scholarly journals On the effect of the flexibility parameter on thermody­namic properties of acrylonitrile and methylvinylpyridine copolymers

2020 ◽  
pp. 71-79
Author(s):  
O.I. Romanko ◽  
E.A. Eliseeva
Keyword(s):  
Thermal Analysis ◽  
Copolymer Composition ◽  
Relaxation Processes ◽  
Segmental Mobility ◽  
Vitrification Temperature ◽  
Filter Materials ◽  
Temperature Ranges ◽  
Effects Of Temperature ◽  
Flexibility Parameters ◽  
Manufacturing Parameters

We used thermal analysis to investigate the effects of temperature (20--300 °C) on the behaviour of acrylonitrile and methylvinylpyridine copolymers and determine the temperature ranges in which segmental mobility develops in them, as well as their glass transition temperatures. Data obtained via differential thermal analysis allowed us to compute activation energies for vitrification processes in copolymers of the series specified and to plot vitrification temperature as a function of copolymer composition. We used the method of increments to compute flexibility parameters for acrylonitrile and 2-methyl-5-vinylpyridine and analyse the effects of flexibility parameters on the manifestation of relaxation processes. The data obtained may be used to amend manufacturing parameters when developing chemisorptive filter materials based on the specified copolymer series.

Studies on the Temperature Stability of Pure and Doped Triglycine Sulphate Crystals Using TGA/DTA

2020 ◽  
Vol 10 (3) ◽  
pp. 206-212
Author(s):  
Vijeesh Padmanabhan ◽  
Maneesha P. Madhu ◽  
Supriya M. Hariharan
Keyword(s):  
Thermal Analysis ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Temperature Stability ◽  
Bandgap Energy ◽  
Dsc Analysis ◽  
Slow Cooling ◽  
As Doping ◽  
Similar Dependence ◽  
Temperature Ranges

Aim: To study the temperature stability of TGS doped with ZnSO4, CdCl2, BaCl2, and compare it with that of pure TGS. Objectives: Synthesizing pure and doped TGS and studying their temperature dependence using TGA, DTA, and DSC analysis. Methods: Slow cooling solution growth was used to grow single crystals of pure and doped TGS. The TGA, DTA and DSC analysis was conducted for determining the temperature stability. Results: The thermal analysis of pure and doped TGS shows that the doped samples show a similar dependence on temperature as pure TGS. The temperature of decomposition of pure and doped samples (BTGS, ZTGS, CdTGS) was 226.60°C, 228.38°C, 229.13°C, and 239.13°C respectively. The melting onset of these samples was 214.51°C, 216.04°C, 217.69°C and 216.04°C respectively. Conclusion: The study shows that doping TGS with the above three described materials did not alter their temperature stability considerably. It is a good result as doping TGS, for varying its characteristics like absorbance, reflectance, bandgap energy, etc., which did not alter its temperature stability. Therefore, TGS doped with the above three dopants can be used at the same temperature ranges as of pure TGS but with much-improved efficiency.

scholarly journals Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4215
Author(s):  
Roxana E. Patru ◽  
Hamidreza Khassaf ◽  
Iuliana Pasuk ◽  
Mihaela Botea ◽  
Lucian Trupina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Current Knowledge ◽  
Cubic Phase ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Low Field ◽  
Conduction Mechanisms ◽  
Temperature Ranges ◽  
Nyquist Plots

The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

scholarly journals Kinetic study of Mongolian coals by thermal analysis

2018 ◽  
Vol 18 (44) ◽  
pp. 20-23
Author(s):  
Jargalmaa S ◽  
Tsatsral G ◽  
Battsetseg M ◽  
Batkhishig D ◽  
Ankhtuya A ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thermal Characterization ◽  
Low Rank ◽  
Weight Changes ◽  
Heating Rates ◽  
Weight Losses ◽  
Brown Coals ◽  
Temperature Ranges ◽  
Kinetics Of

Thermal analysis was used for the thermal characterization of the coal samples. The experiments were performed to study the pyrolysis and gasification kinetics of typical Mongolian brown coals. Low rank coals from Shivee ovoo, Ulaan ovoo, Aduun chuluun and Baganuur deposits have been investigated. Coal samples were heated in the thermogravimetric apparatus under argon at a temperature ranges of 25-1020ºC with heating rates of 10, 20, 30 and 40ºC/min. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were performed to measure weight changes and rates of weight losses used for calculating the kinetic parameters. The activation energy (Ea) was calculated from the experimental results by using an Arrhenius type kinetic model.

Thermal Analysis of Concrete from Panels Subjected to Fire Experiments

2018 ◽  
Vol 272 ◽  
pp. 47-52 ◽  
Author(s):  
Hana Šimonová ◽  
Iva Rozsypalová ◽  
Pavla Rovnaníková ◽  
Petr Daněk ◽  
Zbyněk Keršner
Keyword(s):  
Thermal Analysis ◽  
Heated Surface ◽  
Cement Matrix ◽  
Concrete Panels ◽  
Diamond Blade ◽  
Nominal Thickness ◽  
Temperature Load ◽  
Effects Of Temperature ◽  
Temperature Loads ◽  
Nominal Temperature

This paper presents the results of the differential thermal analysis of cement matrix samples taken from concrete panels with nominal dimensions of 2300 × 1300 × 150 mm after one-sided exposure to high temperatures. The panels were subjected to maximum nominal temperature loads of 550, 600, 800 and 1000 °C. Concrete was also taken from a reference panel (without temperature loading) and investigated. Five samples with a nominal thickness of 20 mm were taken for thermal analysis. They were cut from the central part of the panels using a diamond blade saw. The thermal analysis covered the effects of temperature load on the concrete to a depth of approximately 100 mm from the heated surface of the panel.

GeCu/Si Bilayer Thin Film for Write-Once Blue Laser Optical Recording Media

2010 ◽  
Vol 123-125 ◽  
pp. 687-690
Author(s):  
Sin Liang Ou ◽  
Po Cheng Kuo ◽  
Don Yau Chiang ◽  
Chin Yen Yeh ◽  
Shih Hsien Ma ◽  
...  
Keyword(s):  
Thin Film ◽  
Thermal Analysis ◽  
Optical Recording ◽  
Blue Laser ◽  
Bilayer Film ◽  
Recording Media ◽  
Dynamic Tests ◽  
Protective Layers ◽  
Temperature Ranges ◽  
Polycarbonate Substrate

GeCu(6 nm)/Si(6 nm) bilayer recording thin film was deposited on nature oxidized silicon wafer and polycarbonate substrate by magnetron sputtering. The ZnS-SiO2 films were used as protective layers. We have studied the thermal property, crystallization mechanism, and recording characteristics of the GeCu/Si bilayer thin film. Thermal analysis shows that the GeCu/Si bilayer film has two reflectivity changes with the temperature ranges, 120 °C ~ 165 °C and 310 °C ~ 340 °C. The results of dynamic tests show that the optimum jitter values at recording speeds of 1X and 4X are 5.8% and 5.9%, respectively. The modulations at 1X and 4X recording speeds are all larger than 0.4.

Thermal Response Analysis and FE Modeling of Weapon

2012 ◽  
Vol 503-504 ◽  
pp. 11-14
Author(s):  
Yan Jun Zhao ◽  
Xin Jun Li ◽  
Yong Hai Wu ◽  
Cheng Xu
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Research Work ◽  
Thermal Response ◽  
Element Model ◽  
Response Analysis ◽  
Fe Modeling ◽  
Effects Of Temperature ◽  
The Finite Element Model

Thermal is a important factor that affect weapon firing accuracy and security in the process of weapon fire, so thermal analysis of weapon has important meaning . Aim at researched Weapon, the finite element model of the gun body was built, the temperature field of the gun body was calculated by FEM. The effects of temperature of the gun body on firer and aiming mechanism were also studied. Current research work will be helpful the weapon design

Thermal analysis of complex relaxation processes in poly(desaminotyrosyl-tyrosine arylates)

Polymer ◽  
2007 ◽  
Vol 48 (4) ◽  
pp. 975-988 ◽  
Author(s):  
George Collins ◽  
Seung-uk Yoo ◽  
Ali Recber ◽  
Michael Jaffe
Keyword(s):  
Thermal Analysis ◽  
Relaxation Processes

scholarly journals Functionalization and Chemical Modification of 2-Hydroxyethyl Methacrylate with Carboxylic Acid

2012 ◽  
Vol 9 (3) ◽  
pp. 1135-1144 ◽  
Author(s):  
Mohammad Hossein Nasirtabrizi ◽  
L. Zargin ◽  
S. Khodabandlou ◽  
S. Rostamzadeh Mansour
Keyword(s):  
Thermal Analysis ◽  
Free Radical ◽  
Carboxylic Acid ◽  
Addition Reaction ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Hydroxyethyl Methacrylate ◽  
H Nmr ◽  
Temperature Ranges ◽  
Ft Ir

Free radical polymerization of the resulting monomers methyl methacrylate (MMA), ethyl methacrylate (EMA), methylacrylate (MA) and ethylacrylate (EA) with 2-hydroxyethyl methacrylate (HEMA) (in 1:1 mole ratio) were carried out using azobis(isoboutyronitrile) (AIBN) as initiator at the temperature ranges 60-70°C. The modification of polymers were carried out by 9-anthracenecarboxylic acid (9-ACA) via the esterification reaction between —OH of poly(HEMA) and —COOH of 9-ACA, in presence of N,N′-dicyclohexyl-carbodiimide (DCC), 4-(dimethylamino) pyridine (DMAP) and N,N-dimethyl formamid (DMF). It was found that the molar ratio acid/alcohol/catalysts= 0.02: 0.02: 0.02 and 0.002, optimal for preparation of the ester. As demonstrated by FT-IR,1H-NMR and dynamic mechanical thermal analysis (DMTA). The Tg value of methacrylate and acrylate copolymers containing 9-ACA groups was found to increase with incorporation of 9-ACA groups in polymer structures. The presence of 9-ACA groups in the polymer side chains created new polymers with novel modified properties that find some applications in polymer industry. These anthracenic factors could take part in cyclo addition reaction with other factors such as anhydrides and kinons.

scholarly journals Thermal Analysis Impact for Hydrates Formation in Oil  & Gas Pipelines

2020 ◽  
Vol 1 (1) ◽  
pp. 16-19
Author(s):  
Tommaso De Pippo ◽  
Tatiana Vasco ◽  
António José
Keyword(s):  
Thermal Analysis ◽  
Thermal Conduction ◽  
Piping System ◽  
Gas Pipelines ◽  
Operating Life ◽  
Gas Industry ◽  
Temperature Ranges ◽  
The Impact ◽  
Oil Gas

The  Oil  &  Gas  industry  has  grown  and  new  discoveries  and  technologies  have  risen  in  order  to  accommodate  the  dynamics   of  such  industry.  With  investments  ranging  billions  of  US  Dollars  is  mandatory  to  create  measures  to  avoid  pressure  vs   temperature  related  issues  during  the  extraction,  transportation  and  of  the  crude  in  order  to  minimize  losses  and  maximize   the  profit  (Borsani,  2001).  Hydrates  in  oil&  gas  pipelines  poses  a  very  big  issue  to  the  industry.  Hydrates  are  normally  formed   when  the  adequate  conditions  (gas,  water,  compatible  pressures  and  temperature  ranges)  are  present.  They  are  in  the   market  several  methodologies  to  prevent  the  evolution  or  emerging  of  hydrates.  An  adequate  thermal  study  during  the   design  of  the  pipeline  and  its  insulation  layers,  constitutes  a  greater  value  on  the  path  to  avoid  hydrates  formation  during   the  pipeline  operating  life.  On  This  paper  the  study  is  dedicated  on  the  impact  of  thermal  analysis  in  one  of  the  pipelines   operating  in  one  of  the  Angolans  Offshore  fields.  COSMOS  Geostar  is  the  tool  used  for  the  investigation.  The  study  was   conducted  in  a  pipeline  considering  the  thermal  conduction  through  a  normal  pipe  section  and  the  thermal  conduction   through  a  field  joint.  This  project  has  proven  the  efficiency  of  COSMOS  in  assisting  on  the  determination  of  a  proper  type,   nature  and  size  of  insulation  to  be  applied  in  a  certain  piping  system  for  crude  oil  production  and/or  transport.    

MAGNETIC PROPERTIES OF AMORPHOUS Fe40Ni38B18Mo4 RIBBONS CONTAINING NANOCRYSTALLITES

2005 ◽  
Vol 19 (06) ◽  
pp. 295-302 ◽  
Author(s):  
K. TIVAKORNASITHORN ◽  
S. NILPAIRUCH ◽  
S. VATANAYON ◽  
I. M. TANG
Keyword(s):  
Thermal Analysis ◽  
Magnetic Properties ◽  
Differential Thermal Analysis ◽  
Saturation Magnetization ◽  
Mössbauer Effect ◽  
Vibrating Sample Magnetometer ◽  
Mossbauer Effect ◽  
Mössbauer Effect Spectroscopy ◽  
Temperature Ranges ◽  
Xrd Patterns

Cut Fe 40 Ni 38 B 18 Mo 4 ribbons were annealed for two hours at various temperatures Ta between 400 and 540°C. All the ribbons were subjected to XRD, VSM (vibrating sample magnetometer) and ME (Mossbauer effect spectroscopy) investigations. A differential thermal analysis scan of an as-cast ribbon showed the presence of two exothermic peaks, the first beginning at 419.9°C and peaking at 429.7°C and the second beginning at 497.3°C and ending at 546.2°C. The XRD patterns of the ribbons showed the formation of FeNi 3 nanocrystallites in the lower T'a ribbons and (Fe, Ni, Mo) 23 B 6 crystallites in the ribbons annealed above 470°C. Different behaviors of the saturation magnetization were seen in the ribbons annealed between 400 and 450°C, between 450 and 490°C, and between 490 and 540°C. The ME spectra of the ribbons annealed in the three different temperature ranges also pointed to the presence of three crystalline Fe-compounds in these ranges. The XRD patterns and the coercivities (Hc) of the lower Ta ribbons point to the formation of nanocrystallites in these ribbons.

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