WOOD-FIBER REINFORCEMENT OF STYRENE-MALEIC ANHYDRIDE COPOLYMERS

Styrene-maleic anhydride (SMA) copolymers containing either 7 or 14% m aleic anhydride were filled with either pine flour or dry-process aspe n fiber from a medium density fiberboard (MDF) plant. Material propert ies of the filled and unfilled SMA plastics were compared with those o f aspen-fiber-filled and unfilled polystyrene (PS). The fiber-filled S MA composites were equivalent or superior to unfilled SMA in strength, stiffness, and notched Izod impact strength. Filled PS composites out performed or matched the performance of filled SMA composites in the p arameters tested. Unnotched Izod impact strength of filled polymers wa s generally inferior to that of the unfilled polymers. Water absorptio n from a 90% relative humidity exposure, a 24-h soak, and a 2-h boil s howed mixed results when compared to the unfilled polymers. Dynamic me chanical analysis showed no change in glass transition temperature (T- g) after the addition of filler for either SMA or PS composites. The p resence of the anhydride functionality on the polymer backbone did not appear to improve the strength of the composite. No evidence was foun d for chemical bond formation between the SMA and wood fiber. (C) 1998 John Wiley & Sons, Inc.