Abstract
The molecular weight and the conformation in solution of phenol-hexamethylenetetramine resins were determined and effect of molar ratio of hexamethylenetetramine to phenol (H/P) on them were discussed.
Under a large value of H/P, the high molecular weight resins which contain a large amount of nitrogen were obtained. From experimental data for fractionated samples, it was known that the nitrogen content of resins did not depend on the molecular weight, but only depended on the molar ratio H/P.
φ√DA represents the compactness of solute molecule in solution, where φ is specific volume and DA is average diffusion coefficient. In the case of H/P= 1/12, φ√DA was 2. 8 which was the same value as formalin novolac. On the other hand, when H/P=1/4, it was 2. 0, indicating the solute molecule to be rather compact. a in Mark-Houwink-Sakurada equation ([η]=KMα) was 0. 2 in the former case, and 0. 15 in the latter case.
From these results, the following reaction mechanisms have been suggested. Under any molar ratio, amine compounds are formed in the early stage of reaction. In the later stage, however, the reaction depends strongly on the molar ratio. When H/P is small, phenol attacks amine compounds to form novolac type molecules. On the contrary, under a large H/P, amine compounds react with each other to form highly branched molecules with tertiary amine structure.
