Free radical decay and micro-structure evolution of PVDF membranes in situ irradiated by synchrotron radiation X-ray

The synchrotron radiation X-ray was used both as the irradiation source and testing tool for the PVDF membranes in-situ. The structural evolution of the PVDF membranes irradiated by the synchrotron radiation X-ray was analyzed by in-situ small angle X-ray scattering (SAXS)/wide angle X-ray scattering (WAXS) and ex-situ (ESR, FTIR and XRD) characterization methods. The alkyl radicals and carbon-carbon double bonds appeared in the irradiated PVDF membranes due to the irradiation effect, which confirmed that PVDF membranes first cracked, followed by cross-linked, during irradiation. The disappearance of the scattering peak at q = 0.05 angstrom(-1) indicated that the synchrotron radiation X-ray destroyed the long periodic structure. The X-ray irradiation destroyed the crystalline region of the irradiated PVDF membranes, thus, leading to a decline in the crystallinity. Thus, overall, the in-situ irradiation and analysis could effectively monitor the structural evolution of the PVDF membranes during the radiation process and reduce the influence of time intervals between irradiation and measurement.