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1.
A two‐component physical organogel was produced by interactions of 6‐deoxy‐6‐amino‐β‐cyclodextrin (β‐CDNH2) and poly(acrylic acid). The microstructure and morphology of the gels were characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. It was revealed that the intermolecular hydrogen bonds between the molecules of β‐CDNH2 and the electrostatic interaction between the carboxyl groups of PAA and amino group of β‐CDNH2 were the main driving forces for the formation and maintenance of the network structures of the gel. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers 相似文献
2.
Structural insights in Dy3+‐doped β‐Tricalcium phosphate and its multimodal imaging characteristics
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Rugmani Meenambal Pavan Poojar Sairam Geethanath Kannan Sanjeevi 《Journal of the American Ceramic Society》2017,100(5):1831-1841
A series of Dysprosium (Dy3+) doped β‐Tricalcium phosphate [β‐TCP, β‐Ca3(PO4)2] were developed for applications in magnetic resonance imaging (MRI) and computed tomography (CT). Characterization studies confirmed the Dy3+ occupancy at Ca2+(1), Ca2+(2), and Ca2+(3) lattice sites of β‐Ca3(PO4)2 and its substitution limit was determined as 4.35 mol%. The transitions from the 6H15/2 ground state to various excited energy levels is validated by the characteristic absorption peaks of Dy3+. Luminescence studies inferred two intense bands at 480 and 572 nm due to 4F9/2→6H15/2 (blue) and 4F9/2→6H13/2 (yellow) transitions of Dy3+. The paramagnetic and nontoxic behavior of Dy3+‐doped β‐Ca3(PO4)2 were confirmed from magnetic and MTT tests, respectively. Dy3+ in the host induces a high X‐ray absorption ability for X‐ray computed tomography (CT) and showed efficient contrast T2‐enhancing modality. Thus the proposed system could be used as a promising probe for multimodality with optical imaging, computed tomography and magnetic resonance imaging. 相似文献
3.
Structural elucidation and iron oxidation states in situ formed β‐Ca3(PO4)2/α‐Fe2O3 composites
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Ponnusamy Nandha Kumar Sandeep K. Mishra Sanjeevi Kannan 《Journal of the American Ceramic Society》2017,100(8):3746-3756
A detailed structural analysis on the in situ synthesized β‐Ca3(PO4)2/α‐Fe2O3 composites is demonstrated. Compositional ratios, the influence and occupancy of iron at the β‐Ca3(PO4)2 lattice, oxidation state of iron in the composites are derived from analytical techniques involving XRD, FT‐IR, Raman, refinement of the powder X‐ray diffraction and X‐ray photoelectron spectroscopy. Iron exists in the Fe3+ state throughout the investigated systems and favors its occupancy at the Ca2+(5) site of β‐Ca3(PO4)2 until critical limit, and thereafter crystallizes as α‐Fe2O3 at ambient conditions. Fe3+ occupancy at the β‐Ca3(PO4)2 lattice yields a Ca9Fe(PO4)7 structure that is isostructural with its counterpart. A strong rise in the soft ferromagnetic behavior of β‐Ca3(PO4)2/α‐Fe2O3 composites is obvious that depends on the content of α‐Fe2O3 in the composites. Overall, the diverse level of iron inclusions at the calcium phosphate system with a Ca/P ratio of 1.5 yields a structurally stable β‐Ca3(PO4)2/α‐Fe2O3 composites with assorted compositional ratios. 相似文献
4.
β‐Polypropylene composites containing calcium carbonate treated by titanate coupling agent (T‐CaCO3) and maleic anhydride grafted PP (PP‐g‐MAH) were prepared by melt compounding. The crystallization, morphology and mechanical properties of the composites were investigated by means of differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized light microscopy, scanning electron microscopy and mechanical tests. It is found that both T‐CaCO3 and NT‐C are able to induce the formation of β‐phase, and NT‐C greatly increases the β content and decreases the spherulitic size of PP. PP‐g‐MAH facilitates the formation of β‐form PP and improves the compatibility between T‐CaCO3 and PP. Izod notched impact strength of β‐PP/T‐CaCO3 composite is higher than that of PP/T‐CaCO3 composite, indicating the synergistic toughening effect of T‐CaCO3 and β‐PP. Incorporation of PP‐g‐MAH into β‐PP/T‐CaCO3 composite further increases the content of β‐crystal PP and improves the impact strength and tensile strength when T‐CaCO3 concentration is below 5 wt%. The nonisothermal crystallization kinetics of β‐PP composites is well described by Jeziorny's and Mo's methods. It is found that NT‐C and T‐CaCO3 accelerate the crystallization rate of PP but the influence of PP‐g‐MAH on crystallization rate of β‐PP composite is marginal. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
5.
A novel highly active β‐nucleating agent, β‐cyclodextrin complex with lanthanum (β‐CD‐MAH‐La), was introduced to isotactic polypropylene (iPP). Its influence on isothermal crystallization and melting behavior of iPP was investigated by differential scanning calorimeter (DSC), wide‐angle X‐ray diffraction (WAXD), and polarized light microscopy (PLM). WAXD results demonstrated that β‐CD‐MAH‐La was an effective β‐nucleating agent, with β‐crystal content of iPP being strongly influenced by the content of β‐CD‐MAH‐La and the isothermal crystallization temperature. The isothermal crystallization kinetics of pure iPP and iPP/β‐CD‐MAH‐La was described appropriately by Avrami equation, and results revealed that β‐CD‐MAH‐La promoted heterogeneous nucleation and accelerated the crystallization of iPP. In addition, the equilibrium melting temperature (T) of samples was determined using linear and nonlinear Hoffman‐Weeks procedure. Finally, the Lauritzen‐Hoffman secondary nucleation theory was applied to calculate the nucleation parameter (Kg) and the fold surface energy (σe), the value of which verify that the addition of β‐CD‐MAH‐La reduced the creation of new surface for β‐crystal and then led to faster crystallization rate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
6.
In this study, β‐cyclodextrin (β‐CD) was covalently grafted on hydroxyapatite (HA) using a coupling agent to improve the drug loading capacity and prolong the drug release. The binding of β‐CD on the HA surface was confirmed by Fourier transformation infrared spectroscopy, thermal gravimetric analysis, and X‐ray powder diffraction. The adsorption capacity of ofloxacin on β‐CD‐grafted hydroxyapatite (β‐CD‐g‐HA) composite was found to be 30 mg g?1 at 37°C and 24 h. The adsorption process is spontaneous, given the negative values of free energy change. Compared with the release of ofloxacin loaded on HA, the release of ofloxacin loaded on β‐CD‐g‐HA was slowed down 28% and 21% in pH 2.0 and pH 7.4 buffer media at 2 h, respectively. Biocompatibility of β‐CD‐g‐HA was assessed by MTT assay, and the result showed that it had no cytotoxicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
7.
Experimental investigation of the LiAlSi2O6‐MgSiO3 and LiAlSi2O6‐CaMgSi2O6 isopleths at 1 atm
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The phase diagrams of the LiAlSi2O6‐MgSiO3 and LiAlSi2O6‐CaMgSi2O6 isopleths were experimentally investigated at 1 atm using the quenching method and differential scanning calorimetry and the phases produced were characterized with the help of X‐ray diffraction and electron probe microanalysis. With the help of thermodynamic optimization, the phase diagrams of both systems were more accurately reported. No detectable solubility of Li2O in diopside and enstatite was found. However, both systems are not simple binary eutectic systems because their phase equilibria are somewhat complex due to the presence of some β‐spodumene solid solution. In the β‐spodumene solid solution, no notable solubility of MgO and CaO was detected; evidence of significant solubility of SiO2 was confirmed. 相似文献
8.
Effect of β‐tricalcium phosphate on the thermal foaming behavior of poly(vinyl alcohol)/water system
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Poly(vinyl alcohol) (PVA)/β‐tricalcium phosphate (β‐TCP, Ca3 (PO4)2) porous composite, which has potential application in articular cartilage repair, was prepared through thermal foaming using water as both plasticizer and physical blowing agent. The effects of β‐TCP content on the foaming behavior, the structure and properties of the porous composites were studied. The results showed that β‐TCP could form hydrogen bonds or coordination interaction with PVA and water; with the incorporation of β‐TCP, the content of nonfreezable bound water in system increased, the water evaporation reduced, beneficial to the controllable foaming of water. The interactions between PVA‐β‐TCP led to the enhanced melt viscosity of PVA. Simultaneously, the β‐TCP particles in matrix could act as heterogeneous nucleation agent to increase the cell density. When β‐TCP content was 7.4 wt %, the porous composite showed the optimal cell structure, i.e., 250 μm average cell size and 87% porosity. The dynamic modulus of the porous composites increased with β‐TCP content and showed frequency‐dependence. The surface contact angle and permeability of the porous composites varied with β‐TCP content, which ranged from 35° to 48° and 11 × 10?14 to 27 × 10?14 m2, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44737. 相似文献
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10.
Two new adsorbents [β‐cyclodextrin–chitosan (β‐CD–CTS) and β‐cyclodextrin‐6–chitosan (β‐CD‐6‐CTS)] were synthesized by the reaction of β‐cyclodextrin (β‐CD) with epoxy‐activated chitosan (CTS) and the sulfonation of the C‐6 hydroxyl group of β‐cyclodextrin with CTS, respectively. Their structures were confirmed by IR spectral analysis and X‐ray diffraction analysis, and their apparent amount of grafting was determined by ultraviolet spectroscopy. The adsorption properties of β‐CD‐CTS and β‐CD‐6‐CTS for p‐dihydroxybenzene were studied. The experimental results showed that the two new adsorbents exerted adsorption on the carefully chosen target. The highest saturated capacity of p‐dihydroxybenzene of β‐CD‐CTS and β‐CD‐6‐CTS were 51.68 and 46.41 mg/g, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 860–864, 2004 相似文献
11.
The nucleating ability of p‐cyclohexylamide carboxybenzene (β‐NA) towards isotactic polypropylene (iPP) was investigated by differential scanning calorimetry, X‐ray diffraction, polarized optical microscopy and scanning electron microscopy. β‐NA is identified to have dual nucleating ability for α‐iPP and β‐iPP under appropriate kinetic conditions. The formation of β‐iPP is dependent on the content of β‐NA. The content of β‐phase can reach as high as 96.96% with the addition of only 0.05 wt% β‐NA. Under non‐isothermal crystallization the content of β‐iPP increases with increasing cooling rate. The maximum β‐crystal content is obtained at a cooling rate of 40 °C min–1. The supermolecular structure of the β‐iPP is identified as a leaf‐like transcrystalline structure with an ordered lamellae arrangement perpendicular to the special surface of β‐NA. Under isothermal crystallization β‐crystals can be formed in the temperature range 80–140 °C. The content of β‐crystals reaches its maximum value at a crystallization temperature of 130 °C. © 2012 Society of Chemical Industry 相似文献
12.
Structural and Crystal Chemical Investigation of Intermediate Phases in the System Ca2SiO4–Ca3(PO4)2–CaNaPO4
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Remo Widmer Frank Gfeller Thomas Armbruster 《Journal of the American Ceramic Society》2015,98(12):3956-3965
Two intermediate compounds of the system Ca2SiO4–Ca3(PO4)2–CaNaPO4 were synthesized by reaction sintering at 1600°C and analyzed structurally, chemically, and optically. The structure of Ca7(PO4)2(SiO4)2 nagelschmidtite (space group P61, a = 10.7754(1) Å, c = 21.4166(3) Å) was determined by single crystal X‐ray analysis. Its unit cell can be interpreted as a supercell (≈ 2 × a, 3 × c) of the high‐temperature polymorph α‐Ca2SiO4. Evidence for pseudo‐hexagonal symmetry is shown. Using electron microprobe, the solid solution Ca7?xNax(PO4)2+x(SiO4)2?x, (x ≤ 2), of nagelschmidtite was confirmed. Volume thermal expansion coefficients of Ca6.8Na0.2(PO4)2.2(SiO4)1.8 and Ca5.4Na1.5(PO4)3.7(SiO4)0.3 were determined using high‐temperature X‐ray powder diffraction, yielding mean αV = 3.95 and 5.21 [×10?5/°C], respectively. Ca15(PO4)2(SiO4)6 is a distinct phase in the binary section Ca2SiO4–Ca3(PO4)2 and was found to extend into the ternary space according to Ca15?xNax(PO4)2+x(SiO4)6?x, (x ≤ 0.1). Quenching experiments of the latter allowed for structural analysis of a strongly disordered, defective high‐temperature polymorph of the α‐Ca2SiO4–α‐Ca3(PO4)2 solid solution. Structural relations between nagelschmidtite, Ca15(PO4)2(SiO4)6 and the end‐member compounds of the system are discussed. 相似文献
13.
A novel star polymer with β‐cyclodextrin (β‐CD) core and polyacrylonitrile arms and its metal complexes (Cu2+, Zn2+, and Ag+) were synthesized and characterized by means of infrared spectra, ultraviolet, GPC, X‐ray photoelectron spectroscopy, differential scanning calorimetry, cyclic voltammetry, and electron spin resonance. The results indicate that the monomers of acrylonitrile were initiated by functionalized β‐CD. The thermal properties of star polymer were improved greatly after transitional metal ions were introduced into it. The novel star polymer metal complexes possess properties of metal ions, polymer, and β‐CD. Furthermore, it shows stable electrochemical activity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
14.
Effects of melt structure on crystallization behavior of isotactic polypropylene nucleated with α/β compounded nucleating agents
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Qiyan Zhang Zhengfang Chen Bing Wang Jinyao Chen Feng Yang Jian Kang Ya Cao Ming Xiang Huilin Li 《应用聚合物科学杂志》2015,132(4)
In this study, the melt structure of isotactic polypropylene (iPP) nucleated with α/β compounded nucleating agents (α/β‐CNA, composed of the α‐NA of 0.15 wt % Millad 3988 and the β‐NA of 0.05 wt % WBG‐II) was tuned by changing the fusion temperature Tf. In this way, the role of melt structure on the crystallization behavior and polymorphic composition of iPP were investigated by differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXD) and scanning electron microscopy (SEM). The results showed that when Tf = 200°C (iPP was fully molten), the α/β‐CNA cannot encourage β‐phase crystallization since the nucleation efficiency (NE) of the α‐NA 3988 was obviously higher than that of the β‐NA WBG‐II. Surprisingly, when Tf was in 179–167°C, an amount of ordered structures survived in the melt, resulting in significant increase of the proportion of β‐phase (achieving 74.9% at maximum), indicating that the ordered structures of iPP played determining role in β‐phase crystallization of iPP nucleated with the α/β‐CNA. Further investigation on iPP respectively nucleated with individual 3988 and WBG‐II showed that as Tf decreased from 200°C to 167°C, the crystallization peak temperature Tc of iPP/3988 stayed almost constant, while Tc of iPP/WBG‐II increased gradually when Tf < 189°C and became higher than that of iPP/3988 when Tf decreased to 179°C and lower, which can be used to explain the influence of ordered structure and α/β‐CNA on iPP crystallization. Using this method, the selection of α‐NA for α/β‐CNA can be greatly expanded even if the inherent NE of β‐NA is lower than that of the α‐NA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41355. 相似文献
15.
A number of polyphosphazenes with negatively charged β‐alanine (β‐Ala) and γ‐amino butyric acid (GABA) side groups were synthesized and studied for their ability to initiate the growth of hydroxyapatite (HAp) during exposure to simulated body fluid (SBF). All the polymers were hydrolytically sensitive, with the final hydrolysis rate dependent on the specific active side groups (GABA > β‐Ala). These systems also underwent extensive mineralization, with calcium phosphate deposited across their entire surface during exposure to SBF (up to 115 wt % gain after 4 weeks). This degree of deposition is a major advance over previously reported polyphosphazene systems, which underwent a maximum of 27 wt % gain after immersion in SBF for 4 weeks. The extent of mineralization over the surface was monitored using environmental scanning electron microscopy (ESEM) coupled with energy dispersive X‐ray spectroscopy (EDS). In addition, X‐ray diffraction (XRD) was used to determine the identity of the mineralized material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41741. 相似文献
16.
Well‐dispersed copper nanorods grown on the surface‐functionalized PAN fibers and its antibacterial activity
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β‐Cyclodextrins/polyacrylonitrile/copper nanorods (β‐CDs/PAN/CuNRs) composite fibers were fabricated by two steps including the preparation for the β‐CDs/PAN composite fibers by electrospining, and the preparation of the β‐CDs/PAN/CuNRs composite fibers by adsorption and reduction. The β‐CDs/PAN/CuNRs composite fibers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy respectively. The results indicated that the CuNRs were not only successfully synthesized on the surface of composite fibers but also the CuNRs were distributed without aggregation on the composite fibers. Furthermore, microorganism Escherichia coli had been used to check the antibacterial efficacy of the β‐CDs/PAN/CuNRs composite fibers. Subsequently, antibacterial tests have indicated that the composite fibers have good bactericidal effects. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41011. 相似文献
17.
Guoqiang Zheng Songwei Li Xiaoli Zhang Chuntai Liu Kun Dai Jingbo Chen Qian Li Xiangfang Peng Changyu Shen 《Polymer International》2011,60(7):1016-1023
On the premise that shear in the slit die of an extruder was minimized as far as possible, β‐nucleated isotactic polypropylene (iPP) was extruded. Simultaneously, once the extrudate (in the melt state) left the die exit, it was stretched at various stretching rates (SRs). For iPP with a low content of β‐nucleating agent (β‐NA), the crystallinity of β‐phase (Xβ) initially increases with increasing SR, and then decreases slightly with further increase in SR. However, for iPP containing a higher content of β‐NA, with increasing SR, Xβ decreases monotonically, indicating a negative effect of SR on β‐phase formation. Small‐angle X‐ray scattering and polarized optical microscopy experiments reveal that, when SR is less than 30 cm min?1, the increasing amount of row nuclei induced by increasing SR is mainly responsible for the increase of Xβ. In contrast, when SR exceeds 30 cm min?1, the overgrowth of shish structures unexpectedly restrains the development of β‐phase, and spatial confinement is considered as a better explanation for the suppression of β‐phase. Copyright © 2011 Society of Chemical Industry 相似文献
18.
Core–shell poly(acrylic acid)/polystyrene/SiO2 (PAA/PS/SiO2) hybrid microspheres were prepared by dispersion polymerization with three stages in ethanol and ethyl acetate mixture medium. Using vinyltriethoxysilane (VTEOS) as silane agent, functional silica particles structured vinyl groups on surfaces were prepared by hydrolysis and polycondensation of tetraethoxysilane and VTEOS in core stage. Then, the silica particles were used as seeds to copolymerize with styrene and acrylic acid sequentially in shell stage I and stage II to form PAA/PS/SiO2 hybrid microspheres. Transmission electron microscope results show that most PAA/PS/SiO2 hybrid microspheres are about 40 nm in diameter, and the silica cores are about 15 nm in diameter, which covered with a layer of PS about 7.5‐nm thick and a layer of PAA about 5‐nm thick. This core–shell structure is also conformed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and differential scanning calorimetry. FTIR results show that silica core, PS shell, and PAA outermost shell are bonded by covalents. In the core–shell PAA/PS/SiO2 hybrid microsphere, the silica core is rigidity, and the PAA outermost shell is polarity, while the PS layer may work as lubricant owning to its superior processing rheological property in polymer blending. These core–shell PAA/PS/SiO2 hybrid microspheres have potential as new materials for polar polymer modification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1729–1733, 2006 相似文献
19.
Elien Haccuria Tijl Crivits Peter C. Hayes Evgueni Jak 《Journal of the American Ceramic Society》2016,99(2):691-704
The Al2O3–CaO–SiO2 system provides the basis for describing many important chemical processes. Although the system has previously been extensively studied, recent advances in experimental technique have provided the opportunity to obtain accurate liquidus measurements in the low‐silica region at fixed temperatures. The experimental procedures involve equilibration of high‐purity oxide powder mixtures at selected temperatures, rapid quenching, and accurate measurement of phase compositions using electron probe X‐ray microanalysis. The liquidus isotherms have been determined at selected temperatures between 1503 and 1873 K in the anorthite, gehlenite, pseudowollastonite, corundum, CaAl12O19, CaAl2O6, lime, Ca3SiO3, and Ca2SiO4 primary phase fields. The results are compared with currently available thermodynamic model predictions of the phase chemistry. 相似文献
20.
Zhao‐Yang Sun Ming‐Xing Shen Gui‐Ping Cao Jie Deng Yuan Liu Tao Liu Ling Zhao Wei‐Kang Yuan 《应用聚合物科学杂志》2010,118(4):2176-2185
A novel insoluble bimodal porous polymer containing β‐cyclodextrin (β‐CD) was prepared to adsorb aromatic amine compound. The process involved copolymerization of styrene and methyl methacrylate with a maleic acid derivative of β‐CD, subsequently, above formed copolymer was foamed by supercritical CO2. The chemical properties and physical structure of obtained copolymer was analyzed using Fourier transform infrared spectra, Thermal gravimetric analysis, X‐ray diffraction, scanning electron microscope, and N2 adsorption techniques. The inclusion adsorption of aromatic amine compounds on β‐CD copolymer was carried out in a batch system. The quantities of aromatic amine compounds adsorbed on β‐CD copolymer reached equilibrium within 60 min. The adsorption kinetic could be fitted to a pseudo‐second‐order kinetic equation, and the linear correlation coefficients varied from 0.9828 to 0.9935. With the influence of molecular structure and hydrophobicity of the aromatic amine compound, the sequence of quantity of aromatic amine compounds adsorbed on β‐CD copolymer is p‐toluidine > aniline > benzidine > o‐toluidine. The adsorption equilibrium data of aromatic amine compound adsorbed on β‐CD copolymer were fitted to Freundlich and Langmuir models, respectively. The linear correlation coefficients of Langmuir model varied from 0.9516 to 0.9940, and the linear correlation coefficients of Freundlich varied from 0.9752 to 0.9976. It is concluded that Freundlich model fits better than Langmuir model, because the adsorption of aromatic amine compound on β‐CD copolymer is a chemical process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献