Journal of Thermal Analysis and Calorimetry

The development of high-performance and low-cost composite nucleating agents has become a pioneering point in expanding the application of isotactic polypropylene (iPP). To this end, this article used a physical blending method to mix nucleating agent organic phosphate salt (LPN-9081) with inorganic fillers such as wollastonite and talc powder. Change the ratio of nucleated mineral-reinforced composition LPN-9081/wollastonite (L/WO) and LPN-9081/talc powder (L/Tac) to study their effects on the crystallization, melting behavior, and mechanical properties of iPP. And a preliminary exploration was conducted on its mechanism. The results suggest that the nucleated mineral-reinforced composition more significantly enhance the crystallization temperature, increasing it by up to 10 °C. Furthermore, it was observed that the mechanical properties of iPP were significantly improved via the synergistic effect of LPN-9081 and the inorganic fillers. In the iPP/L/WO system, the addition of the composite nucleating agent improved rigidity by 146% while maintaining toughness. Similarly, compared with iPP system, the iPP/L/Tac system has improved its rigidity by 107% and toughness by 50%. Using the nucleated mineral-reinforced compositions mentioned above can reduce industrial expenses, while increases the rigidity and toughness of iPP, expanding its potential of applications.

Phase transition behaviors and morphology of thin crystals of 1-heptadecanol and 1-octadecanol with sample masses from 3 μg to 1 mg were investigated by the high-sensitive DSC and AFM. The solid transition and the melting temperatures depressed with the decrease in sample mass. The phase transition behaviors were divided into three groups, the transitions were same to the bulk (more than 0.1 mg), the solid-state transition temperature depressed (from 0.1 to 0.03 mg), both the melting and the solid-state transition temperature depressed (<0.03 mg). The crystal morphologies of 0.1, 0.01, 0.005 mg sample were observed by AFM for the representative of each groups. The morphologies of crystals were classified into three groups, the large droplets with the curved shape, the middle droplets with flat and round shape and the polygonal shape. The crystal morphologies correlated with the phase transition behaviors.

The thermal behaviour of a new kind of hybrid system based on silanized poly(ether-urethanes) (SPURs) has been analyzed by thermogravimetric analysis (TG). The influence of the chemical nature of employed alkoxysilanes, polyether diol molecular weight and the physical state of the obtained hybrids (cured and non-cured) has been studied. The results show that in the non-cured state, aminosilane-based systems present a higher stability compared with those based on isocyanatesilane. However, in the cured state, both types of hybrids present a similar thermal stability, but much higher than their corresponding partners before the curing process. The presence of the inorganic silica network improves the thermal stability of all the systems studied.

Most of the pharmaceutical products are formulated as solid dosage form, which may present drug–excipient interactions that lead to changes in the chemical nature of the drug, such as solubility and bioavailability and may compromise its safety and effectiveness. Differential scanning calorimetry (DSC) is a widely used method for the rapid evaluation of the drug-excipient compatibility and the stability of the mixture formed; however, there is no consensus on the preparation methods of the drug–excipient mixtures. The aim of this study was to investigate the influence of the mixing method on the drug–excipient compatibility studies by means of DSC analysis, using tenofovir disoproxil fumarate as a drug model. Statistical analysis revealed significant differences in the heat of fusion of the drug in the mixtures prepared by several mixing methods. Vortex Mixer with a Pop-Off Cup used for 3 min proved to be very satisfactory for these studies. A polymorphic transition was observed in the mixture prepared with the mortar and pestle. Therefore, this method should be avoided since it may induce errors in the interpretation of DSC results. In this way, the mixing method used to prepare a mixture for studies of interactions between the API and the excipients in a pharmaceutical formulation has a great influence on the results and it must be chosen carefully.

The calculation of the coefficient of compressibility z, entropy S and the heat capacity Cv of noble gases Neon (Ne) and Argon (Ar) is given. The calculations are carried out on the base of generalization of thermodynamics in fractional derivatives. The parameter α determined from the “fractal” state equation is also given. Obtained results are in good agreement with the tabulated data that indicates the prospects of the proposed method for calculation of thermodynamic characteristics of a wide range of substances including both monatomic gases and complex compositions.

For gypsum slurry samples taken from wet flue gas desulfurization (WFGD) systems, a mercury partitioning effect was observed between the solid and liquid components. This partitioning effect, which appears to be pseudo-second-order, is a function of time which results in an increase in mercury content for the solid portion of the gypsum slurry as time increases. Moreover, the mercury content for the solid portion of the slurry reaches a plateau after 24 h. Thus, the sampling method for the gypsum slurry is an important factor in determining an accurate mercury mass balance in the WFGD systems. Temperature-controlled decomposition techniques were employed to acquire an understanding of the mercury species in WFGD gypsum. It was determined that the primary mercury species in WFGD gypsum was mercuric sulfide (HgS). Moreover, the content of HgS as well as mercuric oxide (HgO) in the solid portion of the slurry was susceptible to the partitioning effect and steadily increased with separation time. Other mercury compounds present were mercury sulfate and mercury chloride; however, these mercury species exhibited less change with separation time. Additionally, a comparison of the mercury present in WFGD gypsum from five different coal-fired power plants using thermal decomposition techniques showed that the distribution of mercury species was not the same; however, HgS was primary and mercury chloride compounds or HgO secondary. HgO varied between 15 and 25 % of the total mercury in gypsum. No clear correlation between mercury speciation and sulfur and chlorine content in the coal was determined. Thermogravimetric analysis was employed to compare the effects of settling time with gypsum quality. Data show that longer settling times results in lower quality gypsum.

An inorganically template metaphosphoric acid-containing nickel salt, nanomaterial, has been synthesized and characterized with different measurement techniques such as differential scanning calorimeter (DSC), ultraviolet–visible and near infrared (UV–Vis–NIR) absorption spectroscopy, transmission electron microscopy (HRTEM), vibrating sample magnetometer and X-ray powder diffraction. The thermal property of this mixture has been studied at a low temperature up to 223 from 303 K with DSC. The specific heat capacity of this mixture has been measured in atmospheric O2 at a rate of 10 K min−1 from 303 to 223 K and vice versa in two thermal cycles. The net specific heat capacity of this mixture is found to be 1747.86 J kg−1 K−1 and −6401.38 J kg−1 K−1 in first and second thermal cycles, respectively. There is a discontinuity in the specific heat at 98 s for 233 K and 9 s for 238 K. This average crystallite size of this nanomaterial is ~23.5 nm. The paramagnetic Curie temperature (θ P) and Curie constant (C) are 34.77 K and 9.11 × 10−3, respectively. This material found was an insulator from UV–Vis–NIR measurements.