injection molding

What are Process Aids and UV Stabilizers?

Share on facebook
Share on linkedin
Share on twitter

Plastics are made by polymerization. This chemical process creates long chains of repeating molecules made primarily of carbon, oxygen, and hydrogen. The physical and chemical properties of the plastic are dictated by the structure of those molecules. Process aids, UV stabilizers, and other additives are added to plastics to change their properties.

Here’s how process aids and UV stabilizers impart specific properties to plastics.

Process Aids: Uses & Benefits

Process aids are added to raw plastics to aid in the conversion of the raw plastic into finished products. Process aids (PPA) usually refer specifically to a chemical that prevents melt fracture when extruding plastic parts.

In plastic extrusion, molten plastic is pressed through a die. For example, to form a tube, melted plastic is pushed through a hollow circular die. As the molten plastic passes through the die, friction between the plastic and the edges of the die cause “melt fracture.” This abrasive action causes surface imperfections in the final product that can make the surface appear wavy or mottled.

PPAs reduce the friction between the melted plastic and the die, analogous to a lubricant. However, the PPA is added directly to the melted plastic rather than being coated on the surface of the extrusion die. PPAs decrease the viscosity and “stickiness” of the melted plastic, improving its melt flow. This not only reduces melt fracture but also reduces melt buildup on the die that can cause die wear and production delays while dies are cleaned.

UV Stabilizers: Uses & Benefits

Organic molecules, whether they make up plastics or your skin, are prone to damage by ultraviolet (UV) rays. When UV rays strike organic molecules, two forms of damage can result.

  • Oxygen molecules absorb the UV rays and reach an excited state. The excited oxygen atom creates a free radical that is highly chemically reactive.
  • Bonds between oxygen, hydrogen, and carbon atoms break, resulting in discontinuities in the polymer chains.

The damage to the molecules of the plastic causes it to become discolored and brittle. While these changes may have little consequence for some plastic goods, protective or load-bearing goods can become significantly weakened through this process. For example, a rope made from plastic will degrade when exposed to the UV radiation in sunlight.

UV stabilizers are added to most plastics that are exposed to the environment. UV stabilizers can act in two different ways inside plastics.

One group of UV stabilizers is referred to as radical scavengers. These UV stabilizers, such as hindered amine light stabilizers, convert free radicals into stable molecules.

The other group of UV stabilizers absorbs UV radiation. This mechanism is analogous to sunscreen applied to the skin. The molecules in the UV stabilizers absorb UV radiation, sacrificing themselves to protect the plastic.

Hazards of Process Aids and UV Stabilizers

Process aids and UV stabilizers are generally safe to add to plastics. Rather than coatings, they are added directly to the raw plastic before extrusion. As such, they are locked into the wall of the plastic and are unlikely to bloom to the surface.

Process aids and UV stabilizers substantially improve the physical and chemical properties of plastic goods. Contact Phoenix Plastics for more information about these and other high-quality plastics additives.



Vapor Corrosion Inhibitors Are Becoming More Popular

During the last couple of years, the market has seen increased activity in a new class of anti-corrosion plastic compounds called VCI (Volatile Corrosion Inhibitor). These new products were developed according to environmental standards. VCI today represents the most economical avenue in combating atmospheric corrosion damage to metals. It is estimated that in the US

Read More »
flame retardant

Using Flame Retardants in Manufacturing

Flame retardants are in many consumer products. These are chemical compounds added to a variety of materials that help prevent or limit their combustibility. Adding these types of chemicals during the manufacturing process slows the spread of fire from consumer goods. Consumers rarely hear of or see the flame retardants that are in everyday products.

Read More »
antimicrobial additives

Top 5 Benefits of Antimicrobial Additives in Plastic Products

Plastic products are strikingly ubiquitous, from space-age industrial components to cheap souvenirs. Though this ubiquity presents an environmental dilemma to any plastic producer, demand for this inexpensive and versatile miracle material is expected only to increase. While the reduction in plastic use remains a difficult sell, thoughtful design of plastic products can be more environmentally

Read More »


Located in Conroe, TX, just north of Houston, Phoenix Plastics was founded in 1996 but our staff has more than 75 years of experience in the plastic industry. Our testing and processing takes place in-house, which allows Phoenix Plastics to maintain high quality standards. Phoenix Plastics is an ISO:9001 certified company.


5400 Jefferson Chemical Rd
Conroe, TX 77301

1.866.760.2311 / Fax: 936.760.2322

Location Hours:
Monday – Friday: 8:00 AM – 4:00 PM CST
Dock Hours: Monday – Friday: 9:00 AM – 3:30 PM CST


Translate »
Scroll to Top