Development Of Plant Fiber Material And Study On Their Mechanical Properties

Aiming at the low efficiency in the use of rice husk, straw and other waste plant fiber and the damage of environment by using paper products and plastic products, the problems in using rice husk, straw and other waste plant fiber to make biodegradable fiber material was studied in this work, aiming at resource utilization and environmental protection.Through adding adhesion agent and other additives to the plant fiber, materials having a certain strength and toughness are to be made by the method of molding, thus the purpose of making practical products of different shapes can be achieved. In the process of research, the proportion of raw materials was adjusted constantly. Through a large number of trials, the dosage of adhesive and additives was determined, the best formula obtained and the molding process(temperature, pressure, molding time) optimized.Finally a formula of plant fiber materials with certain intensity was obtained, that is, 53% rice husk powder, 10% polyvinyl alcohol, 4% urea formaldehyde resin, 0.5% nano silicon dioxide, 12.5% heavy calcium carbonate and 20% water(mass fraction). Meanwhile, a suitable production process for the formula of material was determined: For the hot pressing process, the hot-pressing temperature is 100~120℃, pressure is not less than 16 MPa, and time is not less than 60 s. The material is then dried at room temperature to the moisture content of 8%.Due to the performance insufficiency for the untreated plant fiber materials, several pretreatment methods were investigated, including alkali treatment, acid treatment and benzene-alcohol extraction. The optimal pretreatment conditions of the several methods were determined. Treatment at low alkali concentration or contacting for a short time can remove the amorphous silicon, while at high alkali concentration or contacting for a long time will affect the structure of lignin. The optimum alkali treatment conditions are 20℃, 6% alkaline solution and 4 hours. Acid treatment can cause hydrolysis of hemicellulose, increasing acid concentration may affects the fiber, the treatment should be operated under low acid concentration(2%)and high temperature(110℃).In addition, the effect on the properties of materials of a single component was determined preliminary in the pretreatment process: The component with largest contribution to the material mechanics performance is cellulose, followed by lignin. Hydrolysis of hemicellulose will increase the overall polarity of fiber, which is advantageous to the material performance enhancement. Amorphous silicon in the fiber has an adverse effect on the material, so it should be removed as far as possible; Wax, fat and other impurities can affect the wettability and polarity of plant fiber, so the performance of the material can increase while they are removed.