| dc.description.abstract | Thermoplastic elastomer which is produced from graft copolymerization of styrene onto natural rubber can be used as lubricant additive. This additive has a function as index viscosity improver. Index viscosity is one of the important aspect to classify the lubricant quality since it has an influence on temperature stability of the lubricant oil. Graft copolymerization by free radical mechanism on emulsion polymerization v technique was conducted at ratio 85:15, ammonium peroxidisulfate as initiator, and sodium dodecyl sulfate as surfactant at 65oC for 7 hours. The graft copolymer was creeped and soaked into acetone to separate the homopolymer of styrene. The pure graft copolymer was dried and masticated. The pure graft copolymer was made into main solution by dissolving on xylene at 20% concentration. The main solution was added on base oil (HVI 60 and HVI 650) at concentration of 1%, 3% and 5%. The result showed that the grafting efficiency was 56.48%. The base oil HVI 60 and HVI 650 has initial index viscosity as 100 and 92, respectively. Further after the addition of graft copolymer the index viscosity was increased to 181, 185, 186 and 141, 143, 145, respectively. The other characterizations include ash content 0.01%, Mg content as 0.003%, density 0.86 g/ml and 0.89 g/ml, and pH 5. Thus the grafted copolymer of natural rubber and styrene can be used as index viscosity improver at concentration 5%. | en |
