Modulated temperature techniques

There is much commercial interest in thin film and nano technologies, and these pose a new challenge for TA techniques since conventional TA deals with statistically averaged properties and phenomena . However, with the advent of a range of modulated (temperature) techniques , micro sample sizes, and consequential rapid response times, the sensitivity of TA techniques generally is sufficiently enhanced to be able to address these immediate application challenges. 

The specific heat (heat capacity, Cp) of a material can be determined quantitatively using DSC and is designated Cp since values are obtained at constant pressure. Traditionally, this is done by subtracting a baseline from the heat flow curve in the manner described below, but values may also be obtained using modulated temperature techniques. Section 1.6. The subtracted curve referenced against a standard gives a quantitative value of Cp, Figure 1.1. The accuracy that can be obtained depends upon the instrument and method in use. 

The mechanism of the charge separation in the colloidal Ti02 particles was studied at low temperature by direct time-resolved and light-modulated EPR techniques [91]. The recombination kinetics in the nanocrystalline semiconductor particles usually is very fast, on... 

The aim of this entry is to discuss the primary thermal analysis technique, TGA, in terms of the associated instrumentation, calibration procedures, and application range. Related techniques, such as TGA-DTA, EGA, SCTA, and modulated temperature TGA, are also discussed, as these reflect the significant developments of the TGA family of techniques that have occurred over the last decade. 

Temperature modulated DSC (MDSC)2°2-204 jg another technique that has proved useful in the study of the glass transition " - where, it has been claimed, the approach is capable of providing better resolution and sensitivity than conventional DSC.2° In this, a modulated temperature programme is superimposed upon the conventional heating ramp and the resulting heat flows are interpreted in terms of two heat capacities an in-phase storage heat capacity and an out-of-phase kinetic heat capacity. Various theoretical procedures have been proposed for this and there is little doubt that the approach can provide information that is complementary to conventional DSC.2 ° However, the technique does involve slow temperature scans (cf. high-speed DSC above) and the authors feel that there are areas where the additional data are not, at present, easy to interpret. 

Recent developments combining modulated temperature differential scanning calorimetry with atomic force microscopy have developed a technique called scanning... 

For example, the most commonly used thermal method is and will almost certainly continue to be differential scanning calorimetry (DSC), hence here we have dedicated three chapters to the technique covering the principles, the optimal use of the method, and pharmaceutical applications. We then include chapters on thermo-gravimetric analysis, modulated temperature DSC, microcalorimetry, high sensitivity DSC, thermal microscopy, thermally stimulated current, and dynamic mechanical analysis, all of which have attracted great interest within the pharmaceutical field. In all cases, these chapters combine elements of theoretical background, measurement optimization, and pharmaceutical applications. It is our profound hope that in this way we will achieve a suitable mixture of depth, relevance, and accessibility. 

Thermoanalytical techniques have had a major application in the understanding of transitions in the skin and of drug penetration of the skin. The application of thermoanalytical techniques to prosthetics and implants is also discussed, as are recent DSC investigations of the oesophagus that provided the information on thermal stability required for successful stent implantation. The use of thermoanalytical techniques such as modulated temperature differential scanning calorimetry (MTDSC) has been be used to characterise polymeric material in order to determine whether there are interactions with drug substances to control and predict drug delivery. 

Modulated temperature differential scanning calorimetry (MTDSC, also called temperature modulated DSC or TMDSC) is an extension of conventional DSC in which a modulated temperature input signal is used This modern technique has proven to be very beneficial for the thermal characterisation of many materials, especially polymers [1-5]. 

Novel mechanical tests are being developed and shown to be useful tools to investigate thermal and structural relaxation. These include the modulated-temperature-thermomechanometry technique (mT-TM) which has been recently employed to investigate blends of core cross-linked (CCS) PS and PMMA (Spoljaric et al. 2011) and nanomechanical thermal analysis. By using silicon microcantilever deflection measurements, the latter technique can provide a measure of temperature-dependent thermal stresses and therefore investigate the influence of physical aging (Yun et al. 2011). 

Crystallisation behaviour of polyethylene (PE) has been intensively studied from both fundamental and application reasons [1-3]. One of the most commonly used techniques is differential scanning calorimetry (DSC). New information on PE crystallisation can be gained if modulated temperature DSC (MT-DSC), which uses a periodical temperature modulation over a traditional linear heating or cooling ramp, is applied. It makes it possible to separate reversing and non-reversing components of the total heat flow because of this characteristics of the MT-DSC technique, it can be regarded as a useful tool to study polymer crystallisation behaviour. 

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