The effect of polypropylene on physical and mechanical properties of particleboard produced from rice straw and industrial wood particles

Background and objective: The main lignocellulosic raw material used in the particleboard industry is wood. The production of panel products from agricultural residues is important considering the increasing worldwide wood fiber shortage. Agricultural residues, which are produced with large quantities annually throughout the world, are the main renewable resources. Compared with synthetic fibers such as glass, natural straw fibers have more advantages such as low cost, low density, abundant and wide distribution, recyclability and biodegradability. Rice is the primary food for more than 40% of the worlďs population, with about 596 million tons of rice and 570 million tons of rice straw produced annually in the world. At present, most of these residues are burnt in situ after harvest. The field burning of rice straw and other agriculture residues in wide areas not only results in serious environment issues, but also wastes precious resources. Faced with worldwide shortages of forest resources, environmental pollution and waste of biological resources resulting from field burning of rice straw and other agricultural residues, there has been a revival of interest in using rice straw and other agriculture residues to produce composite panels. This research investigated the use of the rice straw –industrial particle wood with polypropylene powder on the mechanical and physical properties of single layer particleboard.
Materials and methods: The variable in this research were the ratio of rice straw to industrial wood particle (at four levels; 0:100, 15:85, 30:70, 45:55) and polypropylene powder (at three levels; 0, 5, 10%). Industrial wood particles from Sanate Choube Shomal Company were used. Urea formaldehyde resin used at 10 percent level of dry weight of raw material as well as ammonium chloride was used as a catalyst at 2 percent level of the dry weight of adhesive. After the mixing process raw material together, mat at temperature of 170°c for 5 minutes under hot press was placed. After making particleboard, physical and mechanical properties of panels analyzed using variance analysis in 5% probability level.
Results: The results showed, increasing polypropylene percent resulted in increasing the bending strength, modulus of elasticity and internal bonding of the boards. The results also indicated that water absorption and thickness swelling after 2 and 24h in water decreased with increased polypropylene percent.
Conclusion: Results showed, there was usability of the rice straw up to 30 percent and polypropylene up to 10 percent for general purpose boards for use in dry conditions.