Analytical process in which materials to be analyzed are directly and indirectly heated and dried by microwave radiation

Abstract

An apparatus for controllably heating material, such as a material to be analyzed for volatiles or non-volatiles contents, directly and indirectly by microwave radiation, includes a chamber, in which the material to be heated is placed, a source of microwave radiation, for radiating onto materials in the chamber and for controllably heating such a material, and a support for such material, which support includes a matrix of a material which transmits microwave radiation, and also includes particulate material therein which absorbs microwave radiation. The absorptive material is one that has a Curie temperature, above which it is transmissive of microwave radiation, so as thereby to prevent excessive heating of the support and the supported material which is to be heated. The matrix material is stable and form-retaining at the Curie temperature of the dispersed material. Preferably the support matrix will be of a silicone rubber or of a polyfluoroalkylene polymer, such as polytetrafluoroethylene, and the dispersed material will be a ferrite, garnet or a mixture thereof. The apparatus may include a turntable for one or more supports, an automatic electronic balance, computerized controls and readout means. Also within the invention are the described support, and processes for heating and drying, in a preferred embodiment of which processes a particulate diluent or dispersant for the sample being treated is employed to prevent overheating of the sample.