Surface tension of phenol-formaldehyde wood adhesives

Abstract

Thirty-six phenol (P) fermaldehyde (F) resins were formulated to complete a factorial arrangement: three NAOH/P molar ratios (0.4, 0.7, and 1.0), three solid contents (37, 40, and 43 percent), and four F/P molar rations (1.6, 1.9, 2.2, and 2.5). Surface tension ranged from 68.4 to 79.9 dynes/cm. and was affected most by NAOH/P ratio, next by F/P ratio, and least by solids content. On the average, surface tension increased as solids content increased, but at ratios of 0.7 and 1.0 this relationship was reversed. The relationship between surface tension and bond quality in loblolly pine plywood was curvilinear. Increases in surface tension caused difficulty in obtaining spontaneous spreading of the glue. Resins with high surface tension tended to form imprevious skins while curing and made inferior bonds.

Citation

Hse, C. -Y. 1972. Surface tension of phenol-formaldehyde wood adhesives. Holzforschung 26(2):82-85