DSC measures the temperatures and heat flow associated with transitions in materials as a function of time and temperature. It determines transition temperatures, melting and crystallization, and heat capacity. In addition to conventional DSC Modulated Differential scanning calorimetry (MDSC) provides unique capabilities improving the quality of interpretation of the experimental results, namely: measurement of heat capacity and heat flow in a single experiment; separation of complex transitions into more easily interpreted components; increased sensitivity and accuracy for detection of weak transitions; direct determination of thermal conductivity. Our Modulated Differential scanning Calorimeter (MDSC) (V4.OB Dupont 2000 ) is heat  flux  insrument, where the sample and the and reference are heated from the same source  and the temperature difference is measured. This signal is converted to a power difference using the calorimetric sensitivity. The major parts of the system are: 1. the MDSC sensors plus amplifier; 2. the furnace and its temperature sensor;  3. the computer and 4. the recorder, printer and data acquisition device. The sensitivity of the system is  1mW, and the accuracy is  1%. Liquid Nitrogen Cooling Accessory and Refrigerated Cooling System connected to the MDSC allow performing of the experiments in the wide temperature range  from-150 to 725 ?C.

Thermogravimetric analysis

Thermogravimetric analysis (TGA) is based  on the measurement of the weight loss of the material as a function of temperature. TGA 2950 operates on a null-balance principle, using an electromechanical transducer coupled to a taut-band suspension system.  The sensitivity of  the balance is  0.1 mg.TGA curve provides information concerning the thermal stability of the initial sample, intermediate compounds that may be formed and of  the residue if any. In addition to thermal stability, the weight losses observed in TGA can be quantified to predict the pathway of degradation or to obtain compositional information. The ability to vary atmosphere during the TGA evaluation, particularly from an inert to a reactive gas, provides additional information about  a material composition and its stability. Our Simultaneous  SDT 2960 analyzer can utilize the unique capability to  perform TGA measurements concurrent with differential thermal analysis  on the same sample. The experimental data offer  more sophisticated understanding  of  reactions occurring at materials heating. SDT also provides evaluation of materials up to 1500 ^oC. This ability to obtain measurements at higher temperatures is most useful for inorganic materials such as cements, clays, ceramics, superconductors and metals.

Several experiments performed in the laboratory of Thermal Analysis include:

1.      Study of the phase changes (glass transition temperature, melting, phase separation) in solid and gel polymer electrolytes of different composition for lithium power sources.

2.      Determination of safety of components of lithium-ion and lithium batteries

3.      Testing of the proton-conducting membranes and catalizators for fuel cells

4.      Study of interrelation of the thermal stability (guest release), composition and structure of the  substituted tetraphenylporphyrines with different inclusion compounds

5.      Thermal characterisation of semiconductors, nanopowders, ceramics, carbides of boron and titanium, clays, and explosive materials in inert and oxidative atmosphere

6.      Study of the effect of cooling rate on the stability of trombin in plazma.

7.      Investigation of thermal transitions in biomembranes, cuticle and silk

8.      Determination of the Curie point, crystallization temperature and energy in metal glasses

   The main organizations we are working with, are: School of Chemistry, School of Physics, School of Medicine, and Faculty of Engineering of Tel-Aviv University; Departments of Physics and Inorganic and Analytical Chemistry of  Hebrew University, Materials Department of the Ben-Gurion University, TAAS, More Energy Ltd, Nanopowders Ltd, IKA, Promex Ltd, Bank of Blood, Advanced Ministry of Defence, Metal Technologies Ltd.

Future trends: to purchase the TGA-Mass Spectrometer Accessory or FTIR for evolved gas analysis ($ 63,000). TGA-MS is based on the quadropole design with a 1-300 atomic mass range. This method is extremely useful in quantitive study of polymers, paints, resins, lubricants, catalysts, ceramics, fuels, inorganics for stoichiometry of reactions, hazardous emissions, degradation products.