Broadline NMR studies of molecular motion in an uncured epoxy resin

Clark-Monks, Colin; Ellis, Bryan

doi:10.1002/pol.1970.160081216

Cited by 6 publications

(2 citation statements)

References 20 publications

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“…For the different materials, the MDA‐cured thermoset has the smallest average linewidth at temperatures below T g . The observed linewidth at −40 °C ( T − T g = −222 °C) approaches the theoretical rigid‐lattice FWHM of ∼ 40 kHz predicted using the Van Vleck equation for dipolar‐coupled spins in MDA‐cured bisphenol A epoxy resins . Ellis and coworkers reported that methyl and phenylene rotations corresponding to β‐relaxation processes would further reduce the FWHM to ∼25.5 kHz.…”

Section: Resultssupporting

confidence: 66%

“…The observed linewidth at −40 C (T − T g = −222 C) approaches the theoretical rigid-lattice FWHM of $ 40 kHz predicted using the Van Vleck equation for dipolar-coupled spins 61 in MDA-cured bisphenol A epoxy resins. 42,62 Ellis and coworkers reported that methyl and phenylene rotations corresponding to β-relaxation processes would further reduce the FWHM to $25.5 kHz. This predicted reduction matches the plateau experimentally observed near (T -T g )/T g $ −0.2 ( Fig.…”

Section: H Nmr Line-shape Variation With Curing Agentmentioning

confidence: 99%

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Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Alam

Jones

2019

J Polym Sci B Polym Phys

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Solid state 1H NMR line‐shape analysis and (double quantum) DQ 1H NMR experiments have been used to investigate the segmental and polymer chain dynamics as a function of temperature for a series of thermosetting epoxy resins produced using different diamine curing agents. In these thermosets, chemical crosslinks introduce topological constraints leading to residual stresses during curing. Materials containing a unique ferrocene‐based diamine (FcDA) curing agent were evaluated to address the role of the ferrocene fluxional process on the atomic‐level polymer dynamics. At temperatures above the glass transition temperature (Tg), the DQ 1H NMR experiments provided a measure of the relative effective crosslink and entanglement densities for these materials and revealed significant polymer chain dynamic heterogeneity in the FcDA‐cured thermosets. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1143–1156

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Section: Resultssupporting

confidence: 66%

Section: H Nmr Line-shape Variation With Curing Agentmentioning

confidence: 99%

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Alam

Jones

2019

J Polym Sci B Polym Phys

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Molecular motion in cured epoxy resin filled with mica flakes

Iisaka

Shibayama

1978

J of Applied Polymer Sci

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SynopsisMolecular motion in cured epoxy resin filled with mica flakes was investigated by dynamic mechanical and broad-line nuclear magnetic resonance measurements. Temperature dependences of dynamic modulus and tan6 were determined a t 10 Hz for samples containing various amounts of filler. A primary dispersion temperature, I " , , corresponding to the glass transition, shifts to higher temperature with increasing filler volume fraction V f . The magnitudes of the slope parameters H , (representing storage modulus E' data above Tg) decreased with increasing V f , but Hg (representing E' data below Tg) remained nearly constant over the whole loading range studied here. NMR line shapes were observed over the temperature range from room temperature to about 2OOOC for unfilled and filled samples. Each sample showed a distorted line shape in the transition region where major narrowing occurs. The distorted line shape was decomposed into both broad and narrow components by Gaussian analysis. The temperature range where both components can be obtained becomes broader with increasing filler content. The possibility is set forth that the filler immobilizes the chain segments and causes a different distribution of local mobility around the junction point.

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Pulsed NMR study of molecular motion in the uncured diglycidyl ether of bisphenol‐A

Larsen

Strange

1973

J. Polym. Sci. Polym. Phys. Ed.

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SynopsisThe diglycidyl ether of bisphenol-A, an uncured epoxy resin, has been studied by pulsed NMR. Values of the proton relaxation times T I , Tt, and TZ have been measured over the temperature range from -160 to 200'C. The resin was studied in its monomeric form and in two mixtures containing higher oligomers. The relaxation times are interpreted in terms of the molecular motion in the resins. The motion responsible for relaxation in the solid monomer form is thought to be methyl group reorientation at low temperatures and general molecular motion at high temperatures. The motions are characterized by activation energies of 5 kcal/mole and 33 kcal/mole, respectively. The solid mixtures exhibit similar effects to the monomer, but an additional relaxation mechanism is observed which is attributed to segmental motion. This motion is characterized by an activation energy of 12-15 kcal/mole. The self-diffusion coefficient was measured in the liquid monomer, and the activation energy for self-diff usion is found to be 11 kcal/mole.

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Broadline NMR studies of molecular motion in an uncured epoxy resin

Cited by 6 publications

References 20 publications

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Molecular motion in cured epoxy resin filled with mica flakes

Pulsed NMR study of molecular motion in the uncured diglycidyl ether of bisphenol‐A

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Broadline NMR studies of molecular motion in an uncured epoxy resin

Cited by 6 publications

References 20 publications

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State 1H NMR Spectroscopy

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State 1H NMR Spectroscopy

Molecular motion in cured epoxy resin filled with mica flakes

Pulsed NMR study of molecular motion in the uncured diglycidyl ether of bisphenol‐A

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Product

Resources

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Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy