Composites Bend the Bar

Flexi-Stix, LLC makes a pultruded thermoplastic exercise bar.

Consulting and marketing company Flexi-StiX, LLC secured a patent for its process of incorporating pultrusion into a thermoplastic tube. The immediate result of its invention is a lightweight exercise tool, but the technology could soon permeate elsewhere.

President Gordon Brown previously co-invented bombproof wallpaper, which Berry Plastics is targeting for military and construction use (you can read about it here). During the wallpaper-making process, he used an extruded thermoplastic urethane for the matrix rather than a typical liquid or epoxy resin. “It was sort of a novel approach, as we now have a way to put reinforcements into polyurethanes,” he says. “The industry needs to deliver cost-effective solutions to our customers through a combination of fibers and resins, and our way was novel in accomplishing that.”

Using that same thought process, Brown focused on another way to give extruded thermoplastics additional strength and stiffness for better performance properties. He combined an extruded thermoplastic tube such as polyvinyl chloride (PVC) with a rectangular pultruded composite (materials such as fiberglass, reinforced vinyl ester, epoxy, carbon, or aramid). The pultruded composite is slipped inside the tube, after which closures are placed on the end to stop the fiberglass from falling out.

It is this entire process that creates a flexible pole. “Straight extruded PVC is flexible, but too much so for most applications,” says Brown. “All pultruded round tubes are too stiff, and aluminum steel and metal are very rigid poles. This offered a way to take low-cost extruded thermoplastics and make them stronger.”

Currently, the tube is primarily used in the exercise industry, sold under the name Body Bar Flex. The product is used to improve balance, flexibility and resistance training. Brown compares his product to Bowflex bars, which are comprised of solidly-extruded Nylon. He believes that added pultruded fiberglass results in greater bending stiffness. “I also noticed that it would bend around the major axis wherever your hand is positioned, which makes it friendly for a customer to use because they can place their hands anywhere and the tube is tough,” he says.

Though workouts were the initial focus of the product, Brown is trying to diversify into a variety of markets. He believes his product could be used for such applications as flag poles, walking sticks, rake handles and fence posts. “I have opportunities to consult with companies, and I always look for somewhere to think outside the box,” he says.

Tags: composites, Flexi-Stix, news, sports & recreation