Completely renewable resource-based, degradable composites of poly(l-lactide) and Nodax™ [poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)] were prepared by a melt blending procedure. oligoNodax-b-poly(l-lactide) diblock copolymers were synthesized and their use as compatibilizers in these melt blends was investigated. The block copolymers were prepared from microbially produced Nodax™ polyhydroxyalkanoate by a two-step transesterification and macroinitiator ring opening polymerization method. Addition of Nodax™ increased the notched Izod impact resistance of the binary blends compared to that of PLLA homopolymer (44 ± 6 J m-1 versus 22 ± 2 J m-1, respectively). Further addition of the oligoNodax-b-poly(l-lactide) block copolymers to form ternary blends resulted in composites with improved dispersion and decreased Nodax™ particle size, but no additional improvement in the notched Izod impact properties. Significant Nodax™ degradation during processing coupled with a high Nodax™ entanglement molecular weight, as well as crystallization and low impact resistance of the Nodax™ dispersed phase are implicated as major factors impeding further toughening.
Bibliographical noteFunding Information:
This work was funded by the Toyota Motor Corporation. The authors thank Chris Frethem for assistance with scanning electron microscopy, and Dr. Kelly Anderson, Dr. Mahesh Mahanthappa, and Dr. Javid Rzayev for many helpful discussions.
Copyright 2009 Elsevier B.V., All rights reserved.
- Block copolymer
- Melt blending
- Nodax polyhydroxyalkanoate
- Polylactide toughening