Polyethylene Wax: Uses, Characterization, and Identification

The characterization of a commercial particulate sample labeled as "polyethylene (PE) wax" used in pigment masterbatch preparation was performed in the present study by comparing its properties with similar materials; a paraffin wax, sorbitan monostearate (Span 60), and myristic acid. The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). Infrared spectroscopy showed that there were vibrations of CH2 and CH3 groups in paraffin wax, CH2, CH3, C-O, and C=O groups in commercial wax and Span 60 and myristic acid. It was found that commercial wax has a melting point of 54.9°C and heat of fusion of 115 J g-1. The particles were in spherical form with 170 μm average diameter and mixed with cylindrical fibers of 5.45 μm diameter and 75 μm in length. There were particles having 560 μm diameter with holes of 145 μm on their surface. In these large 266particles, there was a crust of 32 μm in thickness coating aglomerated small particles. It was found that the commercial wax was not "PE wax" as it was labeled. The melting point, functional groups, and the crystal structure of commercial wax had closer similarity to Span 60 than that of paraffin wax and myristic acid. However, its onset temperature of mass loss was much lower than that of Span 60 and the heat of fusion of Span 60 was much lower than that of commercial wax. Thus, it was concluded that further studies with more advanced methods are necessary to make a complete identification of commercial PE wax samples.