Characterization and atomistic modeling of the effect of water absorption on the mechanical properties of thermoset polymers

Cui, Teng; Verberne, P.; Meguid, S. A.

doi:10.1007/s00707-017-1997-y

Cited by 22 publications

(25 citation statements)

References 49 publications

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“…A strategy that has been employed for GCMC simulations for studying polymeric adsorbents in dilated/plasticized conditions is to prepare the model polymer matrix in a swollen state. Several works [23][24][25][26] have accomplished this by including temporary molecules, usually the adsorbate of interest, during the model construction of the polymer matrix. These temporary molecules effectively serve as 'molecular obstacles' and result in additional inefficient packing of polymer chains to accommodate them 25 (i.e.…”

Section: Monte Carlo Samplingmentioning

confidence: 99%

Sorption‐induced polymer rearrangement: approaches from molecular modeling

Anstine

Colina

2020

Polymer International

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With the growing need for chemical separation and chemical storage solutions, polymeric adsorbents have emerged as a promising class of candidate materials because of their potentially tunable sorption properties, membrane structure and relatively cost consciousness. Moreover, the developing field of polymeric membrane materials has shown particular success at integrating both experimental and computational studies. However, these material systems are known to suffer from varying degrees of induced membrane structural rearrangement upon adsorbate uptake, and thus many polymeric membrane performance metrics are often considered to degrade with an increasing number of 'guest' species. In this mini-review, we highlight methodology tradeoffs and provide insights into atomistic molecular simulations used to study adsorption with flexible frameworks, which have the potential to predict separation, storage or catalytic capabilities a priori to experimental efforts. Specifically, molecular simulation methods that have been applied to provide predictions of polymeric membrane properties that have included consideration for sorbate-induced polymer chain rearrangement, swelling and/or plasticization are reviewed. The examples and methodologies described provide demonstrations of the applicability of simulations as an approach to understand adsorption-based phenomena at an atomistic/molecular level, and as a tool to carry out screening studies aimed at efficiently providing analysis for a diversity of polymeric adsorbent-adsorbate systems.

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Section: Monte Carlo Samplingmentioning

confidence: 99%

Sorption‐induced polymer rearrangement: approaches from molecular modeling

Anstine

Colina

2020

Polymer International

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“…The effect of moisture on Young’s modulus was the result of the competition of various mechanisms. With the increase of moisture concentration, Young’s modulus might change a lot [ 59 , 60 , 61 , 62 , 63 ].…”

Section: Resultsmentioning

confidence: 99%

“…The effect of moisture on the yield strength of the epoxy polymer was similar to its effect on the Young’s modulus. The hydrogen bonds between the water molecules and the epoxy polymer resulted in post cross-linking of the system [ 62 ]. The improved post cross-linking had greater hindrance on the kinematic ability of the chains.…”

Section: Resultsmentioning

confidence: 99%

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Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

Sheng

Sun

et al. 2021

Polymers

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In spite of a high market share of plastic IC packaging, there are still reliability issues, especially for the effects of moisture. The mechanism between moisture and epoxy polymer is still obscure. A multi-step cross-linking approach was used to mimic the cross-linking process between the DGEBA resin and JEFFAMINE®-D230 agent. Based on the molecular dynamics method, the thermo-mechanical properties and microstructure of epoxy polymer were analyzed. In this paper, the degree of cross-linking ranged from 0% to 85.4% and the moisture concentration ranged from 0 wt.% to 12 wt.%. The hydrogen bonds were investigated in the moisture invaded epoxy polymer. Although most of the hydrogen bonds were related to water molecules, the hydrogen bonds between the inside of epoxy polymer were reduced only a little as the concentration of moisture increased. The diffusion coefficient of the water molecules was found to increase with the increase of moisture concentration. When the moisture concentration was larger than 12 wt.% or smaller than 1.6 wt.%, the diffusion coefficient was less affected by the epoxy polymer. In addition, the free volume and the thermal conductivity of the epoxy polymer were considered. It was found that the moisture could increase the thermal conductivity from 0.24 to 0.31 W/m/K, identifying a coupling relationship between moisture and thermal properties. Finally, the mechanical properties of epoxy polymer were analyzed by uniaxial tensile simulation. The COMPASS and DREIDING force fields were used during the uniaxial tensile simulation. A better result was achieved from the DREIDING force field compared with the experiment. The degree of cross-linking was positively correlated with mechanical properties. For the system with the largest degree of cross-linking of 85.4%, the Young’s modulus was 2.134 ± 0.522 GPa and the yield strength was 0.081 ± 0.01 GPa. There were both plasticizing and anti-plasticizing effects when the water molecules entered the epoxy polymer. Both the Young’s moduli and yield strength varied in a large range from 1.38 to 2.344 GPa and from 0.062 to 0.128 GPa, respectively.

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“…Moisture absorption in the neat epoxy resin is thought to follow Fickian diffusion, , with absorbed moisture, inducing swelling, fluctuations of bulk elastic properties, , a decrease in the glass transition temperature ( T g ), , and has also been reported to impact the ultimate failure modes . The diffusion of moisture in both neat epoxies and their composites has been shown to be not only dependent on the chemical resin composition but also on the curing protocol, , stoichiometric ratio, environmental conditions, and the inclusion of modifiers .…”

Section: Introductionmentioning

confidence: 99%

Moisture Ingress at the Molecular Scale in Hygrothermal Aging of Fiber–Epoxy Interfaces

Vuković

Walsh

2020

ACS Appl. Mater. Interfaces

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Almost all applications of carbon fiber reinforced composites are susceptible to water aging, either via ambient humidity or through direct exposure to liquid water environments. Although the impacts of water aging in composites can be readily quantified via experimental efforts, details regarding the mechanisms of moisture ingress and aging, particularly at the incipient stages of aging under hygrothermal conditions, have proven challenging to resolve using experimental techniques alone. A deeper understanding of the factors that drive incipient moisture ingress during aging is required for more targeted approaches to combat water aging. Here, molecular dynamics simulations of a novel epoxy/carbon fiber interface exposed to liquid water under hygrothermal conditions are used to elucidate molecular details of the moisture ingress mechanisms at the incipient stages of the aging process. Remarkably, the simulations show that the fiber–matrix interface is not vulnerable to a moisture-wicking type of incipient water ingress and does not readily flood in these early stages of water aging. Instead, water is preferentially absorbed via the matrix–water interface, an ingress pathway that is facilitated by the dynamic mobility of polymer chains at this interface. These chains present electronegative sites that can capture water molecules and provide a conduit to transiently exposed pores and channels on the polymer surface, which creates a presoaked staging reservoir for subsequent deeper ingress into the composite. Characterization of the absorbed water is according to hydrogen bonding to the matrix, and the distributions and transport behavior of these waters are consistent with experimental observations. This work introduces new insights regarding the molecular-level details of moisture ingress and spatial distribution of water in these materials during hygrothermal aging, informing future design directions for extending both the service life and shelf life of next-generation composites.

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Characterization and atomistic modeling of the effect of water absorption on the mechanical properties of thermoset polymers

Cited by 22 publications

References 49 publications

Sorption‐induced polymer rearrangement: approaches from molecular modeling

Sorption‐induced polymer rearrangement: approaches from molecular modeling

Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

Moisture Ingress at the Molecular Scale in Hygrothermal Aging of Fiber–Epoxy Interfaces

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