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

The mechanical properties of an homologous series of compounds based o n 4-hydroxybenzoic acid have been determined by the formation of compa cted beams and subjecting them to 4-point bending. From results with u nnotched 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 stres s intensity factor, K(IC), critical strain energy release rate, G(IC), and fracture toughness, R, to be determined. Evaluation of these para meters as a function of the beam porosity allowed extrapolation to val ues at zero porosity, providing an estimate of the material properties . The materials were found to be brittle and stiff, the former increas ing with chain length of the ester whereas the latter decreases with c hain length of the ester. These changes correlated with cohesive energ y density CED, derived from solubility parameters.