The Rheology, Degradation, and Processing of Renewable Resource Polymers

Renewable resource polymers have shown potential as a replacement to conventional fossil fuel-based polymers in many applications including single use products. This study presents recent results on poly-lactic acid (PLA) and a series of polyhydroxyalkanoate (PHA) copolymers. These polymers are derived from renewable resources and degrade under the appropriate conditions. The PHA copolymers are poly-3-hydroxybutyrate-co-3-hydroxyvalerate (poly-3HB-3HV) with 5, 8, and 12 mol % HV comonomer. A rheological characterization in shear, extensional, and transient modes examines their flow behavior under varying flow fields and identifies the degradation of the materials occurring at typical processing conditions. Suitable conditions are determined for processing the polymers using a DSM Xplore microcompounder with the cast film attachment. Blends of PLA and PHA are produced and subsequent testing characterizes the films as a function of PHA composition using DSC, WAXD, tensile testing, and SEM to examine the thermal, mechanical, and structural properties.