Apparatuses, processes and articles for controllably heating and drying

Abstract

An apparatus for controllably heating material directly and indirectly by microwave radiation comprises a chamber in which the material to be heated (often to dryness, as for analysis) is placed, a source of microwave radiation for radiating into materials in such chamber for controllably heating such a material, and a support for such material, which support comprises a matrix of microwave radiation-transmissive material and a particulate microwave absorptive material dispersed in such matric material, which microwave absorptive material has a Curie temperature, above which it becomes microwave transmissive, so as thereby to prevent excessive heating of the support and the material thereon which is to be controllably heated, and which matrix material is stable and form-retaining at the Curie temperature of the dispersed material. Preferably the support will be of a silicone rubber or a polyfluoroalkylene polymer matrix, such as polytetrafluoroethylene, and the dispersed material therein will be a ferrite, garnet or mixture thereof. The apparatus may include a turntable for carrying a plurality of supports or it may include an automatic electronic balance, in both of which embodiments of the invention computerized controls and/or readout means may be present. Also within the invention are the described support, and processes for effecting such heating and/or drying, in one of which processes a particulate diluent or dispersant for the sample being treated is employed to prevent overheating thereof.