Search for: differential-scanning-calorimetry
Total 107 records
New polysaccharide-g-polyacrylonitrile copolymers: synthesis and thermal characterization [electronic resource], Article Polymers for Advanced Technologies ; Volume 14, Issue 7, pages 508–516, July 2003 ; Pourjavadi, Ali ; Sharif University of Technology
Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric-initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were...
Article Journal of Thermal Analysis and Calorimetry ; Volume 92, Issue 3 , 2008 , Pages 917-920 ; 13886150 (ISSN) ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
Using two techniques of thermogravimetry and differential scanning calorimetry under O2 gas atmosphere from 25 to 600°C, the thermal behavior of laboratory-produced compound lead(IV) oxide α-PbO2 was investigated. The identity of products at different stages were confirmed by XRD technique. Both techniques produced similar results supporting the same decomposition stages for the compound. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported. © 2008 Springer Science+Business Media, LLC
Relationship between the stored energy and indentation hardness of copper after compression test: Models and measurements, Article Journal of Materials Science ; Volume 43, Issue 10 , 2008 , Pages 3500-3504 ; 00222461 (ISSN) ; Sharif University of Technology
Utilizing the differential scanning calorimetry (DSC) and Vickers hardness tests, the relationship between the stored energy and indentation hardness of copper after compression test is achieved experimentally. Three dislocation models are utilized to develop the relationships between the stored energy and hardness for justifying the experimental relationship. The relationships show that the stored energy is increased by increasing the hardness, non-linearly. By comparing the models' results with the experimental data, the validity of each model at different ranges of hardness is determined. © 2008 Springer Science+Business Media, LLC
Article Polymers for Advanced Technologies ; Volume 14, Issue 7 , 2003 , Pages 508-516 ; 10427147 (ISSN) ; Pourjavadi, A ; Sharif University of Technology
Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using cericinitiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were...
M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza
Blend of Polycarbonate/ poly(butylene terephthalate) is among the most famous blends of polycarbonate/polyester with vast engineering applications and unique properties. Miscibility and compatibilization of this blend are important as they directly influence the general properties.Transesterification which occurs in the melt state, is a series of cutting and rejoining of dissimilar polymer chains. The reaction ruins the order of pure chains and forms block copolymers of different natures. Further progress in transesterification lead into a completely random copolymer of initial chains. Time, temperature and addition of catalyst can effectively influence transesterification.In this study,...
Article Journal of Thermal Analysis and Calorimetry ; Vol. 116, Issue. 2 , 2014 , pp. 915-921 ; ISSN: 13886150 ; Khaleghian, M ; Sharif University of Technology
Using two techniques of thermogravimetry and differential scanning calorimetry under O2 and N2 gas atmosphere from 25 to 600 °C, the thermal behavior of chromium(VI) oxide CrO3 was investigated. The identity of products at different decomposition steps was confirmed by XRD technique. Both techniques produced similar results supporting the same steps for the compound. The received products were investigated by SEM electron microscope. The form and the size of crystals were investigated. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported
Article Iranian Endodontic Journal ; Volume 11, Issue 4 , 2016 , Pages 286-292 ; 17357497 (ISSN) ; Khalatbari, M. S ; Meraji, N ; Ghorbanzadeh, A ; Sadri, E ; Sharif University of Technology
Iranian Association of Endodontics 2016
Introduction: The aim of this study was to compare several metallurgic properties of Neoniti instrument with four other commonly used endodontic rotary files. Methods and Materials: Neoniti A1 (25/0.08), RaCe (25/0.06), Mtwo (25/0.06), Twisted file (25/0.06) and ProTaper Next X2 (25/0.06) were examined by differential scanning calorimetry (DSC) before and after heat treatment at 500°C. X-ray diffraction (XRD) was also performed on the specimens. Furthermore, scanning electron microscopy (SEM) and x-ray energy-dispersive spectrometric (EDS) analyses were carried out on randomly selected fractured files. Results: In SEM tests, dimpled ruptures, characteristic of ductile fracture, were seen in...
Thermal behavior of alkaline lead acetate, a study of thermogravimetry and differential scanning calorimetry, Article Scientia Iranica ; Volume 15, Issue 4 , 2008 , Pages 435-439 ; 10263098 (ISSN) ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
Sharif University of Technology 2008
The compound, alkaline lead acetate, Pb(CH3COO)2·PbO·H2O (ALA), was purchased from the Fluka Company. The X-ray diffraction film and SEM electron microgaph of this compound were obtained and reported in this paper for the first time. The thermal behavior of alkaline lead acetate (ALA) was studied using thermogravimetery (TGA) and Differential Scanning Calorimetery (DSC) techniques under an O2 gas atmosphere from 25 to 600°C. Four distinct energy changes associated with weight changes were observed, all of them being exothermic in the DSC results. The amount of ΔH for each peak is reported. © Sharif University of Technology
Article Materials Science and Technology ; Volume 23, Issue 8 , 2007 , Pages 987-991 ; 02670836 (ISSN) ; Sadmezhaad, K ; Barber, Z. H ; Sharif University of Technology
In the present paper, the fabrication and characterisation of typical high temperature Ni(Ti+ Hf) alloyed thin films produced by simultaneous sputter deposition from separate elemental Ni, Ti and Hf targets are presented. Film composition, determined by energy dispersive X-ray spectroscopy, was controlled by adjusting the ratio of powers applied to each target. Films deposited at room temperature had an amorphous structure and subsequent annealing at 550°C was carried out in a high vacuum environment, based on crystallisation temperature evaluation by differential scanning calorimetry (DSC). High temperature martensitic transformation, confirmed by DSC and variable temperature X-ray...
Article Polymers for Advanced Technologies ; Volume 16, Issue 9 , 2005 , Pages 659-666 ; 10427147 (ISSN) ; Faraji Dana, S ; Zohuriaan Mehr, M. J ; Sharif University of Technology
Novel hydrogels based on zwitterionic monomer [3-(methacrylamido)propyl] dimethyl (3-sulfopropyl) ammonium hydroxide (MPDSAH) and a strong acid monomer (2-acrylamido-2-methylpropane sulfonic acid, AMPS) were synthesized through solution polymerization under normal conditions to achieve nearly quantitative gel yield. The structure of the gels was confirmed using infrared spectroscopy. Thermal properties were simultaneously studied by differential scanning calorimetry and thermogravimetric analysis (DSC/TGA). The effects of the polymerization variables on the swelling capacity of the products were investigated. It was found that, in a certain range of the monomers mol ratio, increase of AMPS...
Article Journal of Applied Polymer Science, New York, NY, United States ; Volume 77, Issue 5 , 2000 , Pages 1144-1153 ; 00218995 (ISSN) ; Zamanlu, M. R ; Zohuriaan Mehr, M. J ; Sharif University of Technology
John Wiley & Sons Inc 2000
Tetraphenylthiophene diamine (TPTDA) was prepared through a modified three-step route to achieve an improved overall yield. TPTDA reacted with succinic, adipic, suberic, sebasic, and fumaric acids via the Yamazaki phosphorylation method to yield novel partially aromatic polyamides (TPT series). A counterpart polyamide series based on p-phenylene diamine (Ph series) was also synthesized under the same conditions. All of the polymers were characterized by means of spectrochemical (Fourier transform infrared spectroscopy. 1H-nuclear magnetic resonance (NMR), and 13C-NMR) and thermal (differential scanning calorimetry and thermogravimetric) methods of analysis. Solubility of TPT polyamides was...
Differential scanning calorimetry study of constrained groove pressed low carbon steel: Recovery, recrystallisation and ferrite to austenite phase transformation, Article Materials Science and Technology (United Kingdom) ; Vol. 30, issue. 7 , 2014 , pp. 765-773 ; ISSN: 02670836 ; Kazeminezhad, M ; Sharif University of Technology
Low carbon steel sheets are subjected to severe plastic deformation (SPD) via constrained groove pressing (CGP) up to five passes. As a result of this process, strain magnitude up to 5?8 is imposed to the sheets, which leads to grain size of 225 nm. These nanostructured steel sheets, due to their high dislocation density and ultrafine microstructure, are very sensitive to heating. In the present study, recovery, recrystallisation and ferrite to austenite phase transformation phenomena for the SPD steel are investigated using differential scanning calorimetry method. The results show that with increasing the strain in steel sheets, the deformed stored energy (released through recovery and...
Effects of non-isothermal annealing on microstructure and mechanical properties of severely deformed 2024 aluminum alloy, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 27, Issue 1 , 2017 , Pages 1-9 ; 10036326 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Nonferrous Metals Society of China 2017
Microstructure and mechanical properties of AA2024 after severe plastic deformation (SPD) and non-isothermal annealing were investigated. The non-isothermal treatment was carried out on the severely deformed AA2024, and the interaction between restoration and precipitation phenomena was investigated. Differential scanning calorimetry, hardness and shear punch tests illustrate that static recovery and dissolution of GPB zones/Cu–Mg co-clusters occur concurrently through non-isothermal annealing. Scanning electron microscope and electron backscatter diffraction illustrate that non-isothermal annealing of deformed AA2024 up to 250 °C promotes the particle-free regions and also particle...
Correlation between isothermal crystallization properties and slow crack growth resistance of polyethylene pipe materials, Article Polymer Testing ; Volume 80 , 2019 ; 01429418 (ISSN) ; Pircheraghi, G ; Rashedi, R ; Sepahi, A ; Sharif University of Technology
Elsevier Ltd 2019
In this study, three PE100 polyethylene materials with fairly different short chain branch distributions were used to characterize the relation between thermal properties and creep test failure time. The samples were thermally characterized using isothermal and non-isothermal differential scanning calorimetry (DSC). The three resins showed different behavior after fitting on the Avrami equation. N-100J2 sample, in which short chain branches (SCBs) are located on longer molecule chains, has a lower chain mobility and higher crystallization time, while N-100J1 has the opposite crystallization properties. Also, these samples had different Avrami index, n. Microstructural evaluation of these...
M.Sc. Thesis Sharif University of Technology ; Forounchi, Masoud
Semi-crystalline polylactic acid (PLA) and amorphous polymethyl methacrylate can form a soluble and miscible alloy in which the crystalline regions in the polylactic acid act as the fixed and immutable region and amorphous regions of the two polymers act as the changeable region. The two polymers can form a lattice structure with physical connections having shape-memory. So that the deformed polymer returns to its original shape above a certain temperature. These materials are used in sensors, smart materials, and medicine. On the other hand, Polyethylene glycol (PEG) is compatible with polylactic acid (PLA) and it seems that adding it will increase the ductility of polylactic acid (PLA). In...
Article Polymer Composites ; Vol. 35, issue. 1 , January , 2014 , pp. 37-44 ; ISSN: 02728397 ; Ahmad Ramazani, S. A ; Jafariesfad, N ; Sharif University of Technology
We present the preparation of polypropylene (PP)/fumed silica (FS) nanocomposites via in situ polymerization in this article. The approach includes preparation and utilization of a bisupported Ziegler-Natta catalytic system in which magnesium ethoxide and FS are used as conjugate supports of the catalyst. Catalyst preparation and polymerization processes are carried out in the slurry phase and under argon atmosphere. Scanning electron microscopy images show a good dispersion of the FS throughout the PP matrix. Results from differential scanning calorimetry reveal that the crystallization temperature of prepared nanocomposites increases by increasing FS loading. Also, crystal content of...
Nanocrystallization kinetics and magnetic properties of the melt spun amorphous (Fe0.5Co0.5)77Si11B 9Cu0.6Nb2.4 alloy, Article Thermochimica Acta ; Vol. 575, issue , 2014 , p. 64-69 ; Samadi, M ; Alihosseini, H ; Madaah Hosseini, H. R ; Sharif University of Technology
Kinetics of crystallization in an amorphous (Fe0.5Co 0.5)77Si11B9Cu0.6Nb 2.4 (at.%) alloy was investigated using differential scanning calorimetry (DSC). Transformed fraction as a function of temperature was obtained by accurate DSC measurement and the experimental data analyzed with Vyazovkin model-free kinetic method. Reconstructed form of the experimental kinetics model, g(α), clearly showed the crystallization mechanism do not belongs to a single model but almost follows the Avrami-Erofe'ev. Magnetic coercivity and hysteresis loss values of the annealed samples at 823 K were 7.5 A m-1 and 1.2 J m-3, compared to 17.1 A m-1 and 37.1 J m-3 for as spun samples. Magnetic measurements show the...
Article Nanoscale ; Volume 5, Issue 16 , 2013 , Pages 7520-7527 ; 20403364 (ISSN) ; Hosseini, H. R. M ; Davami, P ; Ostadhossein, F ; Song, M ; Gjoka, M ; Sharif University of Technology
The effect of quenching wheel speed on the structure and Curie temperature of Fe73.5Si13.5B9Nb3Cu1 alloy has been investigated using X-ray diffraction, differential scanning calorimetry, transition electron microscopy and a SQUID magnetometer. Ribbons were melt-spun at different wheel speeds and then were annealed to nucleate nano crystals embedded in the amorphous matrix. The results indicated that the thickness of the ribbons was inversely proportional to the wheel speed following the power law of the type t ∝ Vs -1.231. DSC and XRD results showed that at higher wheel speeds the greater potential energy triggers the formation of Fe (Si) crystallites and thus, increases the crystallinity....
Synthesis, characterization and comparison of PAM, cationic PDMC and P(AM-co-DMC) based on solution polymerization, Article Journal of Industrial and Engineering Chemistry ; Volume 17, Issue 3 , 2011 , Pages 580-586 ; 1226086X (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
High molecular weight homopolymers of acrylamide (PAM) and (2-methacryloyloxyethyl) trimethyl ammonium chloride (PDMC) and copolymer of DMC with acrylamide (P(AM-co-DMC)) were synthesized using solution polymerization technique. The synthesized polymers were characterized by Fourier transform infrared (FTIR), 1HNMR, 13CNMR spectroscopy and differential scanning calorimetry (DSC) and viscometery. 1HNMR and 13CNMR studies confirmed the structure of the synthesized polymers. The behavior of the synthesized polymers was investigated in water-acetone and water-methanol mixtures. The plot of intrinsic viscosity of either PAM or P(AM-co-DMC) with respect to acetone (methanol)/water ratio in...
Morphological and mechanical properties of polyamide 6/nanodiamond composites prepared by melt mixing: effect of surface functionality of nanodiamond, Article Polymer International ; Volume 66, Issue 4 , 2017 , Pages 557-565 ; 09598103 (ISSN) ; Shojaei, A ; Sharif University of Technology
John Wiley and Sons Ltd 2017
Surface chemistry of as-received nanodiamond (ND) was first tailored by dry thermal oxidation to obtain carboxylated ND (ND-COOH) and by wet chemistry to obtain ethylenediamine-functionalized ND (ND-EDA). Then, the surface-functionalized ND particles were dispersed in polyamide 6 (PA6) using the melt-mixing method. Transmission optical and scanning electron microscopies indicated a fine dispersion at low nanodiamond concentrations, e.g. 0.25 wt%, particularly with ND-EDA. Differential scanning calorimetry revealed that ND-EDA favoured the α-phase crystal and enhanced the degree of crystallinity of PA6. Experimental data indicated that ND-EDA had considerably improved tensile properties at...