Lubricant is an indispensable additive in PVC processing. For lubricants, the commonly referred function in industry`s can be summarized in two points, they are: it reduces the friction pre-melting particles of polyvinyl chloride and the macromolecules in the polyvinyl chloride melt. It is actually the most typical summary of the two aspects of lubricant action (internal and external lubrication). Then, we will discuss and analyze the internal and external lubrication of PVC Lubricant from the technical level for you.
1.Internal lubrication
In terms of PVC, the internal lubrication of the lubricant and the plasticizer can be regarded as the same kind of material, playing the role of plasticizing or softening. The difference is that the polarity of the lubricant is lower and the carbon chain is longer. Therefore, compared with plasticizers, lubricants and PVC are less compatible. Lubricants are incompatibly (and moderately compatible) with polyvinyl chloride, so only a small number of lubricant molecules can pass through the chains of the polymer like plasticizers, weakening their mutual attraction. When the polymer is deformed, the chains can slip and rotate more easily without lowering the glass temperature of the polymer too much.
2.External lubrication
External lubrication refers to the interface lubrication mechanism. The lubricant is attached on the surface of the molten resin or on the surface of the processing machine or mold, forming a layer of lubricant molecules. lubrication interface which is formed by the existence of molecular layer of lubricant, reduced the friction between the resin and the processing machinery as as result. The viscosity of the sliding interface film and its lubrication efficiency depend on the melting point and processing temperature of the lubricant. In general, lubricants with long molecular carbon chains play a better role of lubrication because they keep the two friction surfaces away from each other.
