There are many cases where a formulator needs to hit a certain density target. For example, a company asked me to make them a golf grip formulation using fillers to increase the density to a value they specified. Most people mistakenly believe that it is possible to calculate the density of a composite by taking the weighted mean of the densities of the polymer and filler. That is not the case. A graph of composite density versus weight % filler is a curve (see diagram below), not a straight line and an equation is needed in order to calculate the correct density.
As an example take 50 weight % filler with a density of 3 and 50 weight % of polymer with a density of 1 g/ml. You would expect the density of the composite to be (3+1)/2 which comes out to 2 g/ml. The actual density of that composite is 1.5 g/ml. What went wrong? The density and other properties of composites all depend on the volume %, not the weight %.
Here is the tool allowing you to instantly see the density of any polymer and filler combination. If you have requests for materials to add then please contact us.
Eastern time (USA)