PPS is an excellent high temperature fibre, in terms of its properties it can be viewed as a high temperature polypropylene in that it has excellent chemical resistance and can't hydrolyse in the presence of heat and moisture. Its biggest drawback is a sensitivity to oxidation, and so care is needed particularly when the O2 level is high. Typical applications would be incinerators, coal fired boilers etc.
Meta aramid (Nomex®) is an excellent all round fibre ideally suited to dry hot environments where hydrolysis isn't likely to occur. These felts are frequently used in asphalt and cement plants.
Polyimide felts (P84), for application purposes, can be viewed as high temperature meta aramids, they have similar properties, perhaps a little weaker with alkalis, but can tolerate say 30 degrees more. Moreover, the complex cross section of the fibres gives them high filtration efficiencies. They find use in incineration, combustion and cement industries.
PTFE is the 'ultimate' fibre; it has the best chemical and thermal resistance of all the fibres routinely used in gas filtration. Two types are available, white and brown; the latter was the first of the fibres, being introduced by DuPont as Teflon. Applications are limited due to the high price, but include combustion, certain waste and incineration processes as well as TiO2 manufacture.
