Progress in the Light Stabilization of Polymers

Photostabilization of Polymers

“…Other methods for the determination of the quenching rate constant (k q ) are described in Section 9.13. For example, the 2,2,6,6-tetramethyl-4-oxopiperidine-1oxy radical (6.29) decomposes at 105-110°C to 1-hydroxy-2,2,6,6tetramethyl-4-oxopiperidine (6.36) and a trace of 2,6-dimethyl-2,5heptadiene-4-one (6.37) according to the mechanism: 1110 The crystals of (6.29), after six months' standing at room temperature, yield 1-hydroxy-2,2,6,6-tetramethyl-3-(2,2,6,6-tetramethyl-4-oxopiperidinoxy)-4-oxopiperidine (6. These data show that the nitroxy radicals are weak quenchers of singlet oxygen with k q "" lOS- Low-molecular-weight nitroxy radicals are unstable at elevated temperatures.…”

“…1110 A mixture of 100 parts of polypropylene powder, 0·2 part of an antioxidant and 0·2-0·4 part of the photostabilizer, after wet blending from methanol, is preheated to 215°C for 2 min, then plasticized in a Brabender Plasticorder for 10 min at 200°C in order to produce a homogeneous material, which is further pressed for 6 min at 260°C under 15 t pressure and then rapidly cooled in cold water. Additives such as thermal stabilizers, antioxidants and photostabilizers should be incorporated into the polymer by wet blending with solvent (e.g.…”

“…Photostabilizing activity of different types of hindered amines1110 Photostabilizing activity of different types of hindered amines1110 …”

Photostabilisation of Polymer Materials

“…HALS was based on the discovery that the 2,2,6,6-tetramethyl-1-piperidinyloxy, free radical(TEMPO)(1)),whichalreadywas knownas aneffective radicalscavenger [46,47], was a very effective UV stabilizer too [48,49]. However, due to its physical and chemical properties TEMPO itself did not led to practical use.…”

“…However, due to its physical and chemical properties TEMPO itself did not led to practical use. The discovery that compounds in which the N-oxyl functionality was replaced by a NÀH functionality also showed good UV stabilization activity was the key finding that led to the development of HALS stabilizers [49]. The discovery that compounds in which the N-oxyl functionality was replaced by a NÀH functionality also showed good UV stabilization activity was the key finding that led to the development of HALS stabilizers [49].…”