Metal-catalyzed oxidation INDEX

The oxidative stability of biodiesel has been the subject of considerable research as it is, besides cold flow, one of the major technical issues with biodiesel. Some recent overview articles are (Knothe, 2007 Dunn, 2008 Jain and Sharma, 2010 Xin and Saka, 2010). This issue affects biodiesel primarily during extended storage. The influence of parameters such as the presence of air, heat, traces of metal, antioxidants, and peroxides as well as the nature of the storage container was investigated in the aforementioned studies. Generally, factors such as the presence of air, elevated temperatures, or the presence of metals facilitate oxidation. Studies performed with the automated Oil Stability Index (OSI) method confirmed the catalyzing effect of metals on oxidation, however, the influence of compound structure of the fatty esters, especially unsaturation, as discussed later, was even greater (Knothe and Dunn, 2(X)3). 

There are some aspects in the raw dry NR grades for adhesive manufacturing to be considered. NR tends to suffer oxidative degradation catalyzed by metals (mainly copper). The susceptibility of NR to oxidation can be measured using the plasticity retention index. The better grades of rubber have the higher plasticity retention index. 

The plasticity retention index (PRI) is a measure of the susceptibility of the raw rubber to oxidative degradation. Oxidation is catalyzed by some metals such as copper, so that the PRI test gives an indirect indication of the presence... 

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