Nipa Palm Leaf or Sweet Bamboo Leaf as Potential Laminar Reinforcement for Crosslinked Tapioca Starch Composite Foams

Laminar crosslinked starch composite foams were prepared from glyoxal crosslinked tapioca starch as matrix and Nipa palm leaves or sweet bamboo leaves as laminar reinforcement. Leaves were treated with 5% sodium hydroxide and tetraethoxysilane (TEOS) at 10 % by weight of the leaf, respectively. The composite starch foams were formed by starch batter sandwiched by a treated leaf layer in compression molding. The investigated properties of starch composite foams were morphology, density, flexural and impact strength, and water resistance. Incorporation of Nipa palm leaf or bamboo leaf to crosslinked starch foam as laminar reinforcing layers reduced the size of foam cell of composites as compared to crosslinked tapioca starch foam resulting in increased density, flexural strength, impact strength, and water resistance of the composite foams. Comparing properties of laminar crosslinked starch composite foams reinforced with a leaf between Nipa palm leaf and bamboo leaf were investigated. It was found that starch composites with Nipa palm leaf as reinforcement have higher flexural and impact strength than those of composite reinforced by sweet bamboo leaf due to both better interface adhesion between Nipa palm leaf and starch and higher bursting strength of Nipa palm leaf. However, some tiny pores on the surface of the Nipa palm leaf accelerated water absorption. Consequently, the water resistance of crosslinked starch composite foams with Nipa palm leaf was lower than those of composite foams with sweet bamboo leaf