Jj. Balatinecz et Bd. Park, THE EFFECTS OF TEMPERATURE AND MOISTURE EXPOSURE ON THE PROPERTIES OFWOOD-FIBER THERMOPLASTIC COMPOSITES, Journal of thermoplastic composite materials, 10(5), 1997, pp. 476-487
Wood-fiber thermoplastic composites were prepared with polypropylene (
PP) and high-density polyethylene (HDPE) matrix resins employing high
shear thermokinetic compounding for fiber dispersion. Wood fibers obta
ined from recycled newspapers were mixed with the matrix polymers at a
level of 30% by weight. In one experiment, sets of six samples were i
mmersed in boiling water for up to 48 hours and subsequently tested fo
r mechanical properties and water absorption. In another experiment, s
amples were exposed to -40 degrees C, -20 degrees C, 0 degrees C, 23 d
egrees C, 40 degrees C and 60 degrees C for two hours and then tested
at the same temperatures for tensile and flexural properties. Results
showed that immersion in boiling water resulted in water absorption of
between 3 and 5%, a decrease in tensile and flexural properties, and
an increase in impact strength. When the composites were exposed to va
rious temperatures, both strength and modulus decreased significantly
with increasing temperatures above ambient (23 degrees C) level for bo
th PP- and HDPE-based composites. The opposite trend was evidenced bel
ow freezing.