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 platinum/Rhodium resistance thermal probe is used as an active device which acts both as a highly localized heat source and as a detector to perform localized differential calorimetry, by thermally inducing and detecting events such as glass transitions, meltings, recystallizations and thermal decomposition within volumes of material estimated at a few &mgr;m3. Furthermore, the probe is used to image variations in thermal conductivity and diffusivity, to perform depth profiling and sub-surface imaging. The maximum depth of the sample that is imaged is controlled by generating and detecting evanescent temperature waves in the sample.

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.

Abstract: Sub-micron chemical analysis of the surface and sub-surface of a sample material is performed at, above or under atmospheric pressure, or on for a sample material submerged in a substance. A thermal and/or topographic image of the surface of the sample material is obtained. A location for study is selected using the image. The activation device is positioned over the selected location and surface and/or sub-surface products are ablated, desorbed or decomposed from the sample material to a chemical analyzer for analysis.

Abstract: A method for controlling a thermogravimetry experiment and for quantitatively determining kinetic constants for decomposition or volatilization reactions using periodic forcing (modulated) temperature functions. A temperature program having a linear part and a periodically varying part superimposed thereon is applied to a sample in a thermogravimetric analyzer. The resulting mass signal is deonvoluted, or separated, into one or more deconvoluted signals.

Abstract: A system and method for performing localized mechanothermal analysis with scanning probe microscopy (“MASM”) is disclosed. In a preferred embodiment an image of the surface or subsurface of a sample is created. A localized region of the sample is selected from the image. Using a scanning microscope, an active or passive thermal probe is positioned at the selected region. A temperature ramp is applied to the localized region. In addition, a dynamic or modulated stress or strain is applied to the localized region. Force data resulting from the applied temperature and stress or strain is collected and processed to produce a graph or fingerprint of the dynamic mechanical and/or calorimetric properties of the selected localized region.

Abstract: A method for controlling a thermogravimetry experiment and for quantitatively determining kinetic constants for decomposition or volatilization reactions using periodic forcing (modulated) temperature functions. A temperature program having a linear part and a periodically varying part superimposed thereon is applied to a sample in a thermogravimetric analyzer. The resulting mass signal is deconvoluted, or separated, into one or more deconvoluted signals.

Abstract: By employing a "modulated-temperature" heating program composed of a series of heat-isotherm stages, it is possible to separate the change in dimensions of an oriented material during heating into two contributions: a thermally "reversing" component which is due to linear thermal expansion and a "non-reversing" part arising from relaxation to the disordered state on heating above T.sub.g. Some preliminary results for biaxially drawn poly(ethylene terephthalate) film are presented.

Abstract: A heater controller for allocating heaters to cool a thermal chamber of a scientific instrument evaporates cryogenic liquid to produce a coolant gas. The gas is injected into a chamber to cool a sample disposal therein. The controller allocates low-capacity heaters in compliance with IEC guidelines to prevent problems generally associated with switching of large current loads, such as heaters. In one embodiment, heaters are activated so as to avoid jump discontinuities by effectively averaging the power delivered by the heaters. A second embodiment reduces complexity by essentially disregarding the problem of the jump discontinuity. A third embodiment groups the heaters according to a binary grouping scheme. The heater controller of the present invention can be used to control temperature according to a user supplied temperature profile.

Abstract: A heat shield and insulation system comprised of multiple layers of metallic sheets separated by small protrusions or dimples in the metallic sheets. The multiple layers are formed by spirally winding a coil of the metallic sheet around the sample enclosure. The protrusions are formed by stamping the metallic sheets, preferably in a random patterns, such that one set of protrusions does not nest in the protrusions formed in a neighboring sheet. The spacing between the layers of metallic sheets is small, such that convection does not occur in the space between the layers. Accordingly, the heat transfer between the layers of the metallic sheets is primarily radiative or via thermal conduction through the gas. The two ends of the helically wound metallic sheet are insulated by multiple thin metallic disks.

Abstract: A Differential Scanning Calorimeter (DSC) which has constant calorimetric sensitivity over its entire range of operating temperatures from -200.degree. C. to 540.degree. C. The DSC sensor consists of a pair of thin-film Resistance Temperature Detectors (RTDs) which are used to sense the temperature of a sample and the temperature difference between the sample and an inert reference. The RTDs are supplied with an excitation current which varies according to the temperature of the reference to achieve constant calorimetric sensitivity, independent of the operating temperature.

Abstract: A dynamic and thermal mechanical analyzer incorporating a slide driven vertically in an air bearing guidance system with a large displacement capacity, very low friction and low mass. The position of the slide is measured by digitizing and interpolating two quadrature output signals generated by an optical encoder with very high spatial resolution and a long stroke. A force is applied to the slide using a linear permanent magnet motor with high force, high force linearity and low sensitivity to temperature variations. Position signals derived from the digitized and interpolated quadrature output signals are analyzed as a function of the applied force to calculate viscoelastic properties of a sample of material.

Abstract: A modulated differential scanning calorimeter ("MDSC") wherein the temperature of the sample and/or the reference is modulated by modulating the characteristics of a gas in thermal contact with the sample and or a reference. In a first embodiment, the major heat flow path between the sample/reference and the furnace is the purge gas in the furnace chamber. The composition of the purge gas in the furnace chamber of the DSC cell is modulated by alternately purging the DSC cell with a high thermal conductivity gas (e.g., helium) and with a low thermal conductivity gas (e.g., nitrogen), thus modulating the flow of heat to and from the cell. In a second embodiment, the sample and reference are heated (or cooled) by a temperature-controlling gas flowing around the sample and reference holders. The gas is heated by being passed through a furnace before it flows around the sample and the reference.

Abstract: The present invention is an infrared-heated differential thermal analyzing instrument. The instrument uses an actively cooled heat sink, and a heat flow restricting element connecting the heat sink to a differential thermal analysis sensor. An IR heater directs IR radiation onto the lateral surfaces of the heat sink and the heat flow restricting element. These lateral surfaces are polished and coated with a high IR reflectance coating, so that heat absorption is minimized. The IR heater preferably uses either elliptical or parabolic mirrors to focus the IR radiation onto the heat sink and the heat flow restricting element. A second embodiment of the invention uses two heat sinks, and two heat flow restricting elements, with one heat sink and one heat flow restricting element mounted on either side of the differential analysis thermal sensor.

Abstract: The present invention is a mechanical cooling system, for use with thermal analysis instruments such as differential scanning calorimeters, which interposes a gaseous heat transfer path between the heat exchanger or evaporator cooling the differential scanning calorimeter cell and the differential scanning calorimeter cell. This configuration improves the performance of the thermal analysis system by reducing noise in the heat flow signal otherwise resulting from evaporation of the refrigerant in the heat exchanger. The mechanical cooling system is attached to the thermal analysis instrument by an arrangement providing for minimum direct physical contact between the mechanical cooling system and the thermal analysis instrument.

Abstract: The interpretation of dynamic differential calorimetry ("DDSC") data is enhanced by parsing the data according to whether it is obtained while the sample is being heated, cooled, or re-heated. Each DDSC scan is split up into three separate components, depending upon whether the sample is undergoing heating, cooling or reheating. Each component can then be analyzed separately to investigate the sample response to temperature change as the sample is being heated, cooled, or re-heated. Each file is deconvoluted separately, using a deconvolution routine that first removes the effect of the phase lag due to the instrument's finite response time.

Abstract: The present invention is a modulated differential thermal analysis technique for determining the composition, phase, structure, identification, or other properties of a material that undergoes a transition as function of temperature or other driving variable. As applied to differential scanning calorimetric analysis (DSC), the preferred embodiment comprises (1) heating a sample of the material with a linear temperature ramp that is modulated with a sinusoidal heating rate oscillation; (2) simultaneously heating a reference at the same linear temperature ramp; (3) measuring the differential temperature of the sample and reference; and (4) deconvoluting the resultant heat flow signal into rapidly and non-rapidly reversible components.

Abstract: The present invention relates to analytical methods for determining the composition of a material that undergoes a transition as a function of a driving variable. As applied to thermogravimetric analysis (TGA), a first preferred embodiment comprises (1) decreasing the heating rate when deviations from a baseline signal are detected; (2) establishing a minimum heating rate; (3) forcing the heating rate to a predetermined maximum whenever the rate of change of the weight change with respect to the temperature falls below a predetermined value; and (4) adjusting the heating rate according to the rate of change of the weight of the sample to track a predetermined rate of change of the weight of the sample.

Abstract: The present invention relates to differential analytical techniques for determining the composition, phase, structure, identification or other properties of a material that undergoes a transition as function of a driving variable. As applied to differential scanning calorimetric analysis (DSC), the preferred embodiment comprises: (1) heating a sample of the material with a linear temperature ramp that is modulated with a sinusoidal heating rate oscillation; and (2) deconvoluting the resultant heat flow signal into rapidly reversible and non-rapidly reversible components.