The Fine Structure Study of Rayon Viscose Fibre 



291 



Fig. 3. Ulira-ihiii section of rayon viscose fibre without 

 dissolution ortiie embedding medium. Part of a cross-section. 

 Magnification 11,000. 



graphs is poor but the micro-structure of the fibre is 

 preserved unchanged. It is only the elements of structure 

 which differs sensibly in density from the embedding 

 medium which are visible. 



The perspex which constitutes the embedding of the 

 cross-sections is dissolved by chloroform in a distillating 

 apparatus (1). The cross-sections are then shadowed with 

 chromium by vacuum evaporation. 



This method gives micrographs with better contrast, 

 but the flow of the solvent, during dissolution, may 

 dislocate the fine structure and modify certain morpho- 

 logical details which may disappear even completely. 



It is good practice to use simultaneously both methods 

 and to judge the results by comparison of these difierent 

 micrographs. 



Before any interpretation of the micrographs, we 

 must have an idea of the scale at which the ultra- 

 thin sections are examined under the electron micro- 

 scope and also of the geometry of the sections. 



Fig. 3 is the ultra-thin transversal section of a 

 fragment of rayon viscose fibre. The separation be- 

 tween the "skin" and "core" is characterized by a 

 crown of microvacuoles. Their mean diameter is 

 between 2000 and 3000 A. The skin of the fibre is 

 made of several concentric successive layers of dif- 

 ferent densities. The first layer or cuticle which 

 is located on the fibre surface possesses the highest 

 density. Its thickness varies from 500 to 1000 A. 

 Then comes an apparently empty layer, its density 

 does not seem different from the density of the 

 embedding medium. For lack of contrast details of 

 structure cannot therefore be distinguished in this 

 layer. A third layer of higher density appears before 

 the crown of vacuoles is reached. The total thickness 

 of the skin is about 2 //. 



The core of the fibre shows a spongy structure. 

 Its density is homogeneously distributed. Large 

 vacuoles can be located in the core. It is these large 

 vacuoles which give the well-known milky appear- 

 ance of some types of rayon viscose libres; they are 

 several microns in diameter and can be seen under 

 an optical microscope. 



The longitudinal sections show a succession of 7 

 layers of dillcrent densities in the skin of this par- 

 ticular rayon viscose fibre. 



In oblique sections of rayon viscose fibres con- 

 centric layers can be clearly distinguished. Elod (4) 

 and Horio. Kobayashi and Kondo (9) have already 

 mentioned the presence of such layers. 



After dissolution of the embedding medium and 

 shadowing, the spongy net-work composed of a 

 very great number of microvacuoles becomes visible 

 in the regions of the skin which appear empty 

 before dissolution of the embedding medium. 



The difference of density between skin and core 

 is clearly visible in both phase contrast microscopy 

 and in electron microscopy, it is therefore possible 

 to get information on density gradient by simple 

 examination in phase contrast microscopy without 

 the use of electron microscopy. For this examination 

 thick sections made by hand with a razor blade 

 may be thin enough. 



References 



1. Barnfs, R. B., Borton, C. J., and Scorr, R. C, /. 



Appl. Pliys. 16, 730-739 (1945). 



2. Bernhard, W., Compt. rend, du coiioque du C.N.R.S. 



Toulouse, 1955. 



3. Cotton and Mouton, /. Chim. Phys. 4, 365 (1906). 



4. Elod, E. and Rauch, H., MelllamI Textilhcr. 1, 1-11 



(1953). 



5. Gautier, a.. Bull, inicroscop. appl. (1) 5, 1-2 (1955). 



6. Hermans, P. H., Textile Research J. XX, 8, 553-569 



(1950). 



7. HiLLiER, J. and Gettner, M. E., J. Appl. Phys. 21, 889- 



895 (1950). 



8. — Science 112, 520-523 (1950). 



9. HoRio, M., Kobayashi, K., and Kondo, T., Textile 



Research J. XVll, 5, 264-280(1947). 



10. IsARD, J. O., Brit. J. Appl. Phys. 6, 5, 176 (1955). 



11. IwANOW, N. and Schneider, R., Bull. I.T.F. 56, 45 



(1955). 



12. Larose, p., J. Textile Inst. 42, 104 (1951). 



13. Latta, H. and Hartmann, J. F., Proc. Soc. Exptl. Biol. 



Med. 74, 436-439 (1950). 



14. MoREHEAD, F. F. and Si.ssoN, W. A., Textile Research 



J. 15,443 (1945). 



15. Kassenbeck, p., Bull. I.T.F. 43, 43-52 (1953). 



16. — Teintex, 531-540 (1955). 



17. — Ann. Scient. Text. Beiges 1, 176-194 (1956). 



18. — Bull. I.T.F. 59, 7 (1956). 



