Microstructure and deformation mechanisms of a solid propellant using 1 H NMR spectroscopy

Azoug, Aurélie; Constantinescu, Andréï; Nevière, Robert; Jacob, Guy

doi:10.1016/j.fuel.2015.01.074

Cited by 34 publications

(20 citation statements)

References 49 publications

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“…where k is the aging reaction rate constant; t is the aging time; ν0 and α are the constants. The Levenberg-Marquardt optimization algorithm [35,36] was used for parameters fitting in Equation (1). The fitting results are shown in Table 1 and the fitting curve is shown in Figure 3.…”

Section: Aging Results Of Crosslinking Densitymentioning

confidence: 99%

“…The crosslinking density of HTPB coating was tested in the VTMR20-010V-T (Shanghai Niumag Electronic Technology Co., Ltd., Shanghai, China) low-field 1 H NMR relaxometer, with a magnet strength of 0.5 T, coil diameter of 10 mm, resonance frequency of 22. 35 MHz, and magnet temperature of 32.00 °C. The Carr-Purcell-Meiboom-Gill (CPMG) (Shanghai Niumag Electronic Technology Co., Ltd., Shanghai, China) sequence was used in the crosslinking density test.…”

Section: Low-field 1 H Nmr Crosslinking Density Testmentioning

confidence: 99%

“…where ∆E 2 and ε 2 are material constants. The test results were fitted by a Levenberg-Marquardt optimization algorithm [35,36]. It is found that in order to get the most accurate fitting effect, the strain amplitude ε c of the fitted storage modulus and loss modulus model were not the same, and was not equal to the strain value corresponding to the maximum loss modulus, which is shown in Table 3.…”

Section: Crosslinking Density Modified Model For Payne Effectmentioning

confidence: 99%

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Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect

Zheng

2020

Polymers

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Hydroxyl terminated polybutadiene (HTPB) coating is widely used in a solid rocket motor, but an aging phenomenon exists during long-term storage, which causes irreversible damage to the performance of this HTPB coating. In order to study the effect of aging on the dynamic mechanical properties of the HTPB coating, the thermally-accelerated aging test was carried out. The variation of maximum elongation and crosslinking density with aging time was obtained, and a good linear relationship between maximum elongation and crosslinking density was found by correlation analysis. The changing regularity of dynamic mechanical properties with aging time was analyzed. It was found that with the increase of aging time, T g of HTPB coating increased, T α , tan β and tan α decreased, and the functional relationships between the loss factor parameters and crosslinking density were constructed. The storage modulus and loss modulus of HTPB coating increased with the increase of aging time, and decreased with the increase of pre-strain. The aging enhanced the Payne effect of HTPB coating, while the pre-strain had a weakening effect. In view of the Payne effect of HTPB coating, the crosslinking density was introduced into Kraus model as aging evaluation parameter, and the crosslinking density modified models with and without pre-strain were established. The proposed models can effectively solve the problem that the Kraus model has a poor fitting effect under the condition of small strain (generally less than 1%) and on the loss modulus, which have improved the correlations between the fitting results and the test results.Polymers 2020, 12, 403 2 of 20 of 1 H NMR (nuclear magnetic resonance), and analyzed the influence of the crosslinking density on the macro-mechanical properties.It was found that with the increase of crosslinking density, the hardness and modulus of the material increased linearly, while the elongation at break decreased linearly. Katarzyna et al. [5] found that the existence of crosslinking resulted in the increase of the glass transition temperature T g . Actually, the linear relationship equation between T g and crosslinking density was derived in the study of Fox and Loshaek [6]. Although the linear equation was not completely consistent with some later results [7-9], they also came to the same conclusion that the crosslinking can increase the glass transition temperature of the polymer. In the study of Celina et al. [10], it was found that the crosslinking density of HTPB elastomers increased with the aging time. The mainly aging reaction was oxidation crosslinking, and the change of crosslinking density affected the mechanical properties of the material. Byungwoo et al. [11] also got the same conclusion. The test results demonstrated that the crosslinking density increased with the increase of aging temperature and aging time, and the crosslinking changed with the change of aging condition. The functional relationship between strain energy density and crosslinking density was established.Dynamic mechanical ...

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Section: Aging Results Of Crosslinking Densitymentioning

confidence: 99%

Section: Low-field 1 H Nmr Crosslinking Density Testmentioning

confidence: 99%

Section: Crosslinking Density Modified Model For Payne Effectmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect

Zheng

2020

Polymers

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“…Hence, T 1 and T 2 decrease when the crosslink density of the system increases [32,33], whereas they are shown to increase with the chain flexibility and mobility [33].…”

Section: Possible Initial Architecture Of Networkmentioning

confidence: 94%

Plasticizer effect on network structure and hydrolytic degradation

Richaud

Derue

Pierre

et al. 2015

European Polymer Journal

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a b s t r a c tThe hydrolytic degradation of fully cured polyester-urethane networks polymerized in the presence of several weight ratios of triacetin was monitored by the residual concentration in elastically active chains obtained from modulus and equilibrium solvent swelling measurements. The presence of triacetin does not change the water uptake but induces a lower rate of degradation. Comparisons were performed with networks in which triacetin was removed before ageing, and with networks in which polyester-urethane was first polymerized and then impregnated by triacetin. Data suggest that the presence of triacetin during polymerization induces the presence of elastically inactive chains such as dangling chains and loops, the hydrolysis of which does not change the elastic properties of the network. This explanation was checked from relaxation measurements by NMR and DMA, and by the analysis of the soluble fraction generated by hydrolysis.

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“…6(a) shows that the relaxation modulus is not linear. Based on NMR measurements, Azoug et al (2014cAzoug et al ( , 2015 showed that propellant has a multiphased matrix due to his manufacturing process. Moreover, they were able to bring up three phases in the matrix of the propellant associated to families of polymer chains and mechanisms of mobility to explain the observed nonlinearity in the relaxation.…”

Section: Materials Without Prestrainmentioning

confidence: 99%

Prestrain-dependent viscosity of a highly filled elastomer: experiments and modeling

Jalocha

Constantinescu

Nevière

2015

Mech Time-Depend Mater

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International audienceHighly filled elastomers exhibit a complex microstructure made up of rigid fillers bounded by a thin layer polymeric matrix. The interactions between the fillers and the binder amplify locally the applied strains and induce a nonlinear viscoelastic behavior. The aim here is to analyze the influence of prestrain on the viscoelastic behavior. This paper proposes a prestrain-dependent viscoelastic constitutive model. The model is a superposition of three relaxation spectra, each corresponding to a family of polymer chains, and can be regarded in either its continuous or discrete expression. More specifically, one of these relaxation spectra is modified to assure the prestrain sensitivity. The parameters of the discrete model are identified from relaxation and DMA experiments performed on a solid propellant, and the obtained predictions match closely the experiments. The novelty of the analysis proposed in this paper is threefold. On the one hand, we report a new series of experimental measures, performed for a large range of frequencies for the DMA experiment and relaxation times for the relaxation experiment, and, on the other hand, we propose a constitutive law compatible with the principles of thermodynamics, which predicts closely the measurements. Finally, the analysis is performed comparing both relaxation and DMA experiments using the spectrum of relaxation times. A peculiarity of the present discussion is the novel identification method used, which identifies directly the relaxation times. This technique leads to models with smaller and optimum numbers of parameters than classical methods based on a logarithmic distribution of relaxation times

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Microstructure and deformation mechanisms of a solid propellant using 1 H NMR spectroscopy

Cited by 34 publications

References 49 publications

Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect

Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect

Plasticizer effect on network structure and hydrolytic degradation

Prestrain-dependent viscosity of a highly filled elastomer: experiments and modeling

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