INVESTIGATION ON CHAR RESIDUES AND MEAN REACTIVITY OF COMPRESSION MOLDED RICE AND COFFEE HUSKS BIO-CHAR REINFORCED POLYPROPYLENE
Fiber-reinforced plastics have gained utilization in recent years for many applications because they are a cheaper alternative to the ordinary petroleum-derived materials. On the other hand, considerable amounts of agricultural wastes still lack enough utilization. In this study, bio-chars of husks from two rice and two coffee varieties in Uganda were utilized as fillers to reinforce polypropylene (PP) and thus develop fiber-reinforced plastics. Bio-char filler material was varied between 0 % and 20 %. The plastics were prepared via melt mixing followed by compression molding. Effects of bio-char content on the thermal stability of the developed plastics were studied by use of an Eltra Thermostep Thermogravimetric analyzer. Thermogravimetric analysis (TGA) results showed that inclusion of bio-char improved the thermal stability of the developed fiber-reinforced plastics. Maximum rate of weight loss ranged from -0.0414 %/min (for 15 % unmodified Wita-9 rice bio-char) to 0.0023 %/min (for pure PP), corresponding to respective peak temperatures of 680.8 °C and 604 °C respectively. Peak temperatures generally increased with increase in filler loading. It was found out by this study that incorporation of bio-char fiber material resulted in increased char residues. These residues tended to hinder combustion. The highest char residues (17.4 %) were obtained when PP was loaded with 15 % neutral Wita-9 rice husks bio-char. The highest mean reactivity attained was 6.1×10-5 %/minute/°C obtained when 10 % unmodified Pussa rice husks bio-char was used to reinforce PP.