Investigation of Rheological, Mechanical and Water Absorption Properties of LDPE-Thermoplastic Corn Starch Blends

In this work, LDPE-Thermoplastic Corn Starch (TPCS) blends containing different amounts of TPCS (0-40wt. %) and a constant amount of LDPE-grafted maleic anhydride, PE-g-MA (3wt. %) as a compatibilizer, were prepared using a single-screw extruder. Scanning electron micrographs of the samples showed that as starch particles in the LDPE matrix increase, dispersion of the particles reduces. However, appropriate dispersion of particles was achieved by adding 25wt. % TPCS. The result of melt flow index (MFI) showed that with increase in TPCS content, the MFI values of all the blends decrease. The rheological measurements indicated that as shear rate increases, the apparent viscosity of the blends decreases, showing shear thinning behaviour. Also, increase in apparent viscosity with increase in TPCS content was observed. The mechanical properties, such as ultimate tensile strength, elongation at break, Young’s modulus and relative impact strength of the blends reduced as TPCS content increased. However, the blends with 25% TPCS have the required tensile properties to produce plastic packaging products, as evidenced by standard specification for polyethylene plastics. The water absorption of the samples increased with increasing TPCS concentrations at a constant time of immersion. These results confirm probable biodegradability of the samples in the environment after being used.

LDPE, Starch, Blend, Biodegradable, Rheology, Mechanical Properties, Water Absorption