Chemically functionalized SiO2 to improve mechanical properties of oil-impregnated monomer casting nylon

ABSTRACT: Toluene-2,4-diisocyanate and dodecanol were used to chemically functionalize nanosilica (TDID-SiO₂). Composites of TDID-SiO₂ and oil-impregnated monomer casting nylon (OMC nylon) were prepared by an in situ anionic ring-opening polymerization. The dispersion of the TDID-SiO₂ in oil was studied along with the mechanical and friction properties of the composites. The results show that the dispersion of the TDID-SiO₂ in oil was significantly enhanced. Specifically, some TDID-SiO₂ was wrapped in oil droplets, and the size of the oil droplets increased from 2.3 to 3.3 μm for 0–0.125 wt % of the TDID-SiO₂ nanoparticles, which was confirmed by scanning electron microscopy. The composites exhibited excellent mechanical properties when 0.10 wt % TDID-SiO₂ was integrated into OMC nylon. The tensile strength, elastic modulus, notched impact strength, flexural strength, and flexural modulus increased by 6.9%, 7.1%, 33.2%, 15%, and 77.5%, respectively, compared to OMC nylon without TDID-SiO₂ nanoparticles. The friction coefficient was effectively controlled and the abrasion quantity was reduced. Thermogravimetric analysis showed that the thermal decomposition temperature was also improved. The improved mechanical and frictional properties of TDID-SiO₂/OMC nylon composite will enhance its application in wear-resistant products in heavy industry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46994.