Tuesday, 24 May 2005

This presentation is part of: Polymeric Biomaterials Posters

Evidence of an Intermediate Amorphous Phase in PLA/PMMA Thermal Blends

Kim-Phuong N. Le, Richard L. Lehman, and James D. Idol. AMIPP Advanced Polymer Center -- Rutgers University, Piscataway, NJ

Poly (L-lactide) (PLA) and Poly (methylmethacrylate) (PMMA) composites are of interest for in-vivo biomedical applications due to functional synergism between the bio-persistent load-bearing phase and the bioresorbable phase. When these polymers are processed to form an immiscible co-continuous blend, useful and interesting properties result. Recent studies in our laboratory have indicated the formation of a new amorphous phase in these blends when they are thermally processed. This phase, termed PG80, has a characteristic glass transition between that of PLA (59-61oC) and PMMA (103-105 oC). The observation of this phase coincides with the synergistic mechanical and enhanced bio-compatibility of the composites. To exploit the positive impact of PG80 at the interface of a seemingly immiscible composite, the process conditions under which PG80 is formed, namely shear and reaction time, have been investigated. Combinations of shear levels and reaction times are achieved in a thermal extruder. Low shear, high reaction time experiments have been conducted by thermally pressing laminated structures of PLA and PMMA thin films where the thickness of each film were of the same magnitude as the domain size in extruded blends. The morphology of the blends was preserved via quenching. Assessment of results by DSC indicate that the PG80 phase forms under a range of shear/reaction time conditions. Possible chemical and physical interactions between the constituent polymers that lead to PG80 formation are discussed.

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