scholarly journals The effects of certain glycols, substituted glycols and related organic solvents on the thermal stability of soluble collagen

1971 ◽  
Vol 125 (2) ◽  
pp. 599-604 ◽  
Author(s):  
G. J. Hart ◽  
A. E. Russell ◽  
D. R. Cooper
Keyword(s):  
Thermal Stability ◽  
Optical Rotation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Thermal Transition ◽  
Denaturation Temperature ◽  
Rotation Measurement ◽  
Skin Collagen ◽  
Positional Isomerism ◽  
Thermal Stability Of

The effects of a number of related diols, substituted diols and glycerol on the thermal stability of acid-soluble calf skin collagen were investigated. Thermal transition temperatures were determined by optical rotation measurement. Short-chain diols with terminal hydroxyl groups, i.e. ethylene glycol and propane-1,3-diol, stabilized the protein at all accessible concentrations. Stabilization was also observed with glycerol and diethylene glycol. Higher homologues in the diol series produced various effects, as did hydroxyl-group positional isomerism. Monoalkyl substitution of diols progressively lowered the denaturation temperature of collagen. Results are discussed in relation to possible mechanisms of perturbant action.

scholarly journals Differential anion effects on thermal stability of collagen in the dispersed and aggregated states

1974 ◽  
Vol 137 (3) ◽  
pp. 599-602 ◽  
Author(s):  
A. E. Russell
Keyword(s):  
Thermal Stability ◽  
Acid Solution ◽  
Thermal Transition ◽  
Dilute Solution ◽  
Dilute Acid ◽  
Dilute Acid Solution ◽  
Skin Collagen ◽  
Collagen Molecules ◽  
Thermal Stability Of ◽  
Calf Skin

The effects of KCNS and KI on thermal transition temperatures of calf skin collagen molecules in dilute acid solution and precipitated collagen fibrils from the same source were compared as a function of salt concentration and pH. The two salts produced qualitatively similar effects on each collagen form, but the response shown by single collagen molecules in dilute solution differed from that observed for molecular aggregates present in native-type fibrils.

scholarly journals Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2254
Author(s):  
Adeleke A. Oyekanmi ◽  
N. I. Saharudin ◽  
Che Mohamad Hazwan ◽  
Abdul Khalil H. P. S. ◽  
Niyi G. Olaiya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Cellulose Nanofibrils ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Silane Coupling ◽  
Cnf Films ◽  
Kenaf Bast ◽  
Thermal Stability Of

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

scholarly journals Anionic surfactant sulfate dodecyl sodium (SDS)-induced thermodynamics and conformational changes of collagen by ultrasensitive microcalorimetry

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Jie Zhang ◽  
Chunhua Wang ◽  
Fengteng Zhang ◽  
Wei Lin
Keyword(s):  
Thermal Stability ◽  
Conformational Changes ◽  
Triple Helix ◽  
Striking Difference ◽  
Thermal Transition ◽  
Scanning Calorimetry ◽  
Helix Structure ◽  
Stabilizing Effect ◽  
Collagen Molecules ◽  
Thermal Stability Of

Abstract In this communication, sulfate dodecyl sodium (SDS)-induced thermodynamics and conformational changes of collagen were studied. We used ultrasensitive differential scanning calorimetry (US-DSC) to directly monitor the thermal transition of collagen in the presence of SDS. The results show that SDS affects the conformation and thermal stability of collagen very differently depending on its concentrations. At CSDS ≤ 0.05 mM, the enhanced thermal stability of collagen indicates the stabilizing effect by SDS. However, a further increase of SDS leads to the denaturation of collagen, verifying the well-known ability of SDS to unfold proteins. This striking difference in thermodynamics and conformational changes of collagen caused by SDS concentrations can be explained in terms of their interactions. With increasing SDS, the binding of SDS to collagen can be dominated by electrostatic interaction shifting to hydrophobic interaction, and the latter plays a key role in loosening and unfolding the triple-helix structure of collagen. The important finding in the present study is the stabilizing effect of SDS on collagen molecules at extreme low concentration. Graphical abstract

scholarly journals Thermal stability of polyurethane coating prepared by using diphenylolpropane

2020 ◽  
Vol 62 (4) ◽  
pp. 81-87
Author(s):  
Indira N. Bakirova ◽  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Weight Loss ◽  
Elevated Temperatures ◽  
Onset Temperature ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Polyurethane Coating ◽  
Urethane Group ◽  
Thermal Stability Of

Thermal stability of polyurethane varnish coating prepared by using diphenylolpropane, polyetherpolyol and polyisocyanate with an equimolar ratio of isocyanate and hydroxyl groups was assessed in the air. The polyurethane weight loss thermogram shows three temperature regions: I – (217-275)°С, II – (275-380)°С, and III – above 380°С. For interpreting thermogram of the polyurethane under study the model substances simulating the urethane groups of a polymer were synthesized. The substance containing the urethane group formed by phenolic hydroxyl of diphenylolpropane was shown to demonstrate relatively low thermal stability and gets broken down into isocyanate and bisphenol. Decomposition of the substance containing the urethane group formed by alcoholic hydroxyl occurs at the higher temperature. The data obtained allow interpreting the occurrence of thermal decomposition step I in TGA curve by structural changes in the blocks formed by diphenylolpropane and polyisocyanate being the least stable when exposed to elevated temperatures. The next step can be attributed to decomposition of more thermostable urethane groups formed by functional groups of oligooxypropylenetriol and polyisocyanate. Transition to the step III accompanied by severe sample weight loss due to decomposition of urethane groups is explained by thermal oxidation of oligoether units of polymer. Based on the data obtained the conclusion was made that the presence of urethane groups formed by phenolic hydroxyl of diphenylolpropane in polymer structure results in the decreased thermooxidative decomposition onset temperature of polymer. At the same time, a deceleration of thermooxidative processes due to the stabilizing effect of diphenylolpropane released at the beginning of thermal decomposition of polyurethane is observed in a high-temperature region. The proposed polyurethane coating is inferior to commercial counterparts in thermal decomposition onset temperature but superior to them in the temperature corresponding to a 50% polymer weight loss.

scholarly journals The preparation, physicochemical and thermal properties of the high moisture, solvent and chemical resistant starch-g-poly(geranyl methacrylate) copolymers

2019 ◽  
Vol 140 (1) ◽  
pp. 189-198 ◽  
Author(s):  
Marta Worzakowska
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Potato Starch ◽  
Hydroxyl Groups ◽  
Methacrylate Copolymers ◽  
Decomposition Processes ◽  
Methacrylate Monomer ◽  
A Minor ◽  
Subsequent Decomposition ◽  
Thermal Stability Of

Abstract The thermal properties together with the identification of the emitted volatiles during heating of the starch-graft-poly(geranyl methacrylate) copolymers with the use of a TG/FTIR-coupled method and some of the physicochemical properties of the copolymers were determined. It was found that the use of the geranyl methacrylate monomer to the graft copolymerization with potato starch allowed to replace ca. 1.46 hydroxyl groups per glycosidic units of starch macromolecule by the poly(geranyl methacrylate) chains under the optimal reaction conditions. Generally, all tested starch graft copolymers exhibited a significant increase in polar solvent resistance, moisture resistance and chemical stability as compared to potato starch. However, the thermal stability of the obtained materials was substantially lower as compared to the thermal stability of potato starch. The beginning of the decomposition of the copolymers was observed below 150 °C. It was due to low thermal stability of the poly(geranyl methacrylate) chains. The decomposition of the prepared materials runs at least four, unseparated stages. The first stage was visible up to 220–240 °C. It was connected with the emission of some aldehyde, acid, alcohol, alkene, ester fragments, H2O and CO2 as a result of the depolymerization, destruction and partial decarboxylation of the poly(geranyl methacrylate) chains. The second stage was spread between ca. 220–240 and 358–375 °C. The emission of organic, saturated, unsaturated, aromatic, oxygen-rich fragments, CO, CO2 and H2O as a result of the decomposition and dehydration of starch was confirmed. Heating of the studied materials between 358–375 and 455–477 °C resulted in subsequent decomposition processes of the residues and the creation of some oxygen-rich saturated and unsaturated fragments, CO, CO2, H2O and CH4. Finally, above 455–477 °C, a minor mass loss as a result of the decomposition processes of the residues formed before was observed. The emission of CO, CO2, H2O, CH4 and some oxygen-rich saturated and unsaturated fragments was confirmed.

scholarly journals Photoinduced Metal-Free Surface Initiated ATRP from Hollow Spheres Surface

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 599 ◽  
Author(s):  
Chun-Na Yan ◽  
Qian Liu ◽  
Lin Xu ◽  
Li-Ping Bai ◽  
Li-Ping Wang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Free Surface ◽  
Methyl Methacrylate ◽  
Hybrid Materials ◽  
Hollow Spheres ◽  
Polymerization Process ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Metal Free ◽  
Thermal Stability Of

Well-defined amphiphilic diblock copolymer poly (methyl methacrylate)-b-poly (N-isopropylacrylamide) grafted hollow spheres (HS-g-PMMA-b-PNIPAM) hybrid materials were synthesized via metal-free surface-initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiators α-Bromoisobutyryl bromide (BIBB) were attached onto hollow sphere surfaces through esterification of acyl bromide groups and hydroxyl groups. The synthetic ATRP initiators (HS-Br) were further used for the metal-free SI-ATRP of methyl methacrylate (MMA) and N-isopropyl acrylamide (NIPAM) using 10-phenylphenothiazine (PTH) as the photocatalyst. The molecular weight of the polymers, structure, morphology, and thermal stability of the hybrid materials were characterized via gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), 1H-nuclear magnetic resonance spectroscopy (1H NMR), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA), respectively. The results indicated that the ATRP initiator had been immobilized onto HS surfaces successfully followed by metal-free SI-ATRP of MMA and NIPAM, the Br atom had located at the end of the main PMMA polymer chain, and the polymerization process possessed the characteristic of controlled/“living” polymerization. The thermal stability of the hybrid materials was increased significantly compared to the pure PMMA and PNIPAM.

Preparation and Characterization of Poly Methyl Methacrylate/Clay Nanocomposite Powders by Microwave-Assisted In-Situ Suspension Polymerization

2020 ◽  
Vol 20 (7) ◽  
pp. 4193-4197
Author(s):  
Seong Deok Seo ◽  
Kyung Chan Kang ◽  
Ji Won Jeong ◽  
Seung Min Lee ◽  
Ju Dong Lee ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Methyl Methacrylate ◽  
Hydroxyl Group ◽  
Silicate Layer ◽  
Clay Nanocomposites ◽  
Gravimetric Analysis ◽  
Poly Methyl Methacrylate ◽  
Nanocomposite Powders ◽  
Thermal Stability Of

The PMMA (poly methyl methacrylate)/clay nanocomposite powders were synthesized by In-Situ suspension polymerizations using microwave heating. The PMMA/clay nanocomposites were also sampled using injection moulding to make specimens for material characterization. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicated the formation of a highly intercalated clay layer in the nanocomposites. It was found that the microstructure of PMMA/clay nanocomposites was strongly dependent of content of clay. Thermo gravimetric analysis (TGA) indicated an improvement in the thermal stability of nanocomposites compared to that of the pure PMMA. Differential scanning calorimetry (DSC) showed that the nanocomposites had a higher glass transition (Tg) temperature than the PMMA. Fourier-transform infrared (FT-IR) spectroscopy indicated an interaction between the carbonyl group of PMMA and hydroxyl group of the clay. Therefore, a possible reason in enhanced material properties of nanocomposites is that the chemical interaction and nanostructure of PMMA polymer and intercalated inorganic silicate layer has increased the thermal stability of the PMMA/clay nanocomposites.

Thermal Stability of Modified Perfluoropolyether Lubricants for Application in Heat Assisted Magnetic Recording

2011 ◽  
Author(s):  
Jumin Rhew ◽  
Hogap Kim ◽  
Hao Zheng ◽  
Ho-Jong Kang ◽  
Frank E. Talke
Keyword(s):  
Thermal Stability ◽  
Free Radical ◽  
Magnetic Recording ◽  
Nmr Spectra ◽  
Hydroxyl Groups ◽  
Heat Assisted Magnetic Recording ◽  
Chemically Modified ◽  
Thermal Stability Of ◽  
End Group ◽  
Pfpe Lubricants

Perfluoropolyether (PFPE) lubricants were chemically modified to maximize their thermal stability for application in heat assisted magnetic recording (HAMR). Benzophenone (BP) was introduced to react with the hydroxyl end group in PFPE to act as a free radical stabilizer. Modification of the PFPE by benzophenone was confirmed by evaluation of the chemical shift and the area change of the hydroxyl peak in the 1H NMR spectra. The thermal stability of modified PFPE lubricants was studied using thermo-gravimetry. The improvement in the thermal stability was found to be a function of the amount of substituted hydroxyl groups in PFPE.

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