چكيده لاتين :
The thermal degradation behaviour and service lifetime of poly (p-phenylenbenzo.
bisoxazole) (PBO) fibres, prepared by our group, were investigated. The thermal
degradation processes of the PBO fibres were studied using TG-DTG at heating
rates of 5.0, 10.0 , 15.0, 20.0 K.minי1 under atmospheric air and at heating rate of
10.0 Krnirr" under nitrogen atmosphere, respectively. The thermal decomposition
process of PBO fibre occurs in a single step in the air, being especially prominent
between 900 K and 960 K. The thermal degradation kinetics of the PBO polymer under
the non-isothermal condition , gave values for activation energy E and the pre-exponential
factor A as 142.51±10 k.Lmol" and 2.43 x107±105 rnirr t , respectively. Under nitrogen
condition, the thermal degradation has started above 907 K. The thermal stability
of PBO in the nitrogen atmosphere was 80 K higher than that in the air atmosphere.
Moreover, the oxygen played an important role in the degradation, which initiated the
degradation of PBO. The decomposition gases of the PBO were analyzed by TG- FTIR.
It was found that CO, CO2 and H20 were the main compounds during the PBO degradation
in the air. PBO fibre is transformed into charred material which is stable enough
and has no aromatic species. The PBO fibre can be used for long time as the temperature
is less than 300°C in air. The serv ice lifetime of the PBO fibres was estimated by
the kinetics of thermal degradation, and the lifetime equation at weight-loss of 5% was
deduced from the equation In t =-19.954 + 17141 IT.
