Kinetics of the Thermal Degradation of Poly(lactic acid) and Polyamide Bioblends

Poly(lactic acid) (PLA) and biosourced polyamide (PA) bioblends, with a variable PA weight content of 10–50%, were prepared by melt blending in order to overcome the high brittleness of PLA. During processing, the properties of the melt were stabilized and enhanced by the addition of a styrene-acrylic multi-functional-epoxide oligomeric reactive agent (SAmfE). The general analytical equation (GAE) was used to evaluate the kinetic parameters of the thermal degradation of PLA within bioblends. Various empirical and theoretical solid-state mechanisms were tested to find the best kinetic model. In order to study the effect of PA on the PLA matrix, only the first stage of the thermal degradation was taken into consideration in the kinetic analysis (α < 0.4). On the other hand, standardized conversion functions were evaluated. Given that it is not easy to visualize the best accordance between experimental and theoretical values of standardized conversion functions, an index, based on the integral mean error, was evaluated to quantitatively support our findings relative to the best reaction mechanism. It was demonstrated that the most probable mechanism for the thermal degradation of PLA is the random scission of macromolecular chains. Moreover, y(α) master plots, which are independent of activation energy values, were used to confirm that the selected reaction mechanism was the most adequate. Activation energy values were calculated as a function of PA content. Moreover, the onset thermal stability of PLA was also determined.

Combustion behaviors of hydrogenated and unhydrogenated colophony esters/petroleum resins using TG-FTIR and DFT analysis

The combustion behavior of tackifying resins (such as glycerol ester of colophony/hydrogenated colophony and C9/hydrogenated C9 petroleum resin, namely GEC, GEHC, C9PR and HC9PR, respectively) were investigated using TG-FTIR and density functional theory (DFT) analyses. Results from combustion characteristics indicate tackifying resins and their wastes are a promising fuel for generating energy. The average activation energies obtained by Friedman method for GEC, GEHC, C9PR and HC9PR were 223.51, 162.16, 166.52 and 116.20 kJ/mol, respectively, revealing that (H)C9PR were more readily combustible than GE(H)C, and their hydrogenated products burned more easily than their unhydrogenated ones, which were strongly supported by the TG-FTIR results. DFT calculations also show that the bond dissociation energy of C-C bond of GEC is higher than those of C9PR and GEHC. The best appropriate reaction mechanism evaluated by integral master plots is f(α)=3(1-α)2/3. Volatiles are mainly composed of H2O, CH4, CO2, CO, alcohol, aromatic and carbonyl compounds.

A Qualitative Study of Illness Narratives that Demonstrate the Master Plot of Overcoming the Monster and Support Stroke Survivors in Utilising it

(1) Background; limited research exists which considers master plots expressed by individuals with Stroke. The literature so far has focused on identified pre-established illness narrative types; (2). Methods: A narrative method was selected and a purposive sample of individuals with Stroke are identified. A categorical-form analysis was undertaken; (3) Results: A narrative master plot named overcoming the monster is identified and explored for its components and located temporally for each participant; (4) Conclusions: Health care professionals need to understand the importance of understanding the master plot overcoming the monster. This research supports the need for health care professionals to recognise and support narratives by listening in a non-directive way.

Thermal Behavior, Reaction Pathways and Kinetic Implications of using a Ni/SiO2 Catalyst for Waste Tire Pyrolysis

Catalytic pyrolysis has been used to upgrading the quality of pyrolytic liquids. Herein, we report a comprehensive study on the catalytic pyrolysis of waste tires using Ni/SiO2 as catalysts. The analyses were carried out by combining thermogravimetry (TGA), TGA interfaced to a Fourier Transform Infrared spectrometer (TGA–FTIR), and pyrolysis coupled to gas chromatography/mass spectrometer (Py–GC/MS) techniques. During waste tire decomposition, the main functional groups detected in the FTIR were alkenes, aromatics, and heteroatoms-containing groups such as nitrogen, sulfur, and oxygen. Meanwhile, by Py-GC/MS were identified mainly D,L-limonene, isoprene, benzene, toluene, xylenes (BTX), and p-cymene. The Py–GC/MS experiments at three different temperatures (350, 400, and 450 °C) suggested an effect of the catalyst on product distribution. The Ni catalyst promoted cyclization reactions and subsequently aromatization, leading to an improved vapors composition. The use of iso-conversional kinetic models along with master plots allows proposing a multiple-step reaction mechanism, which was well described by the Avrami-Erofeev, Random Scission, and truncated Sestak–Berggren models. The values of activation energies show differences for the catalyzed and uncatalyzed pyrolysis (111.0 kJ mol-1 and 168.4 kJ mol-1), validating the effectivity of Ni/SiO2. Finally, the thermal Biot (>1) and PyI and PyII numbers (10-3<PyI <10-1 and 10-2< PyII<10-3) confirms that the process is being occurred between the kinetic and the convection-limited regimes.

Epic

An enumeration of generic qualities will define epic less helpfully than will an assessment of its behaviors. Among major literary kinds, epic offers the most long-standing and globally distributed evidence of the human habit of thinking by means of narrative. What it cherishes is the common good; what it ponders are the behaviors and values that forward or threaten collective welfare. What it reckons are the stakes of heroic risk that any living culture must hazard in order to prosper, by negotiating core identities with margins and adjusting settled customs to emergent opportunities; and it roots all these in the transmission of a tale that commands perennial attention on their account. Such dialectics underlie epic’s favorite narrative templates, the master plots of strife, quest, and foundation; and they find expression in such conventions as the in medias res opening and suspended closure; the epic invocation, ancestral underworld, superhuman machinery, and encyclopedic simile; the genre’s formal gravitation towards verse artifice and the lexical and syntactic mingling of old with new language. The genre steadfastly highlights the human condition and prospect, defining these along a scale of higher and lower being, along a timeline correlating history with prophecy, and along cultural coordinates where the familiar and the exotic take each other’s measure.

Thermal Stability of Ionic Liquids: Current Status and Prospects for Future Development

Ionic liquids (ILs) are the safest solvent in various high-temperature applications due to their non-flammable properties. In order to obtain their thermal stability properties, thermogravimetric analysis (TGA) is extensively used to analyze the kinetics of the thermal decomposition process. This review summarizes the different kinetics analysis methods and finds the isoconversional methods are superior to the Arrhenius methods in calculating the activation energy, and two tools—the compensation effect and master plots—are suggested for the calculation of the pre-exponential factor. With both parameters, the maximum operating temperature (MOT) can be calculated to predict the thermal stability in long-term runnings. The collection of thermal stability data of ILs with divergent cations and anions shows the structure of cations such as alkyl side chains, functional groups, and alkyl substituents will affect the thermal stability, but their influence is less than that of anions. To develop ILs with superior thermal stability, dicationic ILs (DILs) are recommended, and typically, [C4(MIM)2][NTf2]2 has a decomposition temperature as high as 468.1 °C. For the convenience of application, thermal stability on the decomposition temperature and thermal decomposition activation energy of 130 ILs are summarized at the end of this manuscript.

Two-scale Phenomenological and Statistical Analysis of the COVID-19 Pandemic

In this work, the daily reported new infection cases and deaths globally due to COVID-19 are approximated by Gaussian functions of the time elapsed since the beginning of the pandemic. This approximation is shown to consistently designate the time evolution of daily rates of new cases and the total duration of the epidemic in any given region or country. At the pandemic scale, this phenomenological analysis is applied for condensing statistical data of the epidemic evolution in twenty-four countries into two “universal master plots” involving in total five adjustable parameters per country. The analysis reveals intrinsic features of the pandemic and local specificities of the epidemic as well, helps in anticipating the epidemic peak date in each country and yields confidence intervals for the average numbers of incidences. Finally, the phenomenology facilitates comparisons of the epidemic evolution in different countries and evaluations of the effectiveness of related health policies.