| Friction and wear tests of steel against steel were conducted on a home-made pin-on-disk device using hexedecane (with or without 1% n-butyl acrylate) as lubricating medium. Scanning electronic microscopy (SEM) of worn scars of balls and width measurements of worn scars of disks indicate that n-butyl acrylate (BA) has good antiwear property at varied loads.To further clarify antiwear mechanisms of BA, tribopolymerization (polymerization initiated by the rubbing surface) tests were investigated. After 8h friction, wear products were obtained from both wear debris and wear fluid separated by centrifugation from each other. The infrared spectroscopy (IR) of washing demonstrated that the species were tribopolymers with similar structure to poly(n-butyl acrylate) (PBA). The thermogravimetry (TG) trace indicated that wear debris were covered by quantitatively organic substances and showed substantial thermal weight loss in the range of polymer characteristic thermal weight loss. A great deal of wear products were also collected via precipitation from worn fluid, characterized by fourier transform infrared spectroscopy (FTIR), gel permeation charomatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC). These analytical results confirmed that the precipitates were PBA with incredible molecular weight.To further reveal tribopolymerization mechanisms of BA, comparison tests were carried out with pure styrene (St) as rubbing medium. However, no substantial species were precipitated from worn fluid. In addition, the respective influence of introducing 1wt% BA and of varied sliding velocities on the mass of products was also discussed. It was founded that n-butanol nearly had not effect on it, yet it increased rapidly with sliding velocities enhancing. Based on these results and Kajdas' tribochemistry theory of esters, we brought forword tribopolymerization mode of n-butyl acrylate: exoelectron-radical-polymerization.
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