Endgroups hydrocelluloses

Accessibility. Many reports [98-103] indicated that when hydrocellulose was treated with an alkali the stable residues still contained noticeable amounts of reducing endgroups [94,101-103]. This phenomenon was ascribed to a physical stopping process [100] when a degrading end reached a crystalline region inaccessible to the alkali. 

In all cases, kp decreased with reaction time. Thus, the accessible reducing endgroups in both hydrocelluloses were more reactive initially, apparently due to their location in less ordered regions of the respective physical structures. As the less ordered material was removed, the accessible reducing endgroups occupied increasingly ordered regions of the structures and were therefore less reactive. 

In both the 60 and 80 C reactions, the fibrous hydrocellulose exhibited higher kpg values than the amorphous hydrocellulose (Table V). This appears to be due to the involvement of more molecules in crystalline domains of the fibrous substrate. The greater inhibition of chemical stopping by cellulose I than cellulose II domains may also have contributed to this effect by allowing more molecules in the fibrous hydrocellulose to peel to a point where the reducing endgroup would be inaccessible. 

During degradation of the fibrous hydrocellulose, no changes in total endgroup content were detected (Table VI). This is consistent with results of previous studies in which chain cleavage was... 

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