Measures of entanglement from knot theory are useful in understanding material properties. This is shown in a series of computer experiments of polymer melts in equilibrium and non-equilibrium conditions that show how the measure of entanglement capture mechanical properties in polymers. The periodic linking number and the writhe of polymer chains is shown to correlate with the loss modules of polymeric weaves. Also, the information obtained from contour reducing algorithms (such as Z1 and CReTA) can be combined with the writhe of polymer chains in a melt to give a new estimator of the entanglement length.