Characteristics of Tapioca-Glucomannan Foam Biocomposites Under Variations in Stearic Acid Concentration and Stirring Speed During Foam Formation

Abstract

Biocomposite foam made from cassava starch–glucomannan has weaknesses such as hydrophilicity and low mechanical properties. The purpose of this study was to determine the effect of stearic acid concentration and stirring speed, as well as their interaction, on the characteristics of cassava starch–glucomannan biocomposite foam and to identify the optimal combination. A factorial randomized block design with two factors was applied in this study. Stearic acid concentration, consisting of three levels (4%, 6%, and 8%), was used as first factor , while stirring speed (60, 90, and 120 rpm) was used as last  factor. The observed variables included density, thickness, thickness swelling, tear resistance, tensile strength, elongation at break, compression set, and biodegradation time. The results showed that stearic acid concentration had a highly significant effect on tensile strength, tear resistance, compression set, thickness swelling, and biodegradation, and also had a significant effect on density and thickness, but had no significant effect on elongation at break. Stirring speed had a highly significant effect on tensile strength, tear resistance, density, thickness swelling, and biodegradation, and also had a significant effect on elongation at break, but had no significant effect on compression set and thickness. The interaction between treatments had a highly significant effect on tensile strength, tear resistance, density, elongation at break, thickness swelling, and biodegradation, but did not have a significant effect on compression set and thickness. The best physical and mechanical characteristics were obtained from the biocomposite foam prepared with 4% stearic acid concentration and a stirring speed of 120 rpm, resulting in a tensile strength of 4.93 N/cm², elongation at break of 2.32%, tear resistance of 3.52 N/cm², compression set of 9.89%, thickness of 9.03 mm, density of 0.22 g/ml, thickness swelling of 0.10%, and a biodegradation rate of 72.6% after 16.78 days.