Chemical and Mechanical Damage to Felts: A Review, 2000 Papermakers Conference Proceedings

Donald L. Gibbon --Observation of hundreds of felt samples as a part of routine field technical support has led to formulation of general principles describing the results of chemical and mechanical felt wear. In addition, a series of experiments has been run exposing untreated Nylon-66 felt samples to the individual chemical components of multi-component felt-cleaning systems at typical machine concentrations temperatures and durations. These experimental exposures produce similar types of damage to that seen in field samples, but at far less severe levels.

It appears that nylon fibers consist of two phases much like epoxy-fiber composites, both phases of essentially the same composition One phase appears disorganized, the binder. The other is organized as parallel groups of nylon molecules, the “sub-fibers.” These are exposed by chemical attack during use.

The preliminary conclusion is that chemical damage largely results from chlorine attack, with an unknown but likely important influence of the mechanical stress of fiber flexing. These combined effects produce an extreme change in fiber condition, manifested as solution of the less-regularly organized parts of the fibers, leaving behind “unbound” fibrils parallel to the fiber axis. These are evidently somewhat embrittled, leading to fracturing, shredding of fiber ends and major loss of batt fibers.