NOR and nitroxide-based HAS in accelerated photooxidation of carbon-chain polymers; Comparison with secondary HAS: An ESRI and ATR FTIR study

• Published in: Polymer degradation and stability Vol. 96; no. 5; pp. 847 - 862
• Main Authors: Pilař, J., Michálková, D., Šeděnková, I., Pfleger, J., Pospíšil, J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-05-2011; Elsevier
• Subjects: Accelerated weathering; Ageing; Applied sciences; Commodity carbon-chain polymers; Compounding ingredients; Degradation; Derivatives; Electron Spin Resonance Imaging (ESRI); Exact sciences and technology; Hindered amine stabilizers (HAS); Identification of polymer oxidation products by ATR FTIR; Nitroxide concentration profiles; Photodegradation; Photooxidation; Physical properties; Polyethylenes; Polymer industry, paints, wood; Polypropylenes; Polystyrene resins; Properties and testing; Stabilization; Stabilizers (antioxydants, antiozonants, etc.); Surface chemistry; Technology of polymers; Photodegradation; Hindered amine stabilizers (HAS); Identification of polymer oxidation products by ATR FTIR; Nitroxide concentration profiles; Accelerated weathering; Commodity carbon-chain polymers; Electron Spin Resonance Imaging (ESRI); Performance evaluation; Transparency; Olefin copolymer; Additive; Optical properties; Piperidine derivatives; Reaction mechanism; Olefin polymer; Styrene polymer; Ultraviolet absorbent; Photochemical degradation; Norbornene copolymer; Polyethylene; Nitroxyl; Propylene polymer; Living polymer; Experimental study; Ultraviolet radiation; Stabilizer agent; Ethylene copolymer; Artificial ageing; Degradation product
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2011.02.004

Understanding processes resulting in heterogeneous degradation in polymers is of extreme importance for improving their stabilization and minimizing negative impact of photooxidation on the material properties. We adopted modern physical techniques for studies of spatial distribution of intermediates and products of photodegradation during accelerated ageing of four commodity polymers, polypropylene (PP), polyethylene (PE), polystyrene (PS) and poly(ethylene-co-norbornene) (Topas
®, TP) stabilized with hindered amine stabilizer (HAS). Concentration profiles of nitroxides inside polymer plaques along the direction perpendicular to their surface were determined by electron spin resonance imaging (ESRI) as a function of the duration of the accelerated photooxidation. We present data characterizing stabilization activity of three alkoxyamine derivatives of HAS (Tinuvin
® NOR 123, Tinuvin
® NOR 371, Flamestab
® NOR 116), Chimasorb
® 119 structurally similar to Flamestab
® NOR 116, and nitroxide-based HAS Dastib
® 1045 and compare them with the data characterizing stabilization activity of the secondary HAS (>NH) Tinuvin
® 770. ESRI data are complemented by ATR FTIR spectroscopic detection of oxidation products on the surface and inside the plaques and by data characterizing diffusive optical transmittance of the polymer plaques in the spectral region 280–400 nm (terrestrial range of the solar UV radiation).