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 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.

GROWTH AND STUDIES OF PROPERTIES OF COPPER SUCCINATE DIHYDRATE SINGLE CRYSTALS

2013 ◽  
Vol 27 (11) ◽  
pp. 1350073
Author(s):  
M. P. BINITHA ◽  
P. P. PRADYUMNAN
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Single Crystals ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Different Temperatures ◽  
Triclinic Structure ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Single crystals of copper succinate dihydrate (CSD) with triclinic structure were grown in silica gel medium. The functional groups in the crystal were analyzed by FT-IR Spectroscopy. Atomic Force Microscopy (AFM) revealed the striations on the surface of grown crystals, which were incorporated during its time of growth. Thermal degradation studies have been carried out by Differential Scanning Calorimetry (DSC). Dielectric constant and AC conductivity have been estimated as a function of frequency at different temperatures.

Synthesis, characterization and separation properties of novel PU membranes crosslinked by β-cyclodextrin

2013 ◽  
Vol 33 (3) ◽  
pp. 285-292 ◽  
Author(s):  
Hong Ye ◽  
Jing Wang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Soft Segment ◽  
Chain Extender ◽  
Scanning Calorimetry ◽  
Structures And Properties ◽  
Separation Factors ◽  
Different Temperatures ◽  
Ft Ir ◽  
A Chain ◽  
Phenol Water

Abstract Polyurethane (PU) pervaporation (PV) membranes are promising for the recovery of phenol from water. The four kinds of PU membranes, with hydroxyl terminated polybutadiene (HTPB) as a soft segment and diamine or β-cyclodextrin (CD) as a chain extender, were prepared. The structures and properties of these membranes were characterized by means of Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and contact angle. Furthermore, the PV performances were investigated for separating phenol/water mixtures at different temperatures. The results showed that CD increased the permeability and selectivity of PU, at the same time. At 80°C, the total fluxes of pure PU membranes with HTPB (Mn=2500 g/mol) (H2500) and with HTPB (Mn=2000 g/mol) (H2000) were 6.96 kg μm m-2 h-1 and 6.09 kg μm m-2 h-1, respectively, while those of PU membranes containing CD with HTPB (Mn=2500 g/mol) (H2500-CD) and with HTPB (Mn=2000 g/mol) (H2000-CD) were 9.16 kg μm m-2 h-1 (increased by 31%) and 8.23 kg μm m-2 h-1 (increased by 26%), respectively. The separation factors of H2500 and H2000 were 23 and 34, while those of H2500-CD and H2000-CD were 33 (increased by 43%) and 40 (increased by 9%). Additionally, the modification of CD crosslinking was simple and easy with less modifying agent.

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%.

Swelling Behavior of Chitosan Hydrogel in Ionic Liquid-Water Binary System

2006 ◽  
Vol 915 ◽  
Author(s):  
Chang Kee Lee ◽  
Sang Jun Park ◽  
Seong Gil Yoon ◽  
Kwang Min Shin ◽  
Su Ryon Shin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Binary System ◽  
Liquid Water ◽  
Binary Systems ◽  
Polymer Network ◽  
Free Water ◽  
Swelling Behavior ◽  
Scanning Calorimetry ◽  
Swelling Properties ◽  
Chitosan Hydrogels

AbstractThe swelling behavior of chitosan hydrogels in ionic liquid–water binary systems was studied using hydrophilic room-temperature ionic liquids (RTILs) to elucidate the swelling properties of chitosan hydrogels. It was confirmed that chitosan hydrogels are much stiffer after immersing in a pure RTIL because the water existing inside the chitosan polymer network is extracted into the RTIL. The pH of the binary system changes when the RTIL is in contact with water. The chitosan hydrogels were fully dissociated at a 90% water content in the BMI-BF4-water binary system. The equilibrium binary system content behavior of the chitosan hydrogels depended upon the amount of free water present. The water behavior in a pure RTIL was examined using differential scanning calorimetry.

scholarly journals Physical Ageing of Amorphous Indapamide Characterised by Differential Scanning Calorimetry

Pharmaceutics ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 800
Author(s):  
Agata Drogoń ◽  
Marcin Skotnicki ◽  
Agnieszka Skotnicka ◽  
Marek Pyda
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Amorphous State ◽  
Modulated Dsc ◽  
Physical Ageing ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Fragility Parameter ◽  
Liquid States

The objective of this study was to characterise amorphous indapamide (IND) subjected to the physical ageing process by differential scanning calorimetry (DSC). The amorphous indapamide was annealed at different temperatures below the glass transition, i.e., 35, 40, 45, 65, 75 and 85 °C for different lengths of time, from 30 min up to a maximum of 32 h. DSC was used to characterise both the crystalline and the freshly prepared glass and to monitor the extent of relaxation at temperatures below the glass transition (Tg). No ageing occurred at 35, 40 and 45 °C at the measured lengths of times. Molecular relaxation time constants (τKWW) for samples aged at 65, 75 and 85 °C were determined by the Kohlrausch-Williams-Watts (KWW) equation. The fragility parameter m (a measure of the stability below the glass transition) was determined from the Tg dependence from the cooling and heating rates, and IND was found to be relatively stable (“moderately fragile”) in the amorphous state. Temperature-modulated DSC was used to separate reversing and nonreversing processes for unaged amorphous IND. The enthalpy relaxation peak was clearly observed as a part of the nonreversing signal. Heat capacities data for unaged and physically aged IND were fitted to Cp baselines of solid and liquid states of IND, were integrated and enthalpy was presented as a function of temperature.

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.

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