Effects of Mixing Some Wood and Non-Wood Lignocellulosic Materials on the Properties of Cement and Resin- Bonded Particleboard.

Abstract

A rapid development of the wood–based panel industry has been reported in recent literature. Major growth opportunities are expected to continue in particleboard market. The supply for wood which is so far the main raw material for particleboard has become problematic. Particleboard industry is intensifying efforts to find suitable substitutes for wood. In recent years effective utilization of thinning produce, wood and agricultural residues has gained increasing importance. Several attempts were made to mix different types of raw materials for making particleboard. Particleboard production is directly linked to some of the key issues of our times, namely; resources conservation, housing and the environment. This study investigated the effect of some conventional treatments on compatibility of cement and some wood and non-wood lignocellulosic materials. It also examined the effect of blending different proportions of the lignocellulosic materials on the properties of particleboards made using cement (inorganic binder) and Urea formaldehyde (organic binder). The three lignocellulosic materials used were Acacia nilotica sawdust, bagasse and cotton stalks. They are waste materials of widely cultivated species in Sudan. They were collected from EL Suki sawmill, EL Gunied sugar factory and the Fields of EL Kamlin state. Four experiments were carried out. The first was conducted to investigate the effect of six treatments {control (untreated material), control +3%CaCl2, hot water extraction, Hot water extraction +3%CaCl2,1%NaOH extraction, and 1%NaOH extraction +3%CaCl2} on the hydration characteristics of the three lignocellulosic materials with cement. Two Dewar flasks and a digital thermocouple were used. The maximum hydration temperature, time to reach maximum temperature and rise in temperature above the ambient were determined for each lignocellulosic material. The most suitable treatment common to all materials was the 1%NaOH+3%CaCl2 .The average maximum hydration temperatures were 63.87 °C, for bagasse, 67.87 °C for cotton stalks and 67.9 °C for sunt sawdust. Bagasse was the least responsive material to the treatments used, followed by cotton stalks and then sunt sawdust. In the second experiment, extractive contents, lignin content, hot water and weak alkali solubility of the three lignocellulosic materials were determined. The results of the above mentioned tests revaled that bagasse attained the highest results of hot water and 1% NaOH extraction. The results were therefore consistent with the hydration characteristics observed. In the third experiment different mixtures and ratios were used to manufacture laboratory size cement bonded particle boards. Analysis of variance and Duncan Multiple Range Test were used to study the significance of the variations, if any. Reasonable panel properties were obtained from the three lignocellulosic materials either pure or mixed using different cement/wood ratios (3:1, 3.5:1 and 4: 1). In the fourth experiment ten different mixtures of the three lignocellulosic materials (Nine homogenous, One layered) of urea formaldehyde resin bonded particleboards were manufactured under the laboratory conditions. The minimum property requirements of commercial particleboard standards EN 312:2003 for MOR,MOE were met or exceeded at 10% resin content level except for pure cotton stalks boards. Addition of bagasse particles to sunt sawdust or cotton stalks or to their mixtures improved the properties of boards made of their respective blends