scholarly journals Effects of various transition metals on the thermal oxidative stabilization of polyacrylonitrile nanofibers

2021 ◽  
Author(s):  
Jung-Hun Lee ◽  
Siying Li ◽  
Ji-Beom Yoo ◽  
Young Jun Kim
Keyword(s):  
Differential Scanning Calorimetry ◽  
Transition Metal ◽  
Transition Metals ◽  
Exothermic Reaction ◽  
Structural Evolution ◽  
Scanning Calorimetry ◽  
Oxidative Stabilization ◽  
Stabilization Process ◽  
Spectral Peaks ◽  
Ft Ir

Abstract In this paper, the polyacrylonitrile (PAN) nanofibers and PAN nanofibers bonded with different transition metal (Fe, Co, Ni, and Cu) acetates were successfully prepared and their thermal oxidative stabilization process were analysed by Fourier-transform infrared spectra (FT-IR) and differential scanning calorimetry (DSC). The structural evolution of process was characterized by examining the FTIR spectral peaks generated at four different thermal oxidative stabilization temperatures. Based on the thermal oxidative stabilization rates obtained from each transition metal, Co-PAN and Cu-PAN are the only effective precursors for the thermal oxidative stabilization process and, according to differential scanning calorimetry, Co-PAN is the most effective and suitable precursor for the PAN with different transition metals. Although Co-PAN increased the exothermic reaction (ΔH) by approximately 140%, it alleviates the heat release rate (ΔH/ΔT) by approximately 44%.

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.

Compatibility between Magnesium Stearate and Pharmaceutical Acidic Active Compounds/Excipients with DSC

2020 ◽  
Vol 856 ◽  
pp. 190-197
Author(s):  
Pornsit Chaiya ◽  
Thawatchai Phaechamud
Keyword(s):  
Differential Scanning Calorimetry ◽  
Magnesium Stearate ◽  
X Ray Diffraction ◽  
Salt Form ◽  
Scanning Calorimetry ◽  
Powder Mixtures ◽  
X Ray ◽  
Pharmaceutical Excipients ◽  
Drug Compounds ◽  
Ft Ir

Compatibility investigation was performed between magnesium stearate and acidic drug compounds (ibuprofen, indomethacin and valproic acid) and acidic pharmaceutical excipients (lactic acid and citric acid) using differential scanning calorimetry (DSC). DSC study indicated the possible incompatibility for the mixture between magnesium stearate and any compounds. Alteration in DSC thermogram was found in all mixtures. The eutectic phenomenon was found in the powder mixture of magnesium stearate and ibuprofen. In addition, the presence of melting endothermic peak of stearic acid in other powder mixtures except the mixture of magnesium stearate and indomethacin indicating breakage of salt form of magnesium stearate. This alteration could relate to the influence on physicochemical properties of drug compounds and pharmaceutical excipients which powder x-ray diffraction (PXRD) and Fourier Transform Infrared Spectroscopy (FT-IR) should be further analyzed to confirm the interactions between compounds.

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.

Perfluoropolyether Modified Waterborne Shape Memory Polyurethaneurea Ionomers for Potential Medical Implant Application

2012 ◽  
Vol 499 ◽  
pp. 53-57
Author(s):  
Qun Xia Li ◽  
Zhong Yu Hou
Keyword(s):  
Molecular Structure ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Shape Memory ◽  
Soft Segment ◽  
Cross Linking ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Weight Percentage ◽  
Ft Ir

A series of cross-linked fluorinated waterborne shape memory polyurethaneurea (PUU) ionomers were synthesized from polycaprolactone diol, perfluoropolyether diol (PFPE), dimethylolproionic acid, isophorone diisocyanate, ethylenediamine (EDA) and diethylenetriamine (DETA). The effect of PFPE content in the soft segment and the degree of cross-linking on the molecular structure and the properties of for these PUU films was examined and studied. Differential scanning calorimetry showed that the transition temperature for these Tm type shape memory PUU could be facially tuned by PFPE weight percentage and EDA/DETA ratio in the range between 30°C to 50°C, in the vicinity of body temperature. The dependence of their properties on hydrogen-bonds evaluated by FT-IR was also discussed.

Investigating the Degradation Phenomena of Teflon Exposed to Acidic Environment

2017 ◽  
Vol 754 ◽  
pp. 7-10
Author(s):  
Giorgio Zattini ◽  
Laura Mazzocchetti
Keyword(s):  
Differential Scanning Calorimetry ◽  
Operation Time ◽  
Ultrasonic Waves ◽  
Acidic Environment ◽  
Aging Effects ◽  
Acid Attack ◽  
Scanning Calorimetry ◽  
Short Operation Time ◽  
Ft Ir ◽  
Different Response

This study provides an overview of the effects of prolonged acid attack on the surface of PTFE gaskets, assessed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The PTFE analysed originates from two manufacturers in form of Teflon adhesive tapes, used as gaskets in an ultrasonic tyre moulds cleaning plant (UMCS). The gaskets were exposed to various acid baths, temperature and ultrasonic waves, and shown anomalous damage and surface degradation in a relatively short operation time. The analyses here reported have been aimed at investigating this unusual behaviour. PTFE samples have been treated with different acid mixes to evaluate possible different aging effects. Both surface and core have been analysed after aging, providing evidence of the degradation phenomena. In particular, different acid treatments have highlighted different response of PTFE and differences among manufacturers.

Synthesis and characterization of novel tetrakis (3-hydroxypropylmercapto)-substituted phthalocyanines

2013 ◽  
Vol 17 (06n07) ◽  
pp. 573-586 ◽  
Author(s):  
Çiğdem Yağcı ◽  
Ahmet Bilgin
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Synthesis And Characterization ◽  
The Novel ◽  
Scanning Calorimetry ◽  
Metal Free ◽  
Visible Spectra ◽  
Ft Ir ◽  
Aromatic Nitro

A phthalonitrile precursor 4-(3-hydroxypropylmercapto)phthalonitrile (3) was synthesized via a base-catalyzed nucleophilic aromatic nitro displacement of 4-nitrophthalonitrile with the 3-mercapto-1-propanol. A novel tetrasubstituted metal-free phthalocyanine (4) ( M = 2 H ) and its metal complexes (5–8) ( M = Zn , Ni , Cu and Co ) bearing 3-hydroxypropylmercapto moieties were prepared by the cyclotetramerization reaction of (3) with the appropriate materials. The visible spectra of the zinc(II) phthalocyanine (5) was recorded with different concentrations and different ions as Ag +, Hg 2+ and Pb 2+ in DMF and also with different solvents as dimethylformamide and pyridine. Fluorescence spectrum of the compound (5) was also studied. Temperature and frequency dependence of AC conductivity for (4–8) was investigated in air and under vacuum and were found to be ~10-8–10-5 S.m-1. Thermal properties of the phthalocyanines were examined by differential scanning calorimetry. All the novel compounds have been characterized by elemental analysis, UV-vis, FT-IR, NMR and MS spectral data and DSC techniques.

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.

SIO2 Filler as Interface Modifier in PMMA/ENR 50 Electrolytes

2013 ◽  
Vol 812 ◽  
pp. 120-124 ◽  
Author(s):  
Mohamad Zamri Sharil Fadli ◽  
Abdul Latiff Famiza
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ionic Conductivity ◽  
Silicon Dioxide ◽  
Lithium Ion ◽  
Pmma Film ◽  
Scanning Calorimetry ◽  
Conducting Path ◽  
Ft Ir ◽  
Overall Performance ◽  
Polymer Blend Film

Previously, it was found that the brittle properties of polymehyl methacrylate (PMMA) film has been improved when blended with epoxidised natural rubber 50 % (ENR 50) hence enhanced the ionic conductivity of PMMA electrolytes. However, the PMMA and ENR 50 blend was not homogeneous thus limits the overall performance of the blend. Therefore, in this study, silicon dioxide (SiO2) filler was incorporated into the polymer blend film to improve the homogeneity and the ionic conductivity of the system. It was found that the addition of SiO2 has succesfully improve the homogeneity of the blend by assisting the dispersion of ENR 50 in the blend and hence provide better conducting path for the lithium ion. This was confirmed from its differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) and optical microscopic (OM) analyses.

Influence of KMnO4 concentration and treatment time on PAN precursor and the resulting carbon nanofibers’ properties

e-Polymers ◽  
2014 ◽  
Vol 14 (5) ◽  
pp. 363-372 ◽  
Author(s):  
Shamim Zargham ◽  
Saeed Bazgir ◽  
Ali Asghar Katbab ◽  
Abosaeed Rashidi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Treatment Time ◽  
Exothermic Reaction ◽  
Reaction Times ◽  
Cyclization Reactions ◽  
Scanning Calorimetry ◽  
Clear Peak ◽  
Scanning Electron

AbstractElectrospun polyacrylonitrile (PAN) nanofibers were impregnated with KMnO4 under varying conditions of concentration and time. The morphological structures, chemical and thermal properties were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The original and preoxidized samples were stabilized and carbonized for characterization with SEM and FTIR. The coloration, weight gain and solubility in N,N-dimethylformamide were also evaluated. A clear peak at 2340 cm-1 corresponding to MnO4–C=N conjugation, together with a wide peak at 1650 cm-1, was revealed in the FTIR spectrum of the preoxidized samples. Based on the DSC results, the cyclization reactions in the preoxidized samples were accelerated by initiating the exothermic reaction at lower temperatures. The modified samples had higher reaction times and ΔH values, broad exotherms, lower initial induction time and lower Ti values than the untreated ones.

The Synthesis and Solubility of a Wholly Aromatic Polyamide Containing Para- and Meta-Substituted Phenylene Rings

2013 ◽  
Vol 320 ◽  
pp. 488-494 ◽  
Author(s):  
Yi Fan Wang ◽  
Jun Sun ◽  
Li Xing Dai
Keyword(s):  
Differential Scanning Calorimetry ◽  
Aromatic Polyamide ◽  
Chain Structure ◽  
Aminobenzoic Acid ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Aromatic Polyamides ◽  
Ft Ir ◽  
Chain Transformation ◽  
Ir And Raman

A series of wholly aromatic polyamides (aramid) containingpara- andmeta-substituted phenylene rings was copolymerized via phosphorylation method with different ratio of 4-aminobenzoic acid and 3-aminobenzoic acid. The inherent viscosities (ηinh) of products were 0.52-0.99 dL/g. The chain structure of the polymers was characterized by Fourier transform infrared spectroscopy (FT-IR) and Raman spectrum. The differential scanning calorimetry (DSC) was also performed to investigate the chain transformation behavior of aramid. With increasing the content ofmeta-substituted phenylene rings in macromolecular chain, the solubility of the polymers was improved obviously without appreciable loss for their original thermal property.

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