Antibacterial Wood-Polymer Filaments for 3D Printing

Guangyi Ai, Huining Xiao, and Meng Gong

A team at the University of New Brunswick (UNB) in the Faculty of Forestry and Environmental Management is currently working on a research project which touches on two innovative aspects of wood product manufacturing. In conjunction with the Wood Science and Technology Centre (WSTC) at the university, the group is researching 3D printing technologies and composite wood-plastic material technologies to develop an “optimized recipe of antibacterial wood-polymer filaments” meeting food safety standards.

 The UNB WSTC is a self-sustaining, applied research and development centre that services the value-added wood products, wood construction innovation, and non-timber forest bioproducts industries in Atlantic Canada. Their mission is to strengthen the innovation capacity of the wood products industry and, through this process, create and foster an effective interface between the university and the wood products industry. The interface is created and maintained by exposing faculty and students to the industry’s current issues and problems and making university expertise available to the industry, like the antibacterial wood-polymer filaments for 3D printing projects.

In the 21st century, with increasing needs for 3D printing and the development of the self-replicating rapid prototype that greatly reduces the cost of 3D printing, additive manufacturing technologies have extended to areas of the aerospace, automotive, medical, architecture, education, and fashion industries.

In collaboration with the WSTC and the Department of Chemical Engineering at UNB, the researchers had two goals. First, to develop an optimized recipe of antibacterial filaments made of spruce wood flour, polylactic acid (PLA), and polyhexanide hydrochloride (PHMB), and second, to examine their properties, including printability, tensile strength, and durability. The materials used in this project included the virgin PLA thermoplastic pellets with a diameter of 3mm, white spruce (Picea glauca) flour, Silane (an anti-mold agent), and polyhexanide hydrochloride (PHMB, an antimicrobial agent).

A twin-screw extruder was used for fabricating wood-PLA composite filaments at a temperature of 185°C and an extrusion speed of 1 m/min. Dog-bone coupon specimens were 3D-printed using the filaments of various receipts developed. The tensile modulus and strength, antibacterial property, and water adsorption of each coupon specimen were then tested and calculated. The scanning electron microscope was used to observe the interfacial bonding between wood flour and PLA.

It was found that wood flour and PHMB clearly had little or no impact on the tensile properties. The highest tensile modulus and strength appeared in the specimens made of the filament with 5% wood flour, 93% PLA, and 2% PHMB. The research team will develop new recipe filaments with good fire resistance, made of PLA and other wood wastes such as the flour from the manufacturing of thermally modified wood products.

For information about the testing and research services offered by the centre, visit their website, Twitter, or LinkedIn page. For questions, please contact Jon Barteaux, Projects and Business Manager, at woodsci@unb.ca.

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