Adhesives, forensic analysis

There are several ways that actual joints can be tested. For quality control purposes, a proof test is commonly used, as described above. This test imposes a stress on the specimen but limits it to a point well below where any destruction of the joint can occur. This type of test only looks for serious flaws in the bonding processes such as interface contamination, air entrapment in the joint, or undercured adhesive. The prototype joints can also be tested to destruction by using similar test methods described above for standardized testing. This, however, is generally not done at great frequency because of the cost. Generally, most actual joint tests are performed to ascertain the cause of failure (i.e., forensic analysis of the failed joint) or for nondestructive determination of the adequacy of the bond. 

Infrared spectroscopy is an established procedure for the forensic analysis of pressure-sensitive adhesive tapes [13, 19-21]. ATR spectroscopy is a often... 

Maynard, P., et aL "Adhesive Tape Analysis Establishing the Evidential Value of Specific Techniques." Journal of Forensic Sciences 46 (2001), 280-287. 

In this chapter the development of the application of surface analytical techniques to adhesion problems, in particular that of XPS. over the past 20 years has been described. Now the use of XPS and SIMS in forensic analysis of interfacial failure surfaces is relatively straightforward and may provide direct information regarding the actual mechanism of adhesion. Recent extensions of the... 

The format of this chapter will follow the areas identified above with sections devoted to the analysis of substrate surfaces, the forensic analysis of failed adhesive joints and organic coatings, and a final section that will look at the methods in which the interfacial chemistry can be probed directly. Specimen preparation is an important part of this last section, and the particular methods relevant to adhesion research will be considered in some detail. The tenor of this chapter is to provide the adhesion scientist with an overview of the different hierarchies of information that can be obtained using surface analysis methods, throughout which there will be illustrations of work from the author s laboratory. 

It should be understood that the reported practices of polymer/additive analysis, being the focus of this book, equally well apply to additive analysis of rubbers, textile fibres, surface coatings, paints, resins, adhesives, paper and food, but specific product knowledge gives the edge. Both fresh and aged materials may be analysed, as well as those of both industrial and forensic origin. 

The power of laser ablation can be extended as a popular method for trace and bulk analysis in conjunction with ICP-OES and is an invaluable tool in the study of surface behaviour particularly where sensitive surfaces are important. The common area for surface knowledge is in environment, medicines, adhesives, powders, slurries, oil-based samples and liquids. It finds application in the analysis of metallurgical samples, non-conductive polymers, ceramic materials, surface mapping, elemental migration, depth profiling, thin film coatings, biological and clinical specimens, forensic, paint chips, inks, bullets, fabrics, etc. 

Re-examines methods in areas with a long history of analysis by pyrolysis including microorganisms, coatings and adhesives, textiles, synthetic polymers, cosmetics, and forensic evidence... 

Lennard CJ and Mazzella WD (1991) A simple combined technique for the analysis of toners and adhesives. Journal of Forensic Science Society 31(3) 365-371. 

There is a core set of skills that any forensic scientist should cultivate as part of a forensic mind-set. The importance of comparison in forensic analyses imposes conditions on methods selected, how they are applied, and how the results ate interpreted. Consider a case in which the forensic chemist is provided a tiny fragment of a thick, fibrous, silvery material with one adhesive surface. The evidence is the only remaining trace of the material that was used to bind a homicide victim. A suspect has been identified and a search of his house reveals three different rolls of duct tape. The forensic question is which roll, if any, could the fragment of tape have come from The identification part of analysis is simple A quick look through a stereomicroscope shows the material to be duct tape. The challenge is how to proceed, given that the evidence cannot be destroyed. 

There is a growing interest in the investigation of iled materials. Since long time ago, a lot of efforts have been devoted to the analysis of failures in metallic parts and structures. Some recent texts are focused in post-failure analysis of polymeric materials (Lewis and Gagg 2010) and polymer composite (Greenhalgh 2009). Most adhesives are polymers, and they are used nowadays in an uncountable number of applications in everyday Kfe, especially applications where a failure in service may lead to economic loss, injury, or death. The ability to determine the cause of failure using forensic engineering techniques is essential. 

This chapter describes the latest forensic engineering techniques used in the investigation of failed adhesive-bonded joints. An overview of the examination and analysis methodology has been introduced. It is difficult to include a complete survey of all the possible practical situations, due to the combination of different types of adherends (metal alloys, polymers... 

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