in 0.75 g starch. This grafted polymer showed 31.45% biodegradability in 60 days. The nanocomposite of starch grafted methyl methacrylate was prepared by incorporating 0.02 g Ni nanoparticles in the reaction flask 15 min before the completion of reaction time. The starch grafted polymer and nanocomposite of this were fully characterized by SEM, FTIR, TGA, and DSC techniques. The soil burial method was applied to estimate the biodegradability of samples. The polymer containing Ni nanoparticles was less biodegradable than without nanoparticles. Such polymers can be efficiently used as packaging material for food items. RESEARCH HIGHLIGHTS: Through a free radical method, methyl methacrylate was grafted onto the backbone of starch in this study. During the process, nickel nanoparticles were added to achieve the nickel nanocomposite of the starch grafted polymer. The breakdown of starch grafted polymer after 60 days in a soil burial experiment was 31.45%, whereas the degradation of nanocomposites was 20.07%. Our synthesized nanocomposite polymers can be effectively employed as packaging material for food items.