Study Tribological Properties of MoDTC and Its Interactions With Metal Detergents

Recently, the synergistic tribological properties between molybdenum dialkyldithiocarbamate (MoDTC) and metal detergents have been the focus of significant attention due to the high requirements of engine oil. In this study, an SRV tribometer and four-ball machine were used to study the tribological performance of MoDTC combined with three types of metal detergents with different base numbers. Meanwhile, the detergency of the three metal detergents was also investigated using the hot tube test and crankcase simulation test. The results showed that (i) a high-based detergent possessed an excellent detergency performance compared with that of low-based detergents. (ii) The tribological properties of the base oil with a content of 0.75% MoDTC were superior to those of other contents at elevated temperatures. (iii) The metal detergents with a higher base number showed the best thermal stability, detergency performance, and anti-wear performance among the three types of metal detergents. The anti-wear mechanism was that the synergistic action of active elements in MoDTC and metal detergents promoted the generation of a tribological film.

Oily Soil Detergency under Microemulsion Conditions: Effects of Oil Loading and Surfactant Adsorption

Detergency process of oily soil removal from fabrics is of interest and the mechanisms of oily soil removal are very complicated involving several factors: interfacial tension, oil loading and surfactant adsorption. In this study, the effects of oil loading and the surfactant adsorption on the detergency performance of oily soil removal were investigated. Mixed surfactant systems of branched alcohol propoxylate sulfate sodium salt (Alfoterra 145-3PO), an extended anionic surfactant, and secondary alcohol ethoxylate (Tergitol 15-S-5), a nonionic surfactant, were used to form microemulsions with motor oil. The CMC and CµC values of the mixed surfactants were 0.015 and 0.04 % total active mixed surfactants concentration, respectively. A polyester/cotton blend [65/35] was selected to use as a testing fabric in detergency experiments. The results showed that the oil loading and fabric weight did not affect the efficiency of oil removal. Furthermore, with the selected formulation (0.1 wt.% Alfoterra 145-3PO and 5 wt.% Tergitol 15-S-5), the oil detachment time was investigated at different temperatures (30-50°C) and different total surfactant concentrations (0.04-0.5 %). The results showed that increasing temperature and surfactant concentration were found to decrease the oil detachment time, leading to increasing oil removal.