Improvement of Paper Properties of Rice Straw Pulps by Microcrystalline Cellulose/Calcium Carbonate

Rice straw is a locally available lignocellulosic material. In this study rice straw was pretreated by soaking it in water for 48 hours at room temperature. The pretreated straw was cooked in 5% NaOH at 100ºC and atmospheric pressure. The structure and mechanical properties of paper made from cooked pulp was investigated. Hydrogen peroxide as a bleaching agent was applied to the pulp to enhance its brightness level in a single stage process in the presence of sodium hydroxide and magnesium sulfate. Rice straw pulp, bleached using 2% hydrogen peroxide solution, was selected to prepare microcrystalline cellulose (MCC). The MCC was characterized by 45.5% crystallinity and nano in size vide XRD and TEM respectively. Microcrystalline cellulose and calcium carbonate were added to unbleached pulp as fillers. Air permeability of filled paper was improved in the presence of MCC more than in the presence of calcium carbonate alone. Optical properties and water permeability of filled pulp showed improvements in the presence of microcrystalline cellulose filler compared to unfilled pulp.