Meaning
Molecular fragmentation occurs when a phenolic antioxidant loses its structural integrity due to exposure to high temperatures or intense mechanical shear. The occurrence of irganox 1010 breakdown reduces the ability of the resin to resist further degradation during the service life of the part. Processing temperatures above 280 degrees Celsius accelerate the loss of the primary antioxidant.
Thermal Oxidation
Scavenging of peroxy radicals by the sterically hindered phenol prevents the cleavage of polymer chains. When the stabilizer concentration drops below a certain level, irganox 1010 breakdown allows the formation of carbonyl groups and vinyl groups. These chemical changes lead to a decrease in the elongation at break for the molded component.
Oxidative Indicator
Oxidation products of the additive include quinone methides which absorb light in the visible spectrum. Presence of irganox 1010 breakdown often coincides with a yellowing of the plastic material. This aesthetic defect results in the rejection of transparent or white parts in a production run.
Degradation Mechanism
Intense shear rates in the extruder screw increase the rate of stabilizer depletion. Adding a secondary antioxidant like a phosphite helps to protect the primary stabilizer from premature irganox 1010 breakdown. Proper stabilization ensures that the melt flow index remains stable throughout the molding cycle and prevents the loss of physical properties in the final product.
