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The molecular dynamics, with an emphasis on the calorimetric and dynamic glass transitions, of non-isocyanate polyhydroxyurethanes (PHUs) produced by the equimolar polyaddition of polyether-based dicyclic carbonates (P-CCs) and various short diamines was studied. The diamine component consisted of a short aliphatic diamine (1,4-diaminobutane, DAB) and a more complex 'characteristic' diamine. The study was conducted to investigate (i) the chemical structure of the characteristic amine, (ii) its molar ratio, and (iii) the structure and molar mass of the P-CC. Infrared spectroscopy, differential scanning calorimetry, and broadband dielectric spectroscopy were employed. The P-CC, constituting the bulk of the systems, was the most crucial component for the glass transition. The characteristic amine influenced the glass transition as a result of its bulky structure, but also presumably as a result of the introduction of free volume and the formation of hydrogen bonds. The dynamic glass transition (α relaxation) trace in the Arrhenius plots showed a subtle change at a certain temperature that merits further study in the future. The charge mobility was fully coupled with the molecular mobility, as evidenced by dc conductivity being directly proportional to the characteristic frequency of α relaxation. The fluctuation in carbonyl units (β relaxation) was mildly affected by changes in their immediate environment. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) is considered one of the most versatile thermal analysis tools for characterizing polymer samples. This paper reports a DSC study of blends of polymethyl methacrylate (PMMA) and polystyrene (PS) prepared in different ratios by weight percentage for all blend ratios used for PMMA:PS (80:20, 60:40, 50:50, 60:40, 20:80) using the solution cast method. The samples were analyzed at heating rates of 5°C/min, 10°C/min and 20°C/min in the temperature range of 50–200°C. The glass transition temperature (Tg) was theoretically calculated using Fox's equation for all the samples. It was found that the experimental glass transition temperature is very close to the theoretical values. DSC thermograms supported the confirmation of the formation of PS–PMMA blends and demonstrated a significant change in their thermal behavior with changes in blend ratio. The activation energy of crystallization was evaluated using both isokinetic and iso-conversional approaches, and similar findings were found. Using various iso-conversional approach models, the activation was determined for pure and blended polymers through their glass transition. Notably, the activation energy values obtained using different iso-conversional methods and specific iso-conversional techniques, such as Ozawa, Kissinger, Boswell, and Augis and Bennett, are relatively consistent. [ABSTRACT FROM AUTHOR]

The preparation of 0.58 Li2S + 0.315 SiS2 + 0.105 LiPO3 glass, and the impacts of polysulfide and P1P defect structure impurities on the glass transition temperature (Tg), crystallization temperature (Tc), working range (ΔT≡ Tc ‐ Tg), fragility index, and the Raman spectra were evaluated using statistical analysis. In this study, 33 samples of this glass composition were synthesized through melt‐quenching. Thermal analysis was conducted to determine the glass transition temperature, crystallization temperature, working range, and fragility index through differential scanning calorimetry. The quantity of the impurities described above was determined through Raman spectroscopy peak analysis. Elemental sulfur was doped into a glass to quantify the wt% sulfur content in the glasses. Linear regression analysis was conducted to determine the impact of polysulfide impurities and P1P defect impurities on the thermal properties. Polysulfide impurities were found to decrease the Tg at rate of nearly 12°C per 1 wt% increase in sulfur concentration. The sulfur concentration does not have a statistically significant impact on the other properties (α = 0.05). The P1P defect structure appears to decrease the resistance to crystallization of the glass by measurably decreasing the working range of the glasses, but further study is necessary to fully quantify and determine this. [ABSTRACT FROM AUTHOR]

The stages of sugar cooking are widely used in the confectionery industry as a practical tool for producing confections with a wide range of physical and textural properties. However, the range of glass transition temperatures (Tg) associated with each sugar cooking stage requires further investigation. Thus, the objective of this study was to characterize the Tg of commercial confections from each sugar cooking stages, thread to hard crack. Twenty-four representative confections were selected from across the six stages. Vacuum oven moisture content, chilled mirror hydrometer water activity, and differential scanning calorimetry Tg parameters were measured. Principle Component Analysis (PCA) and cluster analysis were performed, categorizing the confections based on their physical and thermal properties. Generally, Tg increased with increasing sugar cooking stage, with noted exceptions. Overall, rubbery confections exhibited a much wider variation in moisture content, aw, and Tg values compared to glassy confections, in agreement with the PCA and cluster analysis results. Water activity proved to be a better predictor of Tg midpoint values for the confections studied herein than moisture content, as aw better reflected the amorphous solid-water interactions within the confectionary matrix. While moisture content and aw did not correlate to Tg in the same fashion, PCA revealed that both parameters assist in characterizing the confections. The confections did not cluster by stage, but the glassy and rubbery confections did cluster separately, yielding one glassy and two rubbery clusters. This research underscores the significant role formulation plays in impacting the physical and thermal properties of confections. [ABSTRACT FROM AUTHOR]

Preserving microbial ecosystems obtained from traditional cheese-making processes is crucial to safeguarding the biodiversity of microbial cheese communities and thus ensuring that the high flavor quality of traditional cheeses is maintained. Few protocols have been proposed for the long-term storage of microbial consortia. This work aimed to develop preservation methods to stabilize the entire microbial community in smear-ripened cheese without multiplication or isolation. A simplified microbial community, capable of reproducing the metabolic pattern of cheese maturation, was used in three independent cheese productions. Cheese samples were taken before and after the ripening step, mixed with maltodextrin or saline solution, and subjected to different stabilization conditions including freezing and freeze-drying, followed by 1 month of storage. Microbial survival was quantified using the colony-forming unit assay. Differential scanning calorimetry was used to relate the physical events occurring within the samples to the microbial storage stability. Freezing at −80 °C resulted in the lowest loss of culturability (<0.8 log unit), followed by freezing at −20 °C and freeze-drying. The ripening bacteria appeared as the most sensitive microorganisms within the community. Moreover, a successful cheese production using the best-stabilized community showed the possibility of preserving and re-using an entire microbial community of interest. [ABSTRACT FROM AUTHOR]

A familiar polyalcohol, 1,2-propanediol (12PDO), is among the simple alcoholic solvents with high solubility for lithium tetrafluoroborate (LiBF4), as well as a wide temperature range for liquids. The viscosity of 12PDO solutions containing LiBF4 was measured in the temperature range of 280‒340 K using a vibrational viscometer, and it exhibited non-Arrhenius behavior fitted with the Vogel–Fulcher–Tamman (VFT) equation, which is an empirical model for describing liquid dynamics. The viscosity (η) increased with the increasing mole fraction of LiBF4 (x), and the variation in η was found to be mainly controlled by the pre-exponential factor η0 in the VFT expression. The VFT-fitting parameters, the strength parameter (D), and ideal glass transition temperature (T0), which indicate the Arrhenius behavior and an ideal glass transition temperature, respectively, correlated with the thermal analysis results that were obtained via differential scanning calorimetry. With the increasing x, the value of D decreased rapidly for x < 0.20, whereas it remained approximately unchanged for x > 0.20. The concentration dependence of T0 also differed at approximately x = 0.20. The changes in D and T0 with x indicated that the intrinsic hydrogen-bonding networks between the solvent molecules were rapidly destroyed by the added ions at reduced salt concentrations, while such a structural breaking effect of the added ions weakened owing to ion associations at increased salt concentrations. Thus, it was observed that the solvation structure and dynamics of the solutions strongly depended on the salt concentration. [ABSTRACT FROM AUTHOR]

A familiar polyalcohol, 1,2-propanediol (12PDO), is among the simple alcoholic solvents with high solubility for lithium tetrafluoroborate (LiBF4), as well as a wide temperature range for liquids. The viscosity of 12PDO solutions containing LiBF4 was measured in the temperature range of 280‒340 K using a vibrational viscometer, and it exhibited non-Arrhenius behavior fitted with the Vogel–Fulcher–Tamman (VFT) equation, which is an empirical model for describing liquid dynamics. The viscosity (η) increased with the increasing mole fraction of LiBF4 (x), and the variation in η was found to be mainly controlled by the pre-exponential factor η0 in the VFT expression. The VFT-fitting parameters, the strength parameter (D), and ideal glass transition temperature (T0), which indicate the Arrhenius behavior and an ideal glass transition temperature, respectively, correlated with the thermal analysis results that were obtained via differential scanning calorimetry. With the increasing x, the value of D decreased rapidly for x < 0.20, whereas it remained approximately unchanged for x > 0.20. The concentration dependence of T0 also differed at approximately x = 0.20. The changes in D and T0 with x indicated that the intrinsic hydrogen-bonding networks between the solvent molecules were rapidly destroyed by the added ions at reduced salt concentrations, while such a structural breaking effect of the added ions weakened owing to ion associations at increased salt concentrations. Thus, it was observed that the solvation structure and dynamics of the solutions strongly depended on the salt concentration. [ABSTRACT FROM AUTHOR]

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx=168±3.7kJ/mol, was found to be higher than the activation energy of the glass transition Еg=156±1.4kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg=32K and the low viscosity values in the same range ƞ(Тg)=3.40E+11Pa.s and ƞ(Тx)=1.87E+10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt. [ABSTRACT FROM AUTHOR]

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx=168±3.7kJ/mol, was found to be higher than the activation energy of the glass transition Еg=156±1.4kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg=32K and the low viscosity values in the same range ƞ(Тg)=3.40E+11Pa.s and ƞ(Тx)=1.87E+10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt. [ABSTRACT FROM AUTHOR]

The present study was designed to investigate the physical stability of three organic materials with similar chemical structures. The examined compounds revealed completely different crystallization tendencies in their supercooled liquid states and were classified into three distinct classes based on their tendency to crystallize. (S)-4-Benzyl-2-oxazolidinone easily crystallizes during cooling from the melt; (S)-4-Benzylthiazolidine-2-thione does not crystallize during cooling from the melt, but crystallizes easily during subsequent reheating above Tg; and (S)-4-Benzyloxazolidine-2-thione does not crystallize either during cooling from the melt or during reheating. Such different tendencies to crystallize are observed despite the very similar chemical structures of the compounds, which only differ in oxide or sulfur atoms in one of their rings. We also studied the isothermal crystallization kinetics of the materials that were shown to transform into a crystalline state. Molecular dynamics and thermal properties were thoroughly investigated using broadband dielectric spectroscopy, as well as conventional and temperature-modulated differential scanning calorimetry in the wide temperature range. It was found that all three glass formers have the same dynamic fragility (m = 93), calculated directly from dielectric structural relaxation times. This result verifies that dynamic fragility is not related to the tendency to crystallize. In addition, thermodynamic fragility predictions were also made using calorimetric data. It was found that the thermodynamic fragility evaluated based on the width of the glass transition, observed in the temperature dependence of heat capacity, correlates best with the tendency to crystallize. [ABSTRACT FROM AUTHOR]

In this study, amorphous solid dispersions (ASDs) of pterostilbene (PTR) with polyvinylpyrrolidone polymers (PVP K30 and VA64) were prepared through milling, affirming the amorphous dispersion of PTR via X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC). Subsequent analysis of DSC thermograms, augmented using mathematical equations such as the Gordon–Taylor and Couchman–Karasz equations, facilitated the determination of predicted values for glass transition (Tg), PTR's miscibility with PVP, and the strength of PTR's interaction with the polymers. Fourier-transform infrared (FTIR) analysis validated interactions maintaining PTR's amorphous state and identified involved functional groups, namely, the 4′–OH and/or –CH groups of PTR and the C=O group of PVP. The study culminated in evaluating the impact of amorphization on water solubility, the release profile in pH 6.8, and in vitro permeability (PAMPA-GIT and BBB methods). In addition, it was determined how improving water solubility affects the increase in antioxidant (ABTS, DPPH, CUPRAC, and FRAP assays) and neuroprotective (inhibition of cholinesterases: AChE and BChE) properties. The apparent solubility of the pure PTR was ~4.0 µg·mL−1 and showed no activity in the considered assays. For obtained ASDs (PTR-PVP30/PTR-PVPVA64, respectively) improvements in apparent solubility (410.8 and 383.2 µg·mL−1), release profile, permeability, antioxidant properties (ABTS: IC50 = 52.37/52.99 μg·mL−1, DPPH: IC50 = 163.43/173.96 μg·mL−1, CUPRAC: IC0.5 = 122.27/129.59 μg·mL−1, FRAP: IC0.5 = 95.69/98.57 μg·mL−1), and neuroprotective effects (AChE: 39.1%/36.2%, BChE: 76.9%/73.2%) were confirmed. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) revealed an anti-sigmoidal composition dependence of the glass transition temperature in a binary mixture of dicyclohexylmethanol [ (C 6 H 11) 2 CHOH , DCHM] and tricyclohexylmethanol [ (C 6 H 11) 3 COH , TCHM]. The equimolar mixture, of which state was suggested to be robust by the dependence, was subjected to adiabatic calorimetry. The glass transition occurred around 257 K with a significant enthalpy relaxation. The excess heat capacity beyond the weighted average of heat capacities of neat compounds changes its sign from positive to negative upon the glass transition on cooling. The negative excess implies a denser molecular packing than neat glasses. The excess enthalpy is graphically given relative to T = 298.15 K. [ABSTRACT FROM AUTHOR]

We have developed an analytical method to quantitatively analyze differential scanning calorimetry (DSC) experimental data. This method provides accurate determination of thermal properties such as equilibrium melting temperature, latent heat, change of heat capacity which can be performed automatically without intervention of a DSC operator. DSC is one of the best techniques to determine the thermal properties of materials. However, the accuracy of the transition temperature and enthalpy change can be affected by artifacts caused by the instrumentation, sampling, and the DSC analysis methods which are based on graphical constructions. In the present study, an analytical function (DSCN(T)) has been developed based on an assumed Arrhenius crystal size distribution together with instrumental and sample-related peak broadening. The DSCN(T) function was successfully applied to fit the experimental data of a substantial number of calibration and new unknown samples, including samples with an obvious asymmetry of the melting peak, yielding the thermal characteristics such as melting and glass transition temperature, and enthalpy and heat capacity change. It also allows very accurate analysis of binary systems with two distinct but severely overlapping peaks and samples that include a cold crystallization before melting. [ABSTRACT FROM AUTHOR]

The local structure and glass transition of Ge-As-Se, Ge-As-Se-Schalcogenide glasses have been studied by X-ray diffraction and differential scanning calorimetry. By applying the theory of topological constraints and considering chemically ordered network models, it has been determined that Ge10As20S10Se60 (average coordination number ⟨ r ⟩ = 2.4), Ge25As10S25Se40 ( ⟨ r ⟩ = 2.6) are the compositions associated with the more stable glasses. This result is related to the larger differences between the glass transition (Tg) and crystallization-transition (Tcr) temperatures (ΔTg-cr∼ 38 and 43 K) at these compositions. Relatively high values of short-range (d∼5.7–6.34 Å) and medium-range (L∼26.59–33.74 Å) order parameters of the local structure in the glass compositions satisfying the mentioned conditions affect the glass-transition temperature (Tg) and cause its value to increase (Tg∼589–689 K). As a result of comparative analyses of X-ray diffraction and differential scanning calorimetry curves it has been determined that there is a correlation between the glass-transition temperature (Tg) with the short range (d) and medium range order (L) parameters of the local structure. [ABSTRACT FROM AUTHOR]

The precipitate and the coacervate are two aggregated states in the polyelectrolyte complexes (PECs). The precipitate‐to‐coacervate transition and glass transition in PECs have been widely reported in the past. In many cases, the two phenomena are studied independently, although both of them are apparently affected by water and small ions. Here, utilizing a PEC system consisting of poly(acrylic acid) (PAA) and a cationic bolaamphiphile (DBON), we explore the states of PECs as a function of salt, temperature, and the molecular weight of PAAs. By a combination of microscopic observation, time‐resolved fluorescence measurements, and differential scanning calorimetry, we identify salt/temperature driven precipitate‐to‐coacervate transitions of the complexes. The thermally induced morphology transformation from the precipitate to coacervate occurs around the glass transition temperature, indicating a strong correlation between the two processes. As the molecular weight of the PAA increases, the thermal transition temperature becomes higher. This finding offers new insights on the mechanistic interactions that dictate the aggregated states of PECs. Based on the photothermal effect of DBON, we also develop a UV light‐induced strategy to mediate the precipitate‐to‐coacervate transition, providing a fantastic platform to create functional PEC materials. [ABSTRACT FROM AUTHOR]

Strontium phosphate glasses containing bismuth oxide were prepared using conventional melt-quenching technique. X-ray diffraction and differential scanning calorimetry (DSC) analysis suggests that stable ternary glasses of composition 70 P2O5-(30-x)SrO-xBi2O3 can be obtained for x = 5–25 mol%. This study examines such physical properties as the density, molar volume (Vm), glass transition temperature (Tg), and structural properties in the interest of explaining the effect on these glasses of Bi-Sr substitution. An almost linear increase in the density when the concentration of bismuth increases between x = 5 and x = 10 mol% followed by monotonic decreasing is noted. However, the calculated molar volume (Vm) behaves in exactly the opposite way. DSC curves showed that the glass transition temperature (Tg) decreases by 555 °C down to 490 °C as the concentration of Bi2O3 increases, due to the increase in the number of bridging oxygens. Structural investigations performed using IR spectroscopy revealed that the structure of the phosphate network contains predominately meta-phosphate (Q2) units, with contributions from pyrophosphate (Q1) and orthophosphate (Q0). The infrared spectra also revealed depolymerization of the phosphate chains in the glass system, with increased Bi2O3 concentration and the formation of P–O–Bi bonds. The study of the gamma ray shielding parameters showed that the prepared glasses can be used for shielding radiation applications. [ABSTRACT FROM AUTHOR]

In the present paper, the study of amorphous-crystalline transformation in (Se80Te20)94−x Ge6Bix (x = 0, 1, 2, 4, 6, 8, 10 and 12 at.%) chalcogenide alloys has been done using non-isothermal differential scanning calorimetry (DSC). Characteristic temperatures indicate that the samples with x = 1 at.% and x = 6 at.% can be considered as a critical configurations at which the system becomes a chemically ordered alloy. Kissinger and Moynihan approaches which utilized dependence of glass transition temperature (Tg) on heating rate (α) are used to deduce activation energy of glass transition (Eg). Crystallization process is characterized by various kinetic parameters such as activation energy and frequency factor deduced using different methods. Dietzel, Hruby, Saad and Poulin criteria are employed to assess glass forming ability and thermal stability of investigated alloys. The alloy with x = 12 at.% of Bi content has highest ∆T confirms maximum thermal stability, further validated from the values of Hruby parameter (Kgl) and thermal stability parameter (S). The fragility index infers that the composition studied in the present study is made from strong glass forming liquids. [ABSTRACT FROM AUTHOR]

The glass transition temperature (Tg) is a parameter used in many glass melt viscosity models as it denotes a temperature around which liquid‐glass transition occurs. In this work, Tg values were measured for a series of low‐activity waste (LAW) glasses using differential scanning calorimetry. These data were combined with Tg data of other waste glasses available from literature. The combined dataset, consisting of 137 data points, was used for the development of several models to estimate Tg from glass composition. When testing the number of influential components and different supervised learning methods, we demonstrated that using more than 10 components or using non‐linear methods brought marginal improvement to the model accuracy. The best model predicts Tg of both LAW and high‐level waste glasses with reasonable accuracy. [ABSTRACT FROM AUTHOR]

A reversible adhesive PAzo-PEG, with a main chain structure of methyl methacrylate and a side chain of azobenzene(Azo) having six methylene spacer groups and a short polyethylene glycol(PEG) chain as a tail group, can undergo solid to liquid transformation under UV and visible light irradiation. It was prepared by atom transfer radical polymerization (ATRP). The azobenzene group undergoes reversible trans-to-cis isomerization under UV and visible light irradiation, and the process is reversible. The reversible photoisomerization process of solid materials was studied by UV-Vis absorption spectroscopy. The solid-to-liquid transition was studied by differential scanning calorimetry (DSC). Results showed that the solid-liquid transition is due to the different glass transition temperatures (Tg) of the cis and trans isomers, and Tg of trans is higher than room temperature while Tg of cis is lower than room temperature, so PAzo-PEG macroscopically exhibits reversible solid-to-liquid transition under light irradiation. The different adhesion capabilities of solid and liquid states of PAzo-PEG endow it with reversible adhesive properties. The solid state exhibits better adhesion properties, with an adhesion strength of 0.97 MPa measured experimentally, while the adhesion strength of PAzo-PEG in the cis state is reduced to 0.03 MPa. After three cycles of adhesion, the adhesive strength maintained 80% of the original strength. [ABSTRACT FROM AUTHOR]

Features intrinsic to disorder and network aspects are ubiquitous in structural glasses. Among this important class of materials, chalcogenide glasses are special—they are built of short‐range covalent forces, making them simpler than silicate glasses that possess mixed ionic and covalent forces. Selenium‐based glasses also display complex elastic phase transitions that have been described from various models, including mean‐field approaches to molecular simulations. These point to the presence of two sharply defined elastic phase transitions, a rigidity and stress transition that are non‐mean‐field in character, and separate the three distinct topological phases of flexible, isostatically rigid, and stressed‐rigid. This article reviews the physics of these glassy networks. The elastic phases and glass transition temperature are explained on a molecular level in terms of topological constraint theory (TCT), connectivity, and the open degrees of freedom. The broader aspects of TCT in relation to phase change materials, high‐k dielectrics, and cements are also commented upon. [ABSTRACT FROM AUTHOR]

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Thermal (differential scanning calorimetry, DSC), proton (low-frequency nuclear magnetic resonance, LF-NMR), and mechanical (differential mechanical thermal analysis, DMTA) relaxations were measured for defatted date-pits as a function of temperature. DSC showed three types of relaxations, lower one structural relaxation (i.e. − 5 °C), followed by a glass transition (i.e. 136 °C) and solids melting–decomposition (i.e. 171 °C). LF-NMR showed three pools of protons, rigid, semi-rigid and mobile. Rigid protons showed two types of relaxations, first one low temperature increase (− 80 to − 40 °C), plateau region (− 60 to − 40 °C) and a positive peak at 120 °C, and semi-rigid showed maximum peak at − 5 °C and minimum peak at 150 °C. Mobile protons showed low relaxation (− 80 to − 40 °C), a maximum peak at 70 °C and a minimum peak at 130 °C. The maximum peak (i.e. − 5 °C) of semi-rigid protons was similar to the DSC structural change, while the maximum peak of rigid protons (120 °C) was similar to DSC glass transition (i.e. 136 °C). The minimum peak of the semi-rigid protons (i.e. 150 °C) was similar to the solids melting–decomposition (171 °C). DMTA showed five regions of mechanical relaxations, glassy region (i.e. onset at 32 °C), glass transition (i.e. 32–85 or 87 °C), first reaction region with a plateau or peak (85–140 °C), second reaction region (87–174 °C), and softening or decomposition region (223 or 242 °C). Mechanical glass showed completely different relaxation as compared to the protons and thermal relaxations. This study showed that LF-NMR, DSC and DMTA could be used to explore the relaxations of a material at nano-, micro- and macro-levels. [ABSTRACT FROM AUTHOR]

New glasses in the TeO2–Na6P6O18 system have been prepared, their thermal behavior has been studied by differential scanning calorimetry in the range 25–580°C, and their heat capacity has been determined as a function of temperature in the range 25–400°C. We have evaluated characteristics of the devitrification process and glassy state, obtained analytical representations of the glass transition temperature and the thermodynamic characteristics of the glasses as functions of their composition at 80°C, and carried out a comparative analysis of the results together with those for previously studied TeO2-based binary systems. Optical transmission of the glasses has been measured in the UV, visible, and IR spectral regions. We have demonstrated the possibility of doping the glasses with rare-earth oxides and studied luminescence properties of the glass with the composition 0.89TeO2–0.08Na6P6O18–0.03Nd2O3. [ABSTRACT FROM AUTHOR]

The crystallization of the 3F5FPhF6 compound from the liquid crystalline antiferroelectric smectic CA* phase is investigated in various conditions using differential scanning calorimetry and polarizing optical microscopy. The kinetics of isothermal melt and cold crystallization is studied on the basis of the Avrami model. The kinetics of non-isothermal cold crystallization is analysed using the Ozawa model and the activation energy is determined by the Augis-Bennett, Friedman's differential isoconversional and Matusita methods. The border temperature between the diffusion-controlled crystallization and thermodynamically-controlled crystallization is estimated. The high fragility index of 105 is determined from the α-process in the smectic CA* phase by the broadband dielectric spectroscopy. The metastable, conformationally disordered crystal phase, forming only via cold crystallization, is reported. [ABSTRACT FROM AUTHOR]

Mixed Matrix Membranes (MMMs) of UiO‐66‐NH2 nanoparticles dispersed in Cellulose Acetate (CA) were prepared with filler loading of 2–20 wt%. MMMs were tested for the upgradation of model biogas (60%–40%) mixture of CH4/CO2 at a feed pressure of 2 bar and 1.5 bar. Detailed characterization of MMMs was performed with Fourier transform infrared spectroscopy (FTIR), Thermo‐gravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Field emission scanning electron microscopy (FESEM) to investigate the physical and thermal properties. MMMs formed are defects‐free, voids‐free, and without polymer rigidification, indicating a better filler polymer interface. MMMs showed improved CO2 permeability while retaining the CO2/CH4 selectivity. The 10 wt.% UiO‐66‐NH2/CA MMM showed optimum gas separation performance with CO2 permeability of 11 Barrer and CO2/CH4 selectivity of 10. The UiO‐66‐NH2/CA MMMs performed better when compared to the pure CA membrane. The experimental permeability and selectivity data were compared with the predicted data using Maxwell, Lewis–Nielsen, Higuchi, and Bruggeman's model. [ABSTRACT FROM AUTHOR]

The structure of liquid lithium pyroborate, Li4B2O5 (J = Li/B = 2), has been measured over a wide temperature range by high‐energy X‐ray diffraction, and compared to that of its glass and borate liquids of other compositions. The results indicate a gradual increase in tetrahedral boron fraction from 3(1)% to 6(1)% during cooling from T = 1271(15) to 721(8) K, consistent with the larger N4 = 10(1)% found for the glass, and literature 11B nuclear magnetic resonance measurements. van't Hoff analysis based on a simple boron isomerization reaction BØ3O2– ⇌ BØO22– yields ΔH = 13(1) kJ mol–1 and ΔS = 40(1) J mol–1 K–1 for the boron coordination change from 4 to 3, which are, respectively, smaller and larger than found for singly charged isomers for J ≤ 1. With these, we extend our model for N4(J, T), nonbridging oxygen fraction fnbr(J, T), configurational heat capacity CPconf(J,T)$C_{\rm{P}}^{{\rm{conf}}}(J,T)$, and entropy Sconf(J, T) contributions up to J = 3. A maximum is revealed in CPconf(J,T=Tg)$C_{\rm{P}}^{{\rm{conf}}}(J,T = {T_{\rm{g}}})$ at J = 1, and shown semi‐quantitatively to lead to a corresponding maximum in fragility contribution, akin to that observed in the total fragilities by temperature‐modulated differential scanning calorimetry. Lithium is bound to 4.6(2) oxygen in the pyroborate liquid, with 2.7(1) bonds centered around 1.946(8) Å and 1.9(1) around 2.42(1) Å. In the glass, nLiO = 5.4(4), the increase being due to an increase in the number of short Li–O bonds. [ABSTRACT FROM AUTHOR]

Although thermosets and various biopolymers cannot be softened without being decomposed, the vast majority of thermoplastics are believed to exhibit thermal transitions solely related to physical alterations of their structure—a behavior typical of low molecular weight substances. In this study, Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry (TGA) were used to study the softening of four common non-hydrogen-bonded thermoplastic polymers (polypropylene, polypropylene-grafted-maleic anhydride, poly(vinyl chloride) and polystyrene) along with a hydrogen-bonded polymer as a reference, namely, poly(vinyl alcohol). It is shown that the softening of these polymers is a thermochemical transition. Based on fundamental concepts of statistical thermodynamics, it is proposed that the thermal transition behavior of all kinds of polymers is qualitatively the same: polymers cannot be softened without being decomposed (in resemblance with their incapability to boil) and the only difference between the various types of polymers is quantitative and lies in the extent of decomposition during softening. Decomposition seems to reach a local maximum during softening; however, it is predicted that polymers constantly decompose even at room temperature and, by heating, (sensible) decomposition is not initiated but simply accelerated. The term "latent decomposition" is proposed to describe this concept. [ABSTRACT FROM AUTHOR]

In the past years, the use of liquid additives as bitumen modifiers has increased to tailor the rheology of bitumen for a wide range of applications. Their chemical composition and mutual interaction result in specific phase morphologies in the binders. Hence, there is a need to evaluate the phase morphology of complex binders and the impact of additives on their physical properties. The RILEM Technical Committee 272-PIM 'Phase and Interphase behaviour of innovative bituminous Materials', Task Group TG1 assessed the phase and interphase properties of bituminous binders. Some preliminary results are presented on blends using three liquid additives and a neat 35/50 bitumen. The goal of formulating the blends was to achieve similar consistency of a pen grade 70/100 bitumen at the original state and to evaluate the binders at both original and after aging. Physical properties were evaluated through rheological characterisation using a dynamic shear rheometer (DSR) in a wide range of conditions. The phase morphology was assessed using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) was also used for the characterisation of the thermal behaviour of the binders. While conventional properties, as obtained from the routine binder testing methods, hardly distinguish between blends, the cross-over temperature, derived from DSR measurements, enabled to dictate the impact of liquid additives on the physical properties of bituminous binders at intermediate temperature. AFM confirmed a difference in phase morphology between the blends, whereas some binders displayed new phases at original and aged conditions. Glass transition, as determined by DSC, also showed a difference in the low-temperature domain that may be explained with the difference in phase morphology. Overall, an in-depth understanding of microstructure morphology and glass transition behaviour of complex binders can assist in designing future specifications to distinguish durable bituminous materials better. [ABSTRACT FROM AUTHOR]

Effects of annealing temperature (Ta: 80–140°C) and time (ta: 3‐30 h) on the crystalline phase transition in poly(lactic acid) (PLA) were studied by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In the DSC curves, the sample annealed at Ta = 80°C with time interval (ta: 10–30 h) demonstrates a peculiarly small exothermal peak (Texo) around 130°C, just prior to the melting point, corresponding to the disorder‐to‐order (α'‐to‐α) phase transition, while the sample annealed at temperature (Ta: 90–110°C) shows a double melting behavior considered as the α'‐α phase transition. Towards low temperatures, the glass modulus Eg reported by DMA thermograms, shows an important increase (~30,000 MPa) at Ta = 80°C for ta = 3 h, due to the extremely high self‐nucleation density in low‐crystallized PLA materials. After a sharp drop to 3600 MPa at Ta = 110°C, a marked improvement of Eg (15,900 MPa) is observed around Ta = 120°C for all samples, regardless of time ta. This interesting effect (improvement of Eg in the range Ta = 100–120°C) can be correlated with the grow of crystallinity in the same domain of Ta, and the α'‐α phase transition Ta (Ta: 90–110°C) determined by the double Tm melting DSC peak, which is confirmed by the increase of Tg for Ta = 90–110°C. [ABSTRACT FROM AUTHOR]

To explore high thermal properties, low dielectric constant and loss for copper clad laminates, poly(phenylene oxide) (PPE) with different end groups (allyl and epoxide groups) were successfully prepared. Firstly, low molecular weight polyphenylene ether was synthesized using the redistribution method. Then the polyphenylene ether thermosetting polymers by modifying their terminal hydroxyl groups were reported and their fundamental materials properties were compared. Through property tests and data analyses, it was found that PPE with vinyl end groups had the best performances, especially high glass transition temperature (about 230°C), the thermal conductivity was 0.32–0.38 Wm−1 K−1, low dielectric constant (about 2.5) and low dielectric loss (about 4.4 × 10−3). The possible reason was that the main chain of polyphenylene ether contains non‐polar crosslinkable group (CC). In a word, through properties comparison of thermosets of PPE, the results demonstrated that the materials of all systems were suitable for using as printed circuit boards. [ABSTRACT FROM AUTHOR]

Biopolymer-based films are created from plant or animal materials such as carbohydrates and proteins. In this study, a biopolymer-based film from gelatin and Bovine Serum Albumin (BSA) was created to form a film through cross-linking interaction of both biopolymers. The synthesized biopolymer film was characterized using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) as morphological evaluation. Besides, the encapsulation efficiency of BSA-gelatin blend film was also evaluated. The coagulation process was performed using acetone carried out at 35 °C for 4 hours under stirring. The formed particles were separated from the solution using high centrifugation around 12,000 rpm for 30 min and then kept at -80 °C. Based on the FTIR spectra showed that BSA and gelatin have the same functional group such as hydroxyl (OH) and Amina I, II, and III which appear at 3278 cm-1, 1633 cm-1, 1542 cm-1, and 1241 cm-1, respectively. After linkage reaction, the gelatin-BSA interaction created more strength interaction that caused no vibration functional groups seen. It also increased glass transition temperature where the resulted melting point of gelatinbased and 70% BSA/gelatin-based films are 152.2 and 260 °C, respectively. The encapsulated BSA in the blend film reached above 90% in the BSA/gelatin ratio of 70%. [ABSTRACT FROM AUTHOR]

In contrast with the numerous application studies conducted on ionic liquids (ILs), systematic investigations on their glass transition thermodynamics and kinetics are relatively scarce. This study aims to map and classify typical ILs simply in terms of their glass transition temperature (Tg), heat capacity change (ΔCp) at Tg, and fragility index (m) as a function of the molar mass (M). For 16 kinds of ILs containing cation groups such as imidazolium, pyrrolidinium, pyridinium, phosphonium, and ammonium, Tg and ΔCp were determined as the representative thermodynamic parameters by performing differential scanning calorimetry (DSC) measurements. The kinetic parameter m and the ideal glass transition temperature (T0) were calculated according to the scanning rate dependence of Tg. The M dependence of Tg, T0, ΔCp, and m and the glass-forming tendency were evaluated among the 16 samples. This mapping and classification of ILs is expected to be useful for the easy prediction of the glass transition and fragility of ILs. [ABSTRACT FROM AUTHOR]

The purpose of this study is to critically analyze different methods of calculation of activation energy of relaxation in sucrose-water system from differential scanning calorimetry data. We consider the use of different thermal cycles for calculations together with Moynihan and Kissinger equations. We study the effect of two methods of glass transition temperature determination (half-step and inflection point) on the activation energy values. Along with experimental DSC data, we use the data simulated using Tool–Narayanaswamy–Moynihan model to validate the use of cooling and heating curves and to check the reproducibility of the activation energy calculations. The obtained results show that the thermal cycle with equal cooling and heating rates provides the most reliable data set and the glass transition temperature definition using inflection point rather than half step can be recommended for calculations. Moreover, due to technical reasons, heating rather than cooling scans provide the most reliable results of activation energy calculations. Furthermore, a simple method based on the width of the glass transition region shows reasonable results for single scan experiments. The activation energies of the glass transition in sucrose-water system with different water contents and different thermal histories were studied. Since it is impossible to apply traditional methods based on Moynihan equation for the activation energy evaluation for freeze-dried samples, we propose using another method based on the properties of the recovery peak. Combining the results obtained by different methods, we present a dependence of activation energy in sucrose-water system on water content. The results show that water decreases the activation energy of relaxation process in sucrose matrix. [ABSTRACT FROM AUTHOR]

The glass transition behavior of polystyrene as a function of different cooling rates with scanning to two different end temperatures, 30°C and −80°C, was investigated for four different substrate conditions using Flash differential scanning calorimetry, a fast scanning nanocalorimetry technique. In addition, structural recovery of polystyrene was performed at 20°C for aging times from 0.01 s to 8 h with scanning to −80°C for the same samples. A broad endotherm appears to grow at low temperatures (T << Tg) as cooling rate decreases and aging time increases, which is influenced by the substrate underlying the film, as well as by the end temperature condition in the scanning experiment. On the other hand, the endothermic overshoot associated with Tg is not influenced by substrate or scan end temperature. In addition, indium and vapor‐deposited gold, both crystalline materials, show the growth of a very similar broad endotherm at low temperatures as cooling rate decreases and aging time increases indicating that the low‐temperature endotherm is an artifact and not a relaxation associated with the material under investigation. Several potential explanations are put forward. [ABSTRACT FROM AUTHOR]

The absolute heat capacity of a matrix‐free polystyrene grafted silica nanocomposite system is investigated using ultrafast Flash differential scanning calorimetry (Flash DSC) and compared to results for a neat polystyrene sample of similar molecular weight. The heat capacity of the polymer in the nanocomposite is 8% lower than that of the neat polystyrene. In addition, the step change in heat capacity at the glass transition Tg is 15% lower, indicating a 2 nm‐thick immobile layer of polymer around the nanoparticles. There is neither an increase in the nanocomposite heat capacity towards that of the neat material nor any additional ∆Cp steps, indicating that the glassy layer around the nanoparticles remains immobile up to 300°C. In addition to the analysis of the absolute heat capacity, the dynamic temperature gradient in the Flash DSC sample increases linearly with increasing rate of measurement, whereas the noise in the heat capacity data increases linearly with the reciprocal of the scanning rate; the optimum rate for measurements lies between 300 and 1000 K/s for the samples studied here and will depend on the sample thickness. [ABSTRACT FROM AUTHOR]

In this work we study the molecular mobility in the amorphous solid state and in the glass transformation region of two compounds, diazepam and nordazepam; these are two benzodiazepines, a family of psychotropic drugs with sedative, anxiolytic and muscle-relaxing properties. The experimental techniques used are thermostimulated currents (TSC) and differential scanning calorimetry (DSC). TSC is a time-dependent technique recognized for its high resolving power; the use of this technique in the depolarization and polarization modes (TSDC and TSPC respectively), provides results that confirm and complement results of dielectric relaxation spectroscopy (DRS) published recently. On the other hand, the variation with the heating rate of the temperature position of the DSC glass transition signal also allowed the estimation of the activation energy at T g and of the dynamic fragility of the two glass formers. [ABSTRACT FROM AUTHOR]

We propose the equation of glass transition of resin basing on experimental investigations of influence of the composition of the epoxy diane resin based composite on the glass transition temperature. It is observed experimentally by the Differential Scanning Calorimetry that the glass transition temperature of non-modified ED-20 resin increases with the hardener L-20 mass fraction. The addition of organosilicon filler PDMS-5 increases little the glass transition temperature from 80 to 85 °C. The addition of nanodispersed pyrogenic silica HDK filler significantly increases the glass transition temperature up to 116 °C. A theory describing the three athermal plateaus in the dependence of the glass transition temperature on the hardener mass fraction is formulated. The equation of glass transition sufficiently fitting the measured points of the glass transition temperature is found. The formulated equation can be useful to prediction the glass transition temperatures of polymer composites based on epoxy resins. [ABSTRACT FROM AUTHOR]

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Glass transition temperatures (Tg) of carbohydrate mixtures consisting of only one monomer and glycosidic binding type (aldohexose glucose, α1-4-glycosidic bonded) were studied by differential scanning calorimetry (DSC). The aim of this work was to systematically assess the predictability of Tg of anhydrous binary and ternary sugar mixtures focusing on the components Tg, molecular chain length, and shape. Binary systems were investigated with glucose as a monosaccharide and its linear di-, tri-, tetra-, penta-, hexa-, and heptasaccharides. Additionally, the Tg of ternary carbohydrate systems prepared with different glucose/maltose/maltotriose mass fractions were studied to evaluate the behavior of more complex mixtures. An experimental method to prepare fully amorphized, anhydrous mixtures were developed which allows the analysis of mixtures with strongly different thermodynamic pure-component properties (Tg, melting temperature, and degradation). The mixtures' Tg is systematically underestimated by means of the Couchman–Karasz model. A systematic, sigmoidal deviation behavior from the Gordon–Taylor model could be found, which we concluded is specific for the investigated glucopolymer mixtures. At low concentrations of small molecules, the model underestimates Tg, meeting the experimental values at about equimolarity, and overestimates Tg at higher concentrations. These deviations become more pronounced with increasing Tg differences and were explained by a polymer mixture-specific, nonlinear plasticizing/thermal volume expansion effect. [ABSTRACT FROM AUTHOR]

An efficient use of plasticizers in rubber compounds requires an understanding of their miscibility behavior. Besides the chemical properties of both rubber and plasticizer, the rigidity of the plasticizer plays an important role for their miscibility. The miscibility is investigated here using the glass transition measured by differential scanning calorimetry and broadband dielectric spectroscopy (BDS). Additionally, the interfacial relaxation and phase separation measured by BDS are confirmed by transmission electron microscopy. While the flexible plasticizer, poly‐(α‐methylstyrene), stays miscible in a silica‐filled polybutadiene rubber compound, the more rigid plasticizer, indene‐coumarone (IC), shows a phase separation at high concentrations. The phase‐separated IC tends to accumulate at the silica surface. [ABSTRACT FROM AUTHOR]

Naproxen (Nap), a non‐steroidal anti‐inflammatory drug, and 5‐fluorouracil (5FU), an anticancer drug, were easily incorporated into a polyurea xerogel. Polyureas (PUr) were synthesized by one pot reaction via sol–gel chemistry. Soft segments were based on polyetheramine‐PEO and hard segments were based on a hexamethylene diisocyanate trimer (HDI). The final materials were characterized by Fourier transform infrared (FTIR) spectroscopy, small‐angle X‐ray scattering (SAXS), and differential scanning calorimetry (DSC). Polyurea can assume many forms revealing its versatility in terms of produced shapes. In good agreement with FTIR, SAXS studies showed a microphase separated structure arising from inter‐hard‐domain spacings, which remains unchanged after incorporation of the drugs. DSC analysis demonstrated that the PEO chain mobility was poorly affected after the drugs incorporation due to the solvation of the drugs through the network. The water uptake and the amount of drug released agree well, playing an important role for controlled Nap and 5FU release. This work opens positive perspectives for ocular drug delivery and wound management, due to the easy processability of the xerogel, which has high feasibility to be moldable as pharmaceutical devices for contact lenses and transdermal patches purposes containing distinct therapeutic agents. [ABSTRACT FROM AUTHOR]

Powders based on plant raw materials have low storage stability due to their sorption and thermal properties and generate problems during processing. Therefore, there is a need to find carrier agents to improve their storage life as well as methods to evaluate their properties during storage. Water adsorption isotherms and thermal characteristics of the pumpkin powder with various inulin additions were investigated in order to develop state diagrams. Differential scanning calorimetry (DSC) was used to obtained glass transition lines, freezing curves and maximal-freeze-concentration conditions. The glass transition lines were developed using the Gordon–Taylor model. Freezing data were modeled employing the Clausius–Clapeyron equation and its development–Chen model. The glass transition temperature of anhydrous material (Tgs) and characteristic glass transition temperature of maximum-freeze-concentration (Tg′) increased with growing inulin additions. Sorption isotherms of the powders were determined at 25 °C by the static-gravimetric method and the experimental data was modeled with four different mathematical models. The Peleg model was the most adequate to describe the sorption data of the pumpkin–inulin powders. Guggenheim-Anderson-de Boer (GAB) monolayer capacity decreased with increasing inulin concentration in the sample. [ABSTRACT FROM AUTHOR]

Abstract In this study, four commercially available bio‐derived epoxy systems (extracted from cashew nutshell liquid) were prepared and characterised. The glass transition temperature (T g), dielectric spectroscopy, DC conductivity and breakdown properties of these epoxy resins were studied. Differential scanning calorimetry (DSC) demonstrated that the T g of the investigated systems ranged from 67 to 122°C. The DC conductivity was very low (

• The glass transition of energetics is important for inert munitions developments. • The glass transition of TNT as a function of cooling rate is determined. • The glass transition of TNT is sensitive to mixing with a silver paste. • The glass temperature of TNT is approximately 10 K lower than prior reports. • TNT has a dynamic fragility index m of approximately 70. In prior work (N. Shamim, Y. P. Koh, S. L. Simon and G. B. McKenna, "The glass transition of trinitrotoluene (TNT) by Flash DSC," Thermochimica Acta, 620 , 36–39 (2015)) results for the glass transition temperature T g of TNT based on measurements using a rapid chip calorimeter were reported. In that work a silver paste was used to contain the liquid TNT on the chip sensor. In the present work we show that there was an interaction between the paste and the TNT that cause the reported T g to be approximately 10 °C higher than what we find for the material when placed directly on the chip calorimeter sensor. The reasons for the differences in T g values and similarities in the glassy fragility index m from the different sample preparations are presented and discussed. [ABSTRACT FROM AUTHOR]

Two important biophysical properties, the thermal and UV-Vis screening capacity, of isolated tomato fruit cuticle membranes (CM) have been studied by differential scanning calorimetry (DSC) and UV-Vis spectrometry, respectively. A first order melting, corresponding to waxes, and a second order glass transition (T g ) thermal events have been observed. The glass transition was less defined and displaced toward higher temperatures along the fruit ripening. In immature and mature green fruits, the CM was always in the viscous and more fluid state but, in ripe fruits, daily and seasonal temperature fluctuations may cause the transition between the glassy and viscous states altering the mass transfer between the epidermal plant cells and the environment. CM dewaxing reduced the T g value, as derived from the role of waxes as fillers. T g reduction was more intense after polysaccharide removal due to their highly interwoven distribution within the cutin matrix that restricts the chain mobility. Such effect was amplified by the presence of phenolic compounds in ripe cuticle membranes. The structural rigidity induced by phenolics in tomato CMs was directly reflected in their mechanical elastic modulus. The heat capacity (Cp rev ) of cuticle membranes was found to depend on the developmental stage of the fruits and was higher in immature and green stages. The average Cp rev value was above the one of air, which confers heat regulation capacity to CM. Cuticle membranes screened the UV-B light by 99% irrespectively the developmental stage of the fruit. As intra and epicuticular waxes contributed very little to the UV screening, this protection capacity is attributed to the absorption by cinnamic acid derivatives. However, the blocking capacity toward UV-A is mainly due to the CM thickness increment during growth and to the absorption by flavone chalconaringenin accumulated during ripening. The build-up of phenolic compounds was found to be an efficient mechanism to regulate both the thermal and UV screening properties of cuticle membranes. [ABSTRACT FROM AUTHOR]

Four series of CaO-ZnO-B2O3-SLS (CZBS) glasses have been synthesized by using waste materials which are eggshell (EG) and soda lime silica (SLS) glass. We utilized eggshells to source calcium oxide (CaO) in this work, whereas we utilized SLS glass to substitute silica. CZBS1, CZBS2, CZBS3 and CZBS4 are the glass series containing weight percentages of CaO (15%, 20%, 25% and 30%) and SLS (70%, 65%, 60% and 55%), respectively, with the addition of 10% of B2O3 and 5% of ZnO in each sample. A conventional melt and quenching method was applied in this work to fabricate the CaO-ZnO-B2O3-SLS glass system. The glass transition temperature (Tg) was determined using differential scanning calorimetry (DSC), which revealed that the Tg increased from 714 to 735 °C, as the CaO content increased. Meanwhile, the glass structural properties were investigated, revealing an amorphous nature with no sharp peak. The experimental elastic moduli obtained by acquiring ultrasonic speeds using the ultrasonic pulse-echo method were compared to the hypothetical elastic moduli obtained by direct estimation of the hypothetical model. [ABSTRACT FROM AUTHOR]

Differential Scanning Calorimetry (DSC) is considered one of the most adaptable thermal analysis characterization techniques. It can be applied to polymers and their blends, composites, multilayer to study various thermodynamic processes like glass transition temperature (Tg), specific heat capacity and other related kinetic properties and also clarify the material structure, morphology and crystallinity of polymers. In the present paper we have reported thermal analysis of Polymethyl methacrylate (PMMA), Polyvinylidene fluoride (PVDF), Polysulfone (PSF), PVDF-PSF blend and PVDF-PMMA double-layer samples using DSC technique. Attempts have been made to calculate the Tg and interpret the corresponding changes that have been observed on blending PVDF with PSF and double-layer formation with PMMA. Blending of PVDF with PSF results the change in Tg of PSF and the occurrence of a single peak confirms the proper miscibility of the two polymers. DSC plot of double layer also proved to be in confirmation about the formation of PVDF-PMMA double layer and demonstrated a significant change in its thermal behavior. [ABSTRACT FROM AUTHOR]

The phenomenon of physical aging of glassy polymers in confined environments has been extensively studied over the last few decades due to its numerous technological and fundamental implications. Understanding aging in confined environments is vital for predicting the long-term performances in applicative conditions for confined glassy polymers. The physical aging of PC/PMMA multilayer films, with layer thicknesses ranging from micro-to-nanoscale, was explored using the Differential Scanning Calorimetry (DSC) technique. Reducing the layer thickness down to 12 nm was shown to have a very different effect on the structural relaxation parameters of the above-mentioned polymers. Recovered enthalpy data for aged films exhibited an acceleration in physical aging under confinement for PC (rigid backbone and rubbery environments), while no change was noted for PMMA (flexible backbone and amorphous environments). A large effect in the amplitude of the structural relaxation process has also been evidenced for confined PC layers. These observations have thoroughly been discussed with respect to the impact of the chemical structure (entanglement), adjacent polymer state (rubbery and amorphous environments) and the nature of molecular mobility (the CRR shape and length are both related to intra-chain and inter-chain relaxation during glass transition),. Moreover, it was found that the accelerated aging of PC was mainly attributed to the dynamic relaxation related to its chemical structure and local modification of intermolecular interactions. [ABSTRACT FROM AUTHOR]

Flexible electronics require materials with high breakdown strength, high dielectric constant, and thermal stability. These conditions are met by composites based on polymers and metal oxides. In this article, we present a new one‐step method for producing composites based on water‐soluble polyvinyl alcohol (PVA) and metal oxides (AlOOH, CuO, and ZnO). The source of oxides is underwater plasma. The oxides are introduced into the polymer matrix when plasma is exposed to the polymer solution. The results of X‐ray, IR, and SEM analysis showed that metal oxides are embedded in the polymer. Differential scanning calorimetry measurements have shown that the glass transition temperature depends on the oxide being incorporated. The electrical properties of polymer composites were studied by current–voltage characteristics. Dielectric properties were measured in the range of 25–106 Hz. The properties of obtained PVA + metal oxide showed that using underwater plasma is a suitable method for producing composites for electronic devices. [ABSTRACT FROM AUTHOR]