Thermostimulated Current Characterizaiton of Poly(ethersulfone)

摘要

Two thermal analysis techniques, differential scanning calorimetry (DSC) and thermostimulated currents, are sued to characterize two Poly(ethersulfones) (PESs) obtained with teh same process by two different manufacturers. The glass transition temperature observed by DSC is the same for both PESs and equal to 235deg C. When PES samples are heated above the glass transition temperature (250-260deg C), one initially white and opaque PES (B) looks transparent while the other one (A) stays in the initial stage. The PES B is visibly degraded upon increasing at a lower temperature than PES A. Below the glass transition temperature, two complex relaxation modes #alpha# and #beta# situated at +170-175 and -120deg C, respectively, are observed. The analysis of the fine structure shows that they are constituted fo elementary processes characterized by relaxation times following compensation laws. For PES A at high temepratures the cooperative movements are precursors of the glass transition. For PES B a double compensation phenomena reveals the biphasic character of the vitreous phase. The comparison between teh two PESs reveals different microstructures that could be due to different processing conditions.