The Characteristics of Citric Acid-Bonded Composite Boards Produced from Alkaline-Modified Fibrovascular Bundle of Salacca Sumatrana Fronds

Fibrovascular bundle (FVB) of Salacca sumatrana fronds is a natural fiber derived from palm plants. The fiber typically had long dimensions and the potential to be used as raw material for oriented boards. Therefore, this study aimed to evaluate the properties of oriented boards made from alkaline-modified FVB of Salacca sumatrana frond. FVB was modified with an alkali pre-treatment, comprising 1% NaOH, 1% NaOH + 0.2% Na2SO3, and 1% NaOH + 0.4% Na2SO3 to improve the dimensional stability. The sample was then manually formed into a three-layer oriented mat using a forming box, which was oriented at 3 different angles of 0 degrees, 45 degrees, and 90 degrees. The results showed that the 1% NaOH + 0.2% Na2SO3 treatment gave the lowest thickness swelling and water absorption, as well as the highest modulus of rupture and elasticity values. Based on Fourier Transform Infrared (FTIR) analysis, there was a bond between FVB hydroxyl groups and the carboxyl groups in citric acid, showing an effective bonding mechanism. Furthermore, orientated boards with an orientation of 90 degrees were the best among all chemically modified types. The results showed that the modified natural fiber of FVB formed a bond with citric acid, leading to excellent mechanical properties.