Effect of alkali and silane treatment on water absorption and mechanical properties of sisal fiber reinforced polyester composites

The present work deals with the effect of water absorption on the mechanical properties of untreated, 10% alkali-treated, and 10% alkali plus 1% silane treated sisal fibers (5%, 10%, and 15%) reinforced polyester composites. Hand lay-up was used to create the composite. The samples were prepared in accordance with ASTM standards, and tests for tensile strength, flexural strength, impact strength, and water absorption were performed. An increase in the tensile, flexural and impact strength was observed with an increase in fibre loading for untreated, alkali-treated and alkali plus silane treated sisal fibre reinforced polyester composites without water absorption, the increase being maximum for 10% alkali plus 1% silane treated fibre composite. Water absorption reduces tensile strength while increasing flexural and impact strength in untreated sisal fiber reinforced composites. There is an increase in tensile, flexural, and impact strength with higher fiber loading for 10% alkali-treated and 10% alkali-treated plus 1% silane treated sisal fiber reinforced polyester composites with and without water absorption. The tensile, flexural, and impact strength of alkali plus silane treated fiber is maximum at any given fiber loading, indicating that the alkali plus silane treatment is effective in improving the fiber matrix interface. Water absorption increases with fiber loading in untreated, 10% alkali-treated, and 10% alkali plus 1% silane treated sisal fiber reinforced polyester composites, with the rate being lowest in alkali plus silane treated fiber reinforced composites.