2.1 Synthesis of EGMD and Estercoat
EGMD and Estercoat are soybean oil-based wax like materials developed in our lab for corrugated coating [8]. It was synthesized following the method reported in our previous study [8] with minor modifications. Stearic acid and ethylene glycol were mixed in a round bottom flask at a molar ratio of 1:0.6 with 1 wt% of amberlyst-15 as catalyst. The mixture was heated at 95 °C in an oil bath for 8 hours to synthesize a mixture of ethylene glycol mono and diester (EGMD). Hot filtration was used to remove the catalyst after the reaction and the collected liquid was cooled and saved. Mono and diacylglycerol (50/50) mixture of 5 wt% was then mixed into the previously collected EGMD at 75 °C to form the Estercoat. Both the EGMD and Estercoat were used for tribological tests.