Thermo-oxidative stability of polyamide 6 films II. Chemiluminescence techniques

Chemiluminescence (CL) and imaging chemiluminescence (ICL) were used to stu dy the thermo-oxidative stability of polyamide 6 in the temperature range o f 100-140 degrees C. The CL intensity time curves (CL curves) for both unst abilised and stabilised polyamide 6 film indicated an initial period at a h igh intensity level of varying shape followed by a basically sigmoidal incr ease and a subsequent maximum. This maximum was found to occur at a time co rresponding to a drop in strain at break. Polyamide 6, stabilised with the phenolic antioxidant Irganox 1098, showed a similar CL curve although shift ed towards lower intensity levels and longer times. The ICL study revealed essentially homogeneous oxidation. Both the ICL study and the CL studies cl early indicated oxidation from the beginning of ageing, also in the presenc e of the phenolic antioxidant. The CL intensity is not directly related to the rate of oxygen uptake. Instead, the CL intensity in oxygen seems to be related to the content of peroxides. However, other species causing lumines cence cannot be excluded. (C) 2000 Elsevier Science Ltd. All rights reserve d.