A Simple Modification of the Busetti-Harvey Stationarity Tests with Structural Breaks at Unknown Time

2014 ◽  
Author(s):  
Anton Skrobotov
Keyword(s):  
Structural Breaks ◽  
Simple Modification ◽  
Stationarity Tests

Variance Shifts, Structural Breaks, and Stationarity Tests

2003 ◽  
Vol 21 (4) ◽  
pp. 510-531 ◽  
Author(s):  
Fabio Busetti ◽  
A. M. Robert Taylor
Keyword(s):  
Structural Breaks ◽  
Stationarity Tests

Simple Modification Measurement of Photodegradability of Polymers by using Photo-induced Chemiluminescence Technique

2013 ◽  
Vol 10 (2) ◽  
pp. 51
Author(s):  
Siti Farhana Zakaria ◽  
Keith R Millington
Keyword(s):  
Free Radicals ◽  
Organic Materials ◽  
Oxidative Degradation ◽  
Working Life ◽  
Bimolecular Reaction ◽  
Synthetic Polymers ◽  
Accelerated Weathering ◽  
Simple Modification ◽  
Uv Absorbers ◽  
Irradiation Period

Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.

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