Sample preparation methods adhesives

Table 6.4 Results of comparison of destructive sample preparation methods for the determination of the concentration of Nb in cyanoacrylate adhesive, in /ig/mlippm)...

There are many metal-type additives in epoxy adhesives and for the sake of analytical input to these products for metal content the following formulations were prepared to study the effect of different sample preparation methods as applied to these products. Four typical epoxy formulations containing active monomer/resin, colorants, curatives and fillers were prepared in the laboratory as part of a study of sample preparation methods for the determination of the concentration of the Ge(AcAc)BF4 additive. The four preparations were formulated as shown in Table 6.14. 

Some of the disadvantages were overcome by the use of the colloidal probe technique to measure adhesion forces (review Ref. [216]). The colloidal probe technique offers the advantage that the same particle can be used for a series of experiments and its surface can be examined afterwards. The accessible range of particle size is typically limited to a range between 1 /zm and 50 pm. The tedious sample preparation, limits the number of different particles used within one study, for practical reasons. Therefore the colloidal probe and centrifugal methods complement each other. 

Only a little sample preparation is needed. Mostly, half-inch diameter aluminium stubs with an adhesive layer of double-sided tape are used for sampling. When the sample has been secured on the stub, it is then examined for spherical metallic particles of defined diameter and chemical composition. The method has many advantages, but its basic drawback is that it is time-consuming if carried out manually. Suitable software for automatically searching through the secured material on the stub (in order to detect particles with specific features) shortens the time of investigation significantly [17]. 

Complex solutions of cyanoacrylate adhesives containing variable levels of fillers need to be measured for stabiliser content. It is difficult to prepare standard solutions with similar composition to the sample. The method of standard addition may address some of these problems with a high degree of accuracy. 

Sample preparation of anaerobic adhesives for metal content is an important step, be it by destructive or non-destructive methods. Inactive metal salts are added directly to anaerobic formulations as fillers or for thixotropic reasons. Generally, active transition metals are not added directly to anaerobic adhesives but are prepared as activators in aerosol solvents to be applied to inactive surfaces as part B of an adhesive formulation. In the majority of cases trace metal analysis of anaerobic adhesives is only required for batches with problematic stability and is best done using destructive methods. 

To study methods of sample preparation for metal analysis of anaerobic adhesives the following laboratory-prepared adhesives containing the usual additives and spiked with and without metals were used for comparison ... 

Table 6.5 Results of analysis of metal for metal content of Type A and Type B adhesives after sample preparation using dry ashing method...

Four laboratory samples of phenolic adhesives were prepared with and without fillers, as shown in Table 6.21, to study methods of sample preparation and analysis for metal content. 

Table 6.27 Results of analysis of polyurethane (PU) adhesives spiked with 0.1 % organometallic catalysts using destructive methods ashing, microwave acid digestion and bomb combustion methods of sample preparation...

Attenuated total reflectance (ATR) accessories are especially useful for obtaining IR spectra of samples that cannot be readily examined by common transmission methods. Such accessories are suitable for studying thick or highly absorbing solid and liquid samples, including films, coatings, powders, threads, adhesives, polymers, and aqueous samples. ATR requires only little sample preparation for most samples, it is one of the most versatile sampling techniques. 

To develop a new method by which we can study the mixing of two components in each domain in the patterned surfaces, we studied CFM of patterned surfaces prepared by fi-CP methods. Figure 5 shows a comparison between the patterned samples prepared by two different fi-CP methods, that is, the wet-inking and the contact-inking methods [57]. All adhesive force maps in Fig. 5 were observed in a 0.1 mM NaFICOs aqueous solution using a CH3 tip on three samples. The z-piezo was modulated sinusoidally at a frequency of 0.5 kHz with amplitudes of... 

DSC is thus a quick and reliable method of analysis, not only in material development, but primarily in the areas of quality assurance, raw material control and failure analysis. DSC is used for identification of incoming plastic materials e.g. HDPE/PA6 and LDPE/EVAL/PA6 composite film. DSC can not only identify the major components of polymers, but can also detect minor components such as adhesives, if these have a melting behaviour which differs from that of the polymers. Quality control of packaging film without sample preparation is based on the measurement of the solid/liquid phase transition of melting by means of DSC. Sass [175] has given various examples of quality assurance and defect analysis of plastics by DSC. There is increased demand for sensitivity and capability because of the growing complexity of materials. 

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