Rotation microfibril

Figure 9. This model shows three left-handed helical submicrofibrils (SM) 1, 2 and 3 which emerged from the cell wall at their termini. It was not clear how the submicrofibrils first associated with other submicrofibrils but once associated they were spun together. This model assumed that cellulose synthesis provided the mechanical force that simultaneously extended and left-hand rotated the submicrofibrils, which in turn drove the secondary formation of three submicrofibrils into a left-hand helical microfibril (M).

The model in Figure 9 predicts that each microfibril would rotate in the process of cellulose ribbon formation. If the A. xylinum cell were held stationary, then the ribbon would be left-hand twisted (2-5) however, if the ribbon were held stationary, then the cell would rotate (32). The latter case explains why ribbons appear untwisted in the pellicle of ribbons shown in Figure 1. Moreover, it has been demonstrated that an A. xylinum cell ceased rotation when Calcofluor (> 0.1 mM) was added to the solution... 

The model proposed above accounts for orientation produced at low extension. To account for the c-axis orientation observed at high extension, either c-axis slip, or breakup of the large lamellar crystallites accompanied by rigid rotation and formation of microfibrils must occur. Both mechanisms can occur as elongation progresses, and an example of the latter is shown in Figure... 

Cellulose is a homopolymer of 6-(l-4) D-glucose molecules linked in a linear chain, with alternating sub-units in the crystalline structure being rotated through 180°. Native cellulose I microfibrils are highly ordered crystals and evidence from... 

Lin R J T, Bhattacharyya D and Fakirov S (2007) Morphology of rotationally molded microfibril reinforced composites and its effect on product performance, Key Eng Mater 334 349-352. 

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