Tribological and Physico-Chemical Properties of Electron Beam Irradiated Polyoxymethylene Copolymer (POM-C)

Abstract

Polyoxymethylene copolymer (POM-C) is an attractive and widely used engineering thermoplastic across many industrial sectors owing to outstanding physical, mechanical, self-lubricating and chemical properties. In this research work, the POM-C samples were irradiated with 1 MeV electron beam energy in five doses (100, 200, 300, 500 and 700 KGy) in vacuum condition at room temperature. The tribological and physico-chemical properties of electron beam irradiated POM-C have been analyzed using Pin on disk tribometer (under dry friction condition), Raman spectroscopy, SEM-EDS, Optical microscopy, 3D Nano surface profiler system and Contact angle analyzer. Electron beam irradiation at a dose of 100 kGy resulted in a decrease of the friction coefficient of POM-C sample due to well suited cross-linking, carbonization, free radicals formation and energetic electrons- atoms collisions (physical interaction). The irradiation doses at 200, 300, 500 and 700 kGy resulted in increase of the friction coefficient as compared to unirradiated POM-C due to severe chain scission, chemical structural and physical degradation. 100 kGy electron beam irradiated POM-C sample also shows lowest surface roughness and highest water contact angle among unirradiated POM-C and all others irradiated POM-C, which gives the lowest friction coefficient and wear loss. The electron beam irradiation transferred the wear of unirradiated POM-C sample from the abrasive wear, adhesive wear and scraping to mild scraping for the 1 MeV, 100 kGy irradiated POM-C sample which can be concluded from SEM-EDS and Optical microscopic observations. The degree of improvement for tribological attribute relies on the electron beam irradiation condition (energy and dose rate).