ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Gutta, the polyisoprene hydrocarbon obtained from gutta percha or balata, is usually considered to differ from rubber in that gutta is a trans-isomer and rubber a cis-isomer of polyisoprene. Most of the data on the basis of which these structures have been assigned come from x-ray diffraction pictures of polycrystalline polymer. Single crystal data have not been published, although such data would provide more detailed information. Chicle gutta has been shown to be a lower molecular weight modification of gutta from gutta percha. As a consequence of its lower molecular weight chicle gutta is a granular, free-flowing powder, whereas gutta percha gutta is horny and tends to clump together. Because of its physical characteristics and lower molecular weight, chicle gutta was used first in an attempt to grow single crystals of gutta. By working with dilute solutions, well-shaped single crystals of chicle gutta as large as 0.35 mm. in the long direction were obtained. From gutta percha Pahang, crystals 0.10 mm. long were isolated. Crystals could be grown either by slow diffusion of solvent or by cooling a supersaturated solution. Crystals were found to be optically anis tropic and to exhibit parallel extinction when examined under crossed Nicols with the polarizing microscope. Crystals obtained were of the alpha modification of gutta.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1953.120110302
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