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Abstract  

Differential thermal analysis has been carried out on AgGaS2 samples in order to investigate the relationship between the superheating of the melt and the supercooling behaviour of the material leading to an improvement of crystal growth conditions. The knowledge gained will be correlated to the crystal growth experiments which had been carried out by using the gradient freezing method.

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Abstract  

Thermogravimetric analysis in conjunction with evolved gas analysis are discussed for powder PMMA, particle diameter of 0.1 mm. Furthermore, differential thermal analysis measurements were performed in both pure nitrogen and oxidative environment. These measurements are conducted to assess major differences associated with particle size. The results indicated for powder PMMA, in pure nitrogen the degradation can be described as three-step reactions, while in oxidative environment it is two-step reactions. Furthermore the reaction in both environments are mainly endothermic. This in contrast to results reported for industrial-grade PMMA with relatively larger particle size of 0.5 mm.

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Data are presented on the heats of phase changes and heat capacities for the even chain number mercury(II) carboxylates from octanoate to octadecanoate. The octanoate and dodecanoate melt directly to the liquid, while the decanoate and octadecanoate pass through a solid → solid transition before melting to the liquid. The tetradecanoate and hexadecanoate pass through a mesophase before finally melting. It is proposed that this mesophase is aG (smectic) phase. Addition of mercuric oxide to the tetradecanoate and hexadecanoate causes the appearance of an additional mesophase. The results are explained in terms of theR theory of fused micellar phases.

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Some of the materials used as chromatography packings, adsorbents or catalyst supports are glasses of controlled porosity (CPGs). The chemical structure of these materials can easily be changed by heating the porous glass. Such thermal modification leads to the enrichment of the CPG surface in boron atoms. The long exposure of CPGs to thermal treatment can even cause the formation of borate crystals in the pores of the glasses. This paper considers the application of thermal analysis to the investigation of porous glasses heated for different periods of time.

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