Water-soluble moisture addition to enhance molding, stiffness, and surface processing of polymer materials

Densified non-woven materials having acoustic and thermal properties are provided. The non-woven material is formed of a thermoplastic material or fibers and a thermoplastic material. The fibers may be an organic, inorganic, or thermoplastic fiber and are desirably devoid of conventional sizing compositions. The densified portion of the non-woven material is formed by applying a moisture additive and subsequently applying heat. Heating the non-woven material causes the water in the moisture additive to turn to steam, which causes a molecular change in the polymer based thermoplastic material(s) of the non-woven material that was treated with the moisture additive. The moisture additive is preferably water, but may include a dilute alkali, a dilute acid, or additives to enhance surface, fire, or mold release characteristics. The water additive may be utilized to surface treat, partially treat, or completely treat the air-laid mat to achieve desired acoustic or thermal properties and/or stiffness.