Development and characterization of bacterial cellulose/natural rubber composite films

Abstract

The composite of bacterial cellulose (BC) and natural rubber (NR) has been developed in this study to combine the prominent properties between strength from three-dimensional structure of BC nanocellulose and flexible molecular chain of isoprene (C5H8). BC membranes were produced by A. xylinum using coconut-water medium under static incubation for 5 days. The BC membrane were then purified and immersed in NR latex solution at various concentrations (0-10 % v/v). The influence immersion temperature (30°C, 50°C, 60°C and 70°C) and a ratio of ethanol in the solvent were also investigated. The results were compared with the unmodified BC. NR particles were characterized by Laser particle size distribution (PSD), the morphology and cross-section of films by Field Emission Scanning Electron Microscopy (FESEM), functional groups and intermolecular interactions by Fourier Transform Infrared Spectroscopy (FTIR), the crystallinity structure by X-ray diffraction (XRD), the thermal properties of composite films by Differential Scanning Calorimetry (DSC), the mechanical properties by Instron testing machine, the water absorption capacity, toluene uptake and biodegradable in soil measurements. According to the experiments, the addition of a certain amount of ethanol slightly affected NR particle size but helped reduce the viscosity of NRL, resulting in more penetration of NR molecules into BC. The optimal condition was the immersion at 2.5–5.0 % NR latex solution, under the temperature of 50-60°C, where the thickness of the composite could be enhanced from ~12 μm of the unmodified BC to ~20-27 μm. The crystallinity structure of the composite films remained as BC structure. The new peak was not occurred from FTIR analysis; however a slight shift of hydroxyl peaks might indicate some weak physical interactions between BC and NR. The results show that the water absorption decreased and the toluene uptake increased as compared to normal BC film. Moreover, the tensile strength and elongation at break of the NR-BC composited films were significantly improved for 3-6 folds in comparison to the normal BC film. The results of biodrgradation in soil showed that the composite films could completely degrade for 5-6 weeks.