| Abstract: | Lignocellulosic substrates such as wood were found to have a marked modifying influence on a well‐defined region of CHT diagrams during hardening of phenol–formaldehyde (PF) and urea–formaldehyde (UF) polycondensates. This was ascribed to more complex resin phase transitions due to resin/substrate interactions peculiar to these substrates. The chemical and physical mechanisms of the interactions of the resin and substrate causing such CHT diagram modifications are presented and discussed. The Di Benedetto equation describing the glass transition temperature Tg of the system as a function of the resin degree of conversion p has been slightly modified to take into account the modified CHT diagram. The modified CHT diagram can be used to good effect to describe the behavior of polycondensation resins when used as wood adhesives during their curing directly into the wood joint. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 915–925, 1999 |
