Structure and Properties of Low-Substituted Hydroxypropylcellulose Films and Fibers Regenerated from Aqueous Sodium Hydroxide Solution

• Published in: Polymer journal Vol. 39; no. 7; pp. 703 - 711
• Main Authors: KIYOSE, Miki, YAMAMOTO, Eriko, YAMANE, Chihiro, MIDORIKAWA, Takehiko, TAKAHASHI, Toshisada
• Format: Journal Article
• Language: English
• Published: Tokyo Society of Polymer Science 01.01.2007; Nature Publishing Group
• Subjects: Applied sciences; Cellulose and derivatives; Crystal structure; Diffraction; Exact sciences and technology; Fibers and threads; Forms of application and semi-finished materials; Hydroxyl groups; Micrographs; Natural polymers; Photomicrographs; Physicochemistry of polymers; Planes; Polymer industry, paints, wood; Scanning electron microscopy; Sodium hydroxide; Technology of polymers; Cell structure; Anisotropic Swelling; Wide-Angle X-ray Diffraction; Layer Structure; Artificial fiber; Crystal orientation; Film; Fractal Aggregation; Coagulation; Experimental study; Selective Uniplanar Orientation; Hydroxypropylcellulose; Oriented polymer; Morphology; Regenerated Film; Cellulose(hydroxypropyl); Formation mechanism; Cellulose ether; Growth from solution
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1295/polymj.PJ2006206

The structure of Low-Substituted Hydroxypropyl Cellulose (LHPC) films obtained from aqueous sodium hydroxide solution by coagulation with aqueous sulfuric acid/sodium sulfate was investigated, mainly by Wide-Angle X-ray Diffraction (WAXD) and SEM. Both edge-on and through view WAXD patterns of films dried under compression revealed that the (110) planes of the LHPC crystals were preferentially oriented parallel to the film's top surface. The d-spacing of (110) planes of LHPC was larger than that of cellulose II by 9%, indicating that a part of the hydroxyl groups in LHPC crystals were replaced with hydroxypropyl groups. The replacement of the (110) diffraction arc in the edge view by a strong streak at low diffraction angle, and the considerable swelling anisotropy of the films in the thickness direction suggested that water molecules penetrated not only into the amorphous regions but also into the LHPC crystals, bringing about planar fracture along the (110) planes.A complicated multicellular structure containing pores of widely varying sizes was observed in SEM micrographs of the side surface of freeze-fractured LHPC film. Each cell was surrounded by thin membranes ca. 0.1-1.0 μm in thickness. The formation of this supramolecular structure and the mechanism of selective uniplanar orientation of (110) crystal planes were discussed on the basis of the WAXD patterns, SEM micrographs and fractal analysis.