Comparative study of the tribological properties of polyamide 6 filled with molybdenum disulfide and liquid crystalline additives

Abstract

Abstract The effect of adding a 1 wt % proportion of thermotropic liquid crystals 4,4′‐dibutylazobenzene (LC1) and 4‐octyl, 4′‐cyanobiphenyl (LC2) on the tribological properties of polyamide 6 (PA 6) is compared with that of the addition of MoS 2 in different concentrations (1 and 5 wt %). Friction and wear are determined in a pin‐on‐disk tribometer by using injection‐molded additivated nylon disks against steel or aluminum pins, below (25°C) and above (80°C) glass transition temperature. Polymeric blends are characterized by differential scanning calorimetry and by optical and scanning electron microscopy and microanalysis. Concentration of liquid crystalline additives is higher at the surface than in the bulk of PA 6 disks. Crystallinity degree of PA‐6 is not significantly changed by the presence of additives. Addition of 1 wt % LC1 improves processibility of PA 6 by increasing its melt flow rate. Cyanoderivative liquid crystal (LC2) shows the best wear‐reducing ability for PA 6/steel contacts at all temperatures. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2426–2432, 2001