Who’s Blend with PVC ?

Additives are blended with PVC to determine the properties of the PVC, we want to form. These include; texture, color, stability, mechanical and electrical properties, clarity and weather fastness.

The relevant additives are mixed with the polymer in a process called compounding which is carried out in one of two ways ::–

One method blends all the ingredients using an intensive high-speed mixer to form a 'dry blend' powder, which is then fed into the processing equipment. The second method blends the ingredients in either a high or low speed mixer and then the powder is transferred to a melt compounder. This produces a melt which, when cool, is cut into granules ready for processing.

A variety of processing methods such as extrusion, injection molding, blow molding and coating are then applied to the PVC compounds to form products.

Common/main additives are as follows :-

• Plasticizers (make products flexible)
• Heat Stabilizers (prevent PVC decomposing when heated)
• Lubricants (control its rate of flow when it is molten and prevents it from sticking to metal surfaces)
• Processing aids and impact modifiers (make plastic more workable or make the final article stronger)
• Fillers (make up half the weight of a PVC plastic article to increase profits)
• Colorant’s (organic dyes or inorganic pigments)
• Flame retardants (PVC is less flammable than most polymers but by adding a few % antimony oxide makes it even less so)

Other specialist additives are antistatic agents, bio-stabilizer’s and viscosity modifiers.

All the additives are tested for environmental compatibility and toxological safety before they are used.