Near critical carbon dioxide sorption equilibria at 50°C and pressures up to 40 atms are analyzed and interpreted on the basis of the multiple sorption mechanisms possible in a glassy amorphous and semi crystalline polymer. Varying the penetrant-polymer testing temperature and external pressure it is possible to meet the full range of possible sorption behavior, from ideal Fickian diffusion to limiting relaxation controlled kinetics. Low sorption levels of low-pressure gases are attained through an ordinary Fickian mechanism. At higher gas pressures, however, higher penetrant sorption levels induce polymer relaxation affecting the final sorption behavior. A highly interacting solvent, as Carbon Dioxide in near critical conditions, leads to anomalous sorption ranging from relaxation controlled Fickian diffusion to limiting Case II and diffusion controlled relaxation, at high solvent uptakes (sorption from high activity vapor or from liquid phases). Generally, swelling has been observed to be accompanied by a solvent induced crystallization as detected by means of High pressure Differential Scanning Calorimeter (DSC) and Wide Angle Xray Scattering (WAXS).

Near Critical Carbon Dioxide Sorption Induced Crystallization in PET

AVERSA, Raffaella;APICELLA, Antonio
2016

Abstract

Near critical carbon dioxide sorption equilibria at 50°C and pressures up to 40 atms are analyzed and interpreted on the basis of the multiple sorption mechanisms possible in a glassy amorphous and semi crystalline polymer. Varying the penetrant-polymer testing temperature and external pressure it is possible to meet the full range of possible sorption behavior, from ideal Fickian diffusion to limiting relaxation controlled kinetics. Low sorption levels of low-pressure gases are attained through an ordinary Fickian mechanism. At higher gas pressures, however, higher penetrant sorption levels induce polymer relaxation affecting the final sorption behavior. A highly interacting solvent, as Carbon Dioxide in near critical conditions, leads to anomalous sorption ranging from relaxation controlled Fickian diffusion to limiting Case II and diffusion controlled relaxation, at high solvent uptakes (sorption from high activity vapor or from liquid phases). Generally, swelling has been observed to be accompanied by a solvent induced crystallization as detected by means of High pressure Differential Scanning Calorimeter (DSC) and Wide Angle Xray Scattering (WAXS).
File in questo prodotto:
File Dimensione Formato  
ofsp.10675.pdf

accesso aperto

Tipologia: Documento in Pre-print
Licenza: Dominio pubblico
Dimensione 453.78 kB
Formato Adobe PDF
453.78 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11591/362794
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact