Photovoltaïques

Échantillon de film EVA

Dans cet exemple, des mesures DSC* ont été effectuées sur un échantillon de film EVA d'environ 7 mg avec le DSC 204F1 Phoenix^®® à des vitesses de chauffage de 10 K/min. Ces expériences DSC ont été réalisées à l'Institut fédéral de recherche et d'essai des matériaux ("BAM"), en Allemagne.

In the 1st heating (blue curve), the Température de Transition VitreuseThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition temperature at -28°C (inflection point) is followed by an endothermic double peak between 50°C and 100°C. This melting behavior can be correlated to a lamellar thickness distribution. The exothermic peak at 158°C indicates the exothermic crosslinking reaction. Noticeable is the rather low reaction enthalpy (-14.15 J/g) in comparison to epoxy resins (typically between -400 J/g and -500 J/g).

In the 2nd heating (red curve), the glass transition occurred at almost the same temperature. The endothermic double peak between 40°C and 80°C
has changed to a broad shoulder with its maximum at 63°C. The higher the crystal thickness, the higher the melting temperature. Therefore, the change from a peak into a broad shoulder is an indication of a distribution of crystals with reduced thickness as a consequence of the thermal treatment in the 1st run. No exothermic reaction peak is present in the 2nd run, indicating that the crosslinking process was finished after the 1st heating.

*Our thanks to Dr. W. Stark and M. Jaunich from the Federal Institute for Materials Research and Testing ("BAM") in Berlin for the measurements and discussion. The results are published in Polymer Testing 30 (2011) 236-242.