The effect of network architecture on the thermal and mechanical behavior of epoxy resins

Crawford, Emmett; Lesser, Alan J.

doi:10.1002/(sici)1099-0488(199806)36:8<1371::aid-polb11>3.0.co;2-4

Cited by 124 publications

(117 citation statements)

References 9 publications

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“…Because the molecular weight between cross-links, M C , strongly affects the properties of cross-linked polymers [14], we constructed models with M C similar to the pDCPD network synthesized by Knorr et al [8]. Although M C can be measured experimentally with dynamic mechanical analysis (DMA) and the theory of rubber elasticity, uncertainty is introduced by finite chain stiffness and interchain interactions [15]. Therefore, we constructed three pDCPD networks with different M C by using linear segments composed of n monomers (Figure 1b This document is a U.S. government work and is not subject to copyright in the United States.…”

Section: Design Of Pdcpd Network For Simulationssupporting

confidence: 72%

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A molecular simulation study of the glass transition of cross-linked poly(dicyclopentadiene) networks

Elder¹,

Andzelm²,

Sirk³

2015

Chemical Physics Letters

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a b s t r a c tCross-linked polymer networks are widely used as structural and protective materials, which require strength and toughness. Experiments have shown that cross-linked poly(dicyclopentadiene) (pDCPD) networks provide similar strength but superior fracture toughness relative to commonly-used network chemistries like epoxy. To better understand pDCPD, we use atomistic molecular dynamics to study the properties of pDCPD networks across the glass transition as a function of molecular weight between crosslinks. Moreover, we identify molecular mechanisms that potentially control mechanical and transport properties. The alpha-relaxation (the glass transition) is linked to intra-chain motions and large-scale segmental motions, while sub-T g relaxations are linked with more localized motions.

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Section: Design Of Pdcpd Network For Simulationssupporting

confidence: 72%

“…The third pDCPD network, pDCPD-1 (n = 1, M C = 198 g/mol), provides information about the behavior of highly cross-linked pDCPD networks. We calculate M C from the network stoichiometry as suggested by Crawford and Lesser [15] as…”

Section: Design Of Pdcpd Network For Simulationsmentioning

confidence: 99%

A molecular simulation study of the glass transition of cross-linked poly(dicyclopentadiene) networks

Elder¹,

Andzelm²,

Sirk³

2015

Chemical Physics Letters

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“…With increasing crosslink density, molecular mobility decreases due to additional tie points in network and it results in T g growth. These observations are in agreement with the trends reported earlier in the literature [7,12,21,23].…”

Section: Correlation Between T G and M Csupporting

confidence: 94%

“…Whereas the value of the material Young modulus on the level of glass transition temperature T g (marked with an arrow in Fig. 5) is approximately one and a half times smaller than the E value at temperature of 21 o C. It is caused by cleavage of secondary bonds in the material during heating [1,7]. Similar results for most thermosets were obtained by other authors [13,17].…”

Section: Young Modulus and Storage Modulus Dependenciessupporting

confidence: 72%

Effect of Molecular Weight on the Yield Behaviour of Epy Epoxy Compound

Urbaniak¹

2016

Adv. Sci. Technol. Res. J.

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A series of epoxy networks with molecular weight between crosslinks (M c ) ranging from 117 to 508 g/mol were investigated by employing as DSC and DMA methods and compression testing over a broad range of test temperatures (from 20 to 120°C) and strain rates (from 0.0208 to 20.8 min -1 ). Mechanical characteristics vs. testing temperature and strain rate developed in relation to working conditions of EPY compound applied for machine foundation chocks as well as effect of crosslinking on glass transition temperature (T g ) presented in this paper let to find out the effect of molecular architecture composed chiefly by M c on the thermal and mechanical properties that govern yield behaviour of the material. The investigations carried out in a.m. ranges of testing temperatures and strain rates showed that whichever change of M c is related to the change in crosslink density causing relative shift in the T g of the compound. However, a sensitivity of the polymer material on changes in strain rate falls down with growth of testing temperature. Obtained results prove that yielding in EPY compound can be examined in categories of the Eyring's plastic flow model in which yielding is described.

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“…The composition and network structure of these cross-linked materials can vary greatly, yielding a range of different properties. Variation of the mechanical and thermal properties of epoxy networks can be achieved by modifying the molecular weight between crosslinks, M c [14]. In the previous work of Crawford and Lesser [14], reductions in the values of M c in a series of model aliphatic epoxies produced the expected increase in glass transition temperature, T g , as well as an increase in the critical yield stress measured above T g .…”

Section: Introductionmentioning

confidence: 99%

Multiscale Creep Compliance of Epoxy Networks at Elevated Temperatures

et al. 2006

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Epoxy networks are thermoset polymers for which an important structural length scale, molecular weight between crosslinks (M c ), influences physical and mechanical properties. In the present work, creep compliance was measured for three aliphatic epoxy networks of differing M c using both macroscale torsion and microscale depth-sensing indentation at temperatures of 25 and 55-C. Analytical relations were used to compute creep compliance (J(t)) for each approach; similar results were observed for the two techniques at 25-C, but not at 55-C. Although creep compliance measurement differed at elevated temperatures, there were clear correlations between M c , glass transition temperature, T g , and the observed time-dependent mechanical behavior via both techniques at 55-C, but these correlations could not be seen at 25-C. This work demonstrates the capacity of depth-sensing indentation to differentiate among epoxy networks of differing structural configurations via J(t) for small material volumes at elevated temperatures.

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The effect of network architecture on the thermal and mechanical behavior of epoxy resins

Cited by 124 publications

References 9 publications

A molecular simulation study of the glass transition of cross-linked poly(dicyclopentadiene) networks

A molecular simulation study of the glass transition of cross-linked poly(dicyclopentadiene) networks

Effect of Molecular Weight on the Yield Behaviour of Epy Epoxy Compound

Multiscale Creep Compliance of Epoxy Networks at Elevated Temperatures

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