Dimensional stability of regenerated cellulose film in relation to orientations of crystalline and noncrystalline phases

Abstract

The dimensional stability of regenerated cellulose film on swelling with water is discussed in relation to the biaxial orientation of the two kinds of structural units, cellulose II crystallites and noncrystalline chain segments, and their anisotropic swelling (anisotropic absorption of water). Considerable dimensional stability in the plane of the film but enormous instability of thickness on swelling in water of some commercial cellophanes is qualitatively interpreted in terms of the planar orientation of crystal (101) planes along the film surface and the orientation of the noncrystalline chain segments parallel to the film surface. The dimensional changes on swelling from the completely dry state to 10% moisture regain were further interpreted quantitatively in terms of the degrees of biaxial orientation of the two kinds of structural units and their degrees of anisotropic swelling by modifying the Hermans monophase model for crystalline and noncrystalline biphase structures. The following degrees of anisotropic swelling of the structural units were thus obtained: qc, [101] = 0.40%, qc, [101] = −0.33%, and qa = 2.42%.

Birefringence of Stretched Cellulose Films

“…The commercial cellulose film generally has a high proportion (about ~/3) of amorphous cellulose. As earlier workers [7] observed, molecular chains constituting the amorphous cellulose seem to possess a strong tendency to orient themselves with the plane of the glucose rings parallel to the film surface. This tendency must be responsible for the relatively higher value of a-c over a-h in the first few samples.…”

“…We may once again recall the observation by earlier workers [5,6,7] that the ( 101 ) plane is oriented parallel to the film surface. In view of the nearly orthogonal disposition of the (101) plane and the plane of the glucose ring in the cellulose II lattice, we may expect the latter to have alignment normal to the film surface in the crystalline portions of the film.…”

“…The cellulose molecule has three principal polarizabilities, and the corresponding refractive indices have been calculated by earlier workers [7]. The highest refractive index is for polarized light vibrating along the direction of the chain.…”

“…From birefringence and orientation studies, Takahara et al [7] concluded that the orientation of the noncrystalline chain segments as well as the ( 101 ) crystal planes is parallel to the film surface for several commercial cellulose films. Our work is a study of the effect of stretch on the birefringence of cellulose films.…”

Nonlinear optical (NLO) polymers. IV. Second-order optical nonlinearity of NLO polyurea and copolyurea with NLO dipole moments aligned transverse to the main backbone

“…The molar ratio between 2R-DIAMINE and m-PDA components in copolyurea was found to be 1/4 with UV-vis spectra. Each refractive index, n X , n Y , and n Z , can be expressed as 18,19 n i ϭ ͑n Ϫ n Ќ ͒cos 2 ⌽ i ϩ n Ќ ͑i ϭ X, Y, Z͒ (4) Here, n X , n Y , and n Z are n values along the drawing direction, perpendicular to the drawing direction in the plane of the film, and the poling direction parallel to the film thickness direction, respectively.…”