WAXS investigation of local structure in epoxy networks

Lovell, R.; Windle, A. H.

doi:10.1016/0032-3861(90)90274-3

Cited by 31 publications

(20 citation statements)

References 30 publications

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“…25 Ultrasound has been combined with DMA and dielectric techniques by Matsukawa et al 26 and with Brillouin scattering and photon correlation spectroscopy by Alig et al 27 Low-resolution nuclear magnetic resonance (NMR) has been used alone 28 and in combination with ultrasound 29 to track the liquidsolid transition in a curing epoxy. Lovell and Windle 30 reported structural studies of epoxy cure with wideangle X-ray scattering (WAXS), and we extended this work to compare observations of epoxy cure by WAXS, NMR, and ultrasound measurements. 31 Although all of these techniques could in principle be used to monitor a cure process, only the dielectric and ultrasonic methods have potential for applications in an industrial manufacturing setting because of cost, physical access, and safety.…”

Section: Introductionmentioning

confidence: 99%

Following network formation in an epoxy/amine system by ultrasound, dielectric, and nuclear magnetic resonance measurements: A comparative study

Challis

Unwin

Chadwick

et al. 2003

J of Applied Polymer Sci

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This article presents a comparison of data obtained from a low-temperature cure of an epoxy/amine system by three independent cure monitoring techniques: ultrasonic wave propagation, dielectric permittivity, and nuclear magnetic resonance. The sizes and thermal histories of the samples studied by the three techniques were controlled for comparability between the methods. The three techniques gave consistent information on the progress of cure and were complementary, in that each was particularly sensitive to different stages of the cure process.

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Section: Introductionmentioning

confidence: 99%

Following network formation in an epoxy/amine system by ultrasound, dielectric, and nuclear magnetic resonance measurements: A comparative study

Challis

Unwin

Chadwick

et al. 2003

J of Applied Polymer Sci

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“…(See the Experimental section for further description of materials.) The crosslinking reactions between epoxy prepolymers and amine hardeners generally involve the opening of the epoxide ring by reaction with amine hydrogens, as shown in Figure 1 4, 10, 11. Also shown in this figure is the etherification reaction between reacted and unreacted epoxy groups.…”

Section: Introductionmentioning

confidence: 99%

Relationships between stoichiometry, microstructure, and properties for amine-cured epoxies

VanLandingham

Eduljee

Gillespie

1999

J. Appl. Polym. Sci.

132

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Changes in microstructure and mechanical properties are investigated as a function of epoxy-amine stoichiometry. The epoxy-amine system studied exhibits a two-phase structure consisting of a hard microgel phase and a dispersed phase of soft, unreacted and/or partially reacted material. The size distribution of the microgel regions tends to increase with increasing amine content. Concurrently, the connectivity of the softer phase increases dramatically. This two-phase structure is inherently fractal, exhibiting a single glass transition temperature, T g . The T g and elevatedtemperature properties of the epoxy are directly correlated with crosslink density and the percentage of microgel phase observed in microstructure studies. The fracture toughness at room temperature increases with increasing amine content, most likely due to the increased presence of the soft phase, which absorbs more energy during crack growth. Changes in modulus values at 30°C with stoichiometry are explained by considering the effective aspect ratio of the polymer structure in the determination of sample rigidity. Relationships between microgel sizes and the sizes of interphase regions that form in composite and adhesive systems are also discussed in terms of interphase properties.

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“…(2) Figure 5 Principales rŽactions chimiques ayant lieu lors de la rŽticulation. Types de cha"nes formŽes lors de la rŽticulation dÕun syst•me Ç prŽpolym•re diŽpoxy/durcisseur diamine primaire È [10]. [10].…”

Section: Réactions (1) Et (2)unclassified

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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WAXS investigation of local structure in epoxy networks

Cited by 31 publications

References 30 publications

Following network formation in an epoxy/amine system by ultrasound, dielectric, and nuclear magnetic resonance measurements: A comparative study

Following network formation in an epoxy/amine system by ultrasound, dielectric, and nuclear magnetic resonance measurements: A comparative study

Relationships between stoichiometry, microstructure, and properties for amine-cured epoxies

Résines époxy réticulées par des polyamines : structure et propriétés

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