Thermooxidative degradation of polyoxymethylene homo- and copolymer nanocomposites with hydroxyapatite: Kinetic and thermoanalytical study

Pielichowska, Kinga

doi:10.1016/j.tca.2014.11.016

Cited by 34 publications

(21 citation statements)

References 48 publications

(61 reference statements)

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“…The change has signaled an alteration in the process mechanism that has been confirmed by FTIR spectroscopy. An increase in the isoconversional activation energy accompanied by a decrease in the degradation temperature has also been reported by Pielichowska for the thermal degradation polyoxymethylene–hydroxyapatite nanocomposite. Again, comparative FTIR analysis of the degradation products for the virgin polymer and nanocomposite has revealed a change in the process mechanism.…”

Section: Thermal and Thermo‐oxidative Degradationsupporting

confidence: 73%

Isoconversional Kinetics of Polymers: The Decade Past

Vyazovkin

2016

Macromol. Rapid Commun.

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This article surveys the decade of progress accomplished in the application of isoconversional methods to thermally stimulated processes in polymers. The processes of interest include: crystallization and melting of polymers, gelation of polymer solutions and gel melting, denaturation (unfolding) of proteins, glass transition, polymerization and crosslinking (curing), and thermal and thermo-oxidative degradation. Special attention is paid to the kinetics of polymeric nanomaterials. The article discusses basic principles for understanding the variations in the activation energy and emphasizes the possibility of using models for linking such variations to the parameters of individual kinetic steps. It is stressed that many kinetic effects are not linked to a change in the activation energy alone and may arise from changes in the preexponential factor and reaction model. Also noted is that some isoconversional methods are inapplicable to processes taking place on cooling and cannot be used to study such processes as the melt crystallization.

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Section: Thermal and Thermo‐oxidative Degradationsupporting

confidence: 73%

Isoconversional Kinetics of Polymers: The Decade Past

Vyazovkin

2016

Macromol. Rapid Commun.

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“…Kinetics of this process may be analyzed using isoconversional methods (Friedman method and Ozawa-Flynn-Wall method), and Fig . 5 Ozawa-Flynn-Wall analysis of the thermal degradation of POM and POM/HAp nanocomposites multiple nonlinear regression method was applied according to the procedure described in [18,19]. The most frequently used mathematical models to describe thermal degradation of polymers used in this work are presented in Table 1 [19][20][21][22].…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, based on our previous findings [18], we assumed that reaction of POM degradation partially undergoes in (1) POM bulk with autocatalytic mechanism as for pristine POM, and (2) on the phase-boundary POMHAp. For T4/10 % HAp, some changes can be observed in comparison with T2/10 % HAp and T3/10 % HAp systems-on the beginning, the slope of experimental points is lower than isoconversional lines, and then, maximum with a higher slope than the slope of Friedman lines is detected.…”

Section: Resultsmentioning

confidence: 99%

The influence of polyoxymethylene molar mass on the oxidative thermal degradation of its nanocomposites with hydroxyapatite

Pielichowska

2015

J Therm Anal Calorim

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In this paper, the influence of mass-average molar mass (M w ) of polyoxymethylene (POM) copolymer on the thermooxidative degradation behavior of its nanocomposites with hydroxyapatite (HAp) is reported. POM copolymers' thermal stability slightly decreases with a decrease in mass-average molar mass. Thermal stability of POM/HAp nanocomposites is lower in comparison with pure POM, and it gets lower with a decrease in massaverage molar mass of POM copolymer. For POM copolymer with the highest molar mass, thermal stability of POM/HAp nanocomposite was ca. 30°C lower than for pure POM. To get a more in-depth insight into the decomposition process, kinetic analysis of POM/HAp nanocomposite thermal degradation process was performed using Friedman, Ozawa-Flynn-Wall and multiple nonlinear regression methods. The best fit for pristine T2, T3 and T4 copolymers with different molar mass of 100768, 74727 and 68377 g mol -1 , respectively, was obtained for onestage degradation mechanism with autocatalysis, while for T2/10 % HAp and T3/10 % it was parallel reaction model with autocatalysis (Bna) and phase-boundary reaction models (R3). For T4/10 % HAp, the best approximation was found for R2-Bna-D3 reaction model. From hyphenated TG-MS and TG-FTIR thermoanalytical studies, it was found that the main degradation product for POM/HAp nanocomposites is formaldehyde and the amount of other degradation products is lower in comparison with nonmodified POM copolymers.

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“…Hence for runs performed at different heating rates, βi, Af(α) will be constant at a fixed conversion degree, α [11]. By measuring the temperature, T and the reaction rate, dα/dt, at the fixed conversion degree, α, for all experiments performed at different heating rates, the activation energy can be calculated from the slope of the representation of ln(dα/dt)α,i vs 1/Tα,i whereas from the intercept ln(Af(α)k0) is obtained [12][13][14][15][16][17][18][19][20][21][22]. Whilst this differential method does not employ any mathematical approximation, as in the case of other integral methods, it can be considered as more accurate than the integral ones.…”

Section: Introductionmentioning

confidence: 99%

Friedman and n-reaction order methods applied to pine needles and polyurethane thermal decompositions

Font

Garrido

2018

Thermochimica Acta

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The Friedman method is applied to two processes: flexible polyurethane foam (PU) pyrolysis and pine needle combustion, considering two types of runs: dynamic and dynamic + isothermal. In both cases, the TG and DTG runs are taken into account. For both materials, the Friedman method is applied twice: one considering only the dynamic runs and the other considering all runs, dynamic and dynamic + isothermal runs. Different expressions for fitting the variation of the apparent activation energy and the pre-exponential function have been obtained and used to simulate the experimental results. The simulated results are compared with the experimental ones and with those simulated with the n-reaction order models. From the discussion carried out, it has been deduced that the Friedman method is valid when taking into account all the experimental data obtained in different operating conditions and after testing that the simulated results are close to the experimental ones.

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Thermooxidative degradation of polyoxymethylene homo- and copolymer nanocomposites with hydroxyapatite: Kinetic and thermoanalytical study

Cited by 34 publications

References 48 publications

Isoconversional Kinetics of Polymers: The Decade Past

Isoconversional Kinetics of Polymers: The Decade Past

The influence of polyoxymethylene molar mass on the oxidative thermal degradation of its nanocomposites with hydroxyapatite

Friedman and n-reaction order methods applied to pine needles and polyurethane thermal decompositions

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