RESINOGKAPIIY 



Type III units of each phase not only can 

 be related to their origin and functions by 

 their light microscopic morphology, but also 

 by their optical properties such as relative 

 and specific refractive indices * and kind and 

 degree of double refraction. Some other 

 physical properties can generally be deter- 

 mined such as softening temperature, scratch 

 and indentation hardness. Such tests usually 

 can be done on the discrete phase in situ 

 ("intangible isolation (6)")- Some other de- 

 structive tests can be devised if the discrete 

 phase is tangibly separable from a suffi- 

 ciently large sample. 



Type IV. This may be a system of phases 

 of the whole material. The phase(s) may 

 be amorphous, continuous or discontinuous, 

 rubbery or glassy, crystallizable or non- 

 crystallizable. If a grafted part shows a 

 boundary with the original polymer, it is 

 best described as a separate unit of Type 

 R". So are other coatings and layers of one 

 phase each. For example, there may be a 

 precoating of phenolic resin on each of two 

 anodized aluminum sheets with an inter- 

 mediate layer of rubber in between (1). In 

 every case, each unit has its own physical- 

 chemical origin and purpose, and it is im- 

 portant that each be observed separately 

 during process-control and development of 

 use. 



Fibers and foils are special examples of 

 Type IV; they are so important that there 

 are special technologies, societies and schools 

 to study them. Yet the study of fibers and 

 foils must be considered as resinography. 

 They are highly polymeric in origin, have 

 important uses in resins as reinforcing parts, 

 have characteristic directional morphology 

 and many optical properties. These proper- 

 ties are generally those of particles of Type 

 I or II which have been oriented to some 

 extent, usually by the application of exter- 

 nal stress or by artificial conditions (e.g., 

 spinning and drawing a fiber; casting a film) 

 (Figure 10). 



Fig. 6. Phenol-fonnaklehyde polymer, experi- 

 mental fracture surface. An electron micrograph 

 of a positive replica. The larger type of particle is 

 classified as Type II and the smaller is probably 

 Type I. 



Fig. 7. Polyacrylonitrile in a very earl}^ stage 

 of bulk polymerization. An electron micrograph 

 showing particles of Type III composed of par- 

 ticles of Type II (5). 



Crystals on the other hand are composed 

 of macromolecules (Type I) which grow by 

 their own attractive forces into geometric 

 or skeletal shapes of characteristic habit and 

 phase. The crystalline habits of any one 

 phase are characteristic of variations in 

 crystallizing conditions. Transformation of 

 one crystalline phase into another is far less 

 common than it is among metallic alloys. 



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