EPR Imaging Determination of High Molecular Weight Nitroxide Radicals in the UV Degradation of Polycarbonate-Poly(acrylonitrile-butadiene-styrene) Polymers

Influence of different types of UV absorber/UV stabilizer combination on the photodegradation of PC/ABS blend

“…From literature13 it is seen that the important step in the UV protection by UV absorber is the excited state intramolecular proton transfer (ESIPT) followed by radiationless deactivation processes. The structural element which is responsible for the electronic deactivation is the internal hydrogen bond.…”

“…The hindered amine light stabilizers (HALS) are well known to be radical scavengers for many classes of polymeric materials 1. They are extensively used to protect PC/ABS blends from photo‐oxidation and thermo‐oxidative degradation 13, 14…”

Testing Methods of Weathered Specimen

“…The experiments are performed by recording ESR spectrum in the absence and in the presence of magnetic field gradient followed by a mathematical treatment of experimental data. 299 The above examples show the versatility of this method. Stabilization of propylene-ethylene copolymers was improved using electron spin resonance imaging of HAS-derived nitroxide radicals.…”

Data on Specific Polymers

“…Distribution of radical in PC is almost flat throughout its thickness (with exception of both surfaces) unlike in ABS in which the center of specimen has very low concentration of radical but high concentrations are just below both surfaces. 292 Nanosilicate fillers improve mechanical properties of PC composite but, because filler affects weathering, the effect is lost shortly after exposure of composite to UV radiation. 293 Similar effects were produced with montmorillonite and Laponite although degradation was not as rapid and surfactants were found to affect it.…”