Factory Promotional Thin Waterproof Polyester Fabric - Bonded TPU waterproof 3 Layer good Stretch Knit Softshell fabric – Yun Ai

Membranes are thin films made from polymers. There are basically two types of membranes – microporous membranes (they’re hydrophobic) and hydrophilic membranes.

The most widely used polymers for microporous fabrics are expanded PTFE (ePTFE) and polyurethanes (PU). Microporous films have about 1.2-1.4 billion tiny holes per square centimeter. These pores are much smaller than the smallest raindrops and they usually range between 0.1 and 10μm (1mm=1000μm). At the same time, they’re larger than water vapor molecules so that they can pass through the pores of the membrane.

So the memrbane have two Kernel argument.Waterproofness and breathability.

Waterproofness 3000mm-20000mm

Breathable 500gsm/24hours-10000gsm/hours

This two data will show us if the membrane quality is good or basic. TPU now is the widely use membrane,except this also have TPE,PU,PTFE etc.