Structure-properties relationship for resols with different formaldehyde/phenol molar ratio

The relationship between the structure and the viscoelastic properties of r esol resins was studied. Six phenolic resins (resol) were synthesized with different molar ratios of formaldehyde to phenol. These resols were cured b y means of temperature and without catalyst. The characterization of the re sol was done by means of infrared spectroscopy and chemical methods. From t he viscoelastic properties of fully cured resins, characteristic properties such as: storage modulus (E'), tan delta, width of the tan delta(Delta T) and damping peak (tan delta) were obtained. The compression modulus and the void content were also determined. A maximum in the methylene bridge and t he result of the viscoelastic properties allow us to say that the resol wit h F/Ph between 1.3 and 1.4 has the highest crosslinking density. (C) 1999 E lsevier Science Ltd. All rights reserved.