1.PTFE impregnation,Heat setting 2 .Air permeability(l/m2/s ... is made of more than two varieties of heat-resisting fiber for getting better chemical performance,. The ... needle-punched felt has many advantages such as heat-resisting, high strength and resistance to corrosion. After ... . Compared with synthetic chemical fiber, FMS is heat-resisting and corrosion resisting with good stability, strength ...