Polymerization of Formaldehyde and Phenol at Different Pressures

Phenol-formaldehyde resole resins were investigated as regards their cure behaviour using both atmospheric and high-pressure conditions. Results obtained using Fourier transform infrared spectroscopy and solid-state 13C (cross-polarization/magic angle spinning) nuclear magnetic resonance showed different polymerization pathways of the resin into the usually used differential scanning calorimetry pressure resistant crucibles and under atmospheric pressure. Under high pressure conditions a competition between oxidation and polymerization reactions was detected, leading to less methylene bridge formation and more remaining free ortho -positions, with a consequent lower degree of polymerization.