An electron microscopic study of the morphology of cured epoxy resin

Gupta, V. B.; Drzal, L. T.; Adams, Walter; Omlor, R. E.

doi:10.1007/bf01113751

Cited by 37 publications

(33 citation statements)

References 21 publications

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“…6 shows the FEGSEM micrograph of a polished section of a fracture surface from a fatigue tested sample. Micro cracks can be seen in the adhesive layer as well as the cavities associated with rubber toughening that have been explained previously by a number of authors [38][39][40][41]. The transverse micro-cracks are indicative of additional damage in the process zone.…”

Section: Mechanical Test Resultssupporting

confidence: 51%

Strength wearout of adhesively bonded joints under constant amplitude fatigue

Shenoy

Ashcroft

Critchlow

et al. 2009

International Journal of Fatigue

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Section: Mechanical Test Resultssupporting

confidence: 51%

Strength wearout of adhesively bonded joints under constant amplitude fatigue

Shenoy

Ashcroft

Critchlow

et al. 2009

International Journal of Fatigue

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“…Indeed, these have suggested the existence of high crosslink density nodules in a matrix of relatively lower crosslink density, [13] while others have revealed homogeneous structure at the nanometric scale. [7] The morphology of our thin polymer films has been studied by AFM.…”

Section: Network Morphologymentioning

confidence: 99%

Influence of substrate chemistry and the network homogeneity of ultra‐thin cross‐linked polymer films cured at their surface on the main relaxations temperatures probing by microthermal analysis

Carriere¹,

Onard²,

Mallarino³

2009

Surface & Interface Analysis

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Thin 200-nm epoxy-amine mixtures were cured on silicon wafers with different surface chemistry to quantify the effect of the chemistry on the glass transition temperature evolution in ultra-thin thermosetting films. Two surface treatments were investigated: the first one only consisted in the activation of the silanols groups at the silicon surface, whereas the second one consisted in the grafting 3-aminopropyltrimethoxysilane (APTMS) monolayer on the silicon wafers. The epoxy films were deposited on these chemistry modified wafers by spin coating a toluene solution of DGEBA-amine mixture at stoichiometric ratio. The same cure processing was used for both samples. Thin films were analysed not only using microthermal and thermomechanical analysis to determine the relaxation transitions temperatures of these films but also using FTIR in infrared reflection absorption spectroscopy mode to determine the curing rate of these networks. It was found that all these thin films showed two different glass transitions, the first one at 96• C and was independent of the surface treatments, whereas the second one increasing from 142• C for the oxidised wafers surface to 167• C for the aminosilane grafted on the silicon wafer. The substrate chemistry extent on the film network structure, the interfacial bonds and interactions are discussed. This work also illustrates the interest in using microthermal analysis to obtain relevant temperature glass transition of thin film at sub-micrometre scale, strongly dependant of local structure and chemistry composition.

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“…Une abondante littŽrature existe sur la morphologie nodulaire des rŽsines Žpoxy, par exemple, [24] et [25]. Pour certains, il existerait des hŽtŽrogŽnŽitŽs spatiales de densitŽ de rŽticulation.…”

Section: Morphologie Nodulaireunclassified

“…Les rŽsines Žpoxy pourraient •tre constituŽes de nodules de forte densitŽ de rŽticu-lation baignant dans une matrice de plus faible densitŽ de rŽticulation. La taille des nodules serait comprise entre 5 et 100 nm et dŽpendrait des conditions de polymŽrisation telles que la concentration en durcisseur [24] et 26], la cuisson [24] et [26], ou lÕagitation lors du mŽlange [27]. Les techniques ayant ŽtŽ utilisŽes pour mettre en Žvidence cette morphologie sont les suivantes : la microscopie Žlectronique ˆ transmission et b alayage, la diffraction des rayons X aux petits angles, la rŽsonance paramagnŽtique Žlectronique, la rŽsonance magnŽtique nuclŽaire et la spectromŽtrie mŽcanique [28] et [29].…”

Section: Morphologie Nodulaireunclassified

Résines époxy réticulées par des polyamines : structure et propriétés

Barrère

Maso

1997

Rev. Inst. Fr. Pét.

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Cet article fait le point sur l'état actuel des connaissances concernant les résines époxy réticulées par des polyamines, et plus particulièrement sur :-la réticulation ; -la structure et la morphologie des systèmes réticulés et les paramètres qui les influencent ; -les relations entre la structure et les propriétés sur une très large gamme de températures.Malgré les nombreuses études réalisées, beaucoup de points apparaissent encore controversés, notamment en ce qui concerne les relations structure/propriétés dans le domaine des tempéra-tures d'utilisation, c'est-à-dire entre la transition secondaire b et la transition a (transition vitreuse). S'il est maintenant admis que le module à l'état vitreux est gouverné par l'importance des mouvements des séquences hydroxypropyléther formées lors de la réti-culation, les résultats concernant les propriétés mécaniques aux grandes déformations (allongement et contrainte à rupture, énergie de propagation de fissures) sont beaucoup plus discutés. Les tendances obtenues semblent dépendre de la manière utilisée pour faire varier la densité de réticulation (cuisson, proportions du mélange, extenseurs de mailles, prépolymères de différentes longueurs, etc.), du système ou encore de l'auteur. Les désaccords entre chercheurs pourraient provenir des conditions de préparation des échantillons, notamment de la vitesse de refroidissement en fin de cuisson et des conditions dans lesquelles sont réalisés les essais mécaniques, comme la vitesse de déformation. EPOXY RESINS CROSSLINKED WITH POLYAMINES: STRUCTURE AND PROPERTIESThis paper sums up the current state-of-the-art on epoxy resins crosslinked with polyamines, and more particularly on:-the crosslinking reactions; -the structure and morphology of crosslinked systems and the parameters that influence them; -the relationships between structure and properties over a wide range of temperatures.In spite of numerous studies devoted to these polymers, many points remain controversial, notably concerning the relationships between structure and properties in the temperature range of interest to most users, which is between the b transition temperature and the a transition temperature (glass transition). If it is now widely accepted that the modulus in the glassy state is mainly controlled by the amplitude of the motions of hydroxypropylether groups created during the crosslinking reactions, the results regarding the ultimate mechanical properties (stress and deformation at break, crack propagation energy) are much more Copyright © 1997, Institut français du pétrole debated. The trends obtained appear to depend upon either the way the crosslink density has been modified (cure cycle, mixture composition, chain extenders, prepolymers of different lengths and flexibilities), or the polymers studied or even the authors. The discrepancies between authors could be due to the sample preparation, particularly the cooling rate at the end of the cure cycle, or the testing conditions, e.g. the strain rate. RESINAS EPOXÍDICAS RETICULADAS POR POLIAMINAS...

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An electron microscopic study of the morphology of cured epoxy resin

Cited by 37 publications

References 21 publications

Strength wearout of adhesively bonded joints under constant amplitude fatigue

Strength wearout of adhesively bonded joints under constant amplitude fatigue

Influence of substrate chemistry and the network homogeneity of ultra‐thin cross‐linked polymer films cured at their surface on the main relaxations temperatures probing by microthermal analysis

Résines époxy réticulées par des polyamines : structure et propriétés

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