THE MECHANICAL-PROPERTIES OF AN HOMOLOGOUS SERIES OF BENZOIC-ACID ESTERS

The mechanical properties of an homologous series of compounds based on 4-hydroxybenzoic acid have been determined by the formation of compacted beams and subjecting them to 4-point bending. From results with unnotched specimens, the tensile strength sigma(T) and Young's modulus E were determined. Beams into which a notch had been introduced after formation allowed the fracture mechanical parameters of critical stress intensity factor, K(IC), critical strain energy release rate, G(IC), and fracture toughness, R, to be determined. Evaluation of these parameters as a function of the beam porosity allowed extrapolation to values at zero porosity, providing an estimate of the material properties. The materials were found to be brittle and stiff, the former increasing with chain length of the ester whereas the latter decreases with chain length of the ester. These changes correlated with cohesive energy density CED, derived from solubility parameters.