Thermal degradation properties of LDPE insulation for new and aged fine wires.

The thermal behavior of new and aged low-density polyethylene (LDPE) insulations was investigated using an SDT Q600 thermal analyzer. The activation energy and pyrolysis reaction model were estimated using the non-isothermal and masterplots methods. The thermal degradation processes present different behaviors of the LDPE insulations before and after thermal aging. The thermogravimetric curves shift to the direction of higher temperature, for the aged LDPE insulation. The values of activation energy evaluated using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods are almost same. However, the activation energy values estimated by the Friedman method were slightly higher than those obtained using the KAS and FWO methods. The suitable pyrolysis reaction models of the new and aged LDPE insulations were attributed to the "Contracting area" (R2) model, which was determined using the generalized masterplots method. In addition, the pre-exponential factor and compensation effect are discussed. Finally, it should be stressed that the aged LDPE insulation generally pyrolyzes more weakly and with more difficulty than the new insulation, i.e., the ignition and flame spread of aged wire in old buildings are not relatively easy. [ABSTRACT FROM AUTHOR]