Oxyluminescence in Polymer Stabilizer Studies

Schard and Russell (138) studied the OL change for polypropylene containing varying amounts of the stabilizer. 4,4 -thiobis 3-methyl-6-rm-butylphenol). The OL was delayed for a short period of time after admission of oxygen to the system to an extent depending on the stabilizer concentration. The rate of OL emission curve rise appeared to vary inversely as a function of stabilizer concentration. Preliminary studies showed that the effect of stabilizer on the OL of polyethylene was quite different from that in polyethylene. The time to maximum intensity of OL was of little value in the former since with 0.1% of stabilizer present, the maximum intensity was attained almost instantly. 

Collins and Wendlandt (155) used OL to determine the stabilizer concen-1 tration in polyethylene. The initial deviation of the curve from the baseline1 as well as the peak maximum temperature were both found to be a function of stabilizer concentration in the polymer. The method was compared to those using TG and DSC. 

Most of the early studies used the isothermal mode (136-140) but more recent ones employed the nonisothermal mode (50, 141-142). Many of the early isothermal studies were carried out at a temperature of 150CC (136-139) but the nonisothermal mode has been used to study polymers up to a temperature maximum of 400°C. This is usually the upper temperature limit 

A compilation of polymers known to exhibit OL is given in Table 9.Z 

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