Wet Spinning and Structure Analysis of α-1,3-Glucan Regenerated Fibers

Abstract

Because of the increasing concerns related to fiber wastes resulting from non-biodegradable plastics and their impact in terms of environmental pollution, the demand for the development of biodegradable fibers has increased. Regenerated fibers of polysaccharides are expected as biomass fibers because of their biodegradability and structural variety. In this study, a linear polysaccharide synthesized by in vitro enzymatic polymerization, α-1,3-glucan, was wet-spun using 8% (w/w) lithium chloride in a dimethylacetamide solution. When ethanol (EtOH) was used in the coagulation bath, the resulting fibers were transparent, flexible, and dense, whereas the fibers produced with water in the coagulation bath were translucent, brittle, and aggregated. The former regenerated fibers exhibited tensile strength (11 cN/tex, 138 MPa), elongation at break (12%), and Young's modulus (3.5 GPa). The X-ray fiber diagram of the regenerated fibers coagulated in EtOH showed that the fibers were well-oriented along the fiber axis. The crystalline structure was determined to consist of a twofold helix with crystal lattice parameters of a = 1.59 nm, b = 0.976 nm, and c (fiber axis) = 0.852 nm.

High Tensile Strength Regenerated α-1,3-Glucan Fiber and Crystal Transition

“…The images of the fibers after solvent substitution, i.e., Regenerated Fiber 1 (Water → EtOH) and Regenerated Fiber 2 (EtOH → Water), are shown in Figure a and b, respectively. There was little significant difference in transparency and appearance between Regenerated Fiber 2 (EtOH → Water) and Fiber (EtOH) which was examined in our previous study . However, the diameter of Regenerated Fiber 2 (EtOH → Water) increased when it was immersed in water owing to swelling, as shown in Table .…”

“…A 10 wt % solution of the α-1,3-glucan in 8 wt % LiCl/DMAc was wet-spun using two types of coagulation baths of EtOH and water as reported previously. It has been confirmed in the previous study that the molecular weight of the fibers was the weight-average molecular weight ( M w ) = 0.8–1.0 × 10 5 . After the wet-spinning, Regenerated Fiber (EtOH) was immersed in water, and Regenerated Fiber (Water) was immersed in ethanol to investigate the transitions in the morphologies, crystal structures, and mechanical properties of the fibers before and after solvent substitution.…”

“…Moreover, there is some research about α-1,3-glucan regenerated fibers via the viscose method. , Although they show high tensile strength 17–23 cN/tex, the viscose method required harmful reagents such as carbon disulfide. Then, our group developed the wet-spinning system of α-1,3-glucan using an 8 wt % lithium chloride (LiCl)/ N , N -dimethylacetamide (DMAc) solution . The mechanical properties and crystal structures of the regenerated α-1,3-glucan fibers were found to depend on the type of used coagulation baths: a fiber coagulated in a water bath has a hydrated crystal form and fragile mechanical properties, whereas a fiber coagulated in an ethanol bath has an anhydrous form and a higher tensile strength of 11 cN/tex. , However, the maximum tensile strength of the regenerated α-1,3-glucan fiber coagulated in ethanol is approximately half that of a regenerated cellulose fiber such as viscose (22 cN/tex).…”

In Vitro Enzymatic Polymerization of α-1,6-Graft-α-1,3-glucan and Structural Analysis of Gel Formation

“…For example, one study demonstrated that α-1,3-glucan is crystalline and forms a fibril-like structure . Moreover, it was also reported that the development of the spinning method of α-1,3-glucan. , In addition, the esterified α-1,3-glucan has much higher thermal stability than other polysaccharides …”

“…15 Moreover, it was also reported that the development of the spinning method of α-1,3-glucan. 16,17 In addition, the esterified α-1,3-glucan has much higher thermal stability than other polysaccharides. 18 However, the glucans described above mostly had linear structures or wild-type noncontrollable branched structures such as that of starch.…”