Differential Scanning Calorimetry Curves Research Articles

Synthesis and self-assembly properties of the first fluorescein-based hexacatenar mesogens

First series of fluorescein-based hexacatenar mesogens consisting of a central fluorescein unit and two 1,2,3-triazole dendritic wings were designed and synthesized by using the Williamson reaction and Cu-assisted alkyne-azide cycloaddition reaction. Polarized optical microscopy textures, differential scanning calorimetry curves, and X-ray diffraction (XRD) data demonstrated that all the compounds can self-assemble into hexagonal columnar mesophases. Organogel test demonstrated that these compounds could form organogel in some moderate polar solvents with irregularly winkled morphologies. Density functional theory calculation demonstrated that these mesogens adopted distorted conformation which might be the reason why narrow mesogenic temperature ranges and irregularly winkled morphologies in these compounds are observed.

Sucrose, Lactose, Thermogravimetry, and Differential Thermal Analysis: The Estimation of the Moisture Bond Types in Lactose-Containing Ingredients for Confectionery Products with Reduced Glycemic Index.

This research is aimed at conducting a comparative analysis of the dehydration process of lactose-containing ingredients and sucrose. Differential scanning calorimetry (DSC) and thermogravimetry (TG) methods were used to investigate the moisture bond types and the process of thermal degradation in native whey, dried skimmed milk, dried whole milk, dried milk whey demineralized, purified lactose, and sucrose. There were several peaks on the DSC and TG curves for lactose-containing ingredients. They determine the loss of the physically absorbed water on surfaces, physically occluded water and hydrate-forming water (up to 180°C), anomerization of lactose (160-220°C), and melting followed by decomposition (above 230°C). The multiple peaks on the dDSC curves from 135 to 170°C indicate the course of the Maillard reaction in the mix with proteins. For the native whey, the amount of chemically bound water was 56.11 ± 1%; for the dried whole milk, it was 59.86 ± 1%; for the milk whey demineralized, it was 64.56 ± 1%; and for the dried skimmed milk, it was67.17 ± 1%. The results are presented as mean values ± SD (n = 3) and were considered statistically significant when P < 0.05. The similar to some extent form of the DSC and TG curves to lactose-containing ingredients and granulated sugar confirms the possibility of using them as the component of bakery and confectionery product formulas to reduce the glycemic index and improve organoleptic properties of products as well as correct their mineral compositions. Considering the constant changing of technologies for obtaining various dairy ingredients as well as the occurrence of their new kinds, such studies contribute to the expansion of existing knowledge and reference data.

Obtaining and characterisation of thermoelectric Mg2Si compound via wet and dry mechanical alloying and spark plasma sintering

Mg2Si thermoelectric compound was obtained by dry and wet (isohexane and benzene) mechanical alloying route. The Mg2Si compound was characterised by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), laser particle size analysis and thermoelectric measurements. After 14 h of milling, the complete reaction of the elements is achieved by both routes. The powders particle size distribution obtained after 14 h of dry or wet milling (using benzene) reveals a bimodal curve. The wet milling moves the particle size distribution towards smaller particle sizes. The SEM analysis confirms the results of particles size analysis. DSC analyses performed for samples milled up to 14 h present stress relief and recrystallisation thermal events. For the benzene wet-milled sample, the DSC curve shows an additional thermal event at 350 °C, associated with benzene removal. Thermoelectric properties were determined on spark plasma sintered compacts. The milling process with benzene leads to a higher value of Seebeck coefficient (≈580 μV/K). The electrical conductivity is low at room temperature and increases exponentially with temperature.

A styrylpyrene‐containing liquid crystal polymer for photoinduced crosslinking

AbstractPhotoresponsive polymers have attracted increasing attention. Herein, we designed and synthesized a photoresponsive liquid crystal polymer (LCP). The LCP was prepared through the copolymerization of a styrylpyrene‐containing photoresponsive monomer and a monomer containing mesogen 4‐cyanophenyl benzoate. Gel permeation chromatography (GPC) curve and 1H nuclear magnetic resonance (1H NMR) spectrum confirmed that the LCP was successfully synthesized. Thermogravimetric analysis and differential scanning calorimetry curves showed that the LCP had high thermal stability, with a decomposition temperature at 5% weight loss of 305°C, and Tg and Ti of 46 and 128°C, respectively. Polarized optical microscopy studies suggested that thermal annealing promoted the orientation of the LCP films. Model compounds containing styrylpyrene units showed photo‐controlled dimerization. Furthermore, the dimerization of the styrylpyrene units could control the crosslinking densities in the LCP, thereby regulating the network structures and properties. These properties demonstrate that the LCP is a promising photoresponsive material.

Study of correlations between glass-transition temperature and local structure of Ge-As-Se, Ge-As-Se-S chalcogenide glasses

ABSTRACT 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 = 2.4), Ge25As10S25Se40 ( = 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.

Discrimination of Selected Cold-Pressed and Refined Oils by Untargeted Profiling of Phase Transition Curves of Differential Scanning Calorimetry

Discrimination of Selected Cold-Pressed and Refined Oils by Untargeted Profiling of Phase Transition Curves of Differential Scanning Calorimetry

Synthesis of Hexagonal Nanophases in the La2O3–MO3 (M = Mo, W) Systems

We report a study of nanophases in the La2O3–MO3 (M = Mo, W) systems, which are known to contain a variety of good oxygen-ion and proton conductors. Mechanically activated La2O3 + MO3 (M = Mo, W) mixtures and the final ceramics have been characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) with Rietveld refinement. The microstructure of the materials has been examined by scanning electron microscopy (SEM), and their conductivity in dry and wet air has been determined using impedance spectroscopy. In both systems, the formation of hexagonal La15M8.5O48 (phase II, 5H polytype) (M = Mo, W) nanophases is observed for the composition 1:1, with exothermic peaks in the DSC curve in the range ~480–520 °C for La15Mo8.5O48 and ~685–760 °C for La15W8.5O48, respectively. The crystallite size of the nanocrystalline tungstates is ~40 nm, and that of the nanocrystalline molybdates is ~50 nm. At higher temperatures (~630–690 and ~1000 °C), we observe irreversible reconstructive phase transitions of hexagonal La15Mo8.5O48 to tetragonal γ-La2MoO6 and of hexagonal La15W8.5O48 to orthorhombic β-La2WO6. We compare the temperature dependences of conductivity for nanoparticulate and microcrystalline hexagonal phases and high-temperature phases differing in density. Above 600 °C, oxygen ion conduction prevails in the coarse-grained La18W10O57 (phase I, 6H polytype) ceramic. Low-density La15W8.5O48 and La15Mo8.5O48 (phase II, 5H polytype) nanoceramics exhibit predominantly electron conduction with an activation energy of 1.36 and 1.35 eV, respectively, in dry air.

Analysis of the As-Cast Microstructure and Properties of the Ni-Based Superalloy MAR-M247® Produced Via Directional Solidification

The presented research investigates MAR-M247® Ni-based superalloy castings produced via directional solidification at various mold preheating temperatures (1510, 1566 °C) and withdrawal rates (3.4, 5.0 mm/min). Casting analyses were carried out via thermodynamic simulations, differential scanning calorimetry (DSC), X-ray diffraction (XRD), light microscopy (LM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), scanning transmission electron microscopy (STEM), and tensile testing. On DSC curve, four effects have been registered during cooling: liquidus (1337 °C), formation of eutectic γ − γ′ (1315 °C), precipitation of Ni7(Hf, Zr)2 (1244 °C), and M5B3 borides (1201 °C). The castings’ primary and secondary dendrite arm spacing decreases with increasing withdrawal rates for both shell mold temperatures. The dendritic regions of the castings are characterized by a relatively homogenous microstructure, consisting of γ′ precipitates surrounded by the matrix, with a mean size in the range of 0.437 to 0.481 μm, depending on the casting parameters. In the interdendritic spaces, γ − γ′ eutectic, MC carbides, M5B3, Ni7(Hf, Zr)2, and M3C2 phases were identified. The ultimate tensile strength of the produced castings was in the range of 970 to 1088 MPa.

Effect of Drug-Polymer Interaction in Amorphous Solid Dispersion on the Physical Stability and Dissolution of Drugs: The Case of Alpha-Mangostin.

Improving drug solubility is necessary for formulations of poorly water-soluble drugs, especially for oral administration. Amorphous solid dispersions (ASDs) are widely used in the pharmaceutical industry to improve the physical stability and solubility of drugs. Therefore, this study aims to characterize interaction between a drug and polymer in ASD, as well as evaluate the impact on the physical stability and dissolution of alpha-mangostin (AM). AM was used as a model of a poorly water-soluble drug, while polyvinylpyrrolidone (PVP) and eudragit were used as polymers. The amorphization of AM-eudragit and AM-PVP was confirmed as having a halo pattern with powder X-ray diffraction measurements and the absence of an AM melting peak in the differential scanning calorimetry (DSC) curve. The solubility of amorphous AM increased in the presence of either eudragit or PVP due to amorphization and interactions of AM-polymer. Furthermore, FT-IR spectroscopy and in silico studies revealed hydrogen bond interactions between the carbonyl group of AM and the proton of eudragit as well as PVP. AM-eudragit with a ratio of 1:1 recrystallized after 7 days of storage at 25 °C and 90% RH, while the AM-PVP 1:4 and 1:10 samples retained the X-ray halo patterns, even under humid conditions. In a dissolution test, the presence of polymer in ASD significantly improved the dissolution profile due to the intermolecular interaction of AM-polymer. AM-eudragit 1:4 maintained AM supersaturation for a longer time compared to the 1:1 sample. However, a high supersaturation was not achieved in AM-PVP 1:10 due to the formation of large agglomerations, leading to a slow dissolution rate. Based on the results, interaction of AM-polymer in ASD can significantly improve the pharmaceutical properties of AM including the physical stability and dissolution.

Doping Silica Fume Enhances the Mechanical Strength of Slag/Fly Ash Geopolymer Paste under Frost Attack

Benign design of alkali-activated slag/FA geopolymer paste has attracted increasing attention for optimizing its service performance. Therefore, the replacement of fly ash (FA) with 10 wt% silica fume (SF) is investigated by mechanical strength after freeze–thawing cycles and microstructure characterization. The results show that an appropriate dosage (30 wt%) of slag is necessary to prepare heat-free curing alkali-activated slag/FA geopolymer paste with excellent mechanical performance. The SF/slag/FA (SF:slag:FA = 10:30:60, wt%) geopolymer paste exerts an enhanced compressive and flexural strength of 95.2 and 3.2 MPa, respectively. Meanwhile, the doped 10 wt% SF facilitates the propagation of (N, C)-A-S-H chains, rather than the formation of C-S-H gels. It is evidenced by the absent exothermic peak at about 861 °C from the differential scanning calorimetry (DSC) curves. The pores volume and tortuosity also rise for the pore diameter &lt; 20 nm from mercury intrusion porosimeter (MIP) results, corresponding to an improved freezing–thawing resistance with the residual compressive strength of 52.8 MPa and the weight loss of 10.5% after 300 freeze–thawing cycles. It explores a cost-effective and benign facile approach to designing heat-free curing alkali-activated slag/FA geopolymer paste with good freezing–thawing resistance.

A novel phase change material matrix: Study on phase transition behavior of bishexadecyl maleate

In this work, an organic phase change material-Bishexadecyl maleate was prepared by direct esterification of maleic anhydride (MA) and hexadecanol (HD). Then, in order to improve the crystalline phase of bishexadecyl maleate (MAHD), the synthesized MAHD was recrystallized with ethanol to prepare ethanol-bishexadecyl maleate (MAHD(E)). Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and x-ray diffraction (XRD) were used to characterize the chemical and crystalline structures of MAHD and MAHD(E). Polarizing Light Microscopy (POM) for observation of phase transition behavior of MAHD/MAHD(E). Differential scanning calorimetry (DSC), Variable temperature Fourier transform infrared spectroscopy (VT-FTIR), and thermo gravimetric analysis (TG) characterize the thermal properties and thermal stability of MAHD/MAHD(E). The results display that MAHD/MAHD(E) have the same chemical structure, and no chemical change occurs within the phase transition temperature, but the crystallinity of MAHD(E) has increased. Compared with HD, the crystallization temperature and melting temperature of MAHD/MAHD(E) is significantly reduced, which effectively expands the application range of HD. POM was observed to have a melting-recrystallization-melting behavior during the heating of MAHD/MAHD(E). This behavior was shown in the DSC curve as an unusual endothermic-exothermic-endothermic curve. After 100 thermal cycles, both MAHD and MAHD(E) exhibit good cycling stability. TG exhibits that the thermal stability of MAHD/MAHD(E) has been dramatically improved compared to HD, it has high application potential in phase change and energy storage. Therefore, MAHD/MAHD(E) is expected to be a substrate for new phase change materials, while the CC in the molecular chain provides potential reactivity with significant potential applications in the field of phase change energy storage.

Research on curing kinetics of multiaxial warp‐knitted composites

AbstractIn this paper, the differential scanning calorimetry (DSC) was used to test the crosslinking reaction system between epoxy resin and curing agent, and the curing kinetic model of the resin system was established by means of phenomenal model. The optimal curing process was obtained based on DSC curve. The quadriaxial warp‐knitted composite specimens were prepared by vacuum‐assisted resin infusion (VARI). The effects of curing process on mechanism properties and failure mechanism of the composite specimens were studied experimentally. Results show that the cross‐linking reaction between epoxy resin and curing agent agrees with the autocatalytic reaction model and the curing kinetics model could be used to characterize the curing process of the matrix. The optimum curing process could be used to improve the interface properties between the matrix and the fiber, and the crack progress will be inhibited as the specimen bearing the external force, and the mechanical properties of the specimen is also improved significantly. Result could provide a theoretical basis for the study of curing kinetics of epoxy resin, the exploration of curing process of composite materials and improve the strength of composits.

Effect of sodium lauroyl sarcosinate on the thermal, optical and moisture absorption properties of polyvinylpyrrolidone film

In the present study, polyvinylpyrrolidone films containing amino acid-based surfactant, namely, sodium lauroyl sarcosinate (SLS), were prepared by casting method. The obtained films (PVP/SLS) were characterized by means of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), optical properties, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and moisture absorption (MA). ATR-FTIR spectra of PVP/SLS films showed the main bands of PVP. The opacity of PVP films increased with the addition of SLS. Furthermore, moisture absorption of PVP/SLS films were higher than the pristine PVP film. TGA curves displayed that the thermal stability of PVP film decreased after the incorporation of SLS. DSC curves indicated that SLS can be used as plasticizer for PVP.

Fold Surfaces of Polymer Crystals Are Nucleation Sites: The Link between Polymer Decoration, Secondary Crystallization, and the Rigid Amorphous Fraction (RAF)

The fold surfaces of polymer crystals may become suitable nucleating sites for uncrystallized material left over during the primary crystallization process. This “nucleation by the folds surface” (NFS) ability is highlighted in the so-called polymer decoration technique in which vapors of polyethylene condense and crystallize on a cold fold surface substrate to form edge-on lamellae that reveal the folds and loops orientations in different growth sectors. In bulk materials, the primary crystallization leaves confined and uncrystallized material between lamellae. NFS, based on epitaxy-type interactions, is expected to take place in these confined and supercooled melt fractions before “true” homogeneous nucleation sets in. The insights provided help elucidate the structural features of the interlamellar layers of crystalline polymers, which overcomes the limits of global, indirect investigation techniques (e.g., differential scanning calorimetry (DSC)) used in attempts to analyze their structure in situ. The interlamellar layer is known to be divided into a rigid amorphous fraction (RAF) located in contact with the fold surfaces and a mobile amorphous fraction (MAF) at its center. The nature of the RAF─amorphous but rigid above its Tg, or crystalline─is still debated. The NFS provides a structural identity for the RAF that associates conformation disorder with stem orientation: the RAF is actually a “condis oriented” fraction. On heating, the small endotherm observed in DSC curves corresponds to its isotropization. The RAF is also a protonucleus for secondary crystallization and induces the growth of edge-on lamellae on top and in the interlamellar spaces of the primary crystals. As such, the RAF has also a layered lamellar structure. Polymer decoration, the “condis oriented” RAF, and the specific edge-on lamellar secondary crystallization are manifestations of the nucleation by the fold surfaces.

Thermal behavior of borax, Na2B4O5(OH)4·8H2O

Abstract Globally, borax is one of the most important borate minerals, both industrially and from a technological viewpoint. Despite its importance, there have been only a few reports on the structural changes of borax upon heating. In this study, we have investigated the thermal behavior and structural characteristics of borax using thermal analysis, in situ high-temperature synchrotron X-ray diffraction, in situ variable-temperature single-crystal X-ray diffraction, and quantum chemical calculations. Differential scanning calorimetry (DSC) curve showed a large endothermic peak at 349 K corresponding to the dehydration reaction of borax. X-ray diffraction (XRD) pattern remained almost unchanged up to 353 K. Above 363 K, the XRD peaks gradually became less intense until they disappeared at 403 K. The unit-cell volume continuously increased with increasing temperature and became constant just before its phase transition to tincalconite. The volumetric thermal expansion coefficient between 113 and 323 K was 7.84 × 10–5 K–1. The a and c lattice parameters exhibited a slight increase trend with increasing temperature, whereas the b lattice parameter increased significantly. Therefore, the thermal expansibilities followed the order b/b0 &amp;gt;&amp;gt; c/c0 &amp;gt; a/a0. The increasing b lattice parameter was closely related to the elongation of the O4···H7B hydrogen-bond interaction along the b-axis. Na-O bond lengths were isotropically expanded with increasing temperature, whereas the B-O bond lengths and angles remained unchanged even after the phase transition to tincalconite. Molecular orbital calculations revealed that an electron cloud shared by two borate tetrahedra led to the formation of a large electron cloud distribution over the B4O5(OH)4 cluster. The intramolecular interactions with substantial covalent character made the cluster quite rigid. The existence of borate minerals containing the B4O5(OH)4 clusters in their structure evidenced the presence of moderately acidic or alkaline water, wherein the borate minerals grew via the incorporation of B4O5(OH)4 clusters. Our results indicate that the connection geometry of the fundamental building block consisting of Bφ3 triangles and Bφ4 tetrahedra (φ: O2–, OH–) can potentially be used as a palaeoenvironmental indicator.

Thermal Stability of Lead-Free Transparent Cloisonné Glazes

Glazes of (70 − x) ZnO-30 B2O3-x Bi2O3 with different Bi2O3 contents were prepared by the conventional melt quench technique. Differential scanning calorimetry (DSC) curves were obtained to determine the glass transition temperature (Tg) and crystallization temperature (Tc) of the glazes. The activation energy of the glass transition (Eg) and crystallization (Ec) were calculated using the Moynihan and Kissinger models, respectively. The glass transition temperature (Tg) decreased linearly with increasing Bi2O3 content. This is because the larger Bi3+ ions reduced network connectivity and opened up the structure. The Tg increased gradually with increasing heating rate (β). This is because the higher heating rate provided more energy for the glass to transition to the liquid state. The activation energy of the glass transition (Eg) decreased with increasing Bi2O3 content. This indicates that the glass-forming ability of the system increased with increasing Bi2O3 content. The energy corresponding to the amorphous-to-crystalline transformation during nucleation and crystal growth (Ec) increased with increasing Bi content to about 30%, and then decreased above 40%. This suggests that higher Ec values have an advantage in preventing crystallization in the crystallization danger region. It can be seen that the addition of Bi2O3 in (70 − x) ZnO-30 B2O3-x Bi2O3 glazes affects the density and distribution of oxygen atoms in the glass structure. It can also be seen that the increased Bi content promotes the formation of Bi-O-Bi bonds, which act as network modifiers to reduce the number of non-cross-linked oxygen atoms and increase network connectivity.

Coupled and Simultaneous Thermal Analysis Techniques in the Study of Pharmaceuticals.

Reliable interpretation of the changes occurring in the samples during their heating is ensured by using more than one measurement technique. This is related to the necessity of eliminating the uncertainty resulting from the interpretation of data obtained by two or more single techniques based on the study of several samples analyzed at different times. Accordingly, the purpose of this paper is to briefly characterize thermal analysis techniques coupled to non-thermal techniques, most often spectroscopic or chromatographic. The design of coupled thermogravimetry (TG) with Fourier transform infrared spectroscopy (FTIR), TG with mass spectrometry (MS) and TG with gas chromatography/mass spectrometry (GC/MS) systems and the principles of measurement are discussed. Using medicinal substances as examples, the key importance of coupled techniques in pharmaceutical technology is pointed out. They make it possible not only to know precisely the behavior of medicinal substances during heating and to identify volatile degradation products, but also to determine the mechanism of thermal decomposition. The data obtained make it possible to predict the behavior of medicinal substances during the manufacture of pharmaceutical preparations and determine their shelf life and storage conditions. Additionally, characterized are design solutions that support the interpretation of differential scanning calorimetry (DSC) curves based on observation of the samples during heating or based on simultaneous registration of FTIR spectra and X-ray diffractograms (XRD). This is important because DSC is an inherently non-specific technique. For this reason, individual phase transitions cannot be distinguished from each other based on DSC curves, and supporting techniques are required to interpret them correctly.

Direct comparison of surface crystal growth kinetics in chalcogenide glass measured by microscopy and DSC

AbstractSurface crystallization in fine powder Se70Te30 chalcogenide glass was studied by differential scanning calorimetry (DSC) and optical microscopy. A complex kinetic analysis of these experimental data reveals that the contracting sphere mechanism (R3 model) is the rate determining step of crystal growth, and the conventional Johnson–Mehl–Avrami–Kolmogorov model cannot be used in this case. Moreover, it is clearly shown that the particle size distribution should be considered in crystallization studies. Actually, when the particle size effect is taken into account, the simulated DSC curves for the R3 model agree very well with the experimental data over the entire temperature range. The crystallization kinetics determined from the nonisothermal DSC data are consistent with previously reported isothermal crystallization data for the same powder fraction. The crystal growth rate calculated from isothermal and nonisothermal DSC data agrees very well with the microscopically measured surface and bulk crystal growth rate.

Thermal and combustion characteristics of honge, jatropha, and honge‐jatropha mixed biodiesels

AbstractThermal characteristics of biodiesels are useful in system design, modeling, and operation. Such investigations are extensively being carried out in combustors, engine, and process industries. This article examines the thermal characteristics of jatropha (Jatropha curcas), honge (Pongamia pinnata), and their equal mixing from thermogravitometry and differential scanning calorimetry (TG‐DSC) curves for the specific 10°C/min heating rate under atmospheric air. Fuel properties are measured following ASTM standards to compare with diesel properties. Each experiment was repeated three times, and the properties showed insignificant scatter. The average properties of the repeated tests are presented. Two phases of decomposition were observed for diesel, whereas three (viz., devolatilization of aqueous fractions, combustion of methyl esters, and combustion of carbonaceous residues) in biodiesels. Jatropha oil methyl ester (JOME) is thermally stable compared to honge oil methyl ester (HOME). Mixed biodiesel (JOME+HOME) is prone to oxidation due to the high content of oleic and linoleic acids. Recorded onset and offset temperatures of mixed biodiesel are low compared to pure biodiesel. Mixed biodiesel exhibited high volatility resembling diesel characteristics. It exhibited an enthalpy of 240 J/g, whereas the enthalpy of diesel, jatropha, and honge exhibited enthalpies of 130, 321, and 570 J/g, respectively. The combustion index (S) of diesel, jatropha, honge, and mixed biodiesel was 41.6, 82.8, 77.74, and 64.6, respectively. Mixed biodiesel reduces the intensity of combustion (Hf), promising better combustion characteristics. Thus, mixed biodiesel shows the potential of an efficient alternative energy source.

Preparation, Characterization, Release and Antibacterial Properties of Cinnamon Essential Oil Microcapsules

In this study, the antibacterial microcapsules of cinnamon essential oil (CEO) were prepared by complex condensation method. Chitosan quaternary ammonium salt (HACC) combined with gum arabic (GA) was selected as the coated wall material. The optimal preparation conditions of CEO microcapsules (CMSs) were determined by response surface methodology (RSM): the core/wall mass ratio was 1:1, the pH value was 4.5, the mass concentration of CaCl2 was 0.7 wt% and the actual encapsulation rate of microcapsules was 90.72% ± 1.89%. The morphology, size, composition and thermal stability of the prepared CMSs were characterized by scanning electron microscopy (SEM), laser particle size analysis (LPDA), Fourier transform infrared spectroscopy (FTIR), thermogravimetric differential thermal analysis (TG–DTA) and differential scanning calorimetry (DSC). In addition, the in vitro drug release and antibacterial properties of CMS were also evaluated. The results showed that CMS was spherical, with an average particle size of 6.31 µm. The obvious weight loss occurred at 269 °C and the corresponding DSC curve had an obvious exothermic peak at 265.5 °C, which had an increase compared with CEO. Microcapsules can achieve slow release, with the lowest and highest release rates being 19.66% and 49.79%, within 30 days. The drug release curve of essential oil of microcapsules was consistent with a first-order release model named ExpDec1. Based on the above research results, the CMS can effectively improve the stability of essential oil, achieve slow release and prolong the antibacterial effect, indicating its potential applications in food, cosmetics and medicine.