Material performanceChemical and pressure stress resistance of polymer films

The usability of polymer films in heat exchangers used in the chemical industry for solvent condensation was evaluated. The mechanical strength and chemical resistance of two high performance polymer films (a polyimide film and a PTFE-glass fibre compound) were investigated at temperatures up to 90°C with constant as well as pulsating pressure loads of 6 bar. The influence of four organic solvents (toluene, hexane, heptane, tetrahydrofurane (THF)) and hot water on the mechanical stability was determined. It could be shown that toluene and THF caused a major weakening of the material, while water, hexane and heptane barely affected the films. The best results showed the PTFE-glass fibre compound having a two monthly durability at constant pressure exposure for all the solvents used, except THF.