Study of Tensile Response of Kapton and Mylar Strips to AR and CO2 Mixtures for the BteV Straw Tube Detector

Gas mixtures are known to affect mechanical properties of plastic materials of interest in HEP gas detectors. We have studied tensile properties of several materials for use in the straw tube detector of experiment BteV at the Fermilab Tevatron. A straw tube is a complex structure made up of two different layers of polymeric material with aluminium deposition and glue, therefore we have decoupled all these elements to better understand gas effect on each one. We have tested four different gas mixtures of Ar and CO2 on several strips of kapton and mylar loaded at about 200g (typical tension for straw tubes in BTeV). We have also considered temperature, pressure and relative humidity effects on strips mechanical tension.