Effects of alkali and alkali/silane treatments of corn fibers on mechanical and thermal properties of its composites with polylactic acid

Different chemically modified (including treatments with alkali alone and a combination of alkali and silane coupling agent) corn fibers (CFs) have been used as reinforcements in polylactic acid (PLA) matrix to improve the mechanical and thermal properties of the CF/PLA composites. A comparative study has been made to find out how the two treatments affect the mechanical and thermal properties such as tensile, flexural, and impact strengths and glass transition temperature (T_g), crystallinity, and heat deflection temperature (HDT) of the CF/PLA composites. Scanning electron microscopy analyses have been conducted to evaluate the fiber–matrix adhesion. It has been observed that the treatment with a combination of alkali and silane is more efficient in strengthening fiber–matrix bonding, and thus more significantly improving the tensile and flexural strengths, crystallinity, T_g, and HDT of the CF/PLA composites than the treatment with alkali alone. However, alkali treatment produces the optimal impact strength. Mechanisms have been proposed to interpret the observed changes in mechanical and thermal properties as a result of fiber treatments. It is inferred that the surface treatment of CFs with a combination of alkali and silane may also be applied in other CF–polymer composite systems. POLYM. COMPOS., 37:3499–3507, 2016. © 2015 Society of Plastics Engineers