Abstract
Curing behavior of high-ortho and high-para resols is studied by Torsional Braid Analysis. Both resols were prepared from 1. 5 mole of phenol and 1. 8 mole of formaldehyde using 0.015 mole of Mg (OH) 2 and 0.03 mole of NaOH as catalyst respectively, which were neutralized with dil. HCl to pH 6 and coated on glass fiber braid for TBA. By GLC, it was found that the Mg (OH) 2- catalyzed resol had higher degree of ortho methylol substitution than NaOH-catalyzed.
The dynamic mechanical properties such as relative rigidity and logarithmic decrement of the resin coated on braid were measured under several heating conditions, resulting in the followings.
(1) Curing of high-ortho resol was faster than that of high-para resol.
(2) The higher the ortho-methylol concentration on resol, the lower the rigidity of the cured resins made therefrom was, particularly, from 200°C to 250°C.
