When the decree came down from corporate management to pursue sustainable solutions, the Arkema Inc. team grappled with how to engineer a 'green' polymer for medical device applications without sacrificing performance. Able to rise to the challenge, however, the company has unveiled Plexiglas Rnew, a biobased acrylic resin that blends PMMA with high levels of carbon from renewable resources.
"We don't have a renewable building block, but we do have the ability to blend our PMMA materials with other, 100% biobased materials to reduce our [polymers'] carbon footprint," says Carmen Rodriguez, business manager for medical resins at Arkema. "We've been able to take a series of biopolymers that are known in the marketplace and blend them into our materials to augment the properties that we need." The Rnew resin, Rodriguez notes, is the first in a series of sustainable thermoplastic polymers that consist of 25% and higher biobased materials, depending on customer requirements.
By introducing biocontent to its Plexiglas acrylic resins, the company was able to achieve unprecedented chemical resistance with the Rnew resin while also improving melt processability, according to Rodriguez. "Chemical resistance in thermoplastics is usually achieved through added crosslinking or increases in molecular weight. But when you do that, your materials become stiffer and more difficult to process," she explains. "Now that we can tailor our polymer formulations to achieve optimal melt processability, we can change the components of our resin formulation to increase chemical resistance. That's a big change in the dynamics of PMMA."
In addition to enhanced chemical resistance and melt processability, the biobased Plexiglas Rnew resin offers improved impact resistance and toughness compared with standard acrylic grades, the company states. Rodriguez notes that a standard-grade PMMA with no impact resistance, for example, might demonstrate an Izod impact strength of 0.2 ft-lb/in, while an impact-resistant material could be as high as 2 ft-lb/in. By blending PMMA with biopolymers, however, Arkema achieved an impact strength of up to 15 ft-lb/in., she adds. These resins are also BPA-free, withstand gamma sterilization, and can provide high optical clarity.
Because of these physical properties and performance characteristics, the Plexiglas Rnew resin is suited for use in a variety of transparent disposable medical devices. Applications include blood collection or separation products, fluid management, and cardiopulmonary devices that require clarity, gamma resistance, chemical resistance, and impact resistance. "Because we can achieve these high impacts, we see these products as an excellent substitute for nonrenewable polycarbonate and copolyesters," Rodriguez states. "These materials are viable today in areas where PMMA would have never previously been considered."