| 摘要 |
<p>PURPOSE:To increase the coupling constant Kt of electric machine providing unstretched film with large thickness piezo-electric characteristics by a method wherein the unstretched film produced by cooling and solidifying the molten copolymer composed of vinylidene fluoride and trifluoroethylene is heat treated after quenching without stretching process. CONSTITUTION:The molten copolymer composed of 70-83mol% of vinylidene fluoride 30-17mol% of trifluoroethylene is quenched at the temperature at least 50 deg.C lower than the crystalline transition temperature Tm'. The refrigerants such as water, liquid nitrogen, liquid air, ammonium and Freon for quenching are actively utilized or the process such as casting said molten copolymer on a refrigerated good thermal conductor is actively adopted. In case of forming said molten copolymer, the melting temperature exceeding the melting point Tm (150-160 deg.C) may be normally acceptable, however, the substantial temperature of 200 deg.C-300 deg.C is preferably adopted considering the effect of temperature dependency on the melting viscocity and the thermal cracking temperature.</p> |
