62 FUNDAMENTALS OF SUBMICROSCOPI C MORPHOLOGY I 



TiVBLE 

 HOMOLOGOUS POLYMERIC SERIES OF CELLULOSE 



According to Staudinger, the experimental data available lead to 

 the following conclusions regarding the molecule type of cellulose 

 (Fig. 50). If some 10 glucose residues are linked together to form a 

 chain, easily soluble cellulose products are obtained, which, owing to 

 their particle length of 50 A, already exhibit slightly colloid properties. 

 Compounds of this kind are known as degradation products of cellu- 

 lose, termed cellodextrines or y-celluloses. If the number of chain 

 links increases to 100, /9-celluloses are obtained which are soluble in 

 10% sodium hydroxide without swelling, to form viscous sols. Not 

 before the degree of polymerization exceeds 100 and approaches 800 do 

 we obtain the so-called a-celluloses, which are no longer attacked by 

 1% sodium hydroxide and which find application in the cellulose 

 industry (rayon, cellophane). They slowly dissolve while swelling in 

 10% NaOH and yield viscous "gel solutions". Native cellulose has a 

 still higher degree of polymerization; if dissolved in Schweizer's 

 solution with complete exclusion of oxygen, a degree of polymeriza- 

 tion of about 2000 for the fibre cellulose of linen, hemp, ramie and 

 others can be calculated from the viscosity. The values determined 

 from the viscosity can be checked osmometrically up to a degree of 

 polymerization of about 1000 (Staudinger, 1936 a, b); beyond this 

 limit extrapolation is carried out according to the linear viscosity 



