Research and Development of Wood/Plastic Composite Materials (I) Physical and Mechanical Properties of the Composites of Sander Dust, Saw Dust, Shaving Fines and Polypropylene

This study was purposed to investigate the feasibility of using wood wastes compounding with plastics for wood/plastic composites, and to evaluate their applicability for industrial, agricultural and other consumptive materials. The wood fibres used as the plastic reinforcing material here were collected from the discarded wastes in wood and its relative industries, including sander dust (SrD), saw dust (SwD) and shaving fines (WF). A thermoplastic polypropylene (PP) (#6331, virgin) and a wetting agent (E-43, 3% for fiber weight) were used. The levels of fibre content (P.C.) for each case was set to 0, 10, 20, 30, 40 and 50% based on total weight. These mixtures were then well mixed, compounded and extruded, and then, granulated to particles and inject molded to standard specimens in respective identical conditions. The compounding of three wood fibres and PP was excellent, with an exception of the case of SrD, 50% F.C., which was found to be some dif-ficulties. The tests of physical and mechanical properties of these specimens were carried out strictly in accordance with the ASTM methods, and determined their respective property values and trend distributions statistically. Followings are the results obtained: 1. The increasing of fibre content (F.C.) decreased the melting flow index (M.F.I.) almost linearly for each composite. Specific gravity (S.G.) however, increased linearly. 2. The maximum tensile strength (M.T.S.) influenced positively by F.C. for three composites at their 20-50% levels, the SrD composite dropped at its 40-50% Ft.. Break point elongation (B.P.E.) influenced negatively by F.C., especially showed severe on its P.C. 10-20% levels. 3. The increasing of F.C. increased the flexural elasticity modulus (F.E.M.) exponentially for all composites, it increased unclearly and inconsistantly, the maximum flexural strength (M.F.S.). 4. The increasing of F.C. decreased the impact resistance -notched (IZOD I.R. -NTD) of composites slightly. Similarly, decreased the -unnotched (IZOD I.R. -UNTD) significantly. Later showed it especially severe on their 10-20% F.C. levels. 5. The increasing of F.C. raised heat distortion temperature (H.D.T.) noticeably. The SwD and the WF composites, F.C. 30% or more, in 111.7℃ or higher conditions, showed greater stiffness than that of the solid wood. 6. Overall water absorption (W.A.) and thickness swelling (T.S.) showed extremely small. The increasing of F.C. increased W.A. and T.S. only a slight. T.S. especially showed little. The largest W.A. and T.S. were found on the SrD composite, but still less than 3% and 5% in 1344 Hrs. immersion respectively. 7. The WF contributed superiorly to S.G., B.P.E., F.E.M. and WA characteristics; the SwD also contributed superiorly to M.T.S., M.F.S., IZOD LR. -NTD, its-UNTD and T.S. characteristics; and the SrD however, had poor contribution to all.