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Mexico State University Using Chilies to Reinforce Plastic

22 May 2011

Researchers at the New Mexico State University’s (NMSU) Department of Industrial Engineering are looking at ways to combine the chili plant with plastic.

Companies use both recycled and virgin plastic to combine with wood products like pallets, furniture waste, recycled oak wood flour, oak and pine from millwork and reclaimed cedar wood chips, among other sources. Over time, researchers have investigated high levels of wood and plastic combinations with functional additives, such as coupling agents, UV stabilizers, antimicrobials and antioxidants.

For the last 18 months, Delia Valles-Rosales, Associate Professor in NMSU’s Department of Industrial Engineering, has directed research on the viability of chili plant composites with a team of IE graduate students. The group is collaborating with Stephanie Walker from the Extension Plant Science Department; Paul Bosland in the Department of Plant and Environmental Sciences in the College of Agriculture, Consumer and Environmental Sciences; Kenny Stevens in the Department of Engineering Technology; Juan Noveron at the University of Texas at El Paso’s Department of Chemistry; and Biad Chili of Mesilla Park.

“We went to Biad and talked to Mr. Don Valles and Mr. Vince Hernandez about the possibility of using chili plants,” Valles-Rosales said. “Biad gets chile from more than 100 farms around the state and eastern Arizona and West Texas. Farmers bring the whole plant and the chilies are dried and separated in the facility, so we can share the plant waste with the farmers who pick some of it up for feed. Our job is to analyze how we’re going to collect these plants and how much it’s going to cost. This could lead to economic development for New Mexico, with mass production of wood-plastic products.”

About 60 percent of a mature chili plant’s weight resides in its stems, leaves and roots which are discarded or used as cattle feed post-harvest. The research utilizes these areas for WPCs.

The research team is exploring a wide range of composite ratios, and also varying grain sizes, 120, 150 and 600 microns, which range from product that resembles sawdust all the way down to a floury, sandy type of grain. The plastics used in the process also are comprised of recycled material.

“We got about 84 samples, about five for each combination, then we conducted the tests,” Halodan said. “We got promising results. Some results exceeded the minimal industry requirements even without any additives added. If we add the coupling agent it’s going to increase quality and durability about 30 to 40 percent, so we’re going to get a good result. The objective is reducing the cost of WPCs while increasing the mechanical physical properties.”

The research meets standards set by ASTM International, a globally recognized leader in the development and delivery of international voluntary consensus standards (specifically ASTM D638-9 – Standard practice for tests to evaluate the tension test of plastics and plastics composites). To meet these standards, exact models of each WPC combination had to be manufactured. Students from mechanical and industrial engineering, and M-TEC (Manufacturing, Technology and Engineering Center) designed plastic molds to create the models, and also were involved in using injection-molding machinery to actually fill the molds with the WPC sample.

The samples are subject to UV light testing and as many other weather and environmental conditions as possible in a very intense fashion, to replicate years of wear in a matter of months to ensure the composite holds up in comparison to other WPC products, as well as regular plastic and wood products of similar type.






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