Biopolymers Add Something to Acrylics

Compounders have blended biopolymers with conventional resins in order to add the “green” factor—renewably sourced content—hopefully while making minimal change to the properties of the familiar petro-based plastic. At the MD&M East show in N.Y.C. last month, Arkema Inc., Philadelphia, revealed what may be the first example of a biopolymer adding technical benefit to a standard resin. Arkema’s Altuglas International unit made the U.S. debut of Plexiglas RNew, a blend of PMMA acrylic and PLA. Adding 20% biopolymer doubles the melt flow of straight acrylic and 30% triples the flow, while retaining excellent clarity. Impact resistance also increases, though Vicat heat resistance drops 10-20%. The blend is aimed at disposable diagnostic devices, lab ware, fluid-collection devices, and other uses. It is sterilizeable by EtO and e-beam and reportedly shows no significant discoloration after gamma irradiation.

In development are more high-performance acrylic/biopolymer blends. These blends show multiaxial impact strength five times that of impact acrylic and equal to PETG. Also, melt flow is more than tenfold higher, which allows use of a higher-molecular-weight acrylic component. That, in turn, adds superior chemical resistance, even in comparison with Arkema’s recently introduced Plexiglas CR acrylic with enhanced lipid and alcohol resistance (reported in March). Arkema is still working to remedy the increase in haze and decrease in heat resistance. Using a variety of biopolymers, Arkema plans to field a family of blends that can be custom tailored for various uses. Arkema hopes to introduce them as early as next year.