The influence of poly(acrylic acid) molar mass and concentration on the properties of polyalkenoate cements Part II Young's modulus and flexural strength

The Young's modulus and flexural strength were determined for glass polyalkenoate cements as a function of poly(acrylic acid), PAA molar mass, concentration, glass volume fraction and cement ageing time. The Young's modulus was independent of PAA molar mass. The Young's modulus increased dramatically with the PAA concentration of the cement until concentrations greater than 50% m/m were reached. The modulus increased with time for nearly all the cements investigated consistent with a continuing ionic cross-linking process in the cement matrix. The modulus increased with an increase in the volume fraction of the higher modulus glass phase. Increasing the glass volume fraction provides more surface area for acid attack resulting in a more cross-linked polysalt matrix, as well as increasing the volume fraction of residual glass particles. Flexural strength was highly dependent on molar mass of the PAA and its concentration. The molar mass dependence of the flexural strength was greatest at higher PAA concentrations.