Journal of Adhesion

Gent, A. N.; Lin, C. W.

doi: 10.1080/00218468908048190pmid: N/A

Abstract Debonding energies have been calculated from peel and lap shear experiments on rubber strips bonded together with a pressure-sensitive acrylic adhesive layer. In some cases, one strip was held stretched during bonding, to create joints with built-in stresses. Good agreement was obtained in all cases, provided that elastic strain energy was taken into account, the work of debonding being about 180 J/m2. For thick rubber strips, about 3–4 mm or greater, the strain induced by peel or shear forces was rather small and the assumption of linear elastic behavior was found to be satisfactory. Good agreement was then obtained with the relations derived by Kendall.1,2

Donaldson, E. E.; Dickinson, J. T.

doi: 10.1080/00218468908048191pmid: N/A

Abstract In past studies, we have investigated the nature of the photon emission accompanying the peeling of pressure sensitive adhesive tapes. These studies included producing clear images of the emitted light created by direct attachment/detachment of the adhesive from photographic film (i.e., autographs). Here we present an extension of this work to very slow peeling rates (< 0.05 mm/s) in which we examine how the resulting autographs from fiber reinforced tape are influenced by the micro-mechanical behavior of this composite tape during high angle peeling.

Carpenter, William C.; Barsoum, R.

doi: 10.1080/00218468908048192pmid: N/A

Abstract Two special finite elements are presented for modeling the adhesive in a bonded configuration. The assumptions of numerous lap joint theories can be modeled with the elements by selecting values of control parameters. An example is presented where control parameters are selected to model the assumptions of Delale and Erodogan and results with the elements are shown to converge to those of that reference. In another example, numerous combinations of control parameters are considered to study the effects of different assumptions on the maximum shear and normal stress in the adhesive.

Nieminen, Antti O. K.; Koenig, Jack L.

doi: 10.1080/00218468908048193pmid: N/A

Abstract Nuclear magnetic resonance imaging (NMRI) is used to study epoxy adhesive bonded structures at a proton resonance frequency of 300 MHz. Oligomeric and almost pure monomeric diglycidyl ethers of bisphenol-A, triethylenetetramine and xylene representing typical raw materials of epoxy adhesives are imaged at 25 and 50°C with varying repetition times to optimize measurement conditions for the adhesives. NMR images with good signal-to-noise ratios from the liquid epoxy adhesives are obtained at 50°C using the shortest possible echo times and a repetition time of 1 s. Chemical shift images of the glue-lines are presented and their possible uses in adhesive studies are discussed. The use of NMRI to detect heterogenous resin/resin and resin/curing agent mixtures is demonstrated. A non-invasive glue-line analysis is made of an aluminium/epoxy/aluminium sample with a model debonding by recording cross-sectional NMR images and a proton shadowgram.

Ennis, B. C.

doi: 10.1080/00218468908048194pmid: N/A

Abstract Thermal analysis (TA) is practically indispensable to the study and characterisation of modern structural adhesives, particularly those based on epoxies. Because a recent paper in this journal-“Linking Cure Process to Adhesive Bulk Strength by Differential Thermal Analysis” by Jozavi and Sancaktar1-advocates TA to those familiar with aspects of adhesion other than analysis and chemistry of adhesives, it is more open to comment than is usual.

Sancaktar, E.; Jozavi, H.

doi: 10.1080/00218468908048195pmid: N/A

Abstract A Comment published in this issue and authored by B. C. Ennis refers extensively to one of our earlier papers entitled “Linking Cure Process to Adhesive Bulk Strength by Differential Thermal Analysis.” We are delighted to see that our work can capture the attention of scientists working in this area and stimulate them to write lengthy reviews. At the same time, however, we feel that this particular note, in various discussions, misinterprets our paper, and does not seem to contribute any new or substantial scientific information to the literature.

Penn, L. S.; Jutis, B.

doi: 10.1080/00218468908048196pmid: N/A

Abstract Amine-terminated hexyl pendent groups were attached by direct chemical reaction to the surface of aramid engineering fiber. The number of groups attached was evaluated by two different methods of quantitative analysis, with parts per million sensitivity, and good agreement was found. Separate tests found no evidence for reaction of pendent groups with simple epoxy. A single filament pull-out test was used to assess directly the effect of the pendent groups on the fiber-matrix bond strength. The increased adhesive performance brought about by the presence of the pendent groups was ascribed either to a decrease in the initial crack size at the interface or to an increase in matrix modulus near the interface.

Kinloch, A. J.

doi: 10.1080/00218468908048197pmid: N/A

Abstract Since we at Imperial College also have an extensive research programme concerned with the fatigue performance of structural adhesives and adhesive joints, I read with interest the paper' on the “Fatigue Performance of Two Structural Adhesives”.

Luckyram, J.; Vardy, A. E.

doi: 10.1080/00218468908048198pmid: N/A

Abstract We are grateful to Dr Kinloch for his alternative interpretation of our experimental observations. Since our hypothesis was expressly declared to be speculative, we would not wish to defend it in the face of clear counter-evidence. Dr. Kinloch is far more knowledgeable than we are in this area and he is correspondingly more likely to provide the correct explanation. Nevertheless, our original ideas may not be wholly wrong.

Sharon, G.; Dodiuk, H.; Kenig, S.

doi: 10.1080/00218468908048199pmid: N/A

Abstract The hygrothermal response of high performance epoxy film adhesives, in their bulk state, has been characterized over a wide range of temperatures, following exposure to a combination of humidity (95% R.H.) and heat (50°C). Experimental results have indicated that the testing temperature has a pronounced effect on both tensile modulus and strength of the adhesives, while the effect of moisture content varies with respect to the adhesive type. The moduli of the film adhesives, which have a wide range of glass transition temperatures (Tg ), have been related to both moisture level in the adhesive and testing temperature. This has been accomplished by employing a dimensionless temperature, which incorporates the wet and dry Tg and the testing, as well as a reference, temperature. The strength properties have shown a higher degree of scatter using the abovementioned dimensionless temperature. Scanning electron microscopy of the fracture surfaces have shown a good agreement between the effects of moisture and the mechanical properties. Adhesives which exhibited good moisture resistance, as manifested by the stability in their tensile properties, showed minor changes in their fracture surfaces regardless of moisture conditioning. Distinctively, the effect on strength properties has been correlated with typical moisture-induced fracture mechanisms.