Specimen preparation method freeze drying

Another method called freeze drying and hot pressing can also be used to prepare nanocomposites but only for unvulcanized NR matrix. In this method, the blends of polymer and chitin whiskers were prepared in water medium to prepare well-dispersed aqueous mixtures, which were then freeze dried to give nanocomposite powders, and the powders were consequently processed into specimen by hot pressing. 

Walter and Bryant [414] described a method for freeze drying latex specimens in a home made vacuum system rather than a commercially available device (as was typical of the state of the art at that time). Later, a freeze drying/image analysis method using commercially available equipment was described [413]. Important details of that method included specimen preparation, placement onto a TEM (or SEM) grid, the hardware for the experiment and the metal coating. 

Cryogenic transmission microscopy (Cryo-TEM) is an excellent method, by using which the objects in solution can be visualized without fixing and staining. As mentioned above, negative staining is a convenient method for the preparation of TEM specimen however, the object can be visualized only in dry state, which is sometimes much different from the structme in solution. In addition, using Cryo-TEM the structmal information inside the object can be obtained in contrast to freeze-fracture replica method. 

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