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[交流]
新的調(diào)制DSC測(cè)量技術(shù)
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The introduction of modulated DSC (MDSC) increased the utility of DSC by adding the ability to separate the sample beat flows resulting from time dependent and time independent processes. The time independent sample heat flow rate is just that which is due to the sample heat capacity. MDSC is based on conventional DSC where the measured signal is the temperature difference between the sample and reference positions of the sensing apparatus. The measured heat flow rates display significant dependence on the period of the modulation, as demonstrated by the well-known decrease of measured heat using rather long periods, typically 60s or more, or various calibration or correction techniques may be applied. Long periods require low average heating rates and result in rather lengthy experiments that reduce the productivity of the DSC. A new MDSC heat flow measuring technique has been developed that greatly reduces the frequency dependence of the heat flow measurement. It includes three components: (1) a new DSC cell that has independent sample and is reference calorimeters and includes two differential temperature measurements, (2) a new DSC heat flow measurement method that is based upon independent sample and reference heat flow rate and (3) a new MDSC heat flow calculation method that uses the independent sample and reference heat flow rate measurements. MDSC experiments using this new technique display greatly reduced period dependence, allowing modulation periods as short as 20s to be used. Higher average heating rates may be used and productivity of the DSC is increased as much as threefold or more. |
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- 附件 1 : 新的調(diào)制DSC測(cè)量技術(shù).pdf
2017-02-17 10:42:34, 437.25 K
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