Studies on UV and Thermo-mechanical Properties of Starch and LDPE based Sustainable Bio-composites

This study delves into the synthesis and characterization of a sustainable bio-composite made from low-density polyethylene (LDPE) as a base polymer and thermoplastic starch as a bio-filler. The bio-composites were prepared with three different concentrations of starch (6%, 12%, and 18%) in the LDPE matrix using an ultra-high-speed thermo-kinetic mixer technique. Fourier Transform Infrared Spectroscopy (FTIR) verified the molecular composition of the biocomposites, while UV-Vis spectrophotometry revealed reduced UV absorbance across the entire spectrum, indicating better interface amongst starch molecules and the LDPE matrix. Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) showed almost no change in melting and crystallization temperatures but a marginal increase in the crystalline behaviour and enthalpy, suggesting the nucleating action of starch molecules in increasing the crystalline region. Izod impact studies demonstrated an increase in impact strength with 6% starch concentration, confirming the nucleating action of starch. Higher starch concentrations (12% and 18%) led to a marginal decrease in impact strength, possibly due to the filler action of non-nucleating starch molecules. The improved properties of the bio-composite indicated excellent dispersion and adhesion of thermoplastic starch particles in LDPE matrix. These findings suggest that the incorporation of starch, particularly at lower concentrations, can enhance the photostability, thermal behaviour, and impact strength of LDPE, making the formulations/composite materials more suitable for outdoor applications.