Composites of resorcinol and hexamethylenetetramine modified nanocellulose whiskers as potential biofiller in natural rubber latex: synthesis, characterization and property evaluation

Surface modification of nanocellulose to improve its compatibility with the polymer matrix is gaining considerable attention these days. Herein, nanocellulose whiskers (NCW) extracted from Acacia caesia were modified with resorcinol and hexamethylenetetramine (RH) by the refluxing method. The characteristic properties of RH-modified NCW were studied using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and UV-visible diffuse reflectance spectroscopy (UV-DRS). A marginal decrease in crystallinity index was observed by surface modification, whereas the thermal stability (T-max) of the NCW increases by 32 degrees C on surface modification. The potential of modified filler in improving the properties of natural rubber latex (NR) was studied by comparing its mechanical, thermal, diffusion, permeability and biodegradability properties with neat NR and NR-NCW composites. Upon 2 phr filler loading, the tensile and tear strengths of modified NCW composites increased by 26 and 38% accordingly compared to the NR-neat. The better filler matrix interaction resulted in the marginal positive shift in the glass transition temperature, transport properties and T-max of the modified composite. The incorporation of NCW also enhanced biodegradability and reduced the permeability of the prepared composites.