PREPARATION AND CHARACTERIZATIONS OF PLASTICS BASED ON STARCH-METHYL MYRISTATE COMPLEXES WITH THE ADDITION OF POLYVINYL ALCOHOL AND TIO?

• Main Author: Jesika Purba, Naomi
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/87206
• Institution: Institut Teknologi Bandung

Starch is a natural polymer that can be isolated from various plants such as cassava, potato, and corn, making it abundant and easy to obtain. Starch can be used as the main raw material for producing plastics, however it exhibits weak mechanical properties. Therefore, several methods are required to improve the mechanical performance of starch-based plastics. This research aims to develop eco-friendly starch-based plastics through the formation of an inclusion complex between starch and methyl myristate (MM), with glycerol and citric acid as plasticizers, as well as the addition of polyvinyl alcohol (PVA) and titanium dioxide (TiO?) particles. Starch was isolated from cassava, yielding a recovery of 5.7% (w/w), with a moisture content of 6.6% (w/w) and an amylose content of 22.9% (w/w). Starch acts as the primary matrix due to its natural degradability, while methyl myristate enhances stability. Plasticizers reduce the rigidity of the starch structure, and PVA serves as a matrix reinforcement. Additionally, TiO? is used as a filler, capable of absorbing light at a wavelength of approximately 200 to 400 nm, providing anti-UV properties. The plastic was produced through gelatinization, complexation, and mixing, employing heat treatment at specific temperatures. Different concentrations of the guest molecule were used: MM 3%, MM 5%, and MM 7% (w/w of the total complex). The complex-to-PVA ratio was varied at 2:1 and 3:1. Plasticizer content varied between 18%, 23%, and 28% (w/w), comprising citric acid at 3%, 4%, and 5% (w/w) and the remainder being glycerol. TiO? was added in amounts of 2% and 4% (w/w). An increase in guest molecule content enhanced starch crystallinity, improving tensile strength. However, data indicated that plastics with 3% guest molecules exhibited the highest mechanical properties, suggesting that higher concentrations may lead to aggregation, reducing tensile strength. Increasing PVA content improved mechanical properties due to PVA’s superior mechanical characteristics, which reinforce the starch matrix. The plasticizer facilitated polymer chain interactions, enhancing elongation. TiO?, acting as a filler, increased the stiffness of the plastic; however, excessive TiO? led to aggregation, decreasing homogeneity. The results showed that the most compatible plastic formulation included 23% plasticizer (18% glycerol and 5% citric acid), 3% methyl myristate, a complex-to-PVA ratio of 2:1, and 2% TiO?, achieving a tensile strength of 5.59 MPa and elongation of 252%. The plastics exhibited hydrophilic behavior with contact angles of 62.8–78.8°, water absorption ranging from 366.6% to 542% of its initial weight, the surface topography with Sa values ranging from 0.038 to 0.1394 ?m and Sq values ranging from 0.0462 to 0.2201 ?m, and absorbing moisture up to 6.91% at 53% relative humidity (RH) on the 15th day.