Mechanical and physical properties of particleboard made from two pulp and paper mill secondary sludges

Abstract

To investigate environmentally friendly alternatives for sludge disposal, three proportions of secondary sludge (SS) from two pulping processes (Kraft and TMP) were incorporated in the formulation of particleboard manufacturing. A 32 factorial design was used where the factors were Urea-formaldehyde (UF) content (5%, 7%, and 9% dry weight of resin per dry weight of particles) and secondary sludge percentage (75%, 100%, and 125% dry weight of SS per dry weight of resin). For each pulping process, 27 panels with SS and 3 control panels (without SS for each resin content) were made for a total of 63 panels. All panels were tested for thickness swell, linear expansion, internal bond strength (IB), flexural modulus of elasticity (MOE) and flexural modulus of rupture (MOR). Results indicated that particleboards made with SS from both pulping processes met the ANSI standards for linear expansion, IB, MOE and MOR. However, none of the tested panels met the standard for thickness swell and adding SS to the formulation affected negatively this property. It was concluded that SS from TMP and Kraft mills can be used to manufacture particleboard panels. However, its' percentage along with other additives' content should be optimized.