Enhanced optical, chemical and mechanical properties for different cellulosic fibers treated by different concentrations of polymers

Different types of cellulosic fibers were used to prepare paper sheets, soluble starch and polyvinyl alcohol solutions with different concentrations were added to paper sheets on surface on both sides. The sheets before and after adding polymer solutions on surface had been subjected to several tests. Mechanical properties increased in case of paper sheets treated with polyvinyl alcohol or soluble starch comparing with untreated. Generally in all cases of paper sheets made from different pulps, the mechanical properties reached their optimum improvement in presence of 1.5% polyvinyl alcohol solution or soluble starch. Brightness greatly enhanced by addition of polyvinyl alcohol while starch had greatly effect on opacity. It was clear that soluble starch had more efficient in improving mechanical properties in paper sheets. Paper sheets made from wood pulp treated with soluble starch or polyvinyl alcohol gave the best results compared with that prepared from bleached bagasse pulp and that from mixed pulp. Crystallinity index from the ratio A1435cm-1/ A 900 cm-1 in infrared spectra indicating that, treated paper sheets contain more hydrogen bonds between the hydroxyl groups in cellulosic chain and polymers, and X-ray diffractometry proved all the above where X-ray data showed that treated paper sheets was accompanied by a significant increase in the fraction of crystalline polymer compared with untreated, and the crystal dimensions apparently increased until all favorable stereochemical adjustment were completed. The morphology of fibers proved that, fibers of the sized paper were tight and smooth. These showed that the sizing emulsion permeated into the paper fibers and interacted with the paper fibers by physical and chemical effects, which strengthened the binding force and bond energy among the fibers, thus enhancing the physical strength of the paper.