Kinetics of the oxidative aging of phthalonitrile resins and their effects on the mechanical properties of thermosets

Lobanova, Marina; Aleshkevich, V.V.; Yablokov, M.Yu.; Morozov, Oleg S.; Бабкин, А.В.; Кепман, А. В.; Авдеев, В. В.; Bulgakov, Boris A.

doi:10.1016/j.tca.2023.179492

Cited by 10 publications

(5 citation statements)

References 57 publications

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“…And the exposure of EPPN at 350°C resulted in significant degradation of the samples after 50 hours that has not allowed samples to be tested. The greater oxidation rate of EPPN‐375 can be explained by a higher cross‐linking degree of this thermoset and consequently lower fracture toughness that resulted in crack formation and increase in oxidation area 43,60 …”

Section: Resultsmentioning

confidence: 99%

“…One of the characteristics of polymer materials significant for their application in structures operating at elevated temperatures is their thermal and thermal oxidative stability 33–38 . The most common method of thermal and thermal oxidative stability evaluation is non‐isothermal TGA method corresponding to short‐term stability 37,39–41 but there are not a lot of works concerning long‐term isothermal oxidative stability of phthalonitrile resins 38,42–44 …”

Section: Introductionmentioning

confidence: 99%

“…It is worth to mention, that phthalonitrile thermosets post‐cured at temperatures over 375°C demonstrate the highest thermal properties (T g over 400°C and T5% > 500°C) 5,43,45–47 . However, mechanical strength of both resins and composites decreases with post‐curing at higher temperatures 29,48,49 .…”

Section: Introductionmentioning

confidence: 99%

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Effect of post‐curing temperature on the retention of mechanical strength of phthalonitrile thermosets and composites after a long‐term thermal oxidative aging

Lobanova,

Aleshkevich,

Babkin

et al. 2023

Polymer Composites

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This work concerns the thermal‐oxidative aging behavior of phthalonitrile thermosets and composites at 280–350°C. The easy‐to‐process resin containing bis(3‐[3,4‐dicyanophenoxy]phenyl)phenyl phosphate with APB as curing agent and the resin‐based composites post‐cured at 330°C, 350°C, and 375°C were studied. The phthalonitrile thermosets post‐cured at 330°C retained flexural strength of 77 MPa after 200 h of thermal aging at 280°C and 37 MPa (40%) after the same time at 300°C while the resins post‐cured at 350°C and 375°C lost over 80% of the flexural strength in these experiments. The same trend of faster oxidation of the samples post‐cured at higher temperatures was observed for the composites. For the first time, crosslinking reactions were observed during the aging, despite the aging temperatures being below the Tg of thermosets. Thus, the work shows a high long‐term thermal oxidative stability of the studied phthalonitrile resins at temperatures up to 300°C and fast destruction of the materials at 350°C despite the resin decomposition temperatures determined by dynamic TGA being over 500°C. The work has shown the negative effect of high‐temperature post‐curing on the operating properties of the phthalonitrile composites as constructive materials for long‐term application at elevated temperatures.Highlights Oxidation of phthalonitrile thermoset occurs at temperatures over 300°C in air. Increase in post‐curing temperature decreases thermal oxidation resistance. Thermosets retained up to 77% of flexural strength after 200 h aging at 300°C. Composites retained over 90% of ILSS after 200 h of aging at 300°C.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of post‐curing temperature on the retention of mechanical strength of phthalonitrile thermosets and composites after a long‐term thermal oxidative aging

Lobanova,

Aleshkevich,

Babkin

et al. 2023

Polymer Composites

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“…In the past decade, thermal analysis has been widely used in a wide range of fields, including inorganic substances [ 18 ], pigments [ 19 ], explosives [ 20 , 21 , 22 ], energetic materials [ 23 , 24 , 25 , 26 ], polymers [ 27 , 28 , 29 , 30 , 31 , 32 ], nanocomposites [ 33 ], and biomass materials [ 34 , 35 ]. The main techniques used for sample measurements are differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA).…”

Section: Thermokinetic Analysis Methodsmentioning

confidence: 99%

Thermal Hazard Analysis of Two Non-Ideal Explosives Based on Ammonium Perchlorate/Ammonium Nitrate and Aluminium Powder

Guo,

Chen,

et al. 2024

Molecules

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In recent years, various kinds of civil explosive detonation accidents have occurred frequently around the world, resulting in substantial human casualties and significant property losses. It is generally believed that thermal stimulation plays a critical role in triggering the detonation of explosives; consequently, the study of the thermal hazards of explosives is of great significance to many aspects of safety emergency management practices in the production, transportation, storage, and use of explosives. It is known that the thermal stability of the ammonium perchlorate-aluminium system and the ammonium nitrate-aluminium system has been extensively investigated previously in the literature. However, there is a paucity of research on the thermal hazard characteristics of non-ideal explosives under varying oxygen balance conditions within the academic sphere. Therefore, this research focused on the study of the thermal hazards of non-ideal explosives based on thermokinetic analysis. The thermal hazards of non-ideal explosive mixtures of ammonium perchlorate and aluminium and of ammonium nitrate and aluminium were studied by thermal analysis kinetics. The thermokinetic parameters were meticulously studied through differential scanning calorimetry (DSC) analysis. The results showed that the peak reaction temperature and activation energy of the ammonium perchlorate-aluminium system were significantly higher than those of the ammonium nitrate-aluminium system. Under the condition of zero oxygen balance, the peak reaction temperature of the ammonium nitrate-aluminium system was 259 °C (heating rate 5 °C/min), and the activation energy was 84.7 kJ/mol. Under the same conditions, the peak reaction temperature and activation energy of the ammonium perchlorate-aluminium system were 292 °C (heating rate 5 °C/min) and 94.9 kJ/mol, respectively. These results indicate that the ammonium perchlorate-aluminium system has higher safety under the same thermal stimulation conditions. Furthermore, research on both non-ideal explosive systems reveals that the activation energy is at its peak under negative oxygen balance conditions, recorded at 104.2 kJ/mol (ammonium perchlorate-aluminium) and 86.2 kJ/mol (ammonium nitrate-aluminium), which indicates a higher degree of safety. Therefore, the investigation into the thermal hazards of non-ideal explosive systems under different oxygen balance conditions is of utmost importance for the enhancement and improvement of safety emergency management practices.

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“…Specifically, these studies have concentrated on the pyrolysis of bulky PN polymers [34][35][36][37], leaving unknown territory for the thermal degradation behaviors of PN foams. During the aging of the phosphorous PN, Lobanova et al [38] found that the weight loss rate in bulky PN samples was slower than that in PN powders due to a lower surface-to-mass ratio, indicating that the thermal decomposition behavior is tightly related to the sample form. Foam is an important and special form of a polymer since the gas phase may hinder heat transfer and thus retard thermal decomposition [39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Understanding the Thermal Degradation Mechanism of High-Temperature-Resistant Phthalonitrile Foam at Macroscopic and Molecular Levels

Yang,

Li,

Lei

et al. 2023

Polymers

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Polymer foam, a special form of polymer, usually demonstrates some unexpected properties that rarely prevail in the bulky polymer. Studying the thermal degradation behavior of a specific polymer foam is important for its rational design, quick identification, objective evaluation, and industrial application. The present study aimed to discover the thermal degradation mechanism of high-temperature-resistant phthalonitrile (PN) foam under an inert gas atmosphere. The macroscopic thermal decomposition of PN foam was carried out at the cost of size/weight loss, resulting in an increasing number of open cells with pyrolyzation debris. Using the TGA/DTG/FTIR/MS technique, it was found that PN foam involves a three-stage thermal degradation mechanism: (I) releasing gases such as H2O, CO2, and NH3 generated from azo-containing intermediate decomposition and these trapped in the closed cells during the foaming process; (II) backbone decomposition from C-N, C-O, and C-C cleavage in the PN aliphatic chain with the generation of H2O, CO2, NH3, CO, CH4, RNH2, HCN, and aromatic gases; and (III) carbonization into a final N-hybrid graphite. The thermal degradation of PN foam was different from that of bulky PN resin. During the entire pyrolysis of PN foam, there was a gas superposition phenomenon since the release of the decomposition volatile was retarded by the closed cells in the PN foam. This research will contribute to the general understanding of the thermal degradation behavior of PN foam at the macroscopic and molecular levels and provide a reference for the identification, determination, and design of PN material.

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Kinetics of the oxidative aging of phthalonitrile resins and their effects on the mechanical properties of thermosets

Cited by 10 publications

References 57 publications

Effect of post‐curing temperature on the retention of mechanical strength of phthalonitrile thermosets and composites after a long‐term thermal oxidative aging

Effect of post‐curing temperature on the retention of mechanical strength of phthalonitrile thermosets and composites after a long‐term thermal oxidative aging

Thermal Hazard Analysis of Two Non-Ideal Explosives Based on Ammonium Perchlorate/Ammonium Nitrate and Aluminium Powder

Understanding the Thermal Degradation Mechanism of High-Temperature-Resistant Phthalonitrile Foam at Macroscopic and Molecular Levels

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