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Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to examine the thermal decomposition of benzoyl peroxide (BPO). The interruption rescanning method was adopted to examine the effect of thermal history on the autocatalysis and thermal decomposition of BPO. Autocatalysis of BPO was verified through isothermal experiments. According to the DSC linear temperature rise data of BPO, mathematical methods were used to decouple and divide the peaks. Kinetic analysis using both the Kissinger and Friedman methods was performed. The initial decomposition temperature of the decoupled BPO ranged between 101.4 and 104.6 °C. The peak temperature was 110.9–126.2 °C, and the decomposition enthalpy was 229.7–524.2 J g–1. The apparent activation energy was higher in the coupling state than after decoupling one. The thermal history and isothermal experiments demonstrated that BPO possessed autocatalytic properties. Results revealed that initial decomposition temperature tended to decrease with the increase in interruption temperature. In addition, the apparent activation energy of BPO decreased following the thermal history analysis because of the formation of intermediate products from BPO in the thermal history experiments, which further promoted BPO's thermal decomposition. This effect led to a decrease in BPO's initial decomposition temperature. [ABSTRACT FROM AUTHOR]

The effects of tannin-cadmium complex on the thermal and oxidation stability of PVC were investigated. Tannin-cadmium complex has been successfully synthesized and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis techniques. Thermal degradation and thermal oxidation-degradation behaviors of PVC formulations obtained by thermal mixing method were evaluated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under inert and oxidizing atmospheres, respectively. The obtained results such as the onset, maximum and final degradation temperatures as well as the degradation rates from TG and DTG curves revealed that the tannin-cadmium has significant impact on the thermal stability of PVC. The experimental data of PVC thermal degradation obtained by DSC studies also clearly showed that the stabilizing efficiency of tannin-cadmium is superior to that of synthetic thermal stabilizer applied as reference. Due to the HCl scavenging and antioxidation activities of tannin-cadmium, the global thermal and morphological properties of PVC stabilized by this product proved the best in morphology and stabilization properties both against thermal and thermal oxidation-degradations. Graphical abstract: [ABSTRACT FROM AUTHOR]

The comprehension of the thermal phenomena of milk powders is still object of investigation, being the result of complex interactions among their components as affected by composition, storage conditions and manufacturing. For a better understanding of the above-mentioned phenomena, the effect of the single milk component (proteins, casein, whey proteins and lactose) on the thermal behavior of whole and skim milk powders was investigated by means of DSC during heating. Whole milk powders exhibited two endothermic transitions related to the fat crystal melting at temperatures between 276 and 325 K. Glass transitions of lactose (309 K) and caseins (347-358 K) with their enthalpy relaxation phenomena were observed in the milk derivatives, being instead highly influenced from a and composition in the dried milk. At higher temperature (353-473 K), different exothermic events, such as lactose crystallization, Maillard reaction and/or decomposition of carbohydrates and proteins, were recognized in the curves of milk and protein derivatives powders. A good explanation of the thermal properties of the milk powders was obtained from the comparison with the heating curves of the single components. Lactose resulted the key component of many thermal events, being the molecule more influenced by the environmental conditions. These results can lead to a better comprehension of the physical properties of the milk powders, fundamental for their functional and commercial quality. [ABSTRACT FROM AUTHOR]

In-situ conversion process for recovery of hydrocarbons from shales requires heating the rock formation to 320 °C in order to break down kerogen polymer into fragments small enough to permeate toward collection facility. Thermal analysis is essential for understanding the properties of shales as they change during heating to the target temperature as well as during the production cycle. This paper discusses the application of a variety of thermal techniques and methods to study properties of oil shales in the contexts of using heat generated by a nuclear power plant during and after the life cycle of nuclear fuel. [ABSTRACT FROM AUTHOR]

The effect of a low profile additive, poly(ε-caprolactone) (PCL), on the thermal and mechanical properties of unsaturated polyester resins (UP) was investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile tests. The morphology of the systems has been studied by scanning electronic microscopy (SEM). Two PCL molecular mass were selected (PCL2: M = 2000 g mol and PCL50: M = 50000 g mol) to analyze the influence of the molecular mass and the content of PCL on the UP resins and to establish the relation between thermomechanical behavior and morphology. DSC and DMTA glass transition temperatures ( T) of the UP cured samples containing PCL indicate that PCL2 is miscible with UP whereas for UP + PCL50 system, T values are very close to the ones corresponding to neat UP. Besides in UP + PCL2 systems, one phase morphology is observed in which PCL2 would act as solvent of the reacting mixture along curing process; however, UP + PCL50 systems present phase-separated morphology. The presence of PCL2 and PCL50 in UP resin leads to a decrease of the tensile strength and the Young′s modulus as much notorious as the PCL concentration increases. For UP + PCL2 system the elongation at fracture increases in relation to neat UP, increasing as well with the PCL content. [ABSTRACT FROM AUTHOR]

The results of thermal analysis of speciality elastomers CSM with different chlorine and sulphur contents is presented in the article. The thermal curves obtained under the atmosphere of inert gas have been interpreted from the point of view of phase transitions and chemical reactions of the examined polymers during their heating. It has been stated that from among the investigated chlorosulphonated polyethylenes, only CSM24, which has the lowest chlorine content, contains a crystalline phase, clearly influences on its T temperature. Results of the thermal analysis obtained under inert gas atmosphere have been compared with results obtained under termooxidative atmosphere. Irrespective of the research atmosphere, the thermal decomposition of investigated CSM takes place in three stages. The maximum rate of thermal destruction of modified by heating elastomers, d m/d t, decreases with the increase in chlorine content in the sample having been heated. [ABSTRACT FROM AUTHOR]

This article focuses on the thermal properties of PA 6 and additives, i.e. ternary copolyamides, concentrates consisting of binary or ternary copolyamides + nanoadditive montmorillonite Bentonite 11958 or Cloisite 15A and PA 6 fibres modified with Bentonite, copolyamide and concentrate. The copolyamides are prepared from ε-caprolactam as a major comonomer and nylon salts AN2 from adipic acid + 1-(2-aminoethyl)piperazine and ADETA from adipic acid + diethylenetriamine. All copolyamides and concentrates exhibit lower melting temperatures T and lower melting enthalpies ΔH compared to neat PA 6. PA 6 fibres modified with 0.25–2.5 wt% MMT exhibit higher melting enthalpies in comparison with unmodified PA 6 fibres. PA 6 fibres modified with 10 wt% of ternary copolyamide containing 21.4 wt% of comonomers AN2 and ADETA have higher melting enthalpy as well. PA 6 fibres modified with 10 and 20 wt% of concentrate containing the same ternary copolyamide + 5 wt% of MMT have higher melting enthalpies and higher tensile strength in comparison with these characteristics of unmodified PA 6 fibres. [ABSTRACT FROM AUTHOR]

This study deals with possibility of the applications of inorganic substances specifically natural bentonite in function of reinforced nanofillers in polymeric materials. X-ray diffraction, FTIR spectroscopy and thermal analysis (TG, DSC and DTA) were used to characterize natural bentonite in more detail. At the prepared model, rubber compounds with various amounts of added filler were determinated vulcanization characteristics and physical–mechanical properties. The measured values were compared with the values of commercially used polymeric materials with the original composition. [ABSTRACT FROM AUTHOR]

In this paper, the thermal behaviours of two organophosphorous compounds, N, N-dimethyl- N′, N′-diphenylphosphorodihydrazidic (NDD) and diphenyl amidophosphate (DPA), were studied by thermogravimetery (TG), differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques under non-isothermal conditions. The results showed that NDD melts about 185 °C before it decomposes. NDD decomposition occurs in two continuous steps, in the 190–410 °C temperature range. First thermal degradation stage for NDD results a broad exothermic peak in the DTA curve that is continued with a small exothermic peak at the end of decomposition process. On the other hand, applying TG-DTA techniques indicates that DPA melts about 150 °C before it decomposes. This compound decomposes in the temperature range of 230 to 330 °C in two steps. These steps are endothermic and exothermic, respectively. Activation energy and pre-exponential factor for the first step of decomposition of each compound were found by means of Kissinger method and were verified by Ozawa–Flynn–Wall method. Activation energy obtained by Kissinger method for the first stage of NDD and DPA decompositions are 138 and 170 KJ mol−1, respectively. Finally, the thermodynamic parameters (Δ G#, Δ H# and Δ S#) for first step decomposition of investigated organophosphorous were determined. [ABSTRACT FROM AUTHOR]

The paper presents results of thermal properties measurements of cis-1,4-polybutadienes with different contents of cis-1,4 mers before and after their conventional cross-linking with the use of dicumyl peroxide and non-conventional cross-linking by means of iodoform. The measurements were carried out under the atmosphere of neutral gas using a micro-calorimeter, DSC and thermogravimetry, TG. The thermal curves have been interpreted from the point of view of phase transitions and chemical reactions of investigated elastomers. [ABSTRACT FROM AUTHOR]

The non-isothermal crystallization behavior of poly(trimethylene terephthalate) (PTT) and its blends with a liquid crystalline polymer, namely Vectra A950 (VA), was studied by differential scanning calorimetry. The values of the half-time of crystallization, t0.5 and the parameter F( T) in the combined Avrami and Ozawa equation indicated that VA can enhance the PTT crystallization rate by acting as a nucleating agent. The crystallization activation energy of the PTT phase increased with increasing VA content. The blends were immiscible, as can be inferred from their morphology. Thermogravimetric analysis of the blends revealed improved thermal stability by the incorporation of VA. [ABSTRACT FROM AUTHOR]

The objects for the studies of this paper are iron sulfates where the iron has second or third valences and where coordination between iron, sulfur and oxygen is different. DSC technique is used to investigate thermal stability and enthalpy changes when iron compounds are treated in different gas medium. The main objective is to compare thermal stability and enthalpy of iron oxy-sulphate, often detected as an intermediate, with commonly known iron sulphates. DSC curves of samples with equal mass under different gas medium, determining different partial pressure of oxygen in the gas phase, are the base for comparative study of the sample’s thermal properties. Obtained different values of the enthalpy and mass losses and kinetic parameters demonstrate that the stability of oxy-sulphate strongly depended on the value of oxygen partial pressure in the gas phase. The new evidences from the experimental study help to propose the mechanism of the decomposition and to compare some of the iron sulphates properties. [ABSTRACT FROM AUTHOR]

The thermal analytical study of most hydrophobic and hydrophilic D/L amino acids reveals significant hydropathy index correlation between the presence of water and crystalline amino acids. The TG derivative mass profiles for arginine and lysine (hydrophilic acids) at various time intervals of atmospheric exposure, show two distinct peaks, one between 50 and 60°C (unbound water), and one close to 100°C (bound-like water). The DSC heat-cool profiles for lysine and arginine confirmed the presence of these multiple waters with two heats of vaporization. The absence of these patterns from the TG and DSC for cysteine and phenylalanine (hydrophobic acids) further supports the conclusions. [ABSTRACT FROM AUTHOR]

Since some combustible, oxidative and reductive chemicals are used in the extracting process in the nuclear reprocessing plant the process has potential hazards of a fire and explosion due to the undesired reaction. In this study to obtain a better understanding of the thermal properties of hydrazine in nitric acid solution which is used for preventing the oxidation of extracted plutonium, thermal analysis was carried out for the mixtures in various conditions. From the results of DSC it was revealed that the vessel material has an influence on the thermal decomposition of hydrazine. It was also found that hydrazine reacted with nitric acid in an autocatalytic manner, and concentration of nitric acid has a strong influence on the thermal hazard of hydrazine and nitric acid mixtures. [ABSTRACT FROM AUTHOR]

TG, DTA and DSC curves of Cd2[Ti2(O2)2O(OH)6]·H2O were recorded and used to determine the isothermal conditions suitable for obtaining the intermediate samples corresponding to the phases observed during the thermal decomposition. The samples were identified by quantitative analysis, IR spectroscopy and X-ray analysis. The experimental results were used to propose a mechanism of thermal decomposition of the investigated compound to CdTiO3. The optimum conditions were also determined for obtaining CdTiO3 with well-defined crystallinity. [ABSTRACT FROM AUTHOR]

The thermodynamic properties of the ADP- and ATP-actin filaments were compared by the method of differential scanning calorimetry. The lower melting point for the ADP-F-actin filament (58.4 vs. 64.5°C for ATP-F-actin) indicated that compared to the ATP-actin filaments its structure was less resistant to heat denaturation. The detailed thermodynamic characterisation of the proteins was carried out by the analysis of the calorimetric enthalpy, the entropy and the free enthalpy changes. All of the determined parameters gave lower values to the ADP-actin filaments than to the ATP-actin filaments. The calculated values of the activation energy also demonstrated that compared to the ADP-F-actin the ATP-F-actin was thermodynamically more resistant to the denaturing effect of heat. Based on all of this information we have concluded that the actin filament prepared from ADP containing magnesium saturated actin monomers at pH 8.0 is thermodynamically less stable than the ones obtained from ATP-actin monomers. [ABSTRACT FROM AUTHOR]

TG, DTA and DSC curves of Cd2[Ti2(O2)2O(OH)6]·H2O were recorded and used to determine the isothermal conditions suitable for obtaining the intermediate samples corresponding to the phases observed during the thermal decomposition. The samples were identified by quantitative analysis, IR spectroscopy and X-ray analysis. The experimental results were used to propose a mechanism of thermal decomposition of the investigated compound to CdTiO3. The optimum conditions were also determined for obtaining CdTiO3 with well-defined crystallinity. [ABSTRACT FROM AUTHOR]

DSC method was used to study thermal stability of nitrocompounds. It was assumed the model to estimate stability of solid phase in which perfect solid phase is totally stable and amorphous-liquid domains connected with impurities decompose according to the kinetic model determined for the liquid phase above the melting point. The influence of sample purity on relative stability, which iskl/ks - ratio of decomposition rate constants in liquid and solid phase, at temperature 20 K below the melting point was predicted. The increase of liquid domains in solid phase causes decrease ofkl/ks ratio (relative stability) at chosen temperature. [ABSTRACT FROM AUTHOR]

Multiblock terpolymers -(PBT-b-PTMO-b-PA12.10)n- comprising the polymer systems in which one of the three blocks (PBT) is not soluble in the hard phase of PA12.10 blocks but is slightly soluble in the soft phase of PTMO blocks have been obtained. The DSC and DMTA method was applied to investigate the thermal properties of these polymers and it was found that the PBT block acts as an element that produce stiffness of -(PBT-b-PTMO-b-PA12.10)n- structure. The terpolymers were compared with the previously described [5] -(PBT-b-PTMO-b-PA12)n- elastomers, in which the rigid PBT block (DP>7) dissolves in the hard phase of PA12 blocks and partly dissolves in the soft phase. It was found that even a small change in the chemical structure of the amide block influences significantly on the structure, phase separation and the properties of terpolymers. [ABSTRACT FROM AUTHOR]

The thermal stability of gelatine-polyacrylonitrile graft copolymers fibres obtained under various conditions of deformation has been studied. The thermal properties of examined fibres depend on the synthetic component of the fibre forming material – polyacrylonitrile which appears in the form of grafted PAN chains and PAN homopolymer. It was stated that the highest thermal stability have those fibres which formation process included two stages of drawing with the use of deformation close to the maximal values, with the value of the total draw ratio amounting to 691%. It should be supposed that with such a drawing process, already in its first stage, are created advantageous conditions for the formation of paracrystalline regions to a larger extent and their orientation along the fibre axis. [ABSTRACT FROM AUTHOR]