Accelerated ageing and degradation in poly-l-lactide/hydroxyapatite nanocomposites

• Published in: Polymer degradation and stability 2011-04, Vol.96 (4), p.595-607
• Main Authors: Delabarde, Claire, Plummer, Christopher J.G., Bourban, Pierre-Etienne, Månson, Jan-Anders E.
• Format: Article
• Language: English
• Subjects: Ageing; Aging; Applied sciences; Biological and medical sciences; Composites; Compressive strength; Crystallization; Degradation; Exact sciences and technology; Forms of application and semi-finished materials; Hydroxyapatite; Mechanical properties; Medical sciences; Nanocomposite; Nanocomposites; Nanostructure; Particle-matrix interfaces; PLLA; Polymer industry, paints, wood; Strain; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Technology of polymers; Technology. Biomaterials. Equipments; Tensile strength
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2010.12.018

Dry, compression molded films of medical grade poly-l-lactide (PLLA) showed a marked reduction in tensile strength and strain after accelerated ageing in aqueous NaOH at 50°C, accompanied by mass loss, surface erosion, increased hydrophilicity and, in the case of the initially amorphous films, cold crystallization owing to the plasticizing effect of the ageing medium. Addition of well dispersed nanosized hydroxyapatite (nHA) particles resulted in increases in the rate of mass loss during ageing, identified with accelerated degradation at the matrix/particle interfaces. However, the associated decreases in tensile strength and strain to fail with ageing time were far less marked in the presence of the nHA than in the unmodified films. This implied that nHA acts as an effective toughener of the bulk material, consistent with TEM observations of the deformed films, which indicated failure of the particle–matrix interfaces to promote plastic deformation of the PLLA.