全芳香族ポリアミドに対する放射線照射効果

抄録

Radiation effects on poly(m-phenylene isophthalamide) (m-PIA) and poly(p-phenylene terephthalamide) (p-PTA) fibers have been studied by use of γ-rays and electron beams.
Deterioration in the mechanical properties was not observed for m-PIA or p-PTA fiber even after irradiation of 1000 Mrad in vacuo. The presence of air favored the degradation of wholly aromatic polyamides as in case of aliphatic polyamides, although a much larger irradiation dose was needed for the former than for the latter to give the same degradation in mechanical properties by irradiation. The irradiation up to 1000 Mrad with electron beams in air revealed that p-PTA is more stable against irradiation than m-PIA.
Viscometric studies were carried out on the irradiated fibers. Only a small change in viscosities of p-PTA was found even after irradiation both in the presence and absence of air up to a large dose, whereas in m-PIA, gel was formed after γ-ray irradiation of about 200 Mrad in vacuo and viscosity decreased to 40% of the original value after γ-ray irradiation of about 500 Mrad in air.
No or a very small change in TGA curves for m-PIA and p-PTA was observed even after the irradiation of 1000 Mrad, showing that the irradiation at room temperature had no appreciable effect on the thermal degradation of these polymers.