Poly(butylene succinate) based biocomposites incorporating thermoplastic millet starch and microcrystalline cellulose

In this study thermoplastic millet starch (TMS) was fabricated by melt mixing method, using millet starch and glycerol as plasticizer at seven concentration of 20, 22.5, 25, 27.5, 30, 32.5, and 35 wt% and its tensile properties and equilibrium moisture content was measured. The results indicated that by increasing the glycerol content, the tensile strength and elastic modulus decreased while elongation at break and the equilibrium moisture content increased. TMS with 20 wt% of glycerol had the most tensile strength and elastic modulus of 9.6 MPa and 787.9 MPa, respectively and TMS with 32.5 wt% of glycerol had the most elongation at break of 12.6% and the equilibrium moisture content of 23.8%. Subsequently, Poly(butylene succinate) (PBS) / TMS / microcrystalline cellulose (MCC) composites were fabricated by melt mixing method, using 6 PBS:TMS weight ratios of 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50 and 4 MCC concentration of 0, 2.5, 5 and 7.5 wt%. According to the results obtained, by increasing TMS concentration, the tensile strength, elongation at break and impact strength of composites decreased while the elastic modulus and water absorption increased. Composite with 50 wt% of TMS and without MCC, had the least tensile strength, elongation at break and impact strength of 8.1 MPa, 1.8% and 0.15 KJ/m 2 , respectively and the most elastic modulus and water absorption of 478.2 MPa and 3.8%, respectively. The FTIR and SEM analysis results showed a weak interaction between PBS and TMS phases. The results of thermal properties indicated that by increasing TMS content to 30 wt%, the degree of crystallinity of the composites increased to 90.6% but then it decreased slightly at 40 and 50 wt% of TMS to 87.7% and 85.8%, respectively. Composite containing 40 wt% TMS and 5 wt% MCC, was thermoformable and could be used for food packaging applications.