Pyrogenic silica is added to unsaturated polyester resins for viscosity control and to achieve the desired thickening (thixotropic effect).
In the low-viscosity polyester resins which have good wetting properties, pyrogenic silica contributes to the formation of flat layers and prevents the formation of cracks and wrinkles in the process of manufacture of fiberglass plastics based on unsaturated polyester resins.
Addition of 10-20% pyrogenic silica to polyisobutylene causes the complete loss of fluidity by the solution. Pyrogenic silica adds thixotropic property to polyester and epoxy resins.
Due to its properties pyrogenic silica binds plasticizer and prevents its exudation. It is also used in polymeric films as anti-gluing agent. Pyrogenic silica improves the physical and mechanical properties of plastics, their exterior surface, and prevents aging of the products.