Characterization and properties of sodium hydroxide/urea regenerated cellulose reinforced poly(3-hydroxybutyrate) biocomposites

Abstract

Pure cellulose was dissolved in 7 wt.% natrium hydroxide (NaOH)/12 wt.% urea at the temperature of -12 °C to prepare the regenerated cellulose (RC). Structural, morphological and thermal properties of cellulose and RC were compared using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results revealed decreased in crystallinity, reduced of FTIR peak intensity and decreased the thermal stability of RC sample. FESEM results showed that the morphological of RC became more spherical. RC/poly(3-hydroxybutyrate) (PHB) biocomposites were prepared by melt mixing in internal mixer with different RC content (1, 3, 5 and 7 wt.%). The structural, morphological, thermal and mechanical properties of the RC/PHB were characterized. From the XRD, the crystallinity was decreased with the increasing of RC fiber loading. The melting temperature of biocomposites was found to increase upon the increasing of RC fiber. TGA results indicated that the char residue and onset temperature of biocomposites were decreased with the increasing of RC loading. Increased loading of RC decreased the tensile strength and elongation at break, while the Young‟s modulus showed the optimum value at 5 wt.%. Based on flexural strength and flexural modulus, 3 wt.% RC was the optimum amount for PHB composite. As for comparison of PHB composite with 3 wt.% cellulose and 3 wt.% RC, DSC result showed the melting point of 3 wt.% RC/PHB composite was higher than 3 wt% cellulose/PHB composite. The tensile properties and impact strength were higher for cellulose/PHB compared to RC/PHB composites, while flexural properties of RC/PHB were higher than cellulose/PHB composites.