COMPOSITES OF STARCH–ETHYL LAURATE COMPLEXES AND POLY(VINYL ALCOHOL) AS BIODEGRADABLE PLASTIC MATERIALS

• Main Author: Widiyani, Fely
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/75476
• Institution: Institut Teknologi Bandung

Conventional plastics from petroleum are difficult to decompose naturally, causing environmental pollution. One alternative to overcome this problem is the development of plastics that can be degraded naturally. This type of plastic is an environmentally friendly plastic, renewable and easily degraded by microorganisms in nature. One of the biomaterials that can be used as a plastic base is starch. Starch is a polysaccharide which is abundant, economical, non-toxic and easily degraded naturally. In this study, plastic was made from PELPVA (Starch–Ethyl Laurate and Poly (Vinyl Alcohol) complex). Starch can be complexed with ethyl laurate to form starch–ethyl laurate inclusion complexes to increase the tensile strength of the plastic with increased crystallinity. Ethyl laurate is a fatty acid derivative which has an aliphatic chain that is hydrophobic and is widely used as a flavoring additive in the food, beverage, pharmaceutical and cosmetic industries. Poly(Vinyl Alcohol) or PVA is used as a mixed polymer because it has high elasticity so it can increase the stretch of the plastic. Composites were prepared using the insitu method by mixing starch with ethyl laurate at 86 ?C for 2 hours with variations in ethyl laurate concentrations of 1, 3, 5, and 7% (w/w to total complex weight). The complex was mixed directly with PVA with variations of 25:75, 50:50 and 75:25 (PEL: PVA) without prior drying. Next, 19% (w/w to the total weight of the film) was added with plasticizer in the form of glycerol and 4% citric acid (w/w to the total weight of the film). The characterization of PELPVA films includes Fourier Transform Infra-Red (FTIR), Thermogravimetric Analysis (TGA), tensile and strain strength tests, contact angle measurements, plastic aging tests or plastic aging in the form of moisture absorption tests and X-Ray Diffraction (XRD) tests. burial in the ground. The FTIR results show that the PELPVA film exhibits characteristic vibrations of its constituent components, but the C=O vibrations of ethyl laurate do not appear. This indicated that ethyl laurate had entered the amylose channel and formed a starch–ethyl laurate inclusion complex so that it could not be detected during the FTIR test. The results of the mechanical tests showed that (1) the PELPVA-3 film (25:75) had a maximum tensile strength and strain of 13.7 MPa and 327.3%, (2) the addition of ethyl laurate caused an increase in the tensile strength of the film, (3) Mixing with PVA causes an increase in the tensile strength and tensile strength of the film. The results of the contact angle measurements showed that the PELPVA film was hydrophilic with a contact angle of 40–70?. The results of PELPVA film burial tests in soil with pH 6.8–7 and humidity 60–80% showed (1) the film degraded on average 55% at 7 days, 64% at 14 days, and 70% at 30 days, (2 ) the film with the best biodegradability was PELPVA-1 film (75:25) which degraded up to 76% at 7 days, 84% at 14 days, and 86% at 30 days, (3) the composition of the PEL complex was greater than that of PVA can increase the biodegradability of the film, (4) the more ethyl laurate added, the lower the biodegradability of the film. The results of the moisture absorption test on the aging process of plastic showed that (1) the maximum moisture absorption of the film occurred on the 28th day which was marked by an average mass increase of 10.7%, (2) after the 28th day, the percentage increase in mass due to absorption humidity tends to decrease, (3) the decrease in moisture absorption after the 28th day occurs by an increase in crystallinity due to retrogradation of starch and has been confirmed by XRD data, (4) the film experienced an increase in the average tensile strength value of 67% and a decrease in the average strain by 11% due to storage. TGA results show that PELPVA film has lower thermal resistance than starch due to the addition of PVA which is easily thermally degraded. This data indicates that PELPVA film has excellent mechanical properties and biodegradability. Therefore, PELPVA film has the potential to be applied as a plastic material that can be degraded naturally.