Bonding adhesive, characterization methods

In deciding which surface chemistry tools to use for the broad area of adhesion and for adhesive bonding in particular, a number of aspects must be considered. More often than not, a combination of instruments must be used to take advantage of the unique information provided by each method. Table 1 shows some of the important aspects of adhesive bonding and some of the characterization methods... 

Aspects of Adhesive Bonding and Applicable Surface Characterization Methods... 

Brinson, H.F., "Durability Predictions of Adhesively Bonded Composite Structures Using Accelerated Characterization Methods," Composite Structures, I.H. Marshall, ed., Elvesier, 1985, p.1-18. 

Physical and chemical characterization methods are essential to assess aspects such as material and processing quality. Raman microprobe is an analytical tool coupled to an optical microscope. Elemental analysis using the x-rays emitted from the specimens in the electronic microscopy techniques can be used for local composition determination or to obtain a map of the distribution of a certain element in a wider area wavelength and energy-dispersive x-ray spectrometers are used for these purposes. Fourier transform infrared spectrometer is widely used for the qualitative and quantitative analysis of adhesives, the identification of unknown chemical compounds, and the characterization of chemical reactions. Thermal methods such as thermomechanical analysis and differential scanning calorimetry are discussed as valuable tools for obtaining information during postfracture analysis of adhesively bonded joints. 

Extensive use of the three-dimensional solubility parameters for predicting adhesion seems not to have been made, although its additional flexibility should make it successful over a wider range of conditions than the single-parameter approach. Some recent studies involving dental adhesion employed the method with success. Asmussen and Uno fl40 successfully correlated the shear bond strength of various dental adhesive resins, characterized in terms of their three-... 

Ion beams provide useful information either as a diagnostic tool or as a precision etching method in. adhesive bonding research. The combination of SIMS with complementary methods such as ISS or AF.S provides a powerful tool for elemental end limited structural characterization of metals, alloys and adhesives. The results shown here indicate that surface chemistry (and interface chemistry) can be decidedly different from bulk chemistry. Often it is this chemistry which governs the quality and durability of an adhesive bond. These same surface techniques also allow an analysis of the locus of failure of bonded materials which fail in service or test. 

Applications of Ion Beam Methods to Characterization of Adhesive Bonding Materials... 

One important influence in the formation of a good adhesive bond is surface or interfacial chemistry. In the broader sense, in which two substances are held together by interfacial forces, adhesion is of importance in many technologies such as in thin films and semiconductors. It is the purpose of this paper to discuss ion beam methods of surface characterization applicable to the broad area of adhesion with emphasis on adhesive bonding. 

Ion Beam Methods to Characterize Adhesive Bonding Materials 123... 

The fracture-based approach derives from continuum fracture mechanics theory, which claims the strength of most real solids is governed by flaws within the material [2]. To help predict this type of behavior, many test methods have been developed to determine fracture properties of adhesives. These tests are used to characterize the mode I, II, and III fracture properties of many types of material systems. In this study, the focus will be on the mode I and II characteristics of bonded joints for automotive applications. 

Sound knowledge of the joint behavior is required for a successful design of bonded joints. To characterize the bonded joint, the loading in the joint and the mechanical properties of the substrates and of the adhesives must be properly defined. The behavior of the bonded joint is investigated by finite element (FE) analysis methods. While for the design of large structures a cost-efficient modeling method is necessary, the nonlinear finite element methods with a hyperelastic material model are required for the detailed joint analysis. Our experience of joint analysis is presented below, and compared with test results for mass transportation applications. 

The failure of an adhesive joint can be considered to involve the initiation and propagation of naturally occurring (intrinsic) flaws or defects. Fracture mechanics is the field of mechanics concerned with the study of the formation and propagation of cracks in materials. The objective of using fracture mechanics is to determine the bond durability of a specific adhesive and provide a basis for estimating the fracture, fatigue, and service life of the adhesive joints. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the resistance of a material to fracture. 

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