title: Effect of Mg content on the thermal stability and mechanical behaviour of PLLA/Mg composites processed by hot extrusion.
abstract: In the field of bioabsorbable composites for biomedical applications, extrusion has been employed as a method to prepare homogeneous blends of polymeric matrices with bioactive ceramic fillers. In this work, the suitability of processing poly-l-lactic acid/Magnesium (PLLA/Mg) composites by hot extrusion has been assessed by a systematic characterization of PLLA/Mg composites containing different amounts of Mg particles up to 7wt%. The results show that extrusion causes a reduction of almost 20% in the viscosity average molecular weight of PLLA, which further decreases with increasing Mg content. Extrusion gave always rise to a homogeneous distribution of Mg particles within the PLLA matrix. This composite processing was not compromised by the degradation of the polymeric matrix because the processing temperature was always below the onset degradation temperature. In the processing conditions employed in the present work, degradation of the composite slightly increases as more Mg is added up to 5wt%, but is very high at 7wt%. This was also evident from the mechanical behaviour, so that Mg particles improved the stiffness and compression strength of neat PLLA until 5wt% of Mg content, which dropped drastically when the material had 7wt% of Mg. The filler strengthening factor decreases with the increment in Mg content. In order to obtain an optimised contribution of Mg particles, a balance between thermal degradation and mechanical resistance of PLLA must be achieved.
authors.affiliation: Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Avda. Gregorio del Amo 8, 28040 Madrid, Spain; Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911, Leganés, Madrid, Spain. Electronic address: scifuent@ing.uc3m.es.
authors.forename: S C
authors.initials: SC
authors.lastname: Cifuentes
authors.affiliation: Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Avda. Gregorio del Amo 8, 28040 Madrid, Spain. Electronic address: marcela@cenim.csic.es.
authors.forename: M
authors.initials: M
authors.lastname: Lieblich
authors.affiliation: Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Avda. Gregorio del Amo 8, 28040 Madrid, Spain. Electronic address: flopez@cenim.csic.es.
authors.forename: F A
authors.initials: FA
authors.lastname: López
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain. Electronic address: rbenavente@ictp.csic.es.
authors.forename: R
authors.initials: R
authors.lastname: Benavente
authors.affiliation: Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Avda. Gregorio del Amo 8, 28040 Madrid, Spain; Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina CIBER-BBN, Spain. Electronic address: jlg@cenim.csic.es.
authors.forename: J L
authors.initials: JL
authors.lastname: González-Carrasco
mesh_terms: D002152:Calorimetry, Differential Scanning; D055119:Elastic Modulus; D008274:Magnesium / Q000737:chemistry*; D011091:Polyesters / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014783:Viscosity
chemical_list: D011091:Polyesters; C033616:poly(lactide); D008274:Magnesium
keywords: Extrusion; Mechanical properties; Metallic reinforcement; Particle-reinforced composite; Polymer-matrix composite; Thermal properties