MODIFICATION OF POLYSTYRENE FROM STYROFOAM PLASTIC WASTE FOR BIODEGRADABLE PLASTICS

• Main Author: Ketut Sumarni, Ni
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/35473
• Institution: Institut Teknologi Bandung

Styrofoam plastic is widely used as packaging of electronic materials and food. Such an extensive use leads to accumulation of waste styrofoam in the environment. If such a waste is accumulated uncontrollaby without special treatments, it could couse environmental pollution, because the styrofoam is difficult to recycle and decompose by microorganisms in nature. To obtain a biodegradable polymer material, it needs modifications in the basic components of polystyrene styrofoam plastic, either through the formation of polyblends or copolymers with other polymer that can be decomposed in nature such as amylose. Generally, a biodegradable polymer that can be decomposed in nature has a chain structure of heteroatom such as amylose and polyester. To form homogenous and compatible polyblends between polystyrene with amylose, polystyrene needs to be modified by sulfonation using acetyl sulfate reagent resulting sulfonated polystyrene (PSS). Amylose can be obtained from cassava starch by extraction with methanol 80% (v/v), and continued with the separation of amylose and amylopectin by precipitation with water. Sulfonated polystyrene is mixed with amylose to form polyblend with the addition of 0.04% glycerol as plasticizer. Without the addition of glycerol, polyblend of PSS amylose is difficult to form a thin membrane or film. Polyblends were prepared in various compositions of PSS / amylose (100/0, 90/10, 80/20, 70/30, 60/40, 50/50) (w/w). Each polyblend was prepared by casting polymer solution in a mixture of solvent of toluene and n-butanol with a composition of 7/3 (v/v) and 1 mL of glycerol as a plasticizer. In preparation of polyblends, PSS was dissolved in toluene, amylose in n-butanol, and into the mixture was added 1 mL of glycerol. Polymer solution was poured into a petri dish and the solvent was then evaporated to form a membrane. Polyblends membranes were characterized by FTIR (Fourier Transform Infra Red) to analyze the fungsional groups, by tensile tester to measure mechanical properties, by TGA (Thermal Gravimetric Analysis) to analyze thermal properties, by SEM (Scanning Electron Microscopy) to reveal surface morphology and by XRD (X-Ray Diffraction) to reveal crystallinity properties, as well as by test biodegradation with activated sludge to analyze biodegradability. FTIR results showed the presence of the absorption peaks of functional groups of each component in the polyblends, which indicates the occurrence of a physical mixture between the two polymers. Polyblends formed between PSS and amylose is more homogeneous compared to polyblends between PS and amylose, due to the polar sulfonate group on the PSS can interact better with polar groups of amylose. Increasing composition of amylose in PSS-amylose polyblend can improve tensile strength, stiffness, thermal properties and crystallinity of polyblends due to the crystallinity amylase. The PSS tends to be amorphous. SEM analysis results showed that polyblend with PSS/amylose composition of 80/20 have more regular of surface pores and more compact compared to polyblend with the PSS/amylose of 50/50. Surface analysis shows that during the biodegradation process, polyblend with PSS/amylose composition of (50/50) has a higher degree of damage, proven by larger cavities compared to polyblend with PSS/amylose composition of 80/20. The experiment indicates that bacteria can degrade the amylose of polyblends. The loss of amylose component cause the membrane to be fragile and rigid, so a further damage of polyblends can occur easily. Thus, the polyblend with PSS/amylose composition of (80/20) has better characteristics of plastic materials than polyblend with other compositions. In addition the highest percentage of mass loss was observed during 40 days of incubation time.