Pine needle/isocyanate composites: Dimensional stability, biological resistance, flammability, and thermoacoustic characteristics

Abstract The pine needle composites using isocyanate prepolymer were evaluated for their dimensional stability, flammability characteristics, biological resistance, and thermoacoustic properties. The thickness swelling and linear expansion of the composite panels affected significantly under wet conditions. The optimum flammability characteristics of the pine needle fibers were obtained at the retention of 7.48 kg/m³ urea phosphate on their surfaces. During natural decay, the treated pine needle composites exhibited 4–8% weight loss compared to 9–13% for the untreated ones. The loss of internal bond strength in both the treated and untreated samples exposed to fungus culture ranged between 35 and 60% only. Termites caused ∼6% less weight loss than the untreated samples showing their moderate resistance behavior. The thermal conductivity and sound transmission loss of samples were 0.136 W/m K and 26.51 dB, respectively, showing their adequate insulation properties. It is concluded that isocyanate bonded pine needle composites can be suitably used as panel products in buildings. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers