Enhanced mechanical and physical properties of starch foam from the combination of water hyacinth fiber (Eichhornia crassipes) and polyvinyl alcohol

Abstract

Water hyacinth (Eichhornia crassipes (Mart.) Solms.) is considered an environmental threat due to its rapid growth and spread. Various studies have utilized water hyacinth fiber (WHF) as a reinforcement to strengthen the mechanical properties of biocomposites. A previous study reported that adding 5% of WHF improves the mechanical properties of the starch foam. The effect of applying a higher concentration of WHF with a combination of polyvinyl alcohol (PVA) on the properties of the starch foam is still unclear. This study investigates the effects of the addition of various concentrations of WHF, with and without polyvinyl alcohol, on the physical and mechanical properties of the starch foam. The foams were produced through a baking process with a thermopressing machine at lower and upper mold temperatures of 170 °C and 180 °C for 100 s. Five different WHF concentrations were tested, namely 0%, 5%, 10%, 15%, and 20%, with and without the addition of 10% polyvinyl alcohol. The products were then tested for their characteristics, including mechanical (compressibility) strength, water absorption, morphological structure, density, color appearance, and biodegradability. The results showed that the addition of 10% WHF improved the physical and mechanical properties of the foams. However, over-supplementation (15% or more) had some weakening effects, such as lowering the compressibility strength, increasing the water absorption, and darkening the physical appearance of the products. The addition of 10% PVA also contributed positively to their compressibility, density, and water absorption characteristics.