Dielectric and morphological investigations of phase separation and cure in rubber‐modified epoxy resins: Comparison between teta‐ and DDM‐based systems

Delides, C.G.; Hayward, D.; Pethrick, Richard A.; Vatalis, A. S.

doi:10.1002/app.1993.070471114

Cited by 24 publications

(7 citation statements)

References 36 publications

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“…The relaxation located ∼100 KHz is ascribed to dipole reorientation of OH groups and water molecules attached to the hydroxyl groups of the epoxy matrix. Plots of the permittivity and loss measured at 1 kHz reflect the changes in the total dipole relaxation for both “bound” and “free” in the resin, Figure (a,b).…”

Section: Resultsmentioning

confidence: 99%

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A dielectric study of water uptake in epoxy resin systems

Garden¹,

Pethrick²

2017

J of Applied Polymer Sci

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The influence of epoxy resin formulation on the nature and extent of moisture is studied using dielectric and gravimetric analysis for samples cured at 40, 50, 60, and 70 8C and aged at 50 8C and 70 8C. The equilibrium moisture uptake depends on the difference between the glass transition and aging temperature. Dielectric relaxation data measured from 1 to 3 3 10 10 Hz indicates the presence of water in at least two different environments. The high frequency relaxation ca. 1 3 10 10 Hz is associated with water clustered in nano-voids, whereas the relaxation at 10 5 Hz arises from a combination of OH pendant group reorientation motion coupled with that of molecularly dispersed water molecules. A correlation exist between the dielectric permittivity and the amount of moisture absorbed. Water initially resident in voids is re-dispersed with aging into the resin matrix aiding plasticization and allowing densification of the matrix. The extent to which changes occur depends on the chemical functions forming the matrix and densification leads to a drop in the amount of water absorbed. In the complex resin systems, water interacts with both OH groups and polyether of the amine curing agent which is not possible with the aliphatic diamine in the simple system.] V C 2017 Wiley Periodicals, Inc. J. Appl. Polym.Sci. 2017, 134, 44717.

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Section: Resultsmentioning

confidence: 99%

“…The WinData software package produced the ɛ ′(ω) and ɛ ″(ω) plotted using Origin software. The method used has been described previously . The measurement of each sample took approximately 3 min and the data presented was the average of three separate measurements.…”

Section: Methodsmentioning

confidence: 99%

A dielectric study of water uptake in epoxy resin systems

Garden¹,

Pethrick²

2017

J of Applied Polymer Sci

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“…Raw data of tanδ for the pure resin and the nanocomposite with 0.5% CB content at subzero temperatures are shown in Figure 6. There is a small peak in tanδ at about -55°C which corresponds to the secondary β-relaxation [23][24][25]. This peak shifts to higher temperatures (around -40°C) in the nanocomposite.…”

Section: Mechanical Propertiesmentioning

confidence: 96%

Structural, mechanical and electrical characterization of epoxy-amine/carbon black nanonocomposites

Kosmidou¹,

Vatalis²,

Delides³

et al. 2008

Express Polym. Lett.

103

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Abstract. This work presents an insight into the effect of preparation procedure and the filler content on both electrical and mechanical properties of a nanocomposite system. For the preparation of the nanocomposites diglycidyl ether of bisphenol A (DGEBA) was used with triethylenetetramine (TETA) as a curing agent. As fillers carbon black (CB) nanoparticles with size from 25 to 75 nm were used. The characterization was done using Dynamic Mechanical Analysis (DMA), Dielectric Relaxation Spectroscopy (DRS), Differential Scanning Calorimetry (DSC), Wide Angle X-ray Diffraction (WAXD) and electrical conductivity measurements. The dependence of the dynamic mechanical and dielectric parameters (E′, E″, tanδ, ε′, ε″, σ and Tg) is associated with the filler content and is controlled by the employed curing conditions. An increase in electrical conductivity, which is observed at about 1% w/w of carbon black, indicates the creation of conducting paths and is associated with the Maxwell Wagner Sillars (MWS) relaxation, probably due to the formation of aggregated microstructures in the bulk composite.

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“…Rubber toughening is improved if the particles of the CTBN are small and evenly dispersed. 32 The size of the particles formed depends on the temperature and rate at which cure occurs (Figure 11). The toughening action of the CTBN relies on the ability of the particles formed to absorb energy and deform and undergo cavitation and as a consequence, the impact and crack resistance are significantly enhanced.…”

Section: Toughened Structural Adhesivesmentioning

confidence: 99%

Design and ageing of adhesives for structural adhesive bonding – A review

Pethrick

2014

Proceedings of the Institution of Mechanical Engineers, Part L:

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This review outlines some of the issues which have to be addressed when selecting an adhesive for a particular structural adhesive bonding application. The designer may find that a number of adhesives provide the required load bearing properties and the selection may require a more detailed consideration of the processes involved in the fabrication of the joint, the temperature over which it is to work and the environment in which it will have to operate. The article attempts to provide the reader with an insight into the effects of factors such as time and temperature used in the cure process, details of the components in the mixture and the effects of various additives on the physical properties of the adhesives which are created. The performance of an adhesive may vary with time as a consequence of stress-induced changes which are triggered by thermal effects or by hygrothermal factors. The review considers joints created using metal substrates and carbon fibre composites. The performance and durability of an adhesive bond is critically dependent on the stability of the interface between the adhesive and adherend and is sensitive to the pre-treatment processes used in the creation of the bond. The review outlines how broadband dielectric measurements can be used to non-destructively monitor the cure of adhesive bonds and the processes involved in ageing of joint. The dielectric method gives an insight into the fundamental processes which are giving rise to the changes in the mechanical properties of the joint as they age.

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Dielectric and morphological investigations of phase separation and cure in rubber‐modified epoxy resins: Comparison between teta‐ and DDM‐based systems

Cited by 24 publications

References 36 publications

A dielectric study of water uptake in epoxy resin systems

A dielectric study of water uptake in epoxy resin systems

Structural, mechanical and electrical characterization of epoxy-amine/carbon black nanonocomposites

Design and ageing of adhesives for structural adhesive bonding – A review

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