Published online by Cambridge University Press: 15 February 2011
The microwave heatability of a low loss polymer (polypropylene) was enhanced by the addition of a conductive powder (iron). The effects of the amount (5–40% iron by volume) and size of the conductive particles on the microwave heatability were studied. The complex permittivity and complex permeability at microwave frequencies and the dc resistivity were measured. Samples were also heated in a multimode microwave cavity. Results show that microwave heating increased with increasing iron concentration. However, the penetration depth of the microwaves decreased with increasing iron content, and dramatically decreased when the polypropylene-iron composites became electrically conductive at the percolation threshold.