Studies on Biocomposites Based on Pine Needles and Isocyanate Adhesives

摘要

The biocomposites have been prepared from processed pine needles and isocyanate containing prepolymer. The physico-mechanical properties of these composites were evaluated as a function of various pine needles treatments such as alkali, steam and alkali-steam combination. It is observed that alkali treated composites exhibited higher internal bond strength than those of other treatments under both dry and wet conditions (accelerated water and cyclic aging). The occurrence of fibre breakage and pull-out under dry condition and swelling of fibre and its adhesive failure under wet condition are responsible for strength related properties of composites. DMA run indicates that steam treated samples imparted higher loss modulus and Tan delta as compared to other treatments showing dominancy of their viscous components. The more dimensional changes in the alkali treated composites are believed to be the poor hydro/hygro thermal stability of bonds formed at the fibre-matrix interface and also the presence of wax residuals on the needle surface. It is observed that biopolymer modified isocyanate pine needle composites showed better physicomechanical performance than the parent adhesive bonded composites. The pine needle isocyanate composites produced satisfied the requirements of commercial standard specification.