| 摘要 |
Making foamed bodies by introducing a biodegradable polymer mixture into a mould ( 10 ) in which it is heated to form a foam and to fill the mould. The mould is defined between two opposed parts ( 12, 14 ) that mate together, and each mould part is of electrically conducting material, and the moulding surfaces are coated with an electrically insulating material ( 16 ). Radio-frequency signals are applied ( 25 ) between the mould parts ( 12, 14 ) so that the polymer mixture is heated by dielectric heating, so a foam tray is formed in less than 15 s. This provides a more rapid cycle time than using heated moulds. The radio frequency signals may be 27.12 MHz, or 40.68 MHz. The polymer may be starch-based. |
