|Renewable Polymer Nanocomposites with Optimal Mechanical Properties |
|Yvonne A. Akpalu, Rensselaer Polytechnic Institute|
12:10 PM, CCR 201
Environmental concerns caused by the solid waste after use of petroleum-based plastic packaging materials have increased the interest in biodegradable packaging materials prepared from renewable sources. Polyhydroxyalkanotes (PHAs), a group of newly developed commercially available renewable polymers, have the potential to replace the 300 billion pounds of petroleum-based amorphous and semicrystalline polymers currently in use for packaging, adhesives, and coating applications. Recent advances in the production of PHAs from genetically engineered bacteria and from transgenic plants have reduced production costs to levels competitive with petroleum-based polymers. Similar to other renewable polymers, the relatively poor mechanical, thermal and barrier properties of PHA films limits their industrial use. We have recently investigated the influence of cooling rate and the addition of nanoparticles on the thermal behavior, solid-state morphology and mechanical properties of a series of PHAs. Since the ultimate properties of polymers can be controlled by processing conditions (e.g., cooling rate) and by the addition of nanoparticles, the systematic and thorough understanding of the effects of cooling rate and particle characteristics on the final morphology and the resulting mechanical properties of PHAs is a necessary first step for improving properties. To this end, we have studied the thermal behavior, crystal structure and morphologies of poly (3-hydroxybutyric acid) (PHB), poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) and nanoparticle-filled poly(3-hydroxybutyric acid-co-3-hydroxyhexanoate) under different cooling rates using differential scanning calorimetry, a cohort of X-ray scattering methods spanning (0.1 – 100 nm) and polarized optical microscopy. In this presentation, we will show that our results provide the fundamental basis for understanding how to control the mechanical properties of PHAs. We also show how this new knowledge can be used to design PHAs and other renewable polymers with optimal mechanical properties.
Host: Dunbar Birnie