Better Adhesives Mean Stronger, Cheaper Wood Products

(This article was originally posted on Inside the Forest Service.)

As great as engineered wood—such as plywood or particle board—is for a range of building and manufacturing uses, it has its limitations, especially in outdoor applications. One of the biggest limitations is not the wood, but the adhesive used to glue the wood veneers or particles together. In the United States, the most commonly used adhesive in outdoor engineered wood products is phenol-formaldehyde resin.

To accelerate development of new and improved wood adhesives for engineered wood products, Forest Service researchers Joseph Jakes, Chris Hunt, Nayomi Plaza, Dan Yelle, Chuck Frihart and Linda Lorenz, along with collaborators at Oregon State University, Argonne National Laboratory and Scion, a New Zealand research lab, are working to understand the optimal adhesive penetration into wood for specific products and applications. They want to know what controls performance at the bond line—where the adhesive meets the wood.

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Plywood from Past to Present: UK Museum Exhibits ‘Material of the Modern World’

Plywood is one of the most common, yet overlooked materials used throughout the world today. But how has this revolutionary wood composite, dating back to 2600 BC Egypt, influenced the changing times?

A new exhibit at the United Kingdom’s Victoria & Albert Museum (V&A), the world’s leading museum of art and design, delves into the history and versatility of plywood, exploring the handy material and how it helped move our world from the past to the present.

 “Plywood: Material of the Modern World” showcases the story of plywood and its resourceful nature, featuring everything from furniture to houses and airplanes.

Despite its first emergence in 1880, the use of plywood increased in the 1920’s, when it signified the beginning of the industrial age. Architects praised the material’s flexibility and began building simple furniture, such as armchairs and stools. An armchair by Finnish architect Alvar Aalto is just one of the pieces shown at the exhibit.

Full-scale house, built at the 1937 Madison Home Show to demonstrate the Forest Product Laboratory’s plywood prefabrication system.

In addition to early 20th century furniture, the showcase features a full-scale prefabricated plywood home, similar to the first all-wood one built here at the Forest Products Laboratory (FPL) in 1937.  “Prefab” houses gained popularity after scientists at the Lab developed a waterproof adhesive that allowed for easier construction and mass-production of the product. Many people sought and bought these humble abodes in response to the Great Depression, seeing them as a means to quick, affordable housing.

Beginning in the 1940’s at the dawn of World War II, plywood played a role once again, and FPL was at the forefront of wartime innovation. Researchers designed and created a number of military applications, including adhesives and papreg, a strong paper-plastic that was used in the floors of gliders. The 1941 DeHavilland Mosquito aircraft, on display at the V&A, was renowned for its strength and lightness. Thanks to the planes plywood fuselages, built at FPL, the Mosquito was the fastest aircraft manufactured for the war.

Other exhibition highlights include an 1800’s elevated plywood railway, an automobile, and displays showcasing how the material influenced DIY efforts of the 1950’s. Various tours and lectures on the groundbreaking influence of plywood are also offered.

“Plywood: Material of the Modern World” will run at the V&A until November 12, 2017.

Blog post by Francesca Yracheta

Newest Forest Products Journal Features Adhesives: Many FPL Researchers Present

Adhesive-bond

Photomicrograph of an adhesive bond of two pieces of wood. The blue areas show the adhesive penetration into the wood structure.

The latest issue (Volume 54, No. 1/2, 2015) of The Forest Products Journal is all about adhesives. Featuring 10 selected articles addressing a theme of efficient use of wood resources in wood adhesive bonding research presented at the 2013 International Conference on Wood Adhesives in Toronto, Canada, we hear from several FPL scientists.

FPL has played an integral role in developing technical understanding of adhesives and setting product and performance standards by organizations such as the ASTM International (formerly American Society for Testing and Materials), American Institute of Timber Construction (AITC), APA–The Engineered Wood Association (APA), and the American Forest and Paper Association (AF&PA).

The first glue development research at the FPL in 1917 was to improve water resistance of the best glues available for manufacture of WWI aircraft components. At that time, FPL began to develop composites in an attempt to conserve our forests and make use of waste wood. Adhesives for housing, other buildings, timber bridges, and other structures has always been important.

In the Introduction to Special Issue: Wood Adhesives: Past, Present, and Future, Team Leader, Wood Adhesives, Forest Biopolymer Science and Engineering, Charles Frihart provides a comprehensive history and explanation of the important role that adhesives have played in the efficient utilization of wood resources.

Speaking about wood products, Frihart says: “Adhesives will continue to be a growing part of efficient utilization of forest resources. However, acquiring suitable wood resources will continue to be a challenge because of a diminished supply of high-quality wood and competition for wood from wood pellet and biorefinery industries. The challenges involve dealing with species that are not currently being used and with a greater mixture of species. More plantation wood could involve increased porosity and lower strength because of increased proportion of earlywood. The wood may also have increased or more variable moisture content as a result of efforts to reduce drying costs.

Wood products volume should continue to increase especially if engineered wood products replace other building materials for multi-story buildings and if there are sufficient housing starts. One challenge could be in bonding wood to other materials if glulam or laminated veneer lumber start using layers of stronger polymers or composites for greater strength. There also might be markets for bonding to modified wood, such as acetylated wood or heat-treated wood.”

Challenges in our changing forests and in changing construction practices will keep Frihart and his team busy for years to come as they find ways to use their adhesive research to adjust to change and best utilize our natural resources.

 

 

Right Up Our Alley: Laminated Wood Bowling Pins

FPL made national news in 2008 and 2011 when Research General Engineer Dave Kretschmann and his team became known for their work with Major League Baseball and the perplexing problem of breaking baseball bats. But did you know that FPL’s foray into sports goes back much farther than our work with baseball?

These photos, taken from the FPL library’s history room, show various experiments on laminated bowling pins. The genesis of these pins came from a conscientious desire to preserve our forests.

A January 1, 1920, Technical Publication,Fabrication and Design of Glued Laminated Wood Structural Members, from the U.S. Department of Agriculture, tells of the earnest Assistant Director of the Forest Products Laboratory at that time who “asserted that it would be possible to save ten billion feet of timber annually, if the American people would put in general practice what is already known relative to the closer utilization and preservation of wood.”

In an attempt to preserve what virgin forest remained, experiments began in 1912 to create bowling pins of laminated construction. Athletic goods, according to this publication, “require but a small number of woods for their manufacture. Special qualities are necessary, however, to meet the requirements of these products.”

These photos show special strength tests that resulted in standards that are still adhered to these days, according to the United States Bowling Congress and its USBC Equipment Specifications and Certifications Manual: “Gluing procedures should conform to those described in the Forest Products Laboratory (U.S. Department of Agriculture) manual entitled ‘Fabrication and Design of Glued Laminated Wood Structural Members.’”

So when you’re knocking back a few sodas or beers and knocking down those pins at the bowling alley, just remember that FPL and utilization of our forest resources helped make your pleasure possible.

Throwback Thursday: The Sticky Business of Plywood

Web_glue-spreading

Who knew that plywood was invented because the military was looking for a lightweight, strong material for airplane wings in World War I? Shortly after America’s entrance into the war, FPL initiated an elaborate investigation into the mechanical properties of plywood for wing ribs.

A new engine bearer was designed for the then revolutionary De Haviland plane. This bearer was of plywood about an inch thick, cut out of a solid sheet of plywood and lightened as much as possible through the use of lightening holes.

Closely associated with most of the aircraft work at FPL was the all-important research into glues. A special staff of chemists and assistants was gathered together and the necessary equipment installed to do this research. Pictured above is one of those pieces of equipment–a glue-spreading machine.

FPL continues its work on adhesives to this day, although none of our researchers have been seen sporting stylish aprons in the process.