Effects of CaO Additions on the Structure and Dielectric Properties of Aluminoborosilicate Glasses

2013 ◽  
Vol 710 ◽  
pp. 127-131 ◽  
Author(s):  
X.M. Yuan ◽  
S.M. Lu ◽  
X.H. Zhang ◽  
Y.J. Cui ◽  
H.T. Wu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Infrared Spectroscopy ◽  
Glass Network ◽  
Frequency Range ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Melting Method ◽  
Tetrahedral Boron

Glasses with compositions xCaO-(60-x)SiO2-5MgO-15Al2O3-20B2O3 (x=0, 3, 6 and 9 mol %) were prepared by conventional melting method. Fourier-transform infrared spectroscopy (FTIR) indicated that the addition of CaO converted trigonal boron ([B) to tetrahedral boron ([B). The glass transition temperatures (Tg) were determined using a differential scanning calorimetry (DSC). Tg increased with increasing CaO content. Thus, the addition of CaO instead of SiO2 strengthened the glass network. The dielectric εr and loss tanδ were measured for the MgO-B2O3-Al2O3-SiO2 glass system in the frequency range 103-105 Hz. The decrease in εr and tanδ could be attributed to the increase in the rigidity of the glass network.

Effects of CeO2 Additions on the Structure and Dielectric Properties of Aluminoborosilicate Glasses

2013 ◽  
Vol 710 ◽  
pp. 132-135
Author(s):  
S.M. Lu ◽  
X.M. Yuan ◽  
X.H. Zhang ◽  
Y.J. Cui ◽  
H.T. Wu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Fourier Transform ◽  
Glass Transition ◽  
Infrared Spectroscopy ◽  
Glass Network ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Melting Method ◽  
Tetrahedral Boron

Glasses with compositions 15Al2O3-20B2O3-50SiO2-5CaO-(10-x)MgO-xCeO2 (x=0, 1, 2 and 3 mol %) were prepared by conventional melting method. Fourier-transform infrared spectroscopy (FTIR) indicated that the addition of CeO2 converted trigonal boron ([B) to tetrahedral boron ([B). The glass transition temperatures (Tg) were determined using a differential scanning calorimetry (DSC). Tg increased with increasing CeO2 content. Thus, the addition of CeO2 instead of MgO strengthened the glass network. The dielectric constant εr and loss tanδ were measured for these glasses at 105 Hz. The decrease in εr and tanδ could be attributed to the increase in the rigidity of the glass network as the CeO2 content increased.

EFFECT OF TiO2 ON STRUCTURE AND DIELECTRIC PROPERTIES OF RO-Al2O3-B2O3-SiO2(R = Ca, Mg) GLASSES

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350030 ◽  
Author(s):  
XUEHONG ZHANG ◽  
ZHAO DU ◽  
HAITAO WU ◽  
YUNLONG YUE
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Fourier Transform ◽  
Glass Transition ◽  
Glass Network ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Melting Method ◽  
Increasing Trend ◽  
Tan Δ

RO - Al 2 O 3- B 2 O 3- SiO 2( R = Ca , Mg ) glasses containing different concentrations of TiO 2 (ranging from 0 to 9 mol.%) were prepared by conventional melting method. When TiO 2 was present in lower concentrations (≤ 6 mol.%), Fourier-transform infrared spectroscopy (FTIR) indicated that titanium ions took part in network forming positions. However, for further increase in the concentration of TiO 2 (> 6 mol.%), FTIR data indicated the formation of TiO 4 tetrahedrons and TiO 6 octahedrons. The glass transition temperatures (Tg) were determined using a differential scanning calorimetry (DSC). The Tg variation with the concentration of TiO 2 showed an increasing trend up to 6 mol.% of TiO 2 and beyond this concentration, Tg was found to decrease. The dielectric constant εr and loss tan δ continued to decrease with the concentration of TiO 2 up to 6 mol.% and beyond that εr and tan δ were found to increase. This behavior was mainly explained in terms of the rigidity of glass network.

scholarly journals Assessment of the denaturation of collagen protein concentrates using different techniques

2019 ◽  
Vol 400 (12) ◽  
pp. 1583-1591 ◽  
Author(s):  
Victor Perez-Puyana ◽  
Francisco J. Ostos ◽  
Pilar López-Cornejo ◽  
Alberto Romero ◽  
Antonio Guerrero
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Infrared Spectroscopy ◽  
Raw Material ◽  
Cd Spectra ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Collagen Protein ◽  
Α Helix

AbstractThe use of collagen and gelatin in the field of regenerative medicine is widely extended. However, most of the studies in this topic are focused on the scaffolds’ properties, but only a few are related to the properties of the raw material used. The raw material analysis not only consists of a study of the composition, but also of the denaturation degree that can influence the processing and properties of the structure of the scaffold. Thus, the denaturation degree analysis of different collagen proteins was performed and assessed by the comparison of four different methods: differential scanning calorimetry (DSC), Fourier transform Infrared Spectroscopy (FTIR) and circular dichroism (CD) spectra and sulfhydryls content analysis. DSC measurements put forward a glass transition between 88°C and 95°C as well as from the FTIR measurements; the characteristic peaks for proteins are evidenced. However, from the sulfur content, only a small proportion of free sulfhydryls are present with respect to their total amount. In addition, CD spectra allow to estimate the secondary structure of the protein by the analysis of the α-helix and β-strand and also quantify the denaturation degree with the ‘positive/negative ratio’ (RPN) from the CD profiles, obtaining values in the range between 25% and 100%.

Synthesis of Ethylene-Propylene Copolymer and their Structures

2014 ◽  
Vol 1035 ◽  
pp. 149-154
Author(s):  
Yan Liu Dang ◽  
Yun Zhao ◽  
Chao Xiang Wang ◽  
Qing Ze Jiao ◽  
Han Sheng Li ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Resonance Spectroscopy ◽  
Differential Scanning Calorimetry Analysis ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Ethylene Propylene ◽  
X Ray

This work reports copolymerization of ethylene-propylene (EP) using a novel phenoxy–ester ligated titanium catalyst. Copolymerization reactions were conducted in toluene at 70 °C with varied E/P flow ratios. Fourier transform infrared spectroscopy, X-ray diffractometer, nuclear magnetic resonance spectroscopy and differential scanning calorimetry analysis were performed to characterize the structures, compositions and glass transition temperatures of the copolymers. The results show that ethylene-propylene copolymers are random polymers and the link ratios of ethylene to propylene are between 0.89 and 1.26. The glass transition temperature of ethylene-propylene copolymer is-43.3 °C.

scholarly journals Swelling properties of chitosan hydrogels

2004 ◽  
Vol 22 (1) ◽  
pp. 32 ◽  
Author(s):  
David R Rohindra ◽  
Ashveen V Nand ◽  
Jagjit R Khurma
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Free Water ◽  
Scanning Calorimetry ◽  
Swelling Behaviour ◽  
Swelling Properties ◽  
Different Temperatures ◽  
Ft Ir ◽  
Chitosan Hydrogels

Chitosan hydrogels were prepared by crosslinking chitosan with glutaraldehyde. The swelling behaviour of the crosslinked and uncross-linked hydrogels was measured by swelling the gels in media of different pH and at different temperatures. The swelling behavior was observed to be dependent on pH, temperature and the degree of crosslinking. The gel films were characterized by Fourier transform Infrared spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). The glass transition temperature (Tg) and the amount of free water in the hydrogels decreased with increasing crosslinking in the hydrogels.

scholarly journals New insight into single phase formation of capric acid/menthol eutectic mixtures by Fourier-transform infrared spectroscopy and differential scanning calorimetry

2020 ◽  
Vol 19 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Hiba H. Ali ◽  
Mowafaq M. Ghareeb ◽  
Mayyas Al-Remawi ◽  
Faisal T. Al-Akayleh
Keyword(s):  
Differential Scanning Calorimetry ◽  
Hydrogen Bond ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Bond Formation ◽  
Capric Acid ◽  
Fourier Transform Infrared ◽  
Scanning Calorimetry ◽  
Hydrogen Bond Formation

Purpose: To examine the structural changes of a eutectic mixture comprising capric acid and menthol which are commonly used in pharmaceutical applications. Methods: A phase diagram was constructed by quantitative mixing of capric acid and menthol under controlled conditions until a single liquid phase was formed. Eutectic mixtures of capric acid: menthol at the ratios of 3:2, 1:4, 1:1, 2:3, and 1:4 were prepared. Hydrogen bond formation and conformational changes were analyzed using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Microscopic imaging was carried out to capture phase change events upon increasing temperature. Results: Menthol confirmed the intact structure of a hexagonal ring. The high degree of broadening of the menthol O-H groups indicates hydrogen bond formation. FTIR band changes related to capric acid suggest a break-up of the methylene arrangement structure due to changes in the C-H band frequencies. The red shift encountered in C=O stretching band emphasizes hydrogen bond formation taking place between the oxygen atom of the hydroxyl group comprising the carboxylic moiety of capric acid and the hydrogen atom of menthol hydroxyl group. DSC results indicate the presence of two polymorphs of the capric acid/ menthol complex. Both exhibited crystallization and conformational change exotherms in addition to two melting endotherms as result of transformation of crystalline components to become partially crystalline due to hydrogen bond formation. Conclusion: The interaction between capric acid and menthol results in a typical preparation of deep eutectic systems that can act as natural-based solvents in numerous pharmaceutical applications. Keywords: Eutectic system, Capric acid, Menthol, Differential scanning calorimetry, DSC, Fourier transform infrared spectroscopy, FTIR

scholarly journals Miscibility, melting and crystallization of poly(ε-caprolactone) and poly (vinyl formal) blend

2007 ◽  
Vol 25 (1) ◽  
pp. 53 ◽  
Author(s):  
David R. Rohindra ◽  
Jagjit R. Khurma
Keyword(s):  
Growth Rate ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Optical Microscopy ◽  
Crystallization Process ◽  
Scanning Calorimetry ◽  
Low Degree ◽  
Solution Cast ◽  
Melting And Crystallization

Solution cast blends of poly(e-caprolactone) [PCL] and poly(vinyl formal) [PVF] from dichloromethane was investigated for miscibility by Differential Scanning Calorimetry [DSC], Fourier Transform Infrared Spectroscopy [FTIR] and optical microscopy. Melting (Tm) and crystallization (Tc) temperatures were for the PCL fraction while the glass transition temperature (Tg) was for PVF fraction in the blends. Blends with 20 wt% and less PCL showed a depression in Tm and Tc. Depression in Tc indicated that during the non-isothermal crystallization process, the presence of PVF decreased the PCL segments migrating to the crystallite-melt interface thus reducing the nucleation rate, growth rate and the thickness of the lamella resulting in a depressed Tm. Crystallinity (Xc) decreased gradually with decreasing content of PCL in the blend and was due to the dilution of PCL by PVF. A depressed Tg was observed for 10 wt% PCL blend and remained the same for all other blend compositions. These observations suggested that this blend system has very low degree of miscibility. The degree of miscibility increased at low polyester concentration. FTIR spectra of the blends with low polyester concentrations showed changes in the C=O, O-H and C-O-C regions in the blended PVF and PCL spectra. Optical microscopy showed phase separation in the melt and in the PCL spherulites.

The Effect of Solvent on the Miscibility of Blends of Poly 1-[4-(3-carboxy-4-hydroxy-phenylazo)benzene Sulphonamido -1,2-ethanediyl, sodium salt)] (PAZO) and Polyhydroxybutyrate, (PHB)

2005 ◽  
Vol 13 (5) ◽  
pp. 443-452 ◽  
Author(s):  
*Lakshmi Sharma ◽  
Koji Nishida ◽  
Toshiji Kanaya
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Sodium Salt ◽  
Cost Effective ◽  
Photonic Materials ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Effect Of Solvent ◽  
Photonic Material ◽  
Commercial World

The commercial world demands new photonic materials, pandering to the consumer's every whim. The target now is to produce an eco-friendly, cost-effective photonic material. This is possible by blending poly 1-[4-(3-carboxy-4-hydroxy-phenylazo)benzene sulphonamido-1,2-ethanediyl, sodium salt)], (PAZO), with polyhydroxybutyrate, (PHB). We analysed the behaviour of PAZO/PHB blends in various solvents, dependent on the solubility parameter calculations for amorphous PHB. Differential Scanning Calorimetry was employed to determine the glass transition temperatures and to assess miscibility. This paper aims to address and establish the effect of the solvent on the miscibility of PHB/PAZO blends. We have established that a complex, is formed at high PHB concentrations, via the O-H bond of the PHB and PAZO in all solvents.

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