Investigation of physical and rheological properties of LDPE/HDPE/thermoplastic starch biodegradable blend films

Abstract In this work, low-density polyethylene/high density polyethylene/thermoplastic starch (LDPE/HDPE/TS) films were prepared with different compositions to obtain environmentally friendly materials. LDPE/HDPE/TS blends, at ratios of 95:5:15, 90:10:15, 85:15:15, 85:15:20, 85:15:25 and 85:15:30, were processed into thin films by single-step single-screw extrusion. Fourier transform infrared (FTIR) spectra confirmed the immiscibility of matrices and TS in the blend, also in the SEM micrographs of the films no miscibility between the PE and starch was observed. in addition, the SEM micrographs showed a fairly good dispersion of TS (at low wt%) in the blend. Differential scanning calorimetry (DSC) analysis depicted an increase in the percentage of crystallinity with increasing HDPE and a decrease in the percentage of crystallinity with increasing TS. With the increase of HDPE content at low wt% of TS in the blend, an improvement was obtained in oxygen barrier property of the prepared films when compared to LD film. Water absorption of the samples decreased to some extent with increasing HDPE and the absorption increased with increasing TS. The rheological properties of LDPE/HDPE/TS blends were investigated before and after biodegradation. Results were fitted with well-known rheological models to achieve more valuable data about the effect of the composition as well degradation condition on the blend property. By adding HDPE in the presence of TS, rheological properties close to the LDPE were obtained for LDPE/HDPE/TS samples.