Plastics are amazingly versatile and useful compounds, but they do have a common Achilles’ heel: heat. Anyone whose kid has left a toy soldier in the oven, or — if you’re old enough to remember them — had their favorite cassette tape warp in a hot car, has experienced first-hand how heat can affect plastic and vinyl materials.
Heat stabilizers solve that problem by helping the materials they’re added to better resist the damage that can stem from exposure to high temperatures. These common polymer additives are precisely why extremely hot water doesn’t melt the PVC plumbing pipes in your home.
When incorporated into a polymer, heat stabilizers protect the properties of the overall compound from heat damage, either during the manufacturing process or during normal use of the finished product. While different polymers have varying degrees of heat resistance, heat stabilizers are added to virtually all polymer types. Polyvinyl chloride (PVC) is the most common polymer that benefits from a heat-stabilizing additive.
Heat stabilizers help preserve the polymer’s appearance, strength, elasticity, durability and performance characteristics. Two basic types of heat stabilizers are used in polymers: organophosphites, which protect polymers during the manufacturing process, and phenolic antioxidants that protect the polymer during its usable life. A variety of additives fall under those two categories. How the polymer will be manufactured, processed and used influences the choice of heat stabilizer.
PVC is the most common polymer that benefits from the addition of heat stabilizers, and it shows up virtually everywhere in everyday life. It’s a preferred construction material, it’s used in medical devices, children’s toys, as protective housing for delicate cables and wires, and even in credit cards. PVC is one of the most versatile polymers, but it’s also susceptible to heat damage. In PVC, heat stabilizers must accomplish several functions, including neutralizing hydrogen chloride, replace weakened carbon-chlorine bonds, and prevent oxidation.
Uncertainty about the type, quantity and properties of any additive is not good for any manufacturer, so one of the many types of polymer testing we do at Polymer Solutions is heat stabilizer analysis.
Among the tests we use for heat stabilizers is chromatography analysis. These analytical methods help us determine the identity and quantity of stabilizers in plastics and polymers, and even make educated predictions regarding how the additives will affect the product’s performance and physical characteristics. We’ve use chromatography methods to deformulate and reverse engineer materials with unknown components, as well as confirm additive levels in consumer products that were degrading too quickly.
Thermogravimetric analysis (TGA) is also useful for heat stabilizer analysis. TGA allows us to examine the thermal stability of materials and tells us about their composition. We frequently use this kind of test when working with PVC materials. Using TGA, we’ve tested rubber seals, vinyl fabrics and automotive components.
A number of common polymer additives allow manufacturers to tailor materials and products for specific needs. Heat additives are among the coolest of these, making already great materials even more useful.