Green composite sponge of natural rubber reinforced with cellulose filler using alginate as a dispersing agent

Composite sponges of natural rubber and cellulose fiber (NR-C) using sodium alginate (SA) as a dispersing agent were successfully fabricated by the Dunlop process. The aim of this work was to develop a green composite NR-C sponge with high mechanical properties and efficient water absorption capacity (WAC). The addition of SA could promote cellulose fiber dispersion in NR matrix and NR-cellulose interactions; accordingly, it resulted in highly macro-porous sponges with improved mechanical properties and higher hydrophilicity. NR-C sponge supplemented with cellulose at 45 parts per hundred rubbers (phr) and SA at 1 phr revealed significantly higher compressive stress and higher modulus of elasticity of about 5 times those of NR sponge. The maximum WAC at around 400 % was obtained from NR-C sponge supplemented with 30-45 phr cellulose and 1 phr SA. The initial water absorption rate and WAC of NR-C sponges were increased up to 5.6 and 1.8 times those of NR sponges, respectively. In addition, NR-C reinforced with high content of cellulose and SA could be sufficiently biodegraded in soil for about 21-27 % in120 days, which was considerably higher than that of NR sponges. According to their improved properties, NR-C composite sponges could be used an adsorbent or supporting material in many applications, including agriculture applications, such as a seed germination sponge or a hydroponic planting material and could also be further developed for biomedical applications as wound dressing.