Analysis of polyolefin stabilizers and their degradation products

Abstract

Polymeric materials are complex samples, as they contain various groups of additives, compounding ingredients, and fillers. An important group of additives are stabilizers. Efficient stabilization is essential especially for polypropylene, as it is sensitive to oxidation and radical attack due to the numerous tertiary carbon atoms in its structure. How long a polymer will be sufficiently stabilized can be deduced from the contained amount of intact stabilizer. Different approaches for the analysis of stabilizers in polyolefins are available, which include sample preparation with subsequent chromatographic separation as well as direct analysis techniques. In round-robin tests, stabilizer concentrations obtained varied strongly. This shows the demand for reliable and robust methods. Stabilizers get consumed while protecting the polymer and are then present as degradation products. They were observed while quantifying intact stabilizers, in migration studies, and - if volatile - in emission studies of polymers. Furthermore, e.g. interactions with other polymer ingredients or irradiation degraded stabilizers. The identification of degradation products provides a better insight into the reactions associated with stabilization. Their quantitation makes it possible to deduce the original level of stabilization. Furthermore, polymer ingredients degrading stabilizers can be identified. Knowledge on these interactions contributes significantly to improved polymer stabilization.

Tailoring the desired optical and mechanical performance of polyester‐plasticized PVC films: the role of different light stabilizers on the photo‐degradation

“…Such stabilizers are properly called UV absorbers (UVAs), such as 2‐hydroxyl‐4‐(octyloxy) benzophenone (UV531), and 2‐(2‐hydroxy‐3‐tert‐butyl‐5‐methylphenyl)‐5‐chlorobenzotriazole (UV326), which form O···H···O bridges or involving O···H···N tunneling . The combination of two kinds of light stabilizers (HALS and UVAs) is common and effective in polymer systems such as polyolefins . However, the photostabilization of polyester‐plasticized PVC containing light stabilizers (HALS and UVAs) has not been well researched according to the best of our knowledge.…”

The consequences of physical post-treatments (microwave and electron-beam) on food/packaging interactions: A physicochemical and toxicological approach

“…The sharp reduction in the rate of Irgafos 168 extractable after irradiation could also be explained by the formation of derivatives. The oxidized form of Irgafos 168, the 2,4-di-tert-butylphenol, and the 1,3-di-tert-butylbenzene, were observed in polypropylene stabilized with Irgafos 168 (Reingruber & Buchberger, 2010). The treatment dose applied to the materials (1-25 kGy) may have been responsible for the different behaviors of the stabilizers and explains the non-detection of some compounds observed by some other authors.…”

Polyolefins and the environment

“…This decreases the concentration of intact stabilizer in the polymer and is hence undesirable. A knowledge on the formation of the degradation products helps to identify these degradation pathways of the stabilizers and to avoid them [187]. Lastly, degradation products of stabilizers generated when protecting the polymer should be identified in order to have a better insight into involved reactions.…”