index after storage in air and in oil relative to the respective new state din 53508 and din 53521 fig2 shows a diagram illustrating the maximum tensile force elongation for nonwoven fabrics a and b after storage at 150 u00b0 c in air and in oil relative to the respective new state din 53508 and din 53521 fig3 shows a diagram illustrating the maximum tensile forces for nonwoven fabrics a and b at various temperatures in the form of an index relative to the respective new state din en 29073 03 fig4 shows an electromicrograph of a membrane support fleece bonded with undrawn polyester fibers nonwoven fabric e comparative example fig5 shows an electromicrograph of a membrane support fleece which according to the invention is composed of 100 low shrinkage pet pbt dual component fiber nonwoven fabric f fig6 shows a dsc curve for a dual component fiber a containing crystalline sheath polymer in this case pet pbt according to the invention and fig7 shows a dsc curve for a dual component fiber b containing amorphous sheath polymer in this case pet copet prior art the bending stiffness was determined in nmm in accordance with iso 2493 the sample din a4 size sample was provided with marks 200 mm apart in the longitudinal and transverse directions the samples were stored for 1 hour at 150 u00b0 c in a circulating air oven and then cooled for 20 minutes at room temperature after which the dimensional change was determined this value was expressed as a percentage of the starting value for the longitudinal and transverse directions the algebraic signs preceding the percentage value indicate whether the dimensional change is positive or negative u2212 the mean.