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Home / News / Morphological structure of waterproof and breathable microporous film

The positive and negative morphology of the typical ePTFE microporous film, longitudinal and transverse cross-section morphology can be seen from the scanning electron micrograph: the surface morphology of the ePTFE microporous membrane is a microporous structure with spider webs, and pores are formed between the microfibers. The direction in which the fibers are arranged is substantially parallel to the direction of stretching; the junction of the fiber bundles is the junction, which is formed by entanglement of a plurality of microfibers, arranged in a direction perpendicular to the stretching direction. The size of the pores between the microfibers determines the size of the pore size of the membrane. The size and size of the nodes determine the porosity of the membrane. The orientation structure of microfibers plays a decisive role in the mechanical anisotropy of the film; the ePTFE microporous film belongs to the asymmetric membrane, and the pore size of the front and back of the membrane is different; the pore size of the membrane is larger than the pore size of the surface. There are also differences in the size of the longitudinal and transverse micropores. The longitudinal micropores are larger than the transverse micropores; the cross section of the membrane is a network structure, and there are very complicated changes in the three-dimensional structure of the pores, such as mesh communication, hole inlay, and channel bending. One channel is composed of a plurality of micropores, and one microhole may be connected to a plurality of channels.
The pore size, pore size distribution, number of pores, and pore number distribution were measured using a Porometer II type material pore size analyzer from Coulter, USA. The PTFE microporous film has an average pore diameter of 0.02 to 15 μm; the porosity is 50% to 90%; the contact angle is 103° to 140°; the film thickness is 24 to 45 μm, and the thickness uniformity of the PTFE film is 5% or less; The tensile strength or tensile strength is 4?40Mpa (4x106~40x106N/m2), the tensile strength or tensile strength is about 10% of the warp direction, and the elongation at break is between 50% and 100%. The moisture content is 0.4x104?1.7x104g/(m2.24h), generally 6000g/(m2.24h); the hydrostatic pressure is 90?170kPa (9~17mH2O); the air permeability is less than 0.3 X 10-2m3/( M2.s) [0.3 mL/(cm2.s); the temperature range of use is 150 to 250 °C.

ePTFE waterproof and breathable membrane

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