Characterization of epoxies cured with bimodal blends of polyetheramines

McAninch, Ian M.; Palmese, Giuseppe R.; Lenhart, Joseph L.; Scala, John J. La

doi:10.1002/app.39322

Cited by 30 publications

(37 citation statements)

References 39 publications

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“…Contraction at subambient temperatures is not significant, given that 0°C was the lowest temperature used. From room temperature, where the samples were loaded, to 0°C, using expansion data described elsewhere , the D230 contracted 0.15% while the D400 contracted 0.18%. At higher temperatures, 50°C above T g , D230 expanded 1.9%, while D400 expanded 1.6%.…”

Section: Resultsmentioning

confidence: 99%

“…For SC clamps lateral movement of the moveable clamp limits errors from the expansion. In related work using the SC clamp , lateral movement of −0.17 mm was measured as a sample cooled to −100°C. Lateral movement due to sample expansion was not measured; however, the clamp without a sample loaded was observed to shift laterally up to 1 mm in response to gentle manual pressure.…”

Section: Resultsmentioning

confidence: 99%

“…The exceptions are for thick SC samples with expansion of 0–1%, and a rubbery ν, i.e., samples that go through their T g relatively near the starting temperature. These conditions may apply to D230 and D400 near their T g s. Those resins experience 0.9 and 0.5% expansion, for D230 and D400 respectively, going from 0°C to their T g s . Poisson's ratio of other epoxy networks has been reported to rapidly approach 0.5 as temperature approaches T g .…”

Section: Resultsmentioning

confidence: 99%

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DMA testing of epoxy resins: The importance of dimensions

McAninch

Palmese

Lenhart

et al. 2015

Polymer Engineering & Sci

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Dynamic mechanical analysis is commonly used to characterize thermoset polymers at temperatures ranging from well below to well above their glass transition temperatures. Many sample fixtures are available; however, the best clamp and best sample dimensions for a given material are not often readily apparent. Five different epoxy amine networks with glass transitions spanning over 1008C were characterized on three-point bending, dual cantilever, and single cantilever clamps with both constant thickness and constant span-to-thickness. Glassy modulus values were accurately measured on all clamps provided span-to-thickness ratios >10 were maintained. Thermal expansion and decreasing sample stiffness with increasing temperature greatly affect measurements in the rubbery region resulting in single cantilever clamps being best suited to measure rubbery data.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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DMA testing of epoxy resins: The importance of dimensions

McAninch

Palmese

Lenhart

et al. 2015

Polymer Engineering & Sci

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“…The extent of cure was measured using near‐infrared (NIR) spectroscopy. NIR spectra (64 scans, 8 cm −1 resolution) of the epoxy‐amine systems both before cure and after post‐cure were obtained in the range of 4000–8000 cm −1 in transmission mode at room temperature on a Thermo Scientific Nicolet iS50 FTIR spectrometer …”

Section: Methodsmentioning

confidence: 99%

Alternative monomers for 4,4′‐methylenedianiline in thermosetting epoxy resins

Bassett

Cosgrove

Schmalbach

et al. 2019

J of Applied Polymer Sci

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4,4′‐Methylenedianiline (MDA) is utilized to produce high temperature epoxy resins as well as other high‐performance composites; however, MDA is a known carcinogen and liver toxicant. Novel dianilines derived from both petroleum and biomass with different quantities and types of methyl and methoxy substituents on the aromatic ring were prepared and studied to reduce toxicity and carcinogenic aspects of the resulting material while maintaining thermal and mechanical integrity. These dianilines were primarily prepared by coupling commercial anilines using paraformaldehyde under acidic conditions. Another dianiline was prepared by nitration of bisphenol A and subsequent reduction of the nitrates to amines. Structure–toxicity relationships indicate that multiple substituents on the aromatic ring are necessary to reduce the toxicity of the dianiline. Epoxy‐amine resins were prepared by blending the dianilines with 50 wt % Epikure W liquid amine curing agent and mixing with a stoichiometric amount of EPON 828 epoxy resin. Methoxy and methyl substituents increase the melting point of the dianilines by as much as 65 °C, thereby worsening the processing of these monomers as liquid thermoset resins. Structure–property relationships show that the addition of a methoxy group to the aromatic ring and moving the amine from the 4,4′ position on the dianiline reduces the glass transition temperature (T g) by approximately 10 °C. A single methyl group has little effect on T g and two methyl groups increase the T g only when both are ortho to the amine, yet this causes a large 14 °C increase in T g. Thermal degradation profiles are not significantly affected by the dianiline. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48707.

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“…Therefore, it seems that there is a relationship between the miscibility of both components and the narrowing of the loss tangent peak for the a relaxation (see Table 1), which is commonly associated with the spatial distribution of crosslinking density [19,30]. A recent work on double epoxy networks also shows a broadening in tan d compared with unimodal networks [31].…”

Section: High Temperature Relaxations T a And Rubber Modulusmentioning

confidence: 99%

Critical examination of chemically modified hybrid thermosets: Synthesis, characterization and mechanical behavior in the plateau regime of polyaminosiloxane-nitrile-DGEBA

Loayza

Cabanelas

González

et al. 2015

Polymer

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Poly(3-aminopropylmethylsiloxane) has been modified with acrylonitrile via aza Michael addition and a broad range of modified oligomers have been prepared with CN:NH 2 ratio ranging between 0.1 and 1. NMR and FTnIR analysis reveals that acrylonitrile modification proceeds without formation of tertiary amines. Modified oligomers have been characterized by DSC and analysis of Tg reveals that the adducts are self-associated probably due to weak hydrogen bonding and dipole interactions. The modified oligomers with a modification degree higher than 0.4 were miscible with DGEBA. The low and high temperature relaxations of the cured thermosets have been measured by DMTA. In addition to the commonly observed b 2 relaxation, a new b 1 process linked by an isosbestic point to b 2 has been found. b 1 is attributed to an extended segment comprising the pendant propionitrile group as well as the ami-nopropyl segment that connects tertiary amines to the polysiloxane backbone. Elastic modulus as well as the a relaxation can be tuned from high Tg and high rubbery modulus to low Tg and high damping thermosets changing the nitrile content. The experimental network structure obtained from elastic measurements and the Tg were related through well established structure-property relations.

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Characterization of epoxies cured with bimodal blends of polyetheramines

Cited by 30 publications

References 39 publications

DMA testing of epoxy resins: The importance of dimensions

DMA testing of epoxy resins: The importance of dimensions

Alternative monomers for 4,4′‐methylenedianiline in thermosetting epoxy resins

Critical examination of chemically modified hybrid thermosets: Synthesis, characterization and mechanical behavior in the plateau regime of polyaminosiloxane-nitrile-DGEBA

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