scholarly journals Effect of components on the curing of glycidyl azide polymer spherical propellant through rheological method

2018 ◽  
Vol 5 (10) ◽  
pp. 181282 ◽  
Author(s):  
Liming He ◽  
Wei He ◽  
Zhongliang Ma
Keyword(s):  
Activation Energy ◽  
Model Fitting ◽  
Curing Kinetics ◽  
Isoconversional Method ◽  
Mechanical Analysis ◽  
Glycidyl Azide Polymer ◽  
Rheological Method ◽  
Cross Links ◽  
Gap Spherical Propellant ◽  
Glycidyl Azide

We have conducted a novel study of the influence of energy components (RDX, AP and CL-20) on curing kinetics of glycidyl azide polymer (GAP) spherical propellant based on rheological method. The autocatalytic model was used to describe curing kinetics and the parameters were determined by the model-fitting method. It was found that the incorporation of components hinders the cross-linking reaction of GAP spherical propellant. Integral isoconversional method was used on rheological kinetics to investigate the changes of the activation energy and we confirmed that the incorporation of components increased the activation energy. It was also found that such components had no effect on the trend of activation energy curves but shrank the peak value at a = 0.2. Dynamic mechanical analysis (DMA) showed the differences between pure curing system and its components. These findings are potentially helpful to control the curing effectively and optimize the processing schedules. The addition of components decreased α translation temperature which means the reduction in cross-links. The differences in the values of loss factor tan δ and β translation showed that pure curing system has lower resistance for side chain to motion.

scholarly journals Mechanical and Thermal Properties of Polyether Polytriazole Elastomers Formed by Click-Chemical Reaction Curing Glycidyl Azide Polymer

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1988 ◽  
Author(s):  
Liming He ◽  
Jun Zhou ◽  
Yutao Wang ◽  
Zhongliang Ma ◽  
Chunlin Chen
Keyword(s):  
Click Reaction ◽  
Hot Spot ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Random Copolymers ◽  
Mechanical And Thermal Properties ◽  
Glycidyl Azide Polymer ◽  
Ordered Structures ◽  
The Cross ◽  
Glycidyl Azide

Energetic binders are a research hot-spot, and much emphasis has been placed on their mechanical properties. In this study, propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PTPET) was synthesized. Then, PTPET and low-molecular-weight ester-terminated glycidyl azide polymer (GAP) were reacted by the click reaction without using catalysts to obtain a polyether polytriazole elastomer. Through tensile tests, where R = 0.5, the tensile strength reached 0.332 MPa, with an elongation at break of 897.1%. Swelling tests were used to measure the cross-linked network and showed that the cross-linked network regularity was reduced as R increased. The same conclusions were confirmed by dynamic mechanical analysis (DMA). In DMA curves, Tg was around −70 to −65 °C, and a small amount of crystallization appeared at between −50 and −30 °C, because locally ordered structures were also present in random copolymers, thereby forming localized crystals. Their thermal performance was tested by Differential Scanning Calorimeter (DSC) and Thermal Gravimetric Analyzer (TG), and the main mass loss occurred at around 350 to 450 °C, which meant that they were stable. In conclusion, the polyether polytriazole elastomer can be used as a binder in a composite propellant.

scholarly journals ISOTHERMAL CURING KINETICS OF POLYMETHACRYLIMIDE/NANO-SiO2 COMPOSITES BASED ON A DYNAMIC THERMOMECHANICAL ANALYSIS

2021 ◽  
Vol 55 (2) ◽  
pp. 293-304
Author(s):  
Jing Zhang ◽  
Yi-min Wu ◽  
Xu Ma ◽  
Bao-Yu Huang ◽  
Song Lv ◽  
...  
Keyword(s):  
Activation Energy ◽  
Integral Method ◽  
Model Fitting ◽  
Curing Kinetics ◽  
Thermomechanical Analysis ◽  
Avrami Model ◽  
Nano Sio2 ◽  
Friedman Method ◽  
Kinetics Of ◽  
Relative Conversion

The isothermal curing kinetics of polymethacrylimide/nano-SiO2 composites were investigated using a dynamic thermomechanical analysis. The relative conversion was defined with the storage modulus. The Avrami model-fitting method, Friedman method and integral method were applied to analyze the curing kinetics. The storage modulus and loss modulus increased appreciably, spanning three orders of magnitude throughout the curing. The frequency correlation of the relative conversion was noticeable at 180 °C because the glass transition took place when the curing degree was not high enough. The Avrami model-fitting analysis gave good fits for the experimental data. The activation energy calculated with the Avrami equation changed from 65.46 kJ/mol to 25.28 kJ/mol at 180–190 °C, while at 190–200 °C, the activation energy changed from 107.14 kJ/mol to 63.82 kJ/mol. The model-free analysis revealed the dependence of the activation energy on the relative conversion. The activation energy increased from 104.3 kJ/mol to 130.6 kJ/mol with the use of the Friedman method when the relative conversion ranged between 0.4–0.8. Similarly, the activation energy calculated with the integral method increased from 71.5 kJ/mol to 103.4 kJ/mol. When the relative conversion exceeded 0.8, the activation energy decreased gradually. The mobility of the reactive groups was hindered and the crosslinking density of the composite was much higher. The curing kinetics became diffusion controlled. The activation energy of the PMI/SiO2 composite was greater than that of PMI, which could be attributed to the hindrance effect caused by nano-SiO2.

Influence of carbon nanofillers on the curing kinetics of epoxy-amine resin

RSC Advances ◽  
2015 ◽  
Vol 5 (110) ◽  
pp. 90437-90450 ◽  
Author(s):  
L. Vertuccio ◽  
S. Russo ◽  
M. Raimondo ◽  
K. Lafdi ◽  
L. Guadagno
Keyword(s):  
Activation Energy ◽  
Curing Kinetics ◽  
Isoconversional Method ◽  
Epoxy Amine ◽  
Carbon Nanofillers ◽  
Advanced Isoconversional Method ◽  
Kinetics Of

Variation of the activation energy with conversion obtained by “advanced isoconversional method”.

scholarly journals Thermal decomposition and their kinetics of mercury(ii) perchlorate complex with 4-aminopyridine and water

2019 ◽  
Vol 8 (3) ◽  
pp. 649-653
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Rapid Heating ◽  
Model Fitting ◽  
Isoconversional Method ◽  
Molecular Formula ◽  
Isothermal Tg ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Perchlorate Complex

Copper perchlorate complex with 4-aminopyridine and water has been prepared with molecular formula [Hg2(C5H6N2)3(ClO4)4].2H2O. It has been characterised by elemental analysis, thermogravimetry, and IR spectroscopic data. Thermal behaviours have been studied by thermogravimetry (TG) in static air and simultaneous thermogravimetry-derivative thermogravimetry analysis (TG-DTG) in flowing nitrogen atmosphere. Complex decomposes in four steps (less resolved). Difference in decomposition under air and inert atmosphere has been also discussed. Kinetics of thermal decomposition has been investigated using isothermal TG data recorded at five different temperatures applying model-fitting as well as isoconversional method on these data. Model-fitting methods have yielded a single value of activation energy whereas isoconversional method has given different values of activation energy for each extent of conversion, α. Response of synthesized complex towards rapid heating has been investigated by recording explosion delay time (DE) at five different temperatures and using these data kinetics of explosion has been analysed. Activation energy for explosion has been also calculated.

scholarly journals Curing kinetics of two commercial urea-formaldehyde adhesives studied by isoconversional method

2011 ◽  
Vol 65 (6) ◽  
pp. 717-726 ◽  
Author(s):  
Mladjan Popovic ◽  
Jaroslava Budinski-Simendic ◽  
Mirjana Jovicic ◽  
Joszef Mursics ◽  
Milanka Djiporovic-Momcilovic ◽  
...  
Keyword(s):  
Activation Energy ◽  
Urea Formaldehyde ◽  
Curing Kinetics ◽  
Isoconversional Methods ◽  
Isoconversional Method ◽  
Reaction Enthalpy ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Kinetics Of

Differential scanning calorimetry (DSC) was used to evaluate the curing kinetics of two commercial urea-formaldehyde (UF) adhesives having different formaldehyde to urea (F/U) ratio of 1.112 (UF1) and 1.086 (UF2). DSC measurements were done in dynamic scanning regime with heating rates of 5, 10, 15 and 20?C?min-1 in order to determine the activation energy for each adhesive. Obtained data were analyzed using isoconversional methods with application of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose kinetic models. In addition, different catalyst levels were tested at the heating rate of 10?C/min. Results showed that the adhesive with higher F/U ratio achieved higher activation energy, while having lower peak temperature of curing reaction. It was also noticed that the increase of catalyst level influenced the increase of reaction enthalpy of the adhesive with lower F/U ratio.

DEVELOPMENT OF A DIRECT INJECTION GAS-HYBRID ROCKET SYSTEM USING GLYCIDYL AZIDE POLYMER

2019 ◽  
Vol 18 (2) ◽  
pp. 157-170
Author(s):  
Yutaka Wada ◽  
S. Hatano ◽  
Ayana Banno ◽  
Yo Kawabata ◽  
Hiroshi Hasegawa ◽  
...  
Keyword(s):  
Direct Injection ◽  
Hybrid Rocket ◽  
Glycidyl Azide Polymer ◽  
Rocket System ◽  
Glycidyl Azide

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

Thermo-catalytic decomposition of polystyrene waste: Comparative analysis using different kinetic models

2019 ◽  
Vol 38 (2) ◽  
pp. 202-212 ◽  
Author(s):  
Ghulam Ali ◽  
Jan Nisar ◽  
Munawar Iqbal ◽  
Afzal Shah ◽  
Mazhar Abbas ◽  
...  
Keyword(s):  
Activation Energy ◽  
Copper Oxide ◽  
Solid Waste ◽  
Thermodynamic Parameters ◽  
Model Fitting ◽  
Catalytic Decomposition ◽  
Decomposition Reaction ◽  
Inert Atmosphere ◽  
Heating Rates ◽  
Model Free

Due to a huge increase in polymer production, a tremendous increase in municipal solid waste is observed. Every year the existing landfills for disposal of waste polymers decrease and the effective recycling techniques for waste polymers are getting more and more important. In this work pyrolysis of waste polystyrene was performed in the presence of a laboratory synthesized copper oxide. The samples were pyrolyzed at different heating rates that is, 5°Cmin−1, 10°Cmin−1, 15°Cmin−1 and 20°Cmin−1 in a thermogravimetric analyzer in inert atmosphere using nitrogen. Thermogravimetric data were interpreted using various model fitting (Coats–Redfern) and model free methods (Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman). Thermodynamic parameters for the reaction were also determined. The activation energy calculated applying Coats–Redfern, Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman models were found in the ranges 105–148.48 kJmol−1, 99.41–140.52 kJmol−1, 103.67–149.15 kJmol−1 and 99.93–141.25 kJmol−1, respectively. The lowest activation energy for polystyrene degradation in the presence of copper oxide indicates the suitability of catalyst for the decomposition reaction to take place at lower temperature. Moreover, the obtained kinetics and thermodynamic parameters would be very helpful in determining the reaction mechanism of the solid waste in a real system.

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