The Young's modulus of binary powder mixtures

Many industrial powder systems are multicomponent and the use of powder fillers is widespread. This study reports on the measurement of the Young's modulus for four model binary powder mixtures,E(mix), and tests the application and predictive capability of published equations to experimental data. Powder blends of poly(tetrafluoroethylene) (PTFE) and lactose, PTFE and calcium carbonate, poly(vinylchloride) (PVC) and lactose, and PVC and calcium carbonate, representing two polymeric matrix powders and two powder fillers, were compressed to form beam specimens over a range of compositions and porosities. The Young's modulus of mixtures,E(mix), obtained from four-point-beam-bending studies was analysed to obtain values at zero porosity,E0(mix), which were fitted into published mixture equations. Results demonstrated that simple mixing rules did not hold. In all cases, negative deviations were obtained for plots ofE0(mix)versus volume % filler fraction, indicating that the polymeric powder components with the lower Young's modulus dominated theE0(mix) value. The Nielsen equation was found to be the preferred mixture relationship since, unlike other tested relationships, experimental data for all systems studied were well fitted by the function and predicted values ofE0(filler) showed reasonably good agreement with figures derived from monocomponent beam specimens.