The surface of guineacorn (Sorghum bicolor) husks particulate (GHP) was modified by alkali (ALK), silane (SIL) and the combination of alkali and silane (ALKSIL) treatments. Bio-composites were then formulated using untreated (UNTRD) and the modified GHP as fillers. The compounding of the GHP and poly (lactic acid) blended with Biomax strong (PLABM) was carried out by a Brabender screw extruder, after which test samples were produced by BOY 22M injection moulding machine. The GHP filler loading was varied between 10 40% at 10% interval. Thermogravimetric analysis (TGA) was conducted on the bio-composites test samples to investigate the effectiveness of the various GHP surface modifications on the interfacial interactions with the PLABM matrix. The result shows that the matrix and its bio-composites exhibited one-step decomposition; which is an indication of high compatibility between PLA and the modified GHP. It was also found that the bio-composites produced were all stable at processing temperatures. Generally, the treated GHP reinforced bio-composites exhibited higher thermal stabilities than the untreated GHP reinforced bio-composite. The thermal stabilities of the GHP treated bio-composites is in the order ALKSIL>SIL>ALK. PLABM was stable up to 295 °C, while the bio-composites show decreasing stabilities with GHP loading, ranging from 285 - 260 °C. The thermal stabilities of the treated filler reinforced bio-composites were also greater than that of the untreated filler reinforced bio-composite.
Key words: guinea-corn husks particulate, poly (lactic acid), surface treatments, thermogravimetric analysis, thermal stability
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