Recycled and Virgin HDPEs as Bleed Inhibitors and Their Rheological Influences on Lubricating Greases Thickened with PP and mPP

Abstract

Polypropylene (PP) thickened lubricating grease exhibits high oil bleed tendency at low temperatures, which makes it a promising candidate for low temperature applications. At elevated temperatures, PP thickened lubricating grease exhibits excessive oil bleeding, which limits its use at high temperatures. Excessive oil bleed adversely affects the lubricating performance of the PP thickened grease. The present work is focused on the study of the oil bleed tendency of PP and Maleated Polypropylene (mPP) thickened greases at various temperatures by incorporating virgin and recycled high density polyethylene (HDPE) into the thickener system. Grease containing various percentages of PP and mPP thickeners were prepared and modified with different percentages of virgin and recycled HDPE. Polymers were characterized through differential scanning calorimetry (DSC) techniques. The oil bleed performance of these greases was evaluated by the conical sieve method (ASTM D 6184) at various temperatures. Storage (G′) and loss modulus (G″) of greases was determined by rheometry at 25 °C. Incorporation of HDPE and recycled HDPE in PP thickened grease decreased oil bleeding compared to the base grease.

Ionic Liquids as Grease Base Liquids

“…This parallel angular frequency sweep represents an approximation of the LVR conditions at steady state, as low frequencies correspond to longer time steps for constant angular deformation [44]. As frequency increases, greases exhibiting strong microstructure will tend to continue the frequency independent parallel trend, as seen for 60 wt % and 70 wt % data for [BMIM][TFSI] and mineral oil.…”

Eco-Friendly Multipurpose Lubricating Greases from Vegetable Residual Oils

“…The penetration values of samples increases with decreasing thickener content. Slight change of a parameter may result change in penetration values [17]. The NLGI consistency number alone is not sufficient for specifying the grease required by a particular application.…”