Differential Thermal Analysis Thermograms Research Articles

Formulation Design and Cell Cytotoxicity of Curcumin-Loaded Liposomal Solid Gels for Anti-Hepatitis C Virus.

Backgrounds Curcumin (CUR) is a low-molecular-weight polyphenolic substance obtained from the tuber part of Curcuma species. Anti-inflammatory and anti-hepatitis C virus (HCV) activities have been associated with CUR. However, its poor aqueous solubility and low systemic bioavailability have been the challenges in improving the therapeutic efficacy of curcumin. Aim The study aimed to produce CUR-loaded liposomal solid gels as anti-HCV delivery systems. Parameters including the physical characteristics and the cell cytotoxicity properties were evaluated. Methods The freeze-drying technique was applied to manufacture the CUR-loaded liposomal solid gels. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and differential thermal analysis (DTA) were involved to reveal the characteristics of the solid gels. Such characteristics were as follows: the morphology and the microscopic structure of the solid gels, the crystallinity structure of the curcumin, and the thermal properties of the mixtures. Furthermore, their cell cytotoxicity was investigated using a Huh7it cell line. Results The SEM images confirmed that curcumin liposomes were intact and trapped in the solid gel matrix. The XRD data showed flat patterns diffractograms of the formulations, confirming the transformation of CUR from crystalline to amorphous form. The DTA thermograms showed a single melting endothermic peak at a higher temperature around 200°C, indicating a single-phase transition of the mixtures. The XRD and DTA data revealed the molecular dispersion of CUR in the developed formulations. The cytotoxicity data provided as cell cytotoxicity 50 (CC50) for all formulations were ≥25 mg. These data confirmed that the developed liposomal solid gels were not cytotoxic to Huh7it cell line, indicating that the anti-HCV activity would be through a specific pathway and not by its toxicity. Conclusion The CUR-loaded liposomal solid gels exhibited the potential and offered an alternative dosage form to improve the therapeutic efficacy of curcumin as an anti-HCV.

Enhancing solubility and antibacterial activity using multi-component crystals of trimethoprim and malic acid

Aim: To improve the solubility and antibacterial activity of trimethoprim (TMP) by preparing its multicomponent crystals with malic acid (MA). 
 Methods: Multicomponent crystals of TMP-MA were prepared by solvent co-evaporation. The solid-state properties were characterised by powder X-ray diffraction (PXRD), differential thermal analysis (DTA), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) analyses. The solubility was investigated in an aqueous medium, while the antibacterial activity against Escherichia coli was investigated using the agar disk diffusion method. 
 Results: The PXRD pattern of the TMP-MA binary system differed from the starting materials, supporting the formation of a new crystalline phase (equimolar ratio). The DTA thermogram showed a single, sharp, endothermic peak at 212.5 °C attributable to the TMP-MA multicomponent crystal's melting point. FT-IR spectroscopy showed a solid-state interaction involving proton transfer between TMP and MA. The multicomponent crystal displayed a 2.5-fold higher solubility and had increased antibacterial activity compared to TMP alone. 
 Conclusions: The TMP-MA binary system forms salt-type multicomponent crystals that significantly increase solubility and antibacterial activity. Multicomponent crystal formation is a viable technique for modifying the physicochemical properties of active pharmaceutical ingredients.

Modifying Thermal and Structural Characteristics of CuAlFeMn Shape Memory Alloy and a Hypothetical Analysis to Optimize Surface-Diffusion Annealing Temperature

In this experimental research study, quaternary Cu-based shape memory alloy with a chemical composition of 73.23Cu-21.93Al-3.36Fe1.48Mn (at.%) and a valence electron concentration (e/a) value of 1.487 was produced by arc melting method. After production, the identical samples of alloy were all subjected to thermal aging at 150 °C for 1 h and then cooled in different coolant materials. A varied number of thermal and structural tests and analyses were carried out successfully to study the alterations in the alloy samples and to see the effects of the aging and quenching/cooling media on alloy’s characteristic martensitic transformation temperatures, eutectoid points, some other kinetic parameters, and structural features. Among these tests, the DSC analyses showed the variations between the thermodynamical parameters such as the martensitic transformation temperatures of the alloy samples that occurred due to the effects of both aging and various quenching environments. Differential thermal analysis (DTA) measurements showed that some eutectoid point shifts (~ 20-25 °C) occurred on the DTA thermograms of the alloy samples which happened mainly due to the thermal aging. A detailed hypothetical analysis and discussion related to the eutectoid temperature made upon DTA results, since the eutectoid temperature has a key role in some thin-film SMA applications for selecting optimum annealing temperature to make good diffusion of the metal layer on the semiconductor surface without causing a deterioration occurs in SMA properties. The results of structural XRD tests showed that the main martensite peak, the intensities of all peaks, and crystallite size values were changed by the effect of aging. In addition, the intensities of all peaks and crystallite size values were also changed by thermal aging and also by quenching the alloy samples in different environments. All obtained results have reflected that modifying the characteristic parameters of this CuAlFeMn SMA by such ways used here may be helpful in various macroscale SMA-based applications and also in designing miscellaneous micro/nanoscale electromechanical systems (MEMS and NEMS) where different modified SMA properties have been demanding.

Glass transition and crystallization kinetics of Na2O – B2O3 – Nb2O5 – Bi2O3 ceramic glasses

A series of Na2O – B2O3 – Nb2O5 – Bi2O3 glasses are synthesized, and their differential thermal analysis (DTA) thermograms are explored at different heating rates. Based on the DTA thermograms, the glass transition temperature (Tgl) and the crystallization peak temperature (Tpc) along with the activation energy of glass transition (EGl) and the activation energy of crystallization (Epc) were determined. The results revealed a decrement of Tgl and EGl upon increasing the Nb2O5 + Bi2O3 content from 0 to 0.15, then, both Tgl and EGl increase beyond this limit. Meanwhile, there is a decrement in the values of Tpc and Epc with a continuous increment of the Nb2O5 + Bi2O3 content. The behavior of the thermal parameters is correlated to the structural variations in the glass network as a function of the Nb2O5 + Bi2O3 content. The XRD curves of the explored glasses indicate the presence of the polycrystalline phases Na2B4O7, BiNbO4, BNbO4 in the amorphous matrix.

Compression force effect on characteristics of loratadine-succinic acid cocrystal prepared by slurry method

Loratadine belongs to second generation antihistamine (H1) drug and is known to form cocrystal with succinic acid in stoichiometry of 1:1 using slurry method. This study was conducted to further investigate cocrystal phase behavior upon compression. Sample of cocrystal phase was compressed with various compression forces into tablet form on 10 mm diameter punch. Then, the tablet was characterized for the mechanical properties and physical characterization was conducted using Differential Thermal Analysis (DTA), X-ray Powder Diffraction (XRPD), and Scanning Electron Microscope (SEM). According to tensile strength profile, cocrystal phase showed better mechanical property as it possessed higher tensile strength value compared to loratadine alone. DTA thermograms exhibited succinic acid characteristic peak alongside with endothermic peak of cocrystal phase which were compressed on higher force. It suggests that cocrystal undergoes partial dissociation to the starting components under compression. Powder diffractograms showed reduced intensity of tableted cocrystal compared to powder one for all compression force. SEM photomicrograph observed a loss of particle boundaries of cocrystal upon compression, as sintering phenomena occurred. It is predicted that compression force can influence physical characteristics of cocrystal of loratadine-succinic acid by driving dissociation and sintering phenomena.

Characterization and Dissolution Study of Micellar Curcumin-Spray Dried Powder for Oral Delivery.

IntroductionCurcumin faces a major challenge in clinical use due to its poor aqueous solubility, which affects its bioavailability over oral use. The present study was carried out to overcome this problem.MethodsAn amorphous micellar curcumin-spray dried powder (MC-SDP) with self-assembled casein was prepared by the addition of sucrose as a protectant. The dry powder of curcumin-loaded micelles was obtained by a spray-drying technique in the presence of sucrose as a protectant. The MC-SDP in the form of dry powder was further developed into tablets to investigate the dissolution profile. The physical properties of preformed powder were characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Quantitative analysis in the form of solutions was analyzed by high-performance liquid chromatography (HPLC).ResultsThe physical properties demonstrated that MC-SDP varies from dented to smoother surfaces as a function of sucrose. Furthermore, melting transitions of curcumin in the form of MC-SDP were broadened in all sample mixtures, as observed in the DTA thermogram. The XRD spectra showed that the sharp and very intense peaks of single curcumin crystalline structure no longer existed in all MC-SDP forms, indicating that the mixtures were amorphous. Moreover, a further dissolution study of MC-SDP showed a significant increase of drug dissolved with the presence of sucrose, where >80% of curcumin from MC-SDP was dissolved within 30 min.ConclusionThe study demonstrated the manufacture of micellar spray-dried powder that would contribute to the development of oral delivery of curcumin.

Fabrication of p-p type nanocomposite of NiO/Co3O4 and CuO/Co3O4 with different contents

Two nanocomposite oxides, NiO/Co3O4 and CuO/Co3O4, have been considered. These nanocomposite oxides of (1-x)NiO/xCo3O4 and (1-x)CuO/xCo3O4 with different contents of (x = 30, 50 and 70 wt%) have produced successfully using microwave irradiation. The resulted powders of pure and mixed nanoparticles (NPs) have been characterized by thermogravimetry (TGA), differential thermal analysis (DTA) and x-ray diffraction (XRD). It can be observed in TGA that the mass loss end of Co3O4, NiO and CuO NPs is at three stages until reach to the decomposition of Co(OH)2, Ni(OH)2 and Cu(OH)2, respectively. The process of mass loss is confirmed by endo- and exo- thermic peaks in DTA thermogram. The structural properties of these nanocomposites have been studied. The XRD result confirmed the formation of pure NPs as well as the nanocomposites of NiO/Co3O4 or CuO/Co3O4 NPs. Size of nanocomposites dependence on both type and concentrations of dopant have been studied. The formation of p-p type has been confirmed by structural investigations.

Thermodynamics and kinetic analysis of carbon nanofibers as nanozymes.

PurposeEvaluation of structural features, thermodynamics and kinetic properties of carbon nanofibers (CNFs) as artificial nanoscale enzymes (nanozyme).MethodsSynthesis of CNFs was done using chemical vapor deposition, and transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to provide information on the morphology, elemental monitoring and impurity assay of the CNFs. The thermal features of the CNFs were evaluated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) derivative and TGA. The calculated thermo-physical parameters were melting temperature (Tm), weight loss maximum temperature (Tmax) and enthalpy of fusion (ΔHfusion). Catalytic activity was assayed by a 4-aminoantypyrine (4-AAP)-H2O2 coupled colorimetric system by UV-visible spectroscopy.ResultsFE-SEM and TEM analysis demonstrated parallel graphitic layers and uniformity of atomic orientation and morphology. The EDX spectra approved carbon element as major signal and presence of partial Ti as impurities of CNFs during CVD process. The DTA thermogram showed the endothermic process had a maximum temperature of 82.27°C at −15.48 mV and that thermal decomposition occurred at about 200°C. The TGA-differential gravimetric analysis thermogram showed that Tmax was 700°C. The DSC heat flow curve showed a melting temperature (Tm) of 254.52°C, ΔHfusion of 3.84 J^.g−1, area under the curve of 58.58 mJ and Te (onset) and Tf (end set) temperatures of 246.60°C and 285.67°C, respectively. The peroxidase activity of the CNFs obeyed the Michaelis–Menten equation with a double-reciprocal curve and the calculated Km, Kcat and Vmax kinetic parameters.ConclusionCNFs as peroxidase nanozymes are intrinsically strong and stable nanocatalysts under difficult thermal conditions. The peroxidase activity was demonstrated, making these CNFs candidates for analytical tools under extreme conditions.

Synthesis of Optode Thin Layer using Sol Gel Hybrid of Trietoxysiloxane monomer and 3-(Trimethoxysilyl) Propilamine with Ionophore 4-(2-Pyridilazo)-1,3-Benzenadiol (PAR)

Optode (Optical sensors) is one of the modern chemical sensors in the field of analytical chemistry that has utilized of inorganic polymers. The optode based on MLCT (Metal to Ligand Charge Transfer) (or MMLL’CT, Mixing Metal-Ligand to Ligand Charge Transfer) or LMCT (Ligand to Metal Charge Transfer) phenomenons have beed generated from oktyltrietxysilane, aminopropyltrimethoxysilane and 4-(2-pyrydilazo) resorcinol (abbreviated as OTES-APTS-PAR) for Cu(II), Cr(III), Ni(II), Fe(III), Cd(II), and Zn(II) ions target. The syntheses of thin layer optode were performed by sol gel method followed by evaporation in glass substrat. The formation of 4-(2-pyrydilazo) resorcinol complexes with ions target have gained strong absorption spectras in visible region because of charge transfer phenomenons. The optical sensor of OTES-APTS-PAR was analysed thermal properties using Differential Thermal Analysis (DTA). DTA thermogram showed a glass transition peaks at a temperature of 315.5 °C. Fourier transform Infrared (FTIR) spectras have showed that the optode materials consisted NH aryl groups indicated IR absorption at 1577.7 cm-1 and also –CH aromatic at 1469.0 cm-1. Synthesized optode materials have strong broad visible absorption with the maximum wavelengths (λmax) = 405 nm and 508.5 nm, respectively. This material have excellent optical responds to several metal ions such as Cu(II), Cr(III), Ni(II), Fe(III), Cd(II), and Zn(II) that was showed from huge Δλmax and the increase of Ktotal

Some aspects of dimensionality and phase transitions of organic–inorganic hybrid perovskite (n-C14H29NH3)2ZnCl4

The differential scanning calorimetery and the differential thermal analysis thermograms were performed over a suitable wide range of temperatures on polycrystalline samples of the titled hybrid. Furthermore, the ac conductivity σ ac(ῳ,T) and the complex dielectric permittivity e *(ῳ,T) as function of temperature 120 K < T < 400 K and some selected frequencies in the range 1 kHz ≤ f ≤ 100 kHz were measured and presented. The combination of the measured parameters confirms, without any doubt, the existence of a first-order reversible solid–solid structural phase transition from intercalation to non-intercalation, at T ≈ 368 K accompanied by a sudden increase of the interlayer spacing by ≈17.5%. The analysis of our data is based on the coordination complex and the dimensionality of the central metal halide arrangements, which, in our case, is isolated square [ZnCl4]−2 tetrahedral coordination and, hence, of zero-dimensionality (0D), but stabilized in a two-dimensional structure through charge-assisted hydrogen-bonding system. The zero-dimensionality results in a large charge density and, hence, of high efficiently packed compared with other hybrids of this series which are usually crystallized in two-dimensional (2D) corner-sharing [MCl6]−2. The rule of hydrogen bonding has been considered. The odd–even effects were given.

Characterization of organic–inorganic hybrid layered perovskite and intercalated compound (n-C12H25NH3)2ZnCl4

We report on some electrical properties and solid–solid phase transitions of organic–inorganic hybrid layered halide perovskite and intercalated compound (n-C12H25NH3)2ZnCl4 which is one member of the long-chain compounds of the series (n-CnH2n+1NH3)2,(n = 8–18). The complex dielectric permittivity ϵ*(ω,T) and the ac conductivity σ (ω,T) were measured as functions of temperature 100 K < T < 390 K and frequency 5 kHz < f < 100 kHz. Moreover, the differential scanning calorimetery and the differential thermal analysis thermograms were performed. The analysis of our data confirms the existence of a structural phase transition at T ≈ (362 ± 2) K, where the compound changes its state from intercalation to non-intercalation with a drastic increase in the c-axis by about 16.4%.The behavior of the frequency-dependent conductivity follows the Jonscher universal power law: σ (ω, T) αῳs(ῳ,T). The mechanism of electrical conduction in the low-temperature phase (phase II) can be described as quantum mechanical tunneling model.

Electrical and thermal investigations of energetic material (n-C16H33NH3)2CdCl4

The thermal energy storage material, namely hexadecyl ammonium tetrachloro cadmate (n-C16H33NH3)2CdCl4, which belongs to the organic–inorganic hybrid layered compounds, was synthesized as an example of long-chain complexes of the series (n-CnH2n+1NH3)2CdCl4 (n = 8–18). The ac conductivity σac(ω, T) and the complex dielectric permittivity ε*(ω, T) were extensively investigated as a function of both frequency (5–100 kHz) and temperature (100 K < T < 400 K). The general trend of the mentioned parameters indicates that the frequency dependent conductivity behaves according to the power law, namely σac(ω, T) α ωs(ω, T) where s is the frequency exponent (0 < s < 1). Furthermore, the differential scanning calorimetric chart and the differential thermal analysis thermogram were performed. The combination of thermal and electrical parameters confirms the existence of two main structural phase transitions of the first-order type at T ≈ 360.70 K (minor) and at T ≈ 350.70 K (major) in addition to two intermediate phases with a transition temperature at T ≈ 353.75 K. (The major transition precedes the minor one.) Different conduction mechanisms and the universality of ac conduction were discussed. The nature of each detected phase transition has been explained on the basis of the most recent crystal structure and particularly the role of the N–HCl hydrogen bonding as a trigger force for phase transitions.

White light generation from Dy3+ doped tellurite glass

This paper reports on the spectral results of Dy3+ (1.0mol%) ions-doped TeO2–ZnO–PbO–PbF2–Na2O (TZPPN) glass. Raman spectrum measurements, differential thermal analysis (DTA) profiles of this rare-earth ion-doped glass were carried out. From the DTA thermogram, glass transition (Tg), crystallization (Tc) and melting (Tm) temperatures were evaluated. Direct and indirect optical band gaps were calculated based on the glasses UV absorption spectra. From the absorption spectra, Judd–Ofelt (J–O) intensity parameters, Ωk, were calculated. Using J–O intensity parameters, several radiative properties such as spontaneous transition probabilities (AR), radiative branching ratios (βR) and radiative lifetimes (τR) were determined for the excitation level 4F9/2. From the emission spectra, a strong yellow emission at 574nm (4F9/2→6H13/2) was observed and it also showed a combination of blue and red emission bands for this glass. The stimulated emission cross-section σ(λp) was also evaluated for the 4F9/2→6HJ (J=11/2, 13/2, and 15/2) transitions. This study indicates that 1mol% Dy2O3-doped tellurite glass can be considered for white light generation with the excitation of blue light (454nm).

Control of Crystallization Kinetics and Study of the Thermal, Structural and Morphological Properties of an Li2O–B2O3–Al2O3 Vitreous System

A glass matrix with nominal composition 50Li2O·45B2O3·5Al2O3 (mol%) was synthesized, and its physical properties were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and atomic force microscopy (AFM). The glass transition temperature T g, the crystallization-onset temperature T x,, the crystallization peak temperatures T c1 and T c2, and the fusion peak temperatures T m1 and T m2 were determined from at least two glass matrix phases to be approximately 382, 457, 486, 574, 761, and 787 °C, respectively, at 5 °C/min heating rate. Heat treatments at 450 °C for an increasing sequence of time intervals allowed control over the amount of crystallization. Additional information on the crystallization kinetics for the LBA glass matrix was gathered from AFM images, DTA thermograms, and XRD diffractograms. The latter technique showed that LiBO2 (ICDD-16568) and Li3AlB2O6 (ICDD-51754) phases are formed in the glass–ceramic system. Debye–Scherrer analysis of the XRD peaks revealed a competition between the evolutions of crystal phases during heat treatment. Activation energies for crystallization, obtained from theoretical models applied to the DTA data showed that the crystallization is heterogeneous. The AFM images demonstrated that this heterogeneous crystallization starts at the surface of the LBA glass matrix and identified crystal sizes in agreement with the results of the Debye–Scherrer analysis. Our study shows that thermal and structural characterization techniques can be combined with theoretical results drawn from well-tested models to offer a unified view of crystallization in a glass–ceramics system.

Dielectric permittivity, ac conductivity and phase transition in hydroxyl ammonium sulfate

The complex dielectric permittivity (ε*=ε′−jε″) and ac conductivity σ (ω, T) as a function of temperature (90–375 K) and frequency (0.4 kHz to ≈100 kHz) were measured in this work for polycrystalline samples of hydroxyl ammonium sulfate, (NH3OH)2SO4. The measured electrical parameters revealed the existence of a structural phase transition at T≈312 K, which was further confirmed by a differential thermal analysis thermogram, where a clear endothermic peak centered at ≈312 K is observed. Regarding the charge transport mechanism, it is likely that the behavior of frequency-dependent conductivity follows the universal dynamic response σ (ω,T)=A(T) ωs(T). Moreover, the temperature dependence of the frequency exponent s (0⩽s⩽1) suggests the quantum mechanical tunneling model to be the most likely one that describes the electrical transport mechanism. The data correlate with the crystal structure and the hydrogen-bonding system.

Correlation between phase structure and electrical conduction in BISNVOX system for intermediate temperature solid oxide fuel cells (IT-SOFC)

Samples of Sn4+-substituted bismuth vanadate, formulated as Bi4Sn x V2− x O11−( x /2)− δ in the composition range 0.07 ≤ x ≤ 0.30, were prepared by standard solid-state reactions. Sample characterization and the principal phase transitions (α ↔ β, β ↔ γ and γ′ ↔ γ) were investigated by FT-IR spectroscopy, X-ray powder diffraction, differential thermal analysis (DTA) and AC impedance spectroscopy. For composition x = 0.07, the α ↔ β and β ↔ γ phase transitions were observed at temperatures of 451 and 536°C, respectively. DTA thermograms and Arrhenius plots of conductivities revealed the γ′ ↔ γ phase transition at 411 and 423°C for x = 0.20 and 0.30, respectively. AC impedance plots showed that conductivity is mainly due to the grain contribution, which is evident in the enhanced short-range diffusion of oxide ion vacancy in the grains with increasing temperature. The highest ionic conductivity (5.03 × 10−5 S cm−1 at 300°C) was observed for the x = 0.17 solid solution with less pronounced thermal hysteresis.

Study on the synthesis of poly(ether‐block‐amide) copolymer based on nylon6 and poly(ethylene oxide) with various block lengths

AbstractVarious segmented block copolyetheramides based on nylon6 (N6) and poly(ethylene oxide) (PEO) with different compositions and block length of the hard and soft segments were synthesized. The effect of composition of the hard and soft segments was studied via FTIR spectroscopy based on the characteristic peak of ester group at wave number of 1730 cm−1. The average block length of the hard and soft segments in block copolymers was determined from H‐NMR analysis. Differential thermal analysis thermograms confirmed a microphase separated morphology over a broad range of temperature, leading to two separated crystalline domains. An increase in the interconnectivity of the polyamide segments controlled by chain extension, greatly improved the formation of polyamide lamellae crystals determined by X‐ray diffractometry. Atomic force microscopy images indicated different morphologies of dispersed phase in the dominant phase, which plays an important role in their performance for membrane processes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Phase transition changes in Bi 4Ce xV 2− xO 11−( x/2) −δ system

Samples of Bi 4Ce x V 2− x O 11−( x/2) −δ were prepared by the conventional solid-state reactions. The phase transition changes were studied by combining results obtained from high temperature X-ray powder diffraction (HT-XRPD), differential thermal analysis (DTA) and conductivity measurements. For x = 0.15 composition, the phase transitions; α ↔ β and β ↔ γ were clearly evident in the temperature ranges 423–450 and 533–550 °C, respectively. Although no subtle change in variation of the unit cell parameters was observed for x = 0.25 composition, the Arrhenius plot and DTA thermogram showed evidence of γ′ ↔ γ phase transition in the temperature range 450–500 °C.

Lattice parameters values and phase diagram for the Cu 2Zn 1− zFe zGeSe 4 alloy system

X-ray powder diffraction and differential thermal analysis (DTA) measurements were made on polycrystalline samples of the Cu 2Zn 1− z Fe z GeSe 4 alloy system. The diffraction patterns were used to show the equilibrium conditions and to estimate crystalline parameter values. It was found that, at room temperature, a single phase solid solution with the tetragonal stannite α structure ( I 4 ¯ 2 m ) occurs across the whole composition range. The DTA thermograms were used to construct the phase diagram of the Cu 2Zn 1− z Fe z GeSe 4 alloy system. It was confirmed that the Cu 2ZnGeSe 4 compound melts incongruently. It was observed that undercooling effects occur for samples with z > 0.9.

An automated system for investigating the thermal properties of crystallizing polymers

Equipment for investigating crystal-melt-crystal phase transitions in polymers of the polyethylene oxide group by the differential thermal analysis (DTA) method is described. An original construction is proposed which enables DTA thermograms to be recorded automatically with computer processing of the results obtained.