SYNTHESIS OF COBALT STEARATE AS OXIDANT ADDITIVE FOR OXO-BIODEGRADABLE POLYETHYLENE

• Main Author: Oktavia Asriza, Ristika
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/32556
• Institution: Institut Teknologi Bandung

High Density Polyethylene (HDPE) is a non biodegradable polymer that is difficult decomposed in nature. Therefore, modifications of HDPE need to be done to facilitate HDPE degraded in nature by means of the addition of an oxidant additive into polymers. The oxidant additive used in this study is a cobalt stearate. Cobalt stearate which can initiate the oxidative degradation process in the polymers was synthesized from stearic acid and cobalt acetate. Oxo-biodegradable polyethylene films were prepared by mixture HDPE and cobalt stearate in various compositions until homogeneous and followed with the melting process. The results of FTIR spectrum showed characteristic absorption at wave number of 1552 cm-1 which indicates the asymmetric stretching vibration of the carboxyl group with the ion cobalt. To determine the effect of cobalt stearate in HDPE, oxo-biodegradable polyethylene film was given un irradiation with UV light or a heating at various temperature during the 10 days. After given a heating, the FTIR spectra showed a new absorption peak at wave number 1712 cm-1 indicating the presence of carbonyl groups in polymers, whereas after irradiation with UV light is not visible the presence of this absorption peak. The increase concentration of cobalt stearate added in HDPE and the higher heating temperature, the intensity of the absorption peak of the carbonyl group increased. The increasing intensity of the carbonyl group absorption is caused due to the presence of damage in the film surface after heating, and this result is supported by analysis the surface properties of the film with using SEM. Based on the mechanical data, modulus Young’s values increasing after additional of cabalt stearate and make the film of HDPE would be rigid and brittle. And the result from analysis thermal, occur lost of weight around 87,76% in the film of HDPE + cobalt stearate 0,2% (w/w) that have been done thermal degradation at 25 oC during 10 days. In the same of treatment, the film of HDPE without additional of cobalt stearate occur lost of weight around 74,19%. Biodegradation tests were performed on oxo-biodegradable polyethylene film which has been given heating or UV light with using activated sludge under optimal conditions the growth of microorganisms. After biodegradation, the maximum weight decreased by 23% in the oxo-biodegradable polyethylene film with a cobalt stearate concentration of 0.2% and after heating at a temperature of 75 oC for 10 days, and only 0.69% in the same film after irradiation UV light for 10 days. Based on the results above, cobalt stearate additive is more effective to initiate the oxidative degradation of HDPE when it is initiated by heating compared to irradiation with UV light.