THE EFFECT OF DRY STRENGTH RESIN AND DEBONDER ADDITION, REFINING, AND WET PRESSING ON STRENGTH-DENSITY RELATIONSHIP IN HANDHSEETS.

ABSTRACT

This paper describes the results of a handsheet study which shows that, surprisingly, at a given pressing level, natural Hydrogen bonds with or without refining, chemical bonds with or without refining, and bonds via debonder addition, are equivalent with respect to the Breaking Length-density relationship. This is especially surprising, since the phenomenology of bonding for these is vastly different; refining is a mechanical treatment that creates morphological changes in the fibers, like fibrillation and curl, while other others are chemical treatments that do not alter the fibers. The fact that at the same density all these treatments yield the same strength should, in my opinion, re-open consideration of the mechanism of strength development via refining. What is needed is an overall theory of bonding that explain these phenomena and can differentiate them from pressing. The present paper does not introduce such a theory, but does present a conceptual "equi-bond-equi-pressing" grid. It concludes that the density-dependent tissue properties, softness, bulk, and absorptive capacity depend on product strength alone.