Crystalline modifications of cellulose. Part VI. Unit cell and molecular symmetry of cellulose I

Fisher, Dennis G.; Mann, J.

doi:10.1002/pol.1960.1204213921

Cited by 35 publications

(8 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They further suggested that the space-group symmetry of the unit cell was not P21 and implied that twofold screw symmetry was not valid. Fisher & Mann (1960) also working on Valonia ventricosa cellulose, while confirming most of the results of Honjo & Wantanabe (1958), disagreed on the point that individual molecular chains did not possess twofold screw symmetry. Further, Dobb, Fernando & Sikorski (1974) also observed a number of reflections in the electron diffraction patterns of ramie and cotton which could only be indexed in terms of a 'superlattice'.…”

Section: Introductionsupporting

confidence: 57%

The crystal structure of cotton cellulose investigated by an electron diffraction technique

Paralikar¹,

Betrabet²,

Bhat³

1979

J Appl Cryst

View full text Add to dashboard Cite

An electron diffraction pattern of cotton cellulose recording over 70 reflections per quadrant out to the tenth layer line could be indexed on the basis of the Meyer & Misch [Heir. Chim. Acta (1937), 20, 232-244-] model. The validity of the observations based on the reciprocal net a'c* when checked by constructing reciprocal net b'c* revealed that three reflections could not be indexed. No systematic absence of odd-order 0k0 reflections was noted. The cotton cellulose, therefore, does not fall into P21 space group.

show abstract

Section: Introductionsupporting

confidence: 57%

The crystal structure of cotton cellulose investigated by an electron diffraction technique

Paralikar¹,

Betrabet²,

Bhat³

1979

J Appl Cryst

View full text Add to dashboard Cite

show abstract

“…[15,16,22 -25,29] The lattice I a is generally present in all algae and bacteria and has a triclinic unit cell structure with one polysaccharide chain. [27,[29][30][31][32] In these two lattices, I a and I b , the conformation of the polysaccharide chains is the same although the hydrogenbonding pattern is different. [33] The I a may be converted into the I b form by annealing the cellulose chains in the solid state.…”

Section: Crystalline Structurementioning

confidence: 87%

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Lima¹,

Borsali²

2004

Macromol. Rapid Commun.

793

343

View full text Add to dashboard Cite

Summary: In this article we present some interesting properties of rodlike cellulose microcrystals (so‐called “whiskers”). These microcrystals can be obtained from different cellulose sources such as wood, cotton, or animal origin. When submitted to acid hydrolysis, the cellulose fibers yield stable aqueous suspensions because of the presence of negative charges on the surface of the microcrystallites during the hydrolysis process. The obtained microcrystals are rod‐shaped particles, the dimensions of which depend on the cellulose origin. For instance, the cotton whiskers have typical dimensions varying from 100 to 300 nm in length, L, and 8 to 10 nm in diameter, d, while those of the tunicate whiskers range from 100 nm to few micrometers in length and 10 to 20 nm in diameter. At very low concentrations, these whiskers are randomly suspended in water and form an isotropic phase. When the concentration reaches a critical value, the whiskers spontaneously display ordered phases showing interesting liquid crystal properties (nematic and chiral nematic). The chiral nematic orders can be retained after evaporation of the solvent (generally water), leaving iridescent films. The reflected color can be controlled by changing either the ionic strength or by applying an electric field. These colloidal particles have been investigated using several techniques including small‐angle neutron scattering (SANS), small angle X‐ray scattering, rheology, and more recently dynamic and static light scattering techniques (DLS and SLS) to highlight their static and dynamic behavior. Because of their geometry, important axis ratio (L/d), and high crystallinity, these rods have been also extensively used to process nanocomposites based on polymer matrices, to reinforce their mechanical properties. All these properties are discussed in this contribution.Rodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.magnified imageRodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.

show abstract

“…SHIFT-the stagger of the center chain along its helix axis with re-2) PHI-the coupled rotation of the chains about their respective helix ROT-the rotation of the second chain about its helix axis with re-spect to the glycosidic oxygen of the corner chain at the origin; axes, PHI ,= Oo being arbitrary; spect to the position of the first chain; one molecular parameter:4) x-the dihedral angle which determines the orientation of the -CH2OH group, and has a value of zero when the C(6)-C(6) bond is cis to the C(4)-(5)bond, counterclockwise rotation of the group when looking down the C(5)-C(6) bond representing positive rotation; two orientational parameters: 5) \ko-the center of the Gaussian microfibril distribution in reciprocal 6) CT -the half-width of this distribution; 7) B-the average isotropic temperature factor; 8) K-the scale factor. space, having a value of zero in the a* direction; two crystallographic parameters: (Molecular model of the cellulose chain.…”

mentioning

confidence: 99%

Electron diffraction of Valonia cellulose. A quantitative interpretation

Claffey

Blackwell

1976

Biopolymers

View full text Add to dashboard Cite

SynopsisThe crystal structure of native cellulose (Vulonia) has been analyzed by electron diffraction. Possible models for the structure were refined by rigid-body least squares methods, which incorporated parameters defining the preferred orientation of the fibrils around their long axes in the cell wall lamellae. The structure was found to consist of an array of chains having the same sense (i.e., parallel), with packing parameters similar to those recently determined by X-ray diffraction. The eight-chain unit cell could be approximated adequately by a two-chain monoclinic unit cell with dimensions a = 8.18 A, b = 7.84 A, c = 10.38 A (fiber axis), and y = 97.04'; the space group is P21.

show abstract

Crystalline modifications of cellulose. Part VI. Unit cell and molecular symmetry of cellulose I

Cited by 35 publications

References 8 publications

The crystal structure of cotton cellulose investigated by an electron diffraction technique

The crystal structure of cotton cellulose investigated by an electron diffraction technique

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Electron diffraction of Valonia cellulose. A quantitative interpretation

Contact Info

Product

Resources

About