|Title: ||Effect of hindered piperidine light stabilizer molecular structure and UV-absorber addition on the oxidation of HDPE. Part 1: Long-term thermal and photo-oxidation studies|
|Citation: ||Journal of vinyl and additive technology, 2004, vol. 10, no. 2, pp. 79-87|
|Publisher: ||John Wiley & Sons|
|Issue Date: ||Jun-2004 |
|Additional Links: ||http://doi.wiley.com/10.1002/vnl.20011|
|Abstract: ||This series of papers explores the effect of structural characteristics of 2,2,6,6-tetramethylpiperidine-based hindered amine light stabilizers (HALS) on the long-term (40 months) thermal (110°C in air) and photo-stabilization (Microscal unit wavelength >300 nm) performance characteristics of high-density polyethylene formulations. Possible synergism with a triazine functional UV absorber is also explored. Under thermal degradation (measured by carbonyl index) the polymeric HALS performed best, mainly because of reduced volatilization. Additionally, >N-methyl HALS generally showed superior performance under thermal degradation. There was no synergism between an N-CH3 polymeric HALS and the UV1164 triazine additive. However, the equivalent N-H polymeric HALS interacted in a complex manner with UV1164, giving synergism and antagonism, depending on HALS/UV1164 ratio. Strong synergism was evident with the monomeric HALS when the total stabilizer level was 0.2% w/w. Reduction in the overall stabilizer level to 0.05% w/w eliminated the synergism. The UV1164 alone led to rapid and intense yellowing; however, the rate and intensity of yellowing reduced dramatically upon combination with HALS, particularly when the UV1164 level was above 0.1% w/w. When the formulation was under UV attack, the molar mass and the type of N-substitution had no influence on stabilization performance because of the relatively low temperature of testing (leading to reduced volatilization), and the similarly effective UV-stabilization routes for N-methyl HALS and N-H HALS. Under UV attack, yellowing reached a maximum and then decreased to approximately the initial level, while HALS/UV1164 combinations generally showed weak antagonism.|
|Description: ||Full-text of this article is not available in this e-prints service. This article was originally published [following peer-review] in Journal of Vinyl & Additive Technology, published by and copyright John Wiley and Sons.|
|Appears in Collections: ||Department of Biological Sciences|
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