The mechanical behavior and the thermal stability of an encapsulant based on ethylene-vinyl acetate (EVA) were studied. The EVA properties were verified at temperatures ranging from −70 • C to 500 • C . Thermogravimetry, differential scanning calorimetry and dynamic mechanical analysis were used in this study. It has been shown that the encapsulant has a good weight stability; however, the encapsulant passes through both a glass transition and a melting phase in the range of operating temperatures. The kinetic parameters of crosslinking were also analyzed. It is possible to achieve 65 % crosslinking at a temperature of 150 • C and a time of 5 minutes. The activation energy of crosslinking is 95.6 kJ/mol.

Polyethylene vinyl acetate (PEVA) is a material widely used among others in cable industry for halogen-free cable insulation. A manufacturing blend is not a pure polymer; it contains various additives such as for example flame retardants. The paper compares properties of a basic granulate with properties of a produced cross-linked cable sheath. Thermal effects were analysed both in positive and negative temperatures in the temperature range from -150 °C to 700 °C. Differential scanning calorimetry, thermogravimetry and dynamical mechanical analysis were applied. The obtained results showed, that melting temperature, glass transition temperature, heat of fusion and crystallinity of the material decrease whereas tensile strength and temperature of thermal decomposition increase with PEVA cross-linking.

Paper is focused on a comparison of thermo mechanical properties of two plastic insulation materials used for cable sheaths. First measurement was analysed in the temperature range from ambient temperature to 60 °C because of possible laying of the cables during higher temperatures than ambient temperature. Tensile strength and elongation at break were measured by universal testing machine at following temperatures: 22 °C (ambient temperature), 40, 50, 55 and 60 °C. Results show maximum temperatures suitable for laying of the cables. The measurement of softening temperatures of sheathing materials by the thermo mechanical analysis (TMA) followed. It was determined, that recognizable change of properties is coming in the temperature interval from 60 to 100 °C, which corresponding with the start of melting. Results from the thermo mechanical analysis in a dynamic mode (DTMA) provide also information about glass transition.

No abstract

A paper deals with thermal analysis of ethylene-vinyl acetate encapsulant material used in photovoltaic modules. Properties were analysed in the temperature range from -70 °C to +130 °C. Differential scanning calorimetry and dynamic mechanical analysis were applied. It has been proven that the encapsulant passes through both a glass transition and a melting phase in the range of operation temperatures of the photovoltaic modules. Obtained results show that the encapsulant materials play essential role from the operation point of view and its properties can by no means be underestimated.