Lightweight, high strength, thermally stable sustainable cellulose acetate-based material

Background

Over the past several years, there has been extensive research into biodegradable composites as a potential replacement for nondegradable petroleum-based materials. Cellulose and its derivatives have been widely used in various industries because they are derived from abundant sources, possess exceptional biodegradability, and can be easily renewed.

Cellulose acetate (CA) possesses several benefits, including its affordability, ability to break down naturally, compatibility with living organisms, strong mechanical properties, and exceptional chemical resistance. Consequently, it has found applications in diverse industries including textiles, paper, pharmaceuticals, membranes, water treatment, tissue engineering, and biosensors. Compared to other engineering plastics like polyamides, CA offers various advantages including enhanced biocompatibility, lower cost, and increased mechanical strength. However, a notable limitation of CA is its brittleness, which is undesirable for applications requiring strength, flexibility, and safety.

Description of the invention

Researchers at the University of Waterloo have developed a cellulose-based ink incorporating cellulose nanocrystals (CNCs) into cellulose acetate, optimized for use in 3D extrusion printing, which can also be moulded and coated. After printing or moulding, a finishing solvent exchange process renders the final objects super lightweight, sustainable, and anticorrosive. When applied onto a metal surface as a coating, the material demonstrated remarkable resistance to corrosion by water and HCl vapour. 

Material Properties:

• Tensile strength can be tuned between 16 MPa and 26 MPa
• Elongation at break is low at ~18% 
• Ability to undergo substantial deformation without brittle fracture, even in a complete compressed state
• Lightweight: low density
• Thermal stability: >250oC
• Resistance to both polar and non-polar solvents

Advantages

This material can elastically deform and avoid fractures commonly observed in commercially available plastics. It has higher thermal stability than CA due to the addition of CNCs. The material is also resistant to water and HCl vapor as well as common liquid solvents like isopropyl alcohol, hydrochloric acid, sodium hydroxide, and dimethyl sulfoxide. As a coating on aluminum is shows remarkable resistance to corrosion by water and HCl vapor. 

Potential applications

• Medical devices, implants, and drug delivery systems
• Sustainable food packaging
• Biodegradable foam packaging
• Automotive and aerospace parts
• Electronics casings