Temperature-modulated differential scanning heat capacity

Pyda et al. (1998) studied in detail the heat capacity of PTT by adiabatic calorimetry, standard DSC and temperature-modulated differential scanning calorimetry (TMDSC) for this measurement. The computation of the heat capacity of solid PTT is based on an approximate group vibrational spectrum and the general Tarasov approach for the skeletal vibrations, using the well-established Advanced Thermal Analysis System (ATHAS) scheme. The experimental heat capacity at constant pressure is first converted to heat capacity at constant volume using the Nemst-Lindemann approximation... 

Pyda M, Wunderlich B (2000) Reversible and Irreversible Heat Capacity of Poly(tri-methylene Terephthalate) Analyzed by Temperature-modulated Differential Scanning Calorimetry. J Polymer Sci, Part B Polymer Phys 38 622-631. 

Temperature-modulated differential scanning calorimetry is a new analytical technique used to obtain information on the heat capacity in the range close to the phase transformation. It is a method applied in many instraments, e.g. as the Modulated DSC (MDSC ) of TA Instm-... 

In a different work, the data obtained by temperature-modulated differential scanning calorimetry (TMDSC) showed the relationship between the interlayer distance (Ad) and the increase of heat capacity (ACp) for PU-clay intercalated nanocomposites [14]. The ACp values of nanocomposites with interlayer distances smaller than the characteristic length of bulk PU (1.45 nm) were reduced. However, for nanocomposites with interlayer spacing larger than 2 nm, cooperatively rearranging of PU was substantially unmodified by the presence of the nanofiller, and ACp values remained the same as that of bulk PU. 

Temperature-modulated differential scanning calorimetry (T-MDSC) applies a thermal modulation in temperature to a conventional DSC mn and determines a dynamic heat capacity from the relationship between the modulation components of temperature and of heat flow. Primary application of this technique has been the measurement of specific heat capacity and the examination of the anomaly in a relaxation process such as alpha process related to the glass transition. An application to the first-order phase transitions of crystallisation and melting of polymer crystals has recently been suggested. The method and typical results are described. 13 refs. 

Journal of Thermal Analysis and Calorimetry 54, No.2, 1998,p.477-99 APPLICABILITY OF TEMPERATURE-MODULATED DIFFERENTIAL SCANNING CALORIMETRY(TMDSC) TO POLYMERIC SYSTEMS. GENERAL THEORETICAL DESCRIPTION BASED ON THE FULL HEAT CAPACITY FORMULATION Scherrenberg R Mathot V Steeman P DSM Research... 

Wagner T, Frumar M, Kasap SO. Glass transformation, heat capacity and structure of Agx(Aso.4Seo.6)ioo-x glasses studied by temperature-modulated differential scanning calorimetry. J Non-Cryst Solids 1999 256/257 160-164. 

A quantitative thermal method, based on the differential of heat capacity signal from modulated temperature differential scanning calorimetry, was described for determining the weight fraction of interface and the extent of phase separation in polymer materials. The interface was modelled as discrete fractions, each with its own characteristic increment of heat capacity. The materials used to demonstrate the range of the method were PS blended with poly(phenylene oxide) (PPO), pure PS, pure PPO, a styrene-isoprene-styrene triblock copolymer (SIS), SIS blended with PPO, PMMA/poly(vinyl acetate) blends and PVC sandwiched with poly(n-butyl acrylate). Two-phase and four-phase systems were used. The calculated results agreed well with experimental results for two- and four-phase systems. 20 refs. 

Pyda, M. Kwon, Y.K. Wunderlich, B. Heat capacity measurements by saw-tooth modulated standard heat-flux differential scanning calorimetry with sample temperature control. Thermochim. Acta 2001, 367 (8), 217-227. 

Pak J, Wunderlich B (2001) Heat Capacity by Sawtooth-modulated, Standard Heat-flux Differential Scanning Calorimeter with Close Control of the Heater Temperature. Thermochim Acta 367/368 229-238. 

In addition to thermal conductivity, modifications of the sthm can yield thermal capacity or more specifically differential scanning calorimetry (dsc). Instead of heating the resistive wire with a constant power, its temperature is modulated with an ac current. The resultant amplitude and phase shift of the wire s temperature is measured with a lock-in-ampIifier. Simultaneously, the temperature of the tip and sample are ramped up slowly so as to measure the change in heat dissipation per change in temperatme, dq/dT. This measure is, of course, related to the local heat capacity of the sample and is correlated with expected phase... 

Pak, (. and Wimderlich, B. (2001) Heat capacity by sawtooth-modulated, standard heat-flux differential scanning calorimeter with dose control of the heater temperature. Thermochim. Acta, 367/368, 229-238. 

DTA (Differential Thermal Analysis) and DSG (Differential Scanning Calorimetry) measure the thermal transitions in materials by monitoring temperatures and heat flows. DTA is qualitative while DSC is quantitative. Glass transition temperatures, phase changes, heat capacity, cure kinetics and thermal degradation can be monitored by these techniques. Modulated DSC can be both faster and more accurate. 

Modulated (temperature) differential scanning calorimetry (MTDSC or MDSC) is used to simultaneously study the evolution of heat flow and heat capacity for the isothermal and non-isothermal reactions of polymer systems. An... 

Differential scanning calorimetry (DSC) has proven to be a very reliable technique to obtain heat capacity at elevated temperatirres in a reasonably short time. DSC also allows the study of the kinetics of nonequilibrium transitions in a wide dynamic range. Because of its simplicity and ease of use, DSC is widely applied in polymer science and is the focus of this chapter. Recent additions such as temperature modulation and fast scanning, both making additional use of chip-based calorimeters, are also discussed in detail. 

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