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Stearic Acid

STEARIC ACID is widely used in the manufacture of PVC plastic pipes, sheets, profiles, and films. It is a PVC heat stabilizer with excellent lubricity and good light and heat stability. In plastic PVC pipe, stearic acid helps to prevent “coking" during processing. It is an effective heat stabilizer in the processing of PVC film, and it can prevent the finished film caused by exposure to sulfide discoloration.

What Makes Stearic Acid Suitable for PVC processing?

Thermal Stability

Thermal stability is an essential characteristic of PVC, defining the final product’s thermal degradation. Thermal degradation affects the physical and mechanical properties of the PVC. Besides, it also limits the circularity and the recyclability of PVC pipes and other products. For this reason, companies in PVC processing use thermal stabilizers that hinder labile chlorines, replacing them with solid functional groups that can withstand elimination.

To effectively perform this function, a thermal stabilizer has to be compatible with the PVC. Besides, it must be added in a condition that reduces diffusion time without thermal degradation. The salts and esters of stearic acid are used as thermal stabilizers in PVC and polymer processing.

Uses of Calcium Stearate in PVC

The reaction of stearic acid and lime forms calcium stearate, which acts as an internal lubricant in PVC processing. The white, silky and fine powder is used to reduce the friction in PVC grains, making it a suitable internal lubricant. Compared to wax, calcium stearate has a higher softening point and does not get greasy when exposed to high temperatures. Calcium stearate is also used as a releasing agent and an acid scavenger in the PVC processing industry.