Gutta-percha polymerisation

Polymerised isoprene. Naturally-occurring polyisoprenes are natural rubber (cA-form) and gutta percha (trans- form). The use of stereo specific catalysts has made possible the manufacture of synthetic cA-polyisoprene and fraws-polyisoprene both of which are now available commercially. 

Gutta Percha is an example of this arrangement. The third type atactic (Greek without order) the groups are arranged randomly above and below the chain. This type of radical is obtained by free radical polymerisation. 

In 1954, 1,4-cA-polyisoprene, the synthetic equivalent of natural rubber, was obtained in the laboratories of Goodrich-Gulf [22] by isoprene polymerisation with new catalysts developed by Natta, and later on 1,4-trans-polyisoprene, a synthetic analogue of gutta percha, was obtained by Natta et al. [23]. 

Mesocolloidal (pol. degree 100—500) Normally plasticised rubber, native balata, and gutta percha i -cellulose, rayon, cellophane-foil Pepsin Insulin i ditto, in the solid state sometimes rubbery Shellac (probably), somewhat polymerised damar and copal. Phenol- or urea-formaldehyde between the A-and B-stages. 

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