Microscopy, optical microtomy

Thin sections (about 2-40/L m thick) provide ideal specimens for study using optical microscopy. However, some materials are too tough, brittle, or hard to be sectioned by microtomy. In geology thin sections of rocks are commonly made by polishing techniques and this method also works well for polymers that cannot be microtomed because they are too hard at room temperature. 

Depth concentration measurement is an important application of surface analytical methods. Examples are depth distribution of additives in plastics, or interface analysis where polymers are in contact with metals or ceramics. All surface methods with a good depth resolution (XPS, AES, SIMS) are suitable for depth or profile measurements. Complete multilayer coating systems require analytical methods that are applicable to small sample sizes and low concentrations. Techniques for obtaining chemical composition and component distribution depth profiles for automotive coating systems, both in-plane (or slab) microtomy and cross-section microtomy, include /xETIR, /xRS, ToE-SIMS, optical microscopy, TEM, as well as solvent extraction followed by HPLC, as illustrated by Adamsons et al. [5]. Surface and interface/interphase analysis can now be done routinely on both simple monolayer coatings and complex multicomponent, multilayered... 

Sampling and subsequent preparation techniques determine the nature and extent of useful information obtained [33]. Microtomy is probably the best technique. To preserve the microstructure, it is advisable to embed, grind and polish the sample. Unfilled plastic samples for optical microscopy are prepared by using a microtome to cut thin sUces, typically 3-20 fim thick, fi om the plastic part. These slices are then placed between two glass slides and examined using transmitted polarised Ught. Magnifications up to lOOOx are typically used. Thus, optical microscopy allows one to see the microstructure of the plastic. 

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