Researchers see large potential in renewable biomass applications

Wisconsin researchers among those looking to trees, wood products as possible replacement to plastics

(Photo courtesy of Junyon Zhu at the USDA Forest Products Lab)

MADISON, Wis. – A search for biodegradable and sustainable replacements for plastic has led to the emerging popularity of fibrillated cellulose, a key component of trees, as an alternative building block. It is being studied for potential use in a wide array of products traditionally made from synthetic materials.

The cell walls of trees, agricultural crop waste, and other plants are composed of a structural material called cellulose, the most abundant biopolymer on the planet. Cellulose has a hierarchical, bundled structure that can be broken down into fibrils with a diameter of roughly 3 nanometers, which is less than 1/100th of a human hair.

Although small, this nanoscale cellulose has large potential.

Early this year, Nature featured the work of a team of researchers that explained how fibrillated cellulose, also known as cellulose nanofibrils or nanocellulose, may play an important role as a building block in developing more sustainable products.

“Fibrillated cellulose has a variety of advanced applications far beyond traditional wood and wood fiber applications. It has the great potential to replace most plastics,” explained Junyon Zhu, contributing author and Scientific Leader and Research General Engineer at the Forest Products Lab located in Madison, Wisconsin (where Zhu has been engaged in the study of fibrillated cellulose).

Several characteristics of fibrillated cellulose make it an effective alternative to petroleum-based polymers, including its renewability, versatility, scalability, and abundance. It has a tensile strength greater than most metals, ceramics, and synthetic polymers, but it also has low density which makes it lightweight. One of the most valuable traits is fibrillated cellulose’s biodegradability. It breaks down quickly in soil, whereas traditional plastics require hundreds of years to degrade.

“The push for using biodegradable and sustainable nanomaterials to replace plastics, especially in European countries, Japan, and Canada, gained fibrillated cellulose great attention,” Zhu said.

The growing demand for fibrillated cellulose is expected to continue as governments introduce more sustainability-focused legislation. An additional driver in commercialization of fibrillated cellulose has been the decline in some printing paper markets, which has forced paper and pulp producers to seek alternative business models in the production of biomaterials.

Fibrillated cellulose technologies are already used in some paper production, but opportunities for future applications are far-reaching. In the short-term, researchers say it can be used in structural and biodegradable materials, such as specialty packing, bioplastics, and energy-efficient buildings. Looking further into the future, fibrillated cellulose technologies may be adopted in the manufacturing of transparent films for electronic devices, porous membranes to transport energy and water, and bioengineered gels used in wound dressings or artificial organs.

Not only is the fibrillated cellulose comparable to metal and petroleum-based nanomaterials in strength and functionality, but according to researchers, it is also cost effective. If the process is ramped up to commercial scale, the cost will drop even further. ­­­There is also an opportunity to integrate the fibrillated cellulose production with the existing paper and wood industries to reduce expenses.

While researchers say fibrillated cellulose has strong potential, various obstacles still stand between the lab and a scaled-up, commercial market. Zhu explained that the key challenge is processing cellulose and separating it into nanoscale fibrils. Because cellulose has a naturally strong structure, the process is difficult and requires chemical and physical processes. Even as a renewable and biodegradable resource, fibrillated cellulose is only as sustainable as its processing. Researchers are also looking for environmentally benign and recyclable chemicals to improve the process. Another remaining challenge includes finding a balance between biodegradability and durability.

“Unfortunately without the strong support and success in the front end processing, achieving true environmental and economic sustainability in fibrillated cellulose production, the commercial benefits will not be realized,” Zhu said.

Despite the challenges, there have been few large scale trial runs with promising results, but the economic viability still needs to be determined. With fast-growing plants such as bamboo and sugarcane, cellulose is a plentiful resource, and it has reached commercialization as a component in multiple international products. Further efforts remain necessary to increase the material’s durability and reduce cost, but the functionality and adjustability of fibrillated cellulose make it a compelling technological advancement.

For scientists at the Forest Products Lab and elsewhere, the work is not over.

“We are continuing to work on fibrillated cellulose production with the aim of achieving environmentally sustainable and commercially economic production. It needs to be emphasized: although wood is renewable and can be sustainably produced, fibrillated cellulose can be considered as a sustainable material only when the production process is sustainable,” Zhu said.

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