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Plastic lumber: ready for prime time.

Once shunned as a poor performer, plastic lumber's improved quality is now earning it some respect. Look for new national standards to propel it into structural applications once solely the domain of wood.

Ten years ago, so-called "plastic lumber" made from recycled post-consumer plastics was scoffed at as a contender for the structural applications that are the domain of pressure-treated soft woods. Plastic lumber gained some initial acceptance mainly for its "green" or "eco-friendly" public-relations value - and then only for low-end uses like park benches, sign posts, picnic tables, and planters. Nowadays, contractors are giving the nod to plastic lumber for more prestigious, structural uses like residential backyard decks, boardwalks, and sea walls. In fact, U.S. manufacturers say the growing interest will soon propel plastic lumber from a niche product to a big-time player against wood and a significant market for recycled plastics.

Plastic lumber manufacturers note that their product, unlike wood, does not rot, crack, splinter, decompose, or degrade and can withstand moisture and changes in temperature as well as attacks by termites and other insects. Plastic lumber can be drilled, nailed, sawed, and routed like wood and requires very little maintenance. It is available in a variety of colors and textures, and needs no painting.

A prime showcase for plastic lumber in structural applications is the $2.6-million Tiffany Street demonstration project in New York City, where 600 tons of plastic lumber was used to create the understructure, pilings, and boardwalk of a public waterfront pier. Plastic lumber is also being tested as railroad ties, joists, and in marine applications such as floating docks, pilings, and fenders. A key factor in its favor, producers say, has been that plastic lumber retains its neat appearance over time better than wood.

Broward County, Fla., recently installed miles of recycled, commingled (mixed plastic) plastic lumber in its West Lake Park for boardwalks, nature trails, floating docks, fishing piers, observation towers, and an amphitheater. The project, which used around 800,000 lb, was contracted to Better Than Wood Industries (BTW), Inc. of Hollywood, Fla.

Interest in plastic lumber has been stoked by a more serious commitment to quality and consistency by the manufacturers, who are pushing for national testing standards that will help establish a benchmark for minimum performance. Two years ago, processors created the Plastic Lumber Trade Association (PLTA), Akron, Ohio, which is working with the American Society for Testing and Materials (ASTM), Philadelphia, to develop such test standards. The first of the standards should be approved later this year. Producers think these standards will give civil design engineers more confidence in the physical properties of plastic lumber, thus ensuring its penetration in construction.


Manufacturers readily admit that plastic lumber acquired a negative image as a low-performance product in the 1980s. "Eight or nine years ago, plastic lumber got off on the wrong foot. Instead of differentiating itself from wood, manufacturers said it performed just like wood. It was used in applications for wood and didn't hold up - that's why it failed," says Ron Kwiatkowski, president of American EcoBoard Inc., a plastic lumber supplier in Farmingdale, N.Y. The use of recycled materials as feedstock for plastic lumber in some ways added to the negative perception. "It carried the burden of a cheap and dirty material. Because we used recycled plastics, our products were thought to be cheap or low grade," recalls Louis Fow, president of Custom-Pac Extrusions Inc., Chagrin Falls, Ohio. At the same time, some lumber producers, intent on capitalizing on the public approval of recycling, used inexpensive or poorly built molds and a wide variety of recycled plastic materials with no set specifications, leaving customers with no idea how their plastic lumber would perform from lot to lot, Fow adds. Michael Enden, executive v.p. at Duratech Industries Inc., Lake Odessa, Mich., remembers it the same way: "Once upon a time, it was easy for a guy with a large amount of plastic trash to just grind it up and make a product. He saw a gold mine, though the board he was making varied [in performance] from day-to-day."

Manufacturers say the dark days for plastic lumber seem to be coming to an end because their product is now gaining respect as a viable alternative to wood in some applications. "There are still some people who won't use plastic lumber because they were burned in the past," says Kwiatkowski. "But now the products are being made carefully to build credibility. We need reliability and consistent quality. We consult with New York State-certified engineers to determine if our product can be designed correctly for an application," he adds.

Anthony Noto, president of Trimax Inc., Ronkonkoma, N.Y., says he has spent millions field testing his plastic-lumber products. Many producers like Trimax now offer customers performance data produced by independent labs and based on standards established for wood. The confidence in product quality is growing to the point where some manufacturers even offer warranties as long as 50 years, with free replacement in case of premature failure.

Rather than being a cheap substitute, plastic lumber actually is more expensive than many soft woods such as pine, against which it competes. Plastic lumber does cost less than premium grades of hard woods, but those compete directly only in some higher-end applications. "Plastic lumber should be more expensive because it performs better in terms of life-cycle costs. It may cost three times as much, but it may last three times as long," says Celeste Johnson, president of Obex Inc. in Stamford, Conn. Many plastic lumber makers agree that cultivating a life-cycle mentality in customers' minds is one of the biggest steps toward getting more users. Trimax found in a study of its plastic lumber versus a soft wood that the wood was 43% cheaper to buy initially, but over four years the cost to maintain the wood boosted its overall cost 164% higher than the initial price of the plastic lumber, which incurred no additional maintenance costs. Installation costs were only 10% higher than for wood.


Despite the evident economic benefits of plastic lumber, the lack of common industry test standards to measure performance is said to hamper market growth. "We believe most plastic lumber manufacturers are looking to get into the structural higher-performance market, but they can't because there are no product specifications. The federal, state, and local governments need standards and specifications so they can write procurement guidelines. Without the guidelines they can't really use it," says Dr. Prabhat Krishnaswamy, a senior researcher with Battelle in Columbus, Ohio. Krishnaswamy is co-chairman of the ASTM committee charged with developing standards for plastic lumber. Measurement test methods and standards are considered essential for plastic lumber in view of the variety of recycled materials that may be used, along with modifiers such as glass fiber, sawdust, ground-up rubber tires, and even peanut shells.

Five national standards for plastic lumber are expected to be in place by November. The first ASTM standards will set test methods for density as well as compressive and flexural moduli. Standards for creep properties and mechanical fastening for plastic lumber products are also being discussed, according to Richard Lampo of the U.S. Army Corps of Engineers. The next step will be to develop performance-based specifications for various applications. Krishnaswamy says a guideline on the minimum range of properties needed for outdoor residential decking boards will be one of the first of those performance specs, which are expected to be approved next year.

Krishnaswamy says these performance standards will cover shear properties, outdoor weathering, hygrothermal cycling, and fastener withdrawal. After that, a performance grading system will be established for different varieties of plastic lumber based on their properties.

Two additional task forces are being created, according to Krishnaswamy: One will address plastic lumber testing and performance standards specifically for marine applications. The second will look into the flammability and combustibility of plastic lumber products. The task force draws heavily on tests done by Battelle; the U.S. Army Corps of Engineers; the Center for Plastics Recycling Research (CPRR) at Rutgers University, New Brunswick, N.J.; the Institute for Recycled Materials at Louisiana State University, New Orleans; and the University of Massachusetts, Lowell.

Battelle recently formed a three-year alliance with the PLTA to develop technologies for structural use of plastic lumber. The team will investigate residential decking, marine uses, and material-handling applications. The group also hopes to develop a database of materials, properties, applications, and product design guidelines.


There are currently 62 producers or fabricators of plastic lumber in the U.S. and around seven more in Canada, according to data from the PLTA and from the newsletter Plastics Recycling Update, published by Resource Recycling Inc. in Portland, Ore. Battelle's Krishnaswamy says use of plastic lumber has been growing by approximately 40% a year, topping 16 million board feet, or about 40 million lb, last year. That figure compares with 81.5 billion board feet of wood used in the U.S. in 1995, according to the National Lumber and Building Material Dealers Association in Washington, D.C.

Some plastic lumber makers have experienced explosive growth. "We had plastic lumber sales totaling $200,000 in 1992. In 1995, sales were $800,000, and we expect even higher sales this year," says Custom-Pac's Fow, who adds that plastic lumber sales encompass half of his total sales of recycled plastic products. J'Lynn Hare, general manager at Rumber Materials Industries, Muenster, Texas, says her company's plastic-board sales have doubled each year since 1991. A number of manufacturers expect to turn a modest profit in 1996 after years of operating in the red. Manufacturers say fluctuating prices for recycled resins have frequently priced plastic lumber out of the market. This, along with the low profitability and competitiveness of the business has forced some companies out of production. "It's been very difficult," says Obex's Johnson.

Still, a number of companies plan to expand their operations:

* Advanced Environmental Recycling Technologies (A.E.R.T.) Inc. recently added a third plastic lumber line at its Junction, Texas, facility and is planning to add a fourth. The company also plans to open a second composite lumber plant later this year. It will have three extrusion lines.

* Custom-Pac increased its plant by 12,000 sq ft and added a third plastic lumber line.

* Trimax plans to upgrade its equipment to raise capacity by 150%.

* BTW is adding a self-built extrusion line to its North Ft. Myers plant, which will double capacity there.

* Alket Industries Inc., Kalona, Ia., is planning to purchase a second extruder line to make plastic lumber.

* Full Cycle, Tampa, Fla., is a new plastic lumber maker that started up in April. It operates two lines.

* A newly formed company called U.S. Plastic Lumber, Boca Raton, Fla., purchased two existing plastic lumber makers - Duratech Industries, Lake Odessa, Mich., and Earth Care Products, Sharon, Tenn. Both new subsidiaries will now be called Earth Care Midwest.


Plastic lumber makers say the first step to producing a reliable product is getting consistent feedstock. In the 1980s, much of the early plastic lumber was made from commingled plastics. Today, many more producers use selected feedstock - primarily HDPE bottles such as milk and water jugs and shampoo and detergent bottles.

Firms such as American EcoBoard, Custom-Pac, Trimax, Chicago-based Eaglebrook Products Inc., and N.E.W. Plastics Corp. of Luxembourg, Wis., purchase sorted HDPE. They typically buy the material in bales or as washed flake. "Even then it's very difficult to keep the material consistent," says N.E.W. president Irving Vincent. "If the bales are left outside in the sun for six months, they will have a different strength than baled bottles put in a warehouse, so we test it as it comes in and try not to stockpile so much." American EcoBoard's Kwiatkowski and Trimax's Noto say their presorted feedstock is further sorted into colored and natural PE, which is then used to make dark- and light-colored lumber, respectively. "[Second sorting] is a labor-intensive process, but it ensures consistency," says Kwiatkowski.

Custom-Pac only uses material with a density between 0.950-0.960 g/cc and with a melt index of 0.1-0.8 g/10 min. "We look at every single truckload," says Fow. Adds Kwiatkowski, "When you don't know your material, every day is a [processing] adventure."

Some manufacturers still favor use of commingled recycled plastics, which reportedly can be 6-10[cents]/lb cheaper than sorted material. Obex's Johnson says that if handled correctly, such material can yield a consistently high-quality product. Obex accepts all types of recycled LDPE, HDPE, PP, PET, PS, PVC, and mixed plastics including bags and PS foam. The feedstock can be either baled or shredded, contaminated with liquids, paper, or food waste. (Obex does not wash feedstock before extruding it into lumber.) Johnson works with her material suppliers to analyze the composition of different resins in each source's commingled blend. The provider makes a commitment to supply a consistent "recipe" having the same percentages of components. With that assurance, Obex can develop a consistent product.

Tom Nosker, director of plastic programs at CPRR, has been testing plastic lumber for at least a decade. He dismisses the notion that sorted material yields a significant difference in mechanical properties over commingled. Since 80-90% of the material in com-mingled plastic waste is HDPE, CPRR finds that the lumber exhibits mechanical properties that are 80-90% of virgin HDPE resin, he says. Nosker argues that although the presence of PS in commingled material can as much as double the compressive modulus, this variation is not significant because the modulus remains a small fraction of that of wood. He says recycled material, whether separated or commingled, typically shows compressive strength similar to wood (around 3200 psi) despite the lower stiffness. Virgin HDPE has a compressive modulus around 160,000 psi, while a plastic lumber product made from recycled HDPE typically has a modulus of about 110,000 psi, according to Nosker. He says a soft wood like yellow pine shows a modulus in the direction of growth of 1.2-1.6 million psi.

BTW Industries says the only appreciable benefit to using sorted materials is aesthetics. "We use recyclable plastics, types 1-7, and we think they enhance the stiffness of our product. So what we trade off in cosmetics we get back in mechanical properties," says Bob Lehrman, operations manager at BTW.

In addition, some plastic lumber makers add other materials to their product to make a reinforced or composite product. Many in the industry expect that reinforced materials will assume a larger share of the structural market.

* Trimax adds 20% chopped glass fiber to its lumber.

* Seaward International, Clearbrook, Va., makes a fiberglass-reinforced product using a pultrusion process.


* Mobil Chemical, Winchester, Va., makes a lumber composite of 40% film reclaim and 60% sawdust.

* Rumber Materials Industries makes tongue-and-groove board out of a 50/50 blend of PE from unwashed milk jugs and grocery bags with shredded rubber tires.

* Strandex Corp., Madison, Wis., developed a composite extrusion process in which profiles can be made using a polyolefin resin (30% of structure) crosslinked with wood sawdust (70%). Any wood dust fiber can be used, although the process has to use a 70% loading to give the final product strength. Strandex, which has been developing the process for two years, typically uses a virgin HDPE resin. Strandex has developed tooling and technical support to run the process. It has licensed the technology to Crane Plastics, Columbus, Ohio, which is using a PVC resin in the process to make vinyl profiles. A spokesman at Strandex says the company is talking with a plastics recycler about using recycled materials with the process.

* Environmental Solutions, Inc., Richmond, Va., is building a plant in Suffolk, Va., to produce 250,000 pallets/yr of recycled HDPE with 40-50% peanut hulls. The company's "Nuevowood" product is said to be suitable also for siding, fascias, soffits, door cores, fencing, and furniture.

In addition, many processors incorporate additives such as uv stabilizers, colorants, and chemical blowing agents to increase the stiffness-to-weight ratio. Plastic lumber typically has a foamed core with a gradation in cell size that leaves a solid outer layer 0.5 to 1 in. thick.


Plastic lumber is either flow molded (extruded into molds) or extruded as a continuous profile. Flow molding machines are said to permit use of commingled plastics. One of the best-known molding systems is the ET-1, a 12-station carousel machine (usually teamed with a single-screw extruder) made by Advanced Recycling Technologies (A.R.T.) of Brussels, Belgium. Eight ET-1 machines were sold in the U.S. in the last decade or so, according to John Maczko, president of Mid-Atlantic Plastic Systems. Maczko represented A.R.T. in the U.S. and sold the ET-1 machines here. A.R.T. is currently represented here by Tex America.

U.S. Plastic Lumber Co.'s continuous-extrusion process produces plastic lumber containing 80% HDPE, 10% LDPE, and a 10% of blend of other plastics, says Enden. The company also designed its own flow molding equipment to produce a premium-grade lumber using 100% post-consumer HDPE bottles.

The recycling systems unit of Maplan Schwerin of Vienna, Austria, part of Starlinger & Co., says its 1 1/2-year-old Intrumat line for making plastic lumber from commingled materials will be offered in the U.S. soon. Intrumat accommodates four to 16 molds, each containing a pressure sensor. Melt flow creates the pressure in the mold and triggers mold closing and indexing. The line, typically fitted with a Maplan single-screw extruder, has a top throughput rate of 3000 lb/hr.

Mid-Atlantic Plastic Systems recently began marketing a brand-new carousel molding machine called the JET 3000 from Julien Environmental Technology of Belgium. The machine was designed by Phillipe Julien, the former owner of A.R.T. and developer of the ET-1 and MT-1 molding machines for processing commingled plastics into plastic lumber. The JET 3000 is a 12-station machine that operates at low pressure. Mid-Atlantic also markets the JEM, a machine for heavy-walled products like pallets. The JEM is available in a shuttle-style model or a seven-station carousel. The JET 3000 costs around $375,000, which includes a set of 12 molds and two blenders. Output rate is 600 lb/hr. The JEM with one mold set starts at $400,000 for the shuffle model. Output ranges from 600 to 1200 lb/hr with 4.5 in. extruder.

Most lumber makers surveyed say the trend in machinery is toward continuous extrusion of sorted material and away from flow molding of commingled plastics. Single-screw machines predominate. American Eco-Board, for example, uses two Davis-Standard single-screws. All manufacturers interviewed run lumber at rates from 500 to 1000 lb/hr.

Equipment used may not represent the latest in sophistication. For example, Obex's Johnson says her firm relies on two "antique Egan machines," while Custom-Pac's two lines use a 41-yr-old, 3.5-in. Prodex machine from HPM and a 39-yr-old, 4.5-in. extruder from Egan (now Egan Davis-Standard). Fow found the 3.5-in. machine sitting in a field in Geauga County, Ohio, outside the grounds of a defunct plant that formerly made PVC pipe. Fow was so satisfied with the machine that he purchased a new 2.5-in. HPM extruder for plastic lumber and a 3.5-in. HPM model for the other products he makes from recycled plastics.

At the opposite end of the scale is Trimax, which bought new twin-screw machines from Berstorff and Werner & Pfleiderer. "We bought both machines new because we intended to go into compounding if the plastic lumber business didn't work," Noto says.

All lumber makers interviewed say their screws, dies, and vacuum calibrators are proprietary designs. Fow says his tooling costs about $6000 per line.

Custom-Pac and Trimax both developed special water-spray cooling to increase the heat-transfer rate from thick products. Noto says Trimax is developing downstream technology to achieve rates approaching 2000 lb/hr. "We're looking to improve on the saws, pullers, spray tanks, everything downstream."
COPYRIGHT 1996 Gardner Publications, Inc.
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Copyright 1996, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
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Author:Knights, Mikell
Publication:Plastics Technology
Article Type:Cover Story
Date:Aug 1, 1996
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