Abstract: PTFE and other ultra high melt viscosity (UHMV) polymeric materials, such as TFM, and UHMW polyethylene are used, rather than FEP or PFA, in the HST process as it has been found that UHMV polymers may be readily substituted for FEP in the HST process with little significant change in the existing process steps. Appropriate expansion of a PTFE tube, after fabricating to the proper dimensions, may be obtained with pressure and heat treatment at a temperature of the order of 200° F., rather than 600-700° F. and the resulting tube is sufficiently stable to be shipped for later shrink application at comparable temperatures onto a roll at a mill. The resulting roll cover has improved mechanical properties at high temperatures and man be reinforced with a conductive additive for providing anti-static qualities or other additives to improve its wear and compressive strength.

Abstract: Corrosive chemicals are contained in metallic vessels, the inside portion of which is coated with a homogeneous, porous polymer containing inorganic filler. The particle size, shape and distribution provides a controlled porosity which allows entrapped permeants from the corrosive chemical to escape, yet does not significantly affect the utility of the protective coating as a chemical corrosion barrier protecting the metallic vessel.