Recycled wood waste derivatives make carbon-fiber composites tougher, study finds

Polymers reinforced with ultra-fine strands of carbon fibers give composite materials their lightweight, yet strong, properties that allow them to be used in versatile applications across a number of industries.

Adding materials called carbon nanotubes to these materials can further enhance the composites’ functionality. But the problem is that the chemical processes used for incorporating carbon nanotube into the materials end up spreading them unevenly on the composites, limiting the strength and other useful qualities that can be ultimately achieved.

In a new study conducted by engineers at Texas A&M University, researchers used a natural plant product, called cellulose nanocrystals, to pin and coat carbon nanotubes uniformly onto carbon-fiber composites. The researchers said their prescribed method is quicker than conventional methods and also allows the designing of carbon-fiber composites at the nanoscale level. The results of the study are published online in the journal American Chemical Society (ACS) Applied Nano Materials.

Composites are built in layers. This layered structure is the source of the composites’ weakness. Any damage to the layers causes fractures, a process technically known as delamination.

To increase strength and give carbon-fiber composites other desirable qualities, such as electrical and thermal conductivity, carbon nanotubes are often added. However, the chemical processes used for incorporating the carbon nanotubes into these composites often cause the nanoparticles to clump up, reducing the overall benefit of adding these particles.

“The problem with nanoparticles is similar to what happens when you add coarse coffee powder to milk—the powder agglomerates or sticks to each other,” Amir Asadi, assistant professor in the Texas A&M University department of Engineering Technology and Industrial Distribution, says. “To fully take advantage of the carbon nanotubes, they need to be separated from each other first, and then somehow designed to go to a particular location within the carbon-fiber composite.”

To facilitate the even distribution of carbon nanotubes, Asadi and his team turned to cellulose nanocrystals, a compound easily obtained from recycled wood pulp. These nanocrystals have segments on their molecules that attract water and other segments that get repelled by water. This unique molecular structure offers the ideal solution to construct composites at the nanoscale level, Asadi says.

The hydrophobic part of the cellulose nanocrystals binds to the carbon fibers and anchors them onto the polymer matrix. On the other hand, the water-attractive portions of the nanocrystals help in dispersing the carbon fibers evenly, much like how sugar, which is hydrophilic, dissolves in water uniformly rather than clumping and settling to the bottom of a cup.

For their experiments, the researchers used a commercially available carbon-fiber cloth. To this cloth, they added an aqueous solution of cellulose nanocrystals and carbon nanotubes and then applied strong vibration to mix all of the items together. Finally, they left the material to dry and spread resin on it to gradually form the carbon nanotube coated polymer composite.

Upon examining a sample of the composite using electron microscopy, Asadi and his team observed that the cellulose nanocrystals attached to the tips of the carbon nanotubes, orienting the nanotubes in the same direction. They also found that cellulose nanocrystals increased the composite’s resistance to bending by 33 percent and its inter-laminar strength by 40 percent based on measuring the mechanical properties of the material under extreme loading.

“In this study, we have taken the approach of designing the composites from the nanoscale using cellulose nanocrystals. This method has allowed us to have more control over the polymer composites’ properties that emerge at the macroscale,” Asadi says. “We think that our technique is a path forward in scaling up the processing of hybrid composites, which will be useful for a variety of industries, including airline and automobile manufacturing.”

Republic announces deal to purchase 2,500 electric collection trucks

Republic Services Inc., Phoenix, Arizona, announced a partnership with Phoenix-based Nikola Corp. on Aug. 10 to develop and purchase 2,500 electric waste and recycling collection trucks. According to Republic, this represents “the industry’s first large-scale commitment to fleet electrification.”

The zero-emissions vehicles, which will have a range of 150 miles and recharge overnight, are expected to be integrated into Republic Services’ fleet beginning in 2023. The deal is expandable to 5,000 vehicles over the life of the agreement.

“This partnership significantly accelerates Republic Services’ progress in fleet innovation to drive profitable growth, reduce emissions, enhance customer loyalty and create long-term shareholder value,” Republic President Jon Vander Ark says. “Our agreement with Nikola represents the industry’s first large-scale commitment to fleet electrification. We expect to realize significant operating cost savings and environmental benefits from these trucks, and we are confident that our customers, communities and employees will benefit from our bold commitment.”

Republic says the collaboration with Nikola represents a transformational step forward in its efforts to leverage technology and innovation to reduce emissions, increase operational efficiency and provide economical, environmentally sustainable solutions to its customers. Among the anticipated benefits of fleet electrification are instant torque, no idling, regenerative braking, up to 90 percent lower emissions on a per-mile basis, quieter operation in neighborhoods, as well as significantly lower maintenance costs.

Minnesota county offers grants promoting deconstruction over demolition for older homes and apartments

Hennepin County, Minnesota, has launched a new grant program aimed at keeping old building materials out of landfills, Finance & Commerce reports.

The program, which offers grants up to $5,000 per project to developers and homeowners for prioritizing deconstruction of old structures over demolition, is meant to help defer some of the cost associated with more nuanced and time-consuming deconstruction services.

To be eligible, the structure must be a home or apartment with up to four units built before 1950 and with a renovation area of at least 250 square feet. Moreover, six material types need to be removed to be reused and at least 550 pounds of wood must be salvaged from the project. All non-reusable building materials must be sent to a county-approved C&D recycler.

“Deconstruction involves carefully dismantling the building structure to preserve building materials so they can be reused,” Olivia Cashman, environmental protection specialist with Hennepin County Environment & Energy, told Finance & Commerce. The additional costs of deconstruction “make it a deterrent, so that is where the grant funds come in,” she continued.

The program, which has a $100,000 budget for 2020, has helped defer costs for 12 projects (mostly for home renovations) since being launched in February. Of these projects, six have already been completed. There are still $45,000 in funds available for the remainder of the year.

Cashman says that although no funding has been allocated yet, she hopes the county will be able to expand the program for 2021.

GFL reaches deal to acquire WCA

Macquarie Infrastructure and Real Assets (MIRA), New York, via Macquarie Infrastructure Partners II (MIP II), announced Aug. 12 that an agreement has been reached to sell Houston-based WCA Waste Corp. to Ontario-based GFL Environmental Inc. MIP II is a closed-end fund that is nearing the end of its fund term.

GFL reports that it will acquire WCA and its subsidiaries for an aggregate purchase price of $1.21 billion. The purchase price for the acquisition will be financed in part with the net proceeds of a private placement of $600 million of equity and through a combination of cash on hand and capacity under the company’s revolving credit facility.

Founded in 2000, WCA provides solid waste collection, transfer, disposal and recycling services across 11 states. WCA currently operates a network of solid waste assets, including 37 collection and hauling operations, 27 transfer stations, three material recovery facilities and 22 landfills supported by more than 1,000 collection vehicles. WCA has an established regional platform with a growing footprint across the Midwest and Southeast, including three key markets in Texas, Missouri and Florida. The company generates annualized revenue of approximately $400 million.

MIP II acquired WCA through a take-private transaction in 2012 and since has supported WCA’s growth and operational improvements. Over the course of MIP II’s ownership, WCA executed on a business plan including the strategic divestiture of noncore assets to allow redeployment of capital to accretive core market opportunities, completing more than 35 acquisitions during MIP II’s ownership.

WCA also has significantly increased its focus on ESG over MIP II’s ownership and published its first annual Sustainability Report in 2018 comprised of a plan including CNG fleet expansion, leachate management and other initiatives developed in conjunction with MIRA.

“During our approximately eight-year investment, WCA has grown to become one of the leading vertically integrated solid waste companies in the U.S.,” Karl Kuchel, CEO of Macquarie Infrastructure Partners, says. “Working alongside the management team at WCA, we are proud to have supported the company in its mission to provide safer, more efficient and sustainable environmental solutions to its more than 700,000 customers.”

“Today marks a new chapter and a continuation of WCA’s story of growth,” Bill Caesar, CEO of WCA, says. “Over MIP II’s ownership, WCA has grown significantly while also professionalizing the business, investing in people and systems to support our growth and to improve administrative and operational efficiency. I am very grateful to everyone in our WCA family and extraordinarily proud of the company that we have built together.”

According to GFL, the acquisition is expected to support the company’s continued organic growth by further extending its reach into new and adjacent markets and by forming a base to pursue synergistic tuck-in acquisitions. GFL expects that the acquisition will expand its U.S. footprint while creating an opportunity to realize meaningful synergies and free cash flow accretion.

Following completion of the acquisition of WCA and the divestiture assets from Waste Management and ADS, GFL will operate in nine provinces in Canada and in 27 states in the U.S.

“We continue to deliver on our goal of pursuing strategic and accretive acquisitions to grow our business. The WCA transaction, which we have been working on for over a year, is another example of this commitment. The high-quality, vertically integrated network of assets, together with our recently announced acquisition of certain divestiture assets resulting from the Waste Management and ADS transaction, will complement our existing footprint and provide us with the runway to further expand in the U.S. through tuck-in acquisitions and [will allow us to provide] our suite of environmental services solutions to new customers. We are excited to welcome almost 1,600 employees of WCA to the GFL family,” GFL founder and CEO Patrick Dovigi says.

Dovigi says he expects the integration of WCA’s business to go smoothly for the company.

“Our multidisciplinary integration team has a successful track record of integrating acquisitions like WCA and the Waste Management/ADS divestiture assets,” Dovigi adds. “We have been working on integration preparation of the divestiture assets since earlier this year, which has allowed us to significantly advance our integration plans. We are well-positioned to bring these operations and WCA on board.”

“Today’s announcement represents a key component of GFL’s acquisition plan, which will help further position the company for continued long-term success,” Scot French, co-governing partner of HPS, says. “We look forward to building on our now seven-year partnership with Patrick and his entire team as they continue to execute their growth strategy.”

The sale agreement is subject to customary closing conditions including regulatory approval and is expected to reach completion in the fourth quarter of 2020.