Development and characterization of natural rubber-cellulose sponge

Abstract

Natural rubber (NR) sponges are a renewable biopolymer material derived from milky sap (latex) from rubber trees. In this study, composite sponges of natural rubber and cellulose (NR-C) with various compositions were synthesized. The Dunlop process was employed to prepare the NR-C sponges in various contents of cellulose fibers as reinforcing agent. The cellulose fibers were extracted from the pulp of eucalyptus trees and sodium alginate (SA) was used as dispersing agent. The aim of this work was to develop a green composite sponge with highly porous, flexible, and hydrophilic properties. The effects of cellulose loading on mechanical performance of sponge were investigated. The porous structure and surface morphology of NR-C sponges were characterized by SEM. In addition, absorption rate and water holding capacity of the sponges were determined. Under the mechanical tests, the NR-C sponges revealed higher compressive stress and higher modulus of elasticity than the NR sponge. It was also shown that the hydrophilic property of the NR-C sponges was improved by adding hydrophilic substances (cellulose and SA) that increased the polarity of the material. The NR-C sponges using 1 phr SA as dispersing agent exhibited highly porous structure with larger pore size than those without SA. Overall, the water adsorption capacity of the NR-C sponges increased with increasing cellulose fibers up to 45 parts per hundred rubbers (phr) and the maximum value was 406.73% at 30 phr cellulose and 1phr SA, which was about 1.81 times that of normal NR sponge. The study of biodegradation behavior showed that NR-C sponges could be higher degraded in soil under the natural environment as compared to NR sponges. According to their properties, NR-C composite sponges can be used an adsorbent or supporting material in many applications.