Cardboard can be manufactured from virgin wood pulp. From an environmental point of view, using virgin wood can be avoided by utilization of other substitute. The increased demand for wooden supplies can be met through enlarged utilization of forest waste, increased utilization of waste paper, increased utilization of non-wood fibrous plants, or other environmentally sound pulping process [1]. Rice hulls are a by-product of the rice industry, with a total of 75 million tons worldwide. Despite numerous exploitations and broad researches have been proliferated, such efforts are handicapped by the limitations of its low nutritive properties, degradation resistance, abrasiveness, low apparent density and high ash content, attributed to another form of pollution phenomenon, rice husk ash [2]. Consequently, useful applications for rice husk are required to solve this problem [3].
Some of the advantages of rice husk mills include:
•
There is insignificant damage on ecological balance since they are based on annually renewable raw materials often plentiful in supply and with disposal problems.
•
No outflow of foreign exchange is needed to import raw materials.
•
Sale of agricultural-residue provides further revenue to farmers who have little other opportunities for outside income.
•
Employment is provided to rural labour.
Agricultural-residues like rice husk and bagasse are locally available either for free or at a very small cost. The major cost in such cases is incurred on collecting and transporting these raw materials. Due to the bulk of these raw materials, transportation can as well be a major cost factor in processing. Nearly all of these raw materials are collected manually and as such the labour costs constitute a big percentage of the total raw material costs. Thus, in countries with very low labour rates, pulp production with these raw materials can be extremely encouraging relative to wood pulping [4]. Consequently, the possibility of manufacturing cardboard from rice husk residues together with bagasse and waste paper was investigated. Their strengths were compared to that of virgin fibres normally used in the production of cardboard for packaging, to see whether the cardboard obtained from rice hulls residues could replace to some extent the pulping material in normal cardboard production. For that purpose, it was important to determine the optimum pulping time in terms of yield, kappa number and lignin content various mixtures of various mixtures of waste papers and rice husk pulp and bagasse pulp and rice husk pulp and to compare the mechanical properties of cardboards manufactured from these mixtures. The optimal amount of virgin fibre to be added also had to be determined so as to maintain strength.