The Effect of Mass Fraction of Rice Straw Fiber on The Mechanical Properties and Water Absorption of Cassava Starch Biocomposite

Abstract

The massive use of plastic packaging has a detrimental impact on the
environment. Alternative solutions are needed, such as replacing plastic
with biocomposites. In this study, biocomposites were made from rice
straw fiber and cassava starch using the solution casting method. The
mass fraction of rice straw fiber was varied at 74%, 78%, 82%, 86%, and
90%. To determine the characteristics of the biocomposites, tensile
testing, bending testing, water absorption testing, macro observation, and
Scanning Electron Microscope (SEM) observation were conducted. The
results showed that as the mass fraction of rice straw fiber increased, the
mechanical properties of the biocomposites decreased and water
absorption increased. The ultimate tensile strength, tensile modulus, and
elongation at break in the tensile test decreased by 79.95%, 66.65%, and
40.45%, respectively. The bending test results showed a decrease in
flexural strength and flexural modulus by 78.53% and 70.37%,
respectively. The water absorption test results showed an increase in
water absorption by 49.1%. Macro and SEM fracture morphology
observations revealed the presence of voids, agglomeration, and fibers
pulled out of the matrix due to weak interfacial bonding, which caused the
low mechanical properties and high water absorption. This study also
compared rice straw fiber/cassava starch biocomposites with commercial
egg tray samples. The results indicated that rice straw fiber/cassava
starch biocomposites have superior mechanical properties and lower
water absorption, suggesting their potential use as biocomposite
packaging products.