| 摘要 |
A differential thermal analyser comprises a heating block (1) containing at least four distinct chambers (2) having open tops and perforated bases, a plurality of holders (5), one in each chamber, all but one for holding a sample and one for reference, a perforated lid (6), an upper plenum chamber (7) situated above the chambers, a lower plenum chamber (8) situated below the chambers, the upper and lower plenum chambers being in communication with one another through the chambers, a heater (9) surrounding the heating block, a temperature programmer for programming the temperature of the block, an arrangement of differential temperature sensors (3), preferably thermocouples for detecting the temperature of each sample holder and giving rise to a differential signal relative to the reference holder which gives rise to a reference signal, a heat shield (10) surrounding the heater and heating block, and means for processing the data. The arrangement prevents transfer of heat and matter via gas flow between samples. The analyser is used to determine the onset of oxydation e.g. of lubricating oil and polyethylene. <IMAGE>
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