Blending elastomer impact modifiers with poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) for improved toughness

Kat Gilmore on September 8, 2025

The Locklin Group at the University of Georgia New Materials Institute utilized industrially compostable elastomer resins Terratek FX1515 and Terratek GDH-B1FA, from Green Dot Bioplastics, in blends with PHB and PHB-co-HHx. The blends demonstrated improved toughness and microbially degraded more than 90 percent under industrial composting conditions within 120 days.

Poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), or PHB and PHB-co-HHx,  are promising replacements for polyolefins in plastics manufacturing, but are limited by their brittleness and poor impact performance.  The Locklin Group at the University of Georgia New Materials Institute utilized industrially compostable elastomer resins Terratek FX1515 and Terratek GDH-B1FA, from Green Dot Bioplastics, in blends with PHB and PHB-co-HHx. The blends demonstrated improved toughness and microbially degraded more than 90 percent under industrial composting conditions within 120 days. 

The elastomer resins were melt-blended with neat PHAs, then extruded as pellets and processed by injection molding to create the biopolymer blends for testing. The resulting materials underwent tensile testing, Izod impact testing, scanning electron microscopy, dynamical mechanical analysis, surface energy and interface tension analysis and biodegradation studies in the Institute’s BioseniaticSM Laboratory. 

Both additives significantly improved tensile and impact performance of the PHB and PHB-co-HHx blends, with the Terratek GDH-B1FA blends exhibiting better elasticity, interfacial tension and miscibility. 

The team’s study, “Impact Modification of Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Terratek FX1515 and Terratek GDH-B1FA,” was recently published in ACS Omega, a journal of the American Chemical Society. Coauthors are Kush G. Patel, Adaeze R. Osakwe, Austin F. Wright, Virginia L. Weber, Huiming Wu, Shawn M. Wallbillich, Michael V. Kandefer, Grant H. Crane, Evan M. White and Jason J. Locklin, who heads the Locklin Group and serves as director of the UGA New Materials Institute. White leads the BioseniaticSM Laboratory team comprised of Wright, Wallbillich and Kandefer. Crane, an assistant research scientist, and all other coauthors are members of the Locklin Group. The work was funded by the RWDC Environmental Stewardship Foundation. Green Dot Bioplastics donated the additives used in the study.