Differential Scanning Caborimetry Research Articles

Elucidating the influence of metal oxides on pyrolytic behaviors and combustion performance of green gas generating agent 5-Aminotetrazole/Sr(NO3)2

5-Aminotetrazole/strontium nitrate (5AT/Sr(NO3)2) propellant is widely utilized as green gas generating agent in fire extinguishers. To enhance the combustion rate and modify the gas production performance of 5AT/Sr(NO3)2 propellant, this study investigated the catalytic effects of adding different metal oxides (Bi2O3, PbO, TiO2, and CoO) on its pyrolysis and combustion process. The pyrolysis behavior, pyrolysis mechanism and combustion performance of 5AT/Sr(NO3)2 propellants were studied by using thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning caborimetry (DSC), mass spectrometry (MS), fourier transform infrared spectroscopy (FTIR) analysis and closed bomb vessel tests. Experimental results indicated that Bi2O3 and PbO predominantly facilitated the thermal decomposition process of 5AT, while TiO2 and CoO primarily catalyzed the thermal decomposition of Sr(NO3)2. Certainly, the addition of metal oxides as catalysts to 5AT/Sr(NO3)2 propellant holds significant potential for improving the application as a gas generating agents in fire extinguishers.

Effect of Ca dopant on magnetic and magnetodielectric properties of Y3Fe5O12

A series of Ca-doped yttrium iron garnet ceramics (Y3-xCaxFe5O12 (x = 0, 0.05, 0.1, 0.15, 0.2)) were prepared by the solid state method. The structure, morphology, valence fluctuation, thermal analysis, magnetization, magnetodielectric and Mössbauer spectrum of Y3-xCaxFe5O12 ceramics were systematically studied. All of the samples crystalized as single phase of garnet structure with the grain sizes of 2–3 μm. The temperature dependent percentage weight loss and heat flow were investigated by thermogravimetric (TG) and differential scanning caborimetry (DSC). The structure of Y3-xCaxFe5O12 ceramics was studied by XRD, Raman and Infrared (IR) spectra. The results indicated that Ca2+ substitution leads to lattice expansion and presence of Ca–O octahedron, which causes the concentration of Fe2+ decrease and Fe4+ increase. As a result, the saturation magnetization first increases and then decreases with the increase of Ca concentration. A six lines asymmetry of magnetic components were observed in Mössbauer spectrum, which was fitted by two hyperfine magnetic sextets corresponding to tetrahedral and octahedral sites, respectively. With the increase of Ca concentration, the intrinsic magnetodielectric (MD) effect disappears completely due to the dramatic decrease of Fe2+-Fe3+ dipoles. Fe3+-Fe4+ dipoles do not contribute to the MD properties of Y3-xCaxFe5O12 ceramics due to the lack of the defects such as electrons or holes being used as media.

Near-infrared quantum cutting platform in transparent oxyfluoride glass–ceramics for solar sells

This study investigated the photoluminescent properties of Er3+/Yb3+ and Ce3+/Er3+/Yb3+ -doped oxyfluoride glass–ceramics. The transparent oxyfluoride glass–ceramics were prepared by high temperature melting method and subsequent heat treatment. Effect of heat treatment schedules on crystallization behavior and microstructure were analyzed by differential scanning caborimetry, X-ray diffraction, infrared spectrum and scanning electron microscopy. The structure of fluoride nanocrystals indicates that the main phase in the oxyfluoride glass ceramics is CaF2 nanocrystal sized at 25nm at the optimal crystallization temperature 600°C for 8h. The Ce3+/Er3+/Yb3+ tri-doped oxyfluoride glass–ceramics shows wider absorption bands comparing with Er3+/Yb3+ co-doped oxyfluoride glass–ceramics. The effective energy transfer processes from Ce3+ to Yb3+, Er3+ to Yb3+ and Ce3+ to Er3+ all can take place simultaneously. The idea of using Ce3+ together with Er3+ and Yb3+ ions could enhance the ultraviolet visible light absorption and the 960–1040nm near infrared emission. Results of this study demonstrate that the tri-activator Ce3+/Er3+/Yb3+ materials are promising for practical application to enhance the energy efficiency of crystalline Si solar cells via spectrum modification.

Preparation and up-conversion characterization of CaF2:Yb3+, Ho3+/BaF2:Yb3+, Ho3+ co-doped glasses and glass–ceramics

Oxyfluoride tellurite glasses with compositions of TeO2–Al2O3–CaF2/BaF2–NaF–YbF3–xHoF3 (x=0.1, 0.3, 0.5, 1.0, 1.5, 2.0mol%) were prepared by conventional melt-quenching method. Effect of heat-treatment schedules on crystallization behavior and microstructure were analyzed by differential scanning caborimetry, X-ray diffraction, infrared spectra and scanning electron microscopy. Cubic CaF2 and BaF2 nano-crystal phases were formed by controlling heat-treatment schedules. Up-conversion emission properties and mechanism of Yb3+ and Ho3+ ions in glasses and glass–ceramics were investigated. The green and red up-conversion emissions were observed under 980nm LD excitation. Up-conversion luminescence intensity in glasses was obvious higher than that in glass–ceramics. And there existed concentration quenching effect among Ho3+ ions resulted from cross-relaxation.

Internal Structure Changes of Nylon 12 in Balloon Forming Process

Medical balloon has been widely used for the treatment of cardiovascular and cerebrovascular diseases, but the theoretical studies in processing process of medical balloon have reported less in the domestic. This paper briefly introduce in the processing process of medical balloon from the nylon 12 as raw materials, through control the conditions of primary molding, secondary molding and final molding process of the operating, then investigate the stress-strain curve of each sample in the molding process by Hydraulic Pressure Tester. And further investigated the material's lattice parameter, melting point, crystallinity and the structure changes of internal groups during the molding process separately by X-ray diffraction (XRD), differential scanning caborimetry (DSC) and infrared transmission spectroscopy (FTIR) experiment. It could be founded that the acting force between the polymeric chain of nylon 12 reduced at first, so that the material has better plasticity and machinability for forming, and then the acting force of polymer chain is enhanced, so that the final balloon has higher strength and stability were discovered during the balloon forming process.

Synthesis and Characterization of a New Kind of Flame-Retardant Thermotropic Liquid Crystal Containing 1,8-octanediamine Softsegment

Using the diacetate of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphorin-10-oxide, p-acetoxy-benzoic acid, terephthalic acid and the condensation product of terephthalic acid and 1,8-octanediamine as monomers, a new kind of flame-retardant thermotropic liquid crystal copolyester containing phosphorus, nitrogen and 1,8-octanediamine softsegment (PN-TLCP) was synthesized by melt condensation polymerization. The structure and properties of PN-TLCP, such as molecular structure, texture of liquid crystal and thermal properties were investigated by fourier transform infrared spectra, X-ray diffraction, hot-stage polarizing optical microscope, differential scanning caborimetry and thermal gravimetric analysis. The results showed that the texture of PN-TLCP was the type of nematic liquid crystalline within the bounds of 180∼330°C, and its melting point was 148°C. It was proved that there were P-O and P=O stretching vibration absorption bands and C-N and C=N mixed absorption bands in Fourier transform infrared spectra of PN-TLCP. Also, the thermal stability and the char yield of PN-TLCP are favorable.

Dissolution of Naproxen in Mesoporous Molecular Sieve MCM-41

The poorly-water soluble drug naproxen(NAP) was loaded on modified and unmodified mesoporous molecular sieves MCM-41.The drug-loaded samples were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),differential scanning caborimetry(DSC),scanning electron microscopy(SEM) analysis,transmission electron microscopy(TEM) analysis,nitrogen adsorption/desorption isotherms,respectively.The results showed that the hexagonal mesoporous structure was still remained after loading with drug molecules,which were entrapped inside the mesopores.The dissolution rate of NAP released from mesoporous molecular sieves MCM-41 was faster compared with the dissolution rate of pure NAP.In simulated intestinal fluid,the MCM-41-NAP and MCM-41-NH2-NAP exhibited 70% mass fraction burst release within 60 min.Remarkably,the dissolution rate of NAP released from all mesoporous materials is faster compared with the dissolution rate of pure NAP.At the same time,the release rate of NAP from the functionalized mesoporous materials was effectively controlled compared with that of the unmodified materials.

Study on the Structure and Properties of Novel Impact Resistance Fabric Composites

In this study, the Kevlar fabric composites were prepared by shear thickening compound to get the high impact resistance. The characterizations of the produced polyborondimethylsioxane (PBDMS) have been obtained by Differential Scanning Caborimetry(DSC), Thermal Gravimetric Analysis(TGA), etc. The controlled stress rheometer was used to characterize the rheological property. Meanwhile the ballistic and stab tests of this Kevlar composite were investigated and found to exhibit significant improvement. The mechanism of energy absorbing was tentatively discussed. It showed that these novel energy absorbing materials could be potentially used to fabricate flexible body armors and high-grade sports accessories with good perspective.

Transparent Oxyfluoride Glass-Ceramics Containing CaF<sub>2</sub> Nano-Crystalline Phase

Transparent oxyfluoride tellurite glass with the composition of TeO2-SiO2-AlF3-CaO-KF system were prepared by conventional melting and annealing technique, and the transparent oxyfluoride glass-ceramics containing CaF2 nano-crystallines were obtained by controlled heat-treatment. The effect of heat-treatment schedules on the crystallization behavior and the microstructure of the glass-ceramics were analyzed by differential scanning caborimetry (DSC) analysis, X-ray diffraction (XRD) analysis, infrared (IR) spectrum and scanning electron microscopy (SEM). The sole CaF2 crystalline phase was confirmed by XRD, the spherical CaF2 nano-crystallines at about 20~100nm embed homogeneously among the glassy matrix after crystallization by SEM observation. The size of CaF2 grains grew with the increase of crystallization temperature and holding time. Te and Si atoms existed in [TeO3] and [SiO4] forms. Part of Al atoms existed in the form of [AlO4] and formed network together with [SiO4] tetrahedron. The other Al atoms acted as modifiers in the form of [AlO6]. The transmittance of glass-ceramics can reach 85% in visible light and 90% in infrared waveband. The novel transparent oxyfluoride tellurite glass-ceramics are excellent matrix materials in up-conversion luminescence field.

Research on Properties of Amorphous Cr-C Alloy Coating in Crystallization Evolution

Amorphous Cr–C alloy coating was prepared by electrodepositing. The microhardness of the coating was tested after annealing from 100°C to 800°C and the crystallization evolution was studied by the analysis of X-ray diffraction (XRD) and differential scanning caborimetry (DSC). The results showed that the crystallization evolution of the coating began at 300°C and finished around 450°C, and intermetallic compound Cr7C3and Cr23C6appeared when heat treatment temperature reached around 600°C. The microhardness, corrosion resistance as well as the adhesion of the coating all increased first with the temperature and then dropped until it attained the proper values. The microhardness reached the maximum of 1610HV0.025at 600°C. While the corrosion resistance and the adhesion force attained the peak value at about 400°C.

Preparation and Crystallization of Nd<sub>2</sub>Fe<sub>14</sub>B/<i>α</i>-Fe Permanent Magnetic Nanomaterial by Mechanical Milling

Nanocomposite Nd2Fe14B/α-Fe magnetic material had been prepared by mechanical milling Nd8Fe86B6 as-cast alloy in Argon and subsequent crystallization. Effect of mechanical milling and crystallization technique on its structure had been investigated by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Caborimetry (DSC), etc. The crystallization behavior of amorphous Nd8Fe86B6 powders had also been studied. The results showed that Nd2Fe14B grain refined quickly and the grain size of α-Fe decreased while extending milling time. After milling for 25h, grain size of α-Fe reached a constant (about 7nm). Higher temperature of complete crystallization as well as finer and more homogeneous grains resulted from longer milling time. During the process of crystallization, the total amorphous phase crystallized into four phases firstly, i.e., Nd4.4Fe77.8B17.8, Nd1.1Fe4B4, Nd2Fe14B and α-Fe. At higher temperature, final mixture was consisted of Nd2Fe14B, α-Fe and a few undecomposed Nd1.1Fe4B4 phase.

Improved understanding of in-situ polymerization of zinc dimethacrylate: The solid bulk polymerization

In this work, we chose the HNBR/ZDMA composite as a system reinforced by the metal salt of unsaturated carboxylic acids (MSUCA) and systematically studied the evolution of the in-situ polymerization of ZDMA particles during peroxide curing. Differential scanning caborimetry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and polarization microscopy were used in this study. The microstructure of the remaining micron-sized dispersions in the cured HNBR/ZDMA was verified for the first time, and a new mechanism for in-situ polymerization of ZDMA, i.e., the solid bulk polymerization initialized onto the surface of ZDMA particles, was put forward. Moreover, we discussed how the micron-sized dispersions generated by the solid bulk polymerization of undiffused ZDMA particles affected the crosslink structures and mechanical properties of the vulcanizate.

Synthesis and spectroscopic properties of Er 3+-doped CaF 2 nanocrystals in transparent oxyfluoride tellurite glass–ceramics

Transparent glass–ceramics in TeO 2–SiO 2–AlF 3–CaO–NaF–ErF 3 system were prepared. Effect of heat-treatment schedules on crystallization behavior and microstructure were analyzed by differential scanning caborimetry, X-ray diffraction, infrared spectrum and scanning electron microscopy. The sole CaF 2 nanocrystal phase was confirmed, grains were spherical and distributed uniformly. Te and Si atoms existed in [TeO 3] and [SiO 4] forms. The full width at half maximum at 1533 nm emission increased from 39.16 nm to 43.37 nm after crystallization. Er 3+ ions were incorporated into CaF 2 nanocrystals with low phonon energies. The transmittance of glass–ceramics reached 78% at 780 nm and 90% at 1017 nm.

Effect of Polyethylene Jacket on Swelling Behavior and Mechanical Properties of PVA Hydrogel Nucleus Pulposus Prosthesis

New prosthetic nucleus which consisted of ultrahigh molecular weight polyethylene (UHMWPE) jacket and polyvinyl alcohol (PVA) hydrogel core was prepared and studied. The hydrogels with similar size were encased in polyethylene jacket of different dimension. Studies indicate that with the decrease of jacket dimension, swelling time of prosthetic nucleus increases, the equilibrium water content and volume change ratio decrease. Differential Scanning Caborimetry (DSC) analysis shows that increasing the jacket dimension results in a slight increase of non-freezable bond water and significant increase in free water. The prosthetic nucleus with larger jacket has better stress relaxation property due to the plasticization of non-freezable water. These results suggest that the dimension ratio of jacket to core at 1.19-1.35 is the most suitable for artificial nucleus pulposus