Effect of Water Absorption on Mechanical Properties of Treated and Untreated Hemp Fiber Reinforced Polyester Composites

The present research work deals with the effect of water absorption on mechanical properties of treated and untreated hemp fiber reinforced polyester composites. Untreated, 10% alkali treated and 10% alkali plus 1% silane treated hemp fiber was added (in 5%, 10% and 15%) to polyester matrix and composites were prepared by hand lay-up process. Samples were prepared as per ASTM standards and test were carried out for tensile strength, flexural strength, impact strength and water absorption. There is an increase in the tensile strength with increase in fiber loading for untreated (41%), alkali treated (64%) and alkali plus silane treated (99%) hemp fiber reinforced polyester composite without water absorption. There is an increase in the tensile strength with an increase in fiber loading for alkali plus silane treated (36%) hemp fiber polyester composite with water absorption, however for untreated and alkali treated hemp fiber polyester composite, initially there is a decrease in the tensile strength followed by subsequent increase in it with increase in fiber loading with water absorption. There is an increase in the flexural strength with increase in fiber loading for untreated (86%), alkali treated (83%) and alkali plus silane treated (160%) hemp fiber reinforced polyester composite without water absorption. There is an increase in the flexural strength with an increase in fiber loading for untreated (63%) and alkali plus silane treated (94%) hemp fiber polyester composite with water absorption, however for alkali treated hemp fiber polyester composite, initially there is an increase in the flexural strength followed by subsequent decrease in it with increase in fiber loading with water absorption. There is a significant increase in the impact strength with increase in fiber loading for untreated, alkali treated and alkali plus silane treated hemp fiber reinforced polyester composite with and without water absorption. Increase in water absorption with fiber loading was observed, the rate being minimum for alkali plus silane treated hemp fiber reinforced composites. © 2022, The Institution of Engineers (India).