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Use of Layered Fillers to Improve the Mechanical Properties of Biodegradable Poly 3-hydroxybutyrate-co-3-hydroxyhexanoate) (Nodax™) Thermoplastics J.E. Mark, The University of Cincinnati, OH, 45220-0172 Grant DMR-0314760 (Polymers Program, Division of Materials Research).
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Use of Layered Fillers to Improve the Mechanical Properties of Biodegradable Poly 3-hydroxybutyrate-co-3-hydroxyhexanoate) (Nodax™) Thermoplastics J.E. Mark, The University of Cincinnati, OH, 45220-0172 Grant DMR-0314760 (Polymers Program, Division of Materials Research) Polyhydroxyalkanoates (PHAs) have attracted much industrial attention due to their biodegradability and biocompatibility. They are produced directly from renewable resources by microbes which accumulate PHAs as carbon and energy storage materials. Copolymers of PHAs provide the best balances of properties, with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) now being the most important member of the Procter & Gamble NodaxTM family of such biodegradable thermoplastics. The properties of these copolymers were found to be greatly improved when they were used in hybrid nanocomposites with any of several layered fillers, which had been introduced by extrusion procedures. The most practical nanocomposite contained exfoliated montmorillonite clay organically modified with either of two types of modifiers. Two other reinforcing fillers studied were talc and mica. All three types of fillers were found to improve elongation moduli and tensile strengths, as shown in the upper and lower figures, respectively. Preliminary results using graphite were similarly encouraging, and this layered filler has the advantage of yielding nanocomposites that are electrically conducting at very low loadings. Recent results can be found in the report: Hassan, M.K.; AbouHusssein, R.; Zhang, X.; Noda, I.; Mark, J.E., Biodegradable copolymer of 3-Hydroxybutyrate-co-Hydroxy-hexanoate (Nodax™), Including Recent Improvements in Their Mechanical Properties. Molec. Cryst. Liq. Cryst.2006,447, 23-44. -⃞- Nodax/20Aclay -⃝-Nodax/25Aclay -∆- Nodax/Talc -⃟- Nodax/Mica