Evolution of viscoelastic behavior of a curing LY5052 epoxy resin in the glassy state

Saseendran, Sibin; Wysocki, Maciej; Vārna, Jānis

doi:10.1080/20550340.2016.1236223

Cited by 20 publications

(46 citation statements)

References 18 publications

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“…Expressions (19) and 20are not suitable for numerical calculations in regions where a is not changing or changing slowly (d kþ1 a 0). Expansion of ln 1 þ x ð Þ% x can be used leading to…”

Section: Expression For Dw Kþ1mentioning

confidence: 99%

“…The shift factor is presented as a product of temperature and DoC dependent functions [18,19] a T, a…”

Section: Materials Propertiesmentioning

confidence: 99%

“…The relationship between Dw kþ1 and Dt kþ1 is given by (19). This expression is valid not only for t ¼ t kþ1 which is the final point in the interval but for any arbitrary instant in the interval…”

Section: Appendicesmentioning

confidence: 99%

“…Recent new studies [18,19] proposed to improve VE models by including DoC and T-dependence of the glassy and rubbery stiffness. In [20,21], a very general and thermodynamically consistent VE model with DoC and T dependences was developed following the derivation scheme suggested by Schapery [22].…”

Section: Introductionmentioning

confidence: 99%

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Viscoelastic model with complex rheological behavior (VisCoR): incremental formulation

Saseendran

Berglund

Vārna

2020

Advanced Manufacturing: Polymer & Composites Science

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A thermo-rheologically complex linear viscoelastic material model, accounting for temperature and degree of cure (DoC), is developed starting with series expansion of the Helmholtz free energy and systematically implementing simplifying assumptions regarding the material behavior. In addition to the temperature and DoC dependent shift factor present in rheologically simple models, the derived novel model contains three cure and temperature dependent functions. The first function is identified as the rubbery modulus. The second is a weight factor to the transient integral term in the model and reflects the current temperature and cure state, whereas the third function is under the sign of the convolution integral, thus affecting the "memory" of the material. An incremental form of this model is presented which, due to improved approximation inside the time increment, has better numerical convergence than most of the similar forms. Parametric analysis is performed simulating stress development in a polymer, geometrically constrained in the mold during curing and cool-down. The importance of using proper viscoelastic model is shown, and the role of parameters in the model is revealed and discussed.

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Section: Expression For Dw Kþ1mentioning

confidence: 99%

“…The shift factor is presented as a product of temperature and DoC dependent functions [18,19] a T, a…”

Section: Materials Propertiesmentioning

confidence: 99%

Section: Appendicesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Viscoelastic model with complex rheological behavior (VisCoR): incremental formulation

Saseendran

Berglund

Vārna

2020

Advanced Manufacturing: Polymer & Composites Science

Self Cite

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show abstract

“…Thus, thermo-mechanical characterization of partially cured EPs was addressed in a number of studies. 5,6,[20][21][22][23][24][25][26][27] In order to determine cure-dependent properties, reliable adjustment of partial degrees of cure (DOC) is of crucial importance. The published studies show diverse sample preparation methods, which comprises precure and dimensioning.…”

Section: Introductionmentioning

confidence: 99%

Aspects of reproducibility and stability for partial cure of epoxy matrix resin

Müller

Winkler

Gude

et al. 2019

J of Applied Polymer Sci

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Partial cure of thermosets is a promising approach to enhance manufacturing possibilities of reinforced and unreinforced polymers. If partial cure is taken into consideration as a genuine process parameter, novel manufacturing technologies can be developed by exploiting the specific properties of incomplete polymer networks. A main concern in this context is to control the kinetic reaction avoiding inhomogeneous or instable degrees of cure. Based on a combination of numerical simulations and experiments, a methodology is presented that enables a systematic assessment of the reproducibility and stability of partial cure. Special attention is paid to the interaction of thermal boundary conditions and the cure kinetic of thick samples as well as the storability of partially cured resin under different conditions. Guidelines for cure cycle selection, mold design, and storage are derived. The possibility to use complex multistep cure schedules and extended storage periods is demonstrated for an unmodified noninhibited epoxy resin.

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Dissipative Dynamics of Polymer Phononic Materials

Krushynska

Gliozzi

Fina

et al. 2021

Adv Funct Materials

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Phononic materials are artificial composites with unprecedented abilities to control acoustic waves in solids. Their performance is mainly governed by their architecture, determining frequency ranges in which wave propagation is inhibited. However, the dynamics of phononic materials also depends on the mechanical and material properties of their constituents. In the case of viscoelastic constituents, such as most polymers, it is challenging to correctly predict the actual dynamic behavior of real phononic structures. Existing studies on this topic either lack experimental evidence or are limited to specific materials and architectures in restricted frequency ranges. A general framework is developed and employed to characterize the dynamics of polymer phononic materials with different architectures made of both thermoset and thermoplastic polymers, presenting qualitatively different viscoelastic behaviors. Through a comparison of experimental results with numerical predictions, the reliability of commonly used elastic and viscoelastic material models is evaluated in broad frequency ranges. Correlations between viscous effects and the two main band-gap formation mechanisms in phononic materials are revealed, and experimentally verified guidelines on how to correctly predict their dissipative response are proposed in a computationally efficient way. Overall, this work provides comprehensive guidelines for the extension of phononics modeling to applications involving dissipative viscoelastic materials.

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Evolution of viscoelastic behavior of a curing LY5052 epoxy resin in the glassy state

Cited by 20 publications

References 18 publications

Viscoelastic model with complex rheological behavior (VisCoR): incremental formulation

Viscoelastic model with complex rheological behavior (VisCoR): incremental formulation

Aspects of reproducibility and stability for partial cure of epoxy matrix resin

Dissipative Dynamics of Polymer Phononic Materials

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