The accelerated thermal degradation of low-density polyethylene (LDPE) was studied in air at atmospheric pressure and temperatures
of 70, 80, 90 and 100C. The changes in elongation at break, traction resistance and density as a result of accelerated thermooxidative
degradation were followed. Thermal analysis curves (TG, DTG and DTA) of non-aged and thermally aged LDPE were recorded, and
the thermal analysis results were compared with those relating to the variations in the elongation at break, the traction
resistance and the density as a consequence of accelerated thermal aging.
To reveal the fire injuring of parchment, the changes in the thermal behaviour of some goat parchments, obtained from skins
originating from different animals, as a result of thermal aging were determined by thermal analysis methods (DSC; simultaneous
TG/DTG, DSC; micro hot table (MHT)). Thermal aging of parchments was revealed to bring about the decrease in shrinkage temperature,
absolute value of enthalpy of denaturation in water and some changes in non-isothermal parameters characteristic for dehydration
process in static air atmosphere.
The results obtained by DSC analysis performed in N2 and O2 flows as well as those obtained by simultaneous TG/DTG, DSC analyses have shown that both softening (melting) process parameters
and parameters of thermo-oxidative processes have not been changed by thermal ageing. The results obtained by thermal analysis
methods were correlated with those obtained by microscopic investigation of parchment samples immersed in water and scanning
electron microscopy (SEM). The application of these microscopic techniques has revealed the morphology changes in the investigated
parchments as a result of thermal degradation.
Authors:M. Prochon, G. Janowska, A. Przepiorkowska, and A. Kucharska-Jastrzabek
can facilitate the cross-linking processes but also can increase the resistance of the elastomeric materials to acceleratedthermalaging. The presence of 15% of nitrogen in keratin ( Table 1 )—an element belonging to the group of flame