Abstract: A balance for a simultaneous differential thermal analysis instrument that combines gravimetric measurements with measurements that require propagation of electrical signals from the sample holder to an apparatus for recording the electrical signals. In one embodiment of the invention, conductive flat planar strip flexure pivots are used in a single-meter movement balance to mechanically and electrically couple the components of the balance mechanism to the apparatus that records the electrical signals.

Abstract: A cooling system employs a single-acting positive displacement bellows pump to transfer a cryogenic liquid such as liquid nitrogen from a storage dewar to a heat exchanger coupled to a measurement chamber of an instrument, wherein cooling takes place by vaporizing the liquid. Preferably, the capacity of the pump is greater than the maximum cooling requirement of the instrument, wherein both vapor resulting from vaporizing of the cryogenic liquid circulated through the heat exchanger and liquid that does not vaporize when circulated through the heat exchanger are returned to the storage dewar, wherein the vapor is subsequently vented from the dewar. Preferably, with the aid of a weir in a return line, the level of liquid in the heat exchanger is maintained full and constant, and the cooling demands are automatically met without the need for other control of the flow rate or level of the liquid.

Abstract: Systems and methods for minimizing extraneous forces and calculating corrected weights of samples based on buoyancy factors for a thermogravimetric analyzer (TGA). The TGA includes a balance chamber and a furnace configured to heat a sample. A null balance is provided in the balance chamber and is used to measure the sample weight change during heating. The furnace includes a cylinder open at the top to receive a sample. The bottom of the cylinder is closed except for a small hole that allows a thermocouple to pass through. An infrared heat source may be provided to heat the cylinder. The balance chamber can be thermally isolated from the furnace using an actively cooled plate and a system of heat shields disposed between the furnace and balance chamber. A thermocouple disk is further provided to limit gas flow in the furnace and increase reliability of sample weight measurements.

Abstract: A sensor for a heat flux differential scanning calorimeter in which the differential temperatures are measured between locations external to the regions of heat exchange between the sensor and sample containers. The measured differential temperatures respond to the magnitude of the heat flow rate between the sensor and the sample and reference containers and are rendered insensitive to variations in the magnitude and distribution of thermal contact resistance between the sensor and the containers.

Abstract: A thermal measurement apparatus and method for performing heat flux differential scanning calorimetry (DSC) is disclosed. A variable thermal resistor is used to couple a measurement assembly to a heat sink in the thermal measurement apparatus, such that samples can be rapidly heated and rapidly cooled. The apparatus can be configured with a highly conductive sample assembly enclosure. The enclosure can include a high emissivity coating. In one embodiment, the enclosure extends along a longitudinal direction that is about the same as that of an infrared lamp assembly used to heat the enclosure, thereby increasing the efficiency of heating the sample enclosure. In one configuration, the variable thermal resistor comprises a gap whose gas composition can be varied during a sample measurement to independently optimize sample heating and cooling rates.

Abstract: A heat flux differential scanning calorimeter (DSC) is disclosed. The DSC can be configured with a highly conductive sample assembly enclosure. The enclosure can include a high emissivity coating. In one embodiment, the enclosure extends along a longitudinal direction that is about the same as that of an infrared lamp assembly used to heat the enclosure, thereby increasing the efficiency of heating the sample enclosure. In one embodiment, a gas-filled thermal resistor is used to couple the measurement assembly to a heat sink, such that samples can be rapidly heated and rapidly cooled.

Abstract: Systems and methods for minimizing extraneous forces and calculating corrected weights of samples based on buoyancy factors for a thermogravimetric analyzer (TGA). The TGA includes a balance chamber and a furnace configured to heat a sample. A null balance is provided in the balance chamber and is used to measure the sample weight change during heating. The furnace includes a cylinder open at the top to receive a sample. The bottom of the cylinder is closed except for a small hole that allows a thermocouple to pass through. An infrared heat source may be provided to heat the cylinder. The balance chamber can be thermally isolated from the furnace using an actively cooled plate and a system of heat shields disposed between the furnace and balance chamber. A thermocouple disk is further provided to limit gas flow in the furnace and increase reliability of sample weight measurements.

Abstract: Systems and methods for minimizing extraneous forces and calculating corrected weights of samples based on buoyancy factors for a thermogravimetric analyzer (TGA). The TGA includes a balance chamber and a furnace configured to heat a sample. A null balance is provided in the balance chamber and is used to measure the sample weight change during heating. The furnace includes a cylinder open at the top to receive a sample. The bottom of the cylinder is closed except for a small hole that allows a thermocouple to pass through. An infrared heat source may be provided to heat the cylinder. The balance chamber can be thermally isolated from the furnace using an actively cooled plate and a system of heat shields disposed between the furnace and balance chamber. A thermocouple disk is further provided to limit gas flow in the furnace and increase reliability of sample weight measurements.

Abstract: A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.

Abstract: A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.

Abstract: A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.

Abstract: A system and method for obtaining the contact thermal resistance for a sample and pan without a priori knowledge of the properties of either sample, by measuring the reversing heat capacity of a sample and its pan (or an empty pan on the reference side of the DSC) at a long period and a short period during a quasi-isothermal MDSC experiment and then finding the value of contact thermal resistance that makes the short and long period heat capacities match. Several different methods may be used to find the contact thermal resistance using quasi-isothermal MDSC with a long and a short period. Two methods are direct calculation methods that use the results from an MDSC experiment used with model equations to calculate the contact thermal resistance. A third method is another direct calculation method, based upon the phase angle between the heat flow and temperature signals. A fourth and fifth method use curve fitting of the apparent heat capacity for multiple values of pan contact thermal resistance.

Abstract: A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.

Abstract: A system and method for obtaining the contact thermal resistance for a sample and pan without a priori knowledge of the properties of either sample, by measuring the reversing heat capacity of a sample and its pan (or an empty pan on the reference side of the DSC) at a long period and a short period during a quasi-isothermal MDSC experiment and then finding the value of contact thermal resistance that makes the short and long period heat capacities match. Several different methods may be used to find the contact thermal resistance using quasi-isothermal MDSC with a long and a short period. Two methods are direct calculation methods that use the results from an MDSC experiment used with model equations to calculate the contact thermal resistance. A third method is another direct calculation method, based upon the phase angle between the heat flow and temperature signals. A fourth and fifth method use curve fitting of the apparent heat capacity for multiple values of pan contact thermal resistance.

Abstract: A modulated differential scanning calorimeter (MDSC) and a method for practicing MDSC that uses two separate temperature difference signals—the difference between the temperatures of the sample and reference positions and the difference between the temperatures of the sample position and a base position. This approach accounts for heat flows associated with the sample and reference pans, and for the difference in sample and pan heating rates to provide more accurate heat flow measurement and improve resolution. It also greatly reduces or eliminates the frequency dependence of the heat capacity calibration factor, which allows for the use of shorter modulation periods. Shorter modulation periods allow the use of higher underlying heating rates, allowing users to decrease the duration of their MDSC experiments.

Abstract: A modulated differential scanning calorimeter (MDSC) and a method for practicing MDSC that uses two separate temperature difference signals—the difference between the temperatures of the sample and reference positions and the difference between the temperatures of the sample position and a base position. This approach accounts for heat flows associated with the sample and reference pans, and for the difference in sample and pan heating rates to provide more accurate heat flow measurement and improve resolution. It also greatly reduces or eliminates the frequency dependence of the heat capacity calibration factor, which allows for the use of shorter modulation periods. Shorter rho modulation periods allow the use of higher underlying heating rates, allowing users to decrease the duration of their MDSC experiments.

Abstract: An improved differential thermal analysis/differential scanning calorimetry (collectively, DSC) assembly with a furnace block assembly having a measurement chamber and a furnace heater. The measurement chamber has a sensor assembly for receiving a sample material and a reference material. The furnace block assembly is coupled to a generally cylindrical cooling flange through a distributed thermal resistor that allows a constrained heat flow between the furnace assembly and cooling flange. The thermal resistor can also withstand the mechanical stresses associated with the differential expansion and contraction of the furnace assembly and cooling flange without permanent deformation of the thermal resistor. The cooling flange can be coupled to various cooling devices, permitting operation of the overall DSC instrument in a variety of temperature regimes for a variety of applications.

Abstract: A method for calculating sample heat flow in a differential scanning calorimeter. A preferred embodiment of the invention calculates the heat flow to the sample while accounting for the effect of heat storage in the sample pans and the difference in heating rate between sample and reference. Accounting for heat flow associated with the pans and the difference between sample and reference heating rates gives a more accurate sample heat flow measurement and improves resolution, which is the ability to separate closely spaced thermal events in the heat flow result.

Abstract: A sensor for a heat flux differential scanning calorimeter in which one absolute temperature measurement and two differential temperature measurements are used. The sensor is calibrated and used based on a four-term model heat flow equation. The calibration is carried out in two experiments which are used to calculate the sensor thermal resistance for the sample and reference positions, respectively, and the sensor heat capacity for the sample and reference positions, respectively. Differential scanning calorimeters using this sensor exhibit improved resolution, improved baseline performance and improved dynamic response.

Abstract: A power compensation differential scanning calorimeter that uses one absolute temperature measurement, two differential temperature measurements, a differential power measurement, and a five-term heat flow equation to measure the sample heat flow. The calorimeter is calibrated by running two sequential calibration experiments. In a preferred embodiment, the first calibration experiment uses empty sample and reference pans, and the second calibration experiment uses sapphire specimens in the sample and reference holders. In an alternate embodiment, sapphire calibration specimens are used in both the first and second calibration experiments.