Barking up the right tree

Nobody wants bark. Even in the context of healthy trees harvested by the forestry industry, bark is considered waste. In sawmills it’s either burned — inefficiently — for heat after the rest of the tree has been processed or simply thrown away.

tree bark

(Robin Riat,

Where everyone else sees waste, Ning Yan of the University of Toronto’s Faculty of Forestry sees opportunity.

“If you look at bark from a chemical composition point of view, it’s very good,” she says. “Bark offers protection to the tree. It has unique antifungal and antioxidant properties. It contains components and chemicals we can use.”

Her research group is leading the Bark Biorefinery Project, which includes partners at Lakehead University, public sector organizations and private sector companies. They are experimenting with bark to make green adhesives that could replace synthetic petroleum-based glues for all kinds of applications.

Her group also makes bio-based foams using bark that can have applications ranging from construction to automotive. And the researchers have found a way to use bark to replace bisphenol A (BPA) as the raw material to make epoxy resins.

“The idea here is that we are using waste biomass to make a renewable chemical that can replace a chemical that comes from petroleum resources.”

She is also using bark to create a product that could replace particle board. Because the chemicals in bark have natural adhesive properties, she is able to make “bark board” in the lab without any glue at all.

“With traditional particle board you need to use glues. You need to add chemicals. We are thinking that the bark will stick to itself.”

Yan’s work with bark is one of many projects she has on the go. She is breaking down wood fibre and making nanocrystals that are also electrically conductive. These could be used to make new materials that can substitute for similar nanomaterials made from petroleum-based sources. She is depositing bioactive agents on paper to make inexpensive diagnostic sensors to detect disease outbreaks or waterborne contaminants. She is making lighter wood panels for use in furniture and construction by replacing either solid wood or particle board with paper honeycombs that provide all the strength at a much lower weight and cost. She has also developed lightweight wood fiber composite panels suitable for cars.

Underlying all her projects are two intertwined philosophies. The first is a belief that forest-based products can be used to replace non-renewable petroleum-based products in a variety of applications.

“We have this tree, which is very good material,” she says. “The convention is to make furniture or lumber out of it, and that’s fine. But maybe we can make something even more valuable.”

She also believes that traditional forest products can be made more sensibly and sustainably.

“Nature has engineered wood to be the perfect material. We can try to imitate it but we cannot do better. It’s lightweight, strong, insulating, biodegradable, and renewable if managed properly. We are going to keep using wood in our daily lives. But how we can use it more responsibly and sustainably?”

The forest industry is a major economic engine for Canada. But it’s not doing well, she says.

“It has been focused on taking trees and making them into simple products. These are products that everyone can make — now we have competitive pressure from China, Brazil and other places. Manufacturing costs are high here and we use very outdated machinery.

“As researchers we try to find new, innovative ways to use these raw materials that are not only more environmentally friendly but also can generate more value.”


A version of this story was originally published by University of Toronto’s Edge magazine.  It has been edited for clarity, accuracy and brevity, and is republished here with permission. 

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