Tiêu đề 34. THERMAL ANALYSIS.pdf ✅

PHARMD GURU Page 3  Commercial DSC equipment can operate at temperatures from -180°C to 700°C, with specialized instruments capable of maximum temperatures of 1600°C.  The DSC must be able to be heated and cooled in a controlled manner.  To achieve the very low end of the temperature range, a special liquid nitrogen cooling accessory is needed. TYPES OF DSC INSTRUMENTATION: There are two main types of DSC instrumentation: 1. Heat flux DSC 2. Power compensated DSC 1) HEAT FLUX DSC: FIG: HEAT FLUX DSC  In a heat flux instrument the same furnace heats both the sample and the reference.  Time temperature is changed in a linear manner while the differential heat flow into the sample and reference is measured.  The sample and reference pans sit on the heated thermoelectric disk, made of a Cu/Ni alloy (constantan).  The differential heat flow to the sample and reference is monitored by area thermocouples attached to the bottom of the sample and reference positions on the thermoelectric disk.