Multiphase polymers etching

Multiphase pol)nners are prepared for SEM by methods such as fractography, etching and extraction and for OM and TEM by thin sectioning methods. The dispersed phase in a multiphase polymer is often directly examined by SEM study of fractured surfaces. Polymers with large dispersed phases that adhere poorly to the matrix are the best candidates for direct analysis but are unfortunately the worst materials. Well adhered and small dispersed phases are... 

SEM micrographs of a polyacetal/polyur-ethane multiphase polymer are shown in Fig. 5.50. The outer surface and a fractured internal surface of this extrudate were chemically etched in order to determine the nature of the dispersed phase. The surface (Fig. 5.50A) shows a complex structure due to etching. The fracture surface after solvent extraction (Fig. 5.50B) is complex, as... 

Walters and Keyte [82] first observed dispersed particles in blends of rubber polymers by phase contrast optical microscopy. Marsh et al. [83] studied elastomer blends by both optical phase contrast and TEM. Electron microscopy was applied to study blends of natural rubber, styrene-butadiene rubber (SBR), cis-polybutadiene (PB) and chlorobutyl rubber [84]. It became obvious that both hardening of the rubber and staining were necessary for producing sections with contrast for TEM. Today, the most common methods of observing multiphase polymers are by phase contrast OM of thin sections, TEM of stained ultrathin sections and SEM of etched or fractured surfaces. 

Different specimen types yield a range of results upon ion or plasma etching. Multiphase polymers generally etch differentially, enhancing the contrast. Melt crystallized polymers can be etched to reveal the spherulites. Surface protuberances and particulate fillers can and do form cones or ridges when etched. Oriented semicrystalline polymers, on the other hand, appear to be the most controversial with respect to the resulting surface textures. Clearly, in such cases the specimen should be prepared by other methods for comparison, and control experiments are essential. There are problems in the industrial laboratory that can be solved, in part, by microscopy of surfaces prepared by etching techniques however, these are far fewer than those addressed by other specimen preparation methods. 

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