Modifications induced by swift heavy ions in poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) and poly(ε-caprolactone) (PCL) films.: Part 1.: Thermal behaviour and molecular mass modifications

Modifications induced by different energetic heavy ions in poly(epsilon -caprolactone) (PCL) and poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) have been investigated by the differential scanning calorimetry (DSC) and steric exclusion chromatography (SEC). A certain dose of damages, depending mainly on the charge and mass of the ion and on the intensity of irradiation, has to be overcome in order to detect any effect on PHB/HV. Actually, at a given intensity of irradiation, superior to 10(10) ions/cm(2), the level of damage intensity increased with the increase in charge and mass of the ion. Moreover, according to the SEC results, there seems to be a critical mass and/or charge threshold above which the dominant type of damages changes. As a matter of fact, high-density irradiation with Ar9+ and Kr15+ resulted mainly in chain scission whereas cross-linking was dominant when irradiating the polymer with Xe24+ and Pb56+. Th, irradiation of PCL in the conditions studied did not modify significantly the values of the melting point, the crystallisation temperature and the molecular masses of the system studied. The main effect of the irradiation detected by the DSC is the cross-linking of the polymer chains. (C) 2000 Elsevier Science B.V. All rights reserved.