| abstract |
An expanded polypropylene bead for forming a dielectric material, including a polypropylene resin containing a ceramic in an amount of from 10 to 80 wt%, having an apparent density of from 0.03 to 1.7 g/cm3, having an intrinsic endothermic peak specific to the polypropylene resin on a DSC curve obtained by a differential scanning calorimetry, and also an endothermic peak at a higher temperature side of the intrinsic endothermic peak, and in that a caloritic value of the endothermic peak at the higher temperature side represents from 2 to 35 % of a caloritic value of the peaks of the entire endothermic curve. |