Abstract: A method of preparing a tear-resistant composite sheet material having hydrophilic, absorptive particles enmeshed in a network of interlaced microfibrous polytetrafluoroethylene forming a fibril matrix, the hydrophilic absorptive particles having absorptive particles with absorptive capacity greater than 1.0 gram of water per gram of dry particle, wherein the method comprises:(1) dry blending one or more hydrophilic, absorptive particulate materials;(2) admixing water to particulate to form a damp mixture;(3) adding gradually, with stirring, to the mixture an equal weight of an aqueous emulsion of polytetrafluoroethylene;(4) mixing the mass to cause initial fibrillation of the polytetrafluoroethylene particles;(5) biaxially calendering the mass to produce a tear-resistant sheet having a tensile strength of at least 0.5 megapascal; and(6) drying the resultant sheet to remove water.

Abstract: A composite wound dressing, optionally having controlled permeability, is highly absorbent toward blood and exudate and comprises a polytetrafluoroethylene fibril matrix, hydrophilic absorptive particles enmeshed in the matrix, and, optionally, a partially occlusive film coated on one surface of the matrix.