Dielectric and mechanical studies of the durability of adhesively bonded aluminium structures subjected to temperature cycling. Part 1: examination of moisture absorption

Pethrick, R P; Armstrong, GS; Banks, W.; Crane, Robert L.; Hayward, D

doi:10.1243/1464420041579463

Cited by 7 publications

(24 citation statements)

References 4 publications

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“…There was no practical means of measuring the ingress of moisture into the bondline prior to bond failure. Recently, moisture absorption has been tracked by measuring changes in the dielectric constant of the adhesive by electrochemical impedance spectroscopy (EIS) [14][15][16][17][18][19][20][21][22][23] and dielectric spectroscopy [24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Detection of Moisture in Adhesive Bonds Using Electrochemical Impedance and Dielectric Spectroscopies

Davis¹,

Pethrick

Doyle

2009

Journal of Adhesion Science and Technology

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The ingress of moisture into an adhesive bonded structure can lead to a variety of effects. Moisture has the ability to plasticize the adhesive but may also segregate into microvoids. The water in the voids will have less of an effect as it does not plasticise the matrix and is unable to influence the interface between the resin and the substrate. Only if the T g of the matrix drops below ambient will it allow expansion of the voids and then there will be consequential lowering of the fatigue characteristics of the resin. Water also has the ability to interact with metallic surfaces leading to changes in the nature of the interaction between adhesive and adherend. Water has a large dipole signature and is easily studied in terms of its effect on the electrical properties of bonded joint structures. In this paper, applications of electrochemical impedance and dielectric spectroscopies are described. Both techniques measure the electrical response of the joint, however the nature of the measurement performed allows slightly different, but complementary, approaches to be adopted. Application of the techniques to similar joint structures illustrates the similarities and differences of the two approaches. The article demonstrates the value of using electrical methods to probe the changes that occur in joints on ageing and emphasizes the value of these methods in developing and understanding of the phenomena that are responsible for loss of bond integrity.

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Section: Introductionmentioning

confidence: 99%

Detection of Moisture in Adhesive Bonds Using Electrochemical Impedance and Dielectric Spectroscopies

Davis¹,

Pethrick

Doyle

2009

Journal of Adhesion Science and Technology

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“…The change in the permittivity above 3 MHz follows a linear behaviour indicative of the continued Fickian nature of the diffusion process. These changes are significantly smaller than those observed in the case where major corrosion of the oxide surface was observed that significantly weakened the interface [23,24]. The low-frequency data presented in Fig.…”

Section: Etch-only System: High-frequency Dielectric Results (300 Khzmentioning

confidence: 66%

“…7c and 7d), no significant further changes are observed. The level of corrosion is, however, relatively minor compared with the levels observed with some of the other systems studied [23,24]. (Fig.…”

Section: Transmission Electron Microscopic Examination Of the Jointsmentioning

confidence: 78%

Study of ageing of adhesive bonds with various surface treatments: Part VI. Dicyandiamide-cured epoxy joints aged at 70°C in a water bath

Comrie¹,

Affrossman²,

Hayward³

et al. 2006

Journal of Adhesion Science and Technology

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Adhesive-bonded aluminium/dicyandiamide-cured epoxy joints prepared using two different surface treatments, a silica/siloxane and an etched only process, were exposed at 70 • C to moisture and their ageing behaviour was studied using broadband dielectric spectroscopy and destructive mechanical tests. The dielectric measurements allow the uptake of moisture and changes in the nature of the surface oxide and pre-treatment to be monitored. Both sets of joints exhibited almost similar changes in their dielectric spectra as a function of exposure time to moisture; small differences being attributed to the influence of the pre-treatment on the moisture absorption behaviour. Changes in the mechanical properties as a result of exposure to moisture were monitored via lap-shear tests. Detailed electron microscopic examination of the surfaces indicated that after prolonged exposure to moisture changes in the physical state of the pre-treatment and oxide layer were observed. Small differences were observed in the dielectric data between the two pre-treatments and are a consequence of the differences in the extent and nature of the oxide to hydroxide conversion and hydration of the surface treatment which occurs on exposure to moisture. Further evidence for the nature of the change that occurred was obtained using X-ray photoelectron spectroscopy of the fracture surfaces. One side of the fractured joint was predominantly resin irrespective of the exposure conditions. The other fracture surface had a more metallic appearance but was covered by a nitrogen-containing organic material with high oxygen content. Predominantly, the initial changes observed in the mechanical strength of the joints are consistent with the plasticization of the adhesive in the joint. The effects observed after prolonged period of exposure to moisture are consistent with an increased contribution from interfacial failure to the loss of the mechanical properties. The losses in mechanical properties are less 1848 R. Comrie et al. dramatic than would be anticipated considering the mild nature of the surface treatments used and the severity of the exposure conditions.

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“…aerospace, aeronautic, electronic and automotive), to more traditional applications (i.e. packaging sport and construction) [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…There are some solutions available in literature to improve the toughness of brittle adhesives, such as: addition of a second polymer with a good toughness, use of woven or knitted reinforcement, inclusion of micro or nano inorganic (silicates, glass, alumina, etc.) or organic particles [8,10,14,15]. Also, natural materials can be used as reinforcement materials (i.e.…”

Section: Introductionmentioning

confidence: 99%

Methods to increase the toughness of structural adhesives with micro particles: an overview with focus on cork particles

Barbosa

Silva

Öchsner

2016

Materialwissenschaft Werkst

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Structural adhesives are used increasingly in new applications replacing conventional joining methods. Epoxy adhesives have the widest range of application of the various classes of adhesives arising principally from their extremely wide set of performance properties. They are known for their high stiffness and strength, as well for their low ductility and toughness. Currently, there is an increasing interest in developing methods of improving toughness. A toughened adhesive in general contains elastic or thermoplastic domains dispersed in discrete form throughout the resin matrix, in order to increase the resistance to crack-growth initiation. This paper provides an overview of the current developments in the use of reinforcement materials and introduces the reader to early findings on the use of micro particles for toughness enhancement of adhesives. The theme of the use of materials of natural origin as reinforcement materials, giving special emphasis to the use of cork particles as toughener material is also presented.

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Dielectric and mechanical studies of the durability of adhesively bonded aluminium structures subjected to temperature cycling. Part 1: examination of moisture absorption

Cited by 7 publications

References 4 publications

Detection of Moisture in Adhesive Bonds Using Electrochemical Impedance and Dielectric Spectroscopies

Detection of Moisture in Adhesive Bonds Using Electrochemical Impedance and Dielectric Spectroscopies

Study of ageing of adhesive bonds with various surface treatments: Part VI. Dicyandiamide-cured epoxy joints aged at 70°C in a water bath

Methods to increase the toughness of structural adhesives with micro particles: an overview with focus on cork particles

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