Toward continuous high-performance bacterial cellulose macrofibers by implementing grading-stretching in spinning.

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials Engineering

Background:

• Challenges exist in the continuous, orderly assembly of cellulose nanofibers (CNFs) for high-performance materials.
• Bacterial cellulose (BC) offers potential due to its inherent properties but requires effective processing for macroscale applications.

Purpose of the Study:

• To develop a continuous and scalable method for preparing high-performance bacterial cellulose (BC) macrofibers.
• To investigate the effect of multi-stage stretching on the orientation and mechanical properties of BC macrofibers.

Main Methods:

• Utilized a wet spinning process combined with a custom-designed grading-stretching device.
• Employed one-stage and two-stage stretching techniques to orient cellulose nanofibers.
• Characterized macrofiber properties using mechanical testing and wide-angle X-ray (WXRD) diffraction.

Main Results:

• One-stage stretching (40% ratio) yielded a macrofiber with Young's modulus of 19.8 GPa and tensile strength of 544.5 MPa.
• Two-stage stretching significantly improved nanofiber orientation, achieving a maximum Young's modulus of 33.2 GPa and tensile strength of 659.8 MPa.
• The achieved mechanical properties surpass those of most previously reported spun and post-stretched CNF macrofibers.

Conclusions:

• The combined wet spinning and grading-stretching strategy enables continuous, high-performance BC macrofiber production.
• Multi-stage stretching is crucial for enhancing nanofiber alignment and maximizing mechanical performance.
• This approach provides a valuable reference for the industrial-scale spinning of nanocellulose materials.