Plastic-like moulded products made from renewable forest resources

The bark of fast-growing wood species such as Pinus and Acacia species cont ains a high amount of tannin, a renewable forest resource. In this study, t he possibility of utilizing radiata pine tannin as a substitute for synthet ic thermosetting resins in the production of moulded products was investiga ted. When tannin powder and wood flour (tannin : wood flour = 1 : 1 w/w) we re mixe and moulded at 190 degreesC and 100 MPa for 10 minutes, plastic-lik e moulded products with a modulus of elasticity (MOE) of 9 to 10 GPa and a modulus of rupture (MOR) of 60 to 70 MPa were obtained without further addi tives. Furthermore, when tannin and wood flour (1 : 1 w/w) were mixed in wa ter and freeze-dried, tannin was partially impregnated into the wood flour, and the MOR of the moulded product increased by more than 10% compared wit h that of products produced without the impregnation process. The moulded p roducts described above showed good water resistance. Moreover, an increase in wood flour content was found to upgrade the mechanical properties effec tively, with a MOR of 90 to 100 MPa being obtained at 75% wood content, des pite a reduction in water resistance. (C) 2001 Kluwer Academic Publishers.