Pour Point and Flow Improvement in Lubes: The Interaction of Waxes with Methacrylate Polymers

The most widely used pour point depressants are methacrylate polymers. Even though they have been employed commercially for many years to depress pour points and improve flow, the exact mechanism by which they do it remains obscure. It is generally believed that they function by disrupting or preventing the formation of three-dimensional wax networks, leaving the amount of crystalline wax unaffected. This paper deals with differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis to study blends of methacrylate polymers with both model paraffinic compounds and a paraffin/microcrystalline wax to gain a better understanding of their interactions. Some important structural requirements for polymer-paraffin interaction with a bearing on pour point depression have been identified. It is also shown that the polymethacrylate can have an effect on the amount of paraffin or wax that can crystallize.