Cellulose hypothetical model

Fig. 6.—Hypothetical Model for the Biosynthesis of Cellulose.184 [Numbers refer to reactions catalyzed by the following enzymes 1, invertase (EC 3.2.1.26) 2, sucrose synthetase 3, hexokinase (EC 2.7.1.1) 4, phosphoglucomutase (EC 2.7.5.1) 5, UDP-glucose pyrophosphorylase and 6, 7, and 8, hypothetical reactions in the pathway to cellulose.]...

Fig. 22.—The Hypothetical Model Proposed by Miihlethaler for Biogenesis of Cellulosic Elementary Fibrils. "...

The conformation parameter a (=A/Af, where Af is A of a hypothetical chain with free internal rotation) for cellulose and its derivatives lies between 2.8-7.5 2 119,120) and the characteristic ratio ( = A2Mb//2, where Ax is the asymptotic value of A at infinite molecular weight, Mb is the mean molecular weight per skeletal bond, and / the mean bond length) is in the range 19-115. These unexpectedly large values of a and Cffi suggest that the molecules of cellulose and its derivatives behave as semi-flexible or even inflexible chains. For inflexible polymers, analysis of dilute solution properties by the pearl necklace model becomes theoretically inadequate. Thus, the applicability of this model to cellulose and its derivatives in solution should be carefully examined. 

Following this lead, Martin and coworkers proceeded with acquisition of further data to clarify the ignition behavior of cellulose, but they rejected the use of ElR as being artificial because of the substantial variation in the overall weight-loss activation energy among the cellulosic materials. However, they found that the hypothetical, heat-flow model serves as a convenient device for correlation of their experimental results and the interpretation of the ignition behavior. 

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