Thermo-mechanical characterisation of fluoropolymer films for concentrated solar thermal applications

The aim of this work is to characterise fluoropolymer films as transparent layers in a pneumatic pre-stressed sun concentrator. Fluoropolymers have been chosen due to their excellent optical and mechanical properties and their extraordinary stability against ultraviolet radiation. A total of five different fluoropolymer films have been selected and their thermal, mechanical and thermo-mechanical properties at application relevant temperatures were characterised. Even though no material complies with the requirements, an ethylene-tetrafluorethylene-copolymer (ETFE) is suggested, with the recommendation to adapt and adjust the film thickness and the production process to influence the morphology and subsequently the thermo-mechanical behaviour of the material.