Effect of Mg content on the thermal stability and mechanical behaviour of PLLA/Mg composites processed by hot extrusion

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 extru...

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Bibliographic Details
Published in:Materials Science & Engineering C 2017-03, Vol.72, p.18-25
Main Authors: Cifuentes, S.C., Lieblich, M., López, F.A., Benavente, R., González-Carrasco, J.L.
Format: Article
Language:English
Subjects:
Biocompatibility
Biomedical materials
Calorimetry, Differential Scanning
Compression
Compressive strength
Degradation
Elastic Modulus
Extrusion
Fillers
Hot extrusion
Magnesium
Magnesium - chemistry
Materials science
Mechanical properties
Metallic reinforcement
Molecular weight
Particle-reinforced composite
Particulate composites
Particulates
Polyesters - chemistry
Polylactic acid
Polymer blends
Polymer-matrix composite
Spectroscopy, Fourier Transform Infrared
Stiffness
Temperature
Thermal degradation
Thermal properties
Thermal resistance
Thermal stability
Viscosity
Weight reduction
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Summary: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. [Display omitted] •PLLA/Mg composites can be fabricated by thermoplastic processes.•Mg particles increase PLLA stiffness (20% for 5wt%) but accelerate its degradation.•A balance between thermal degradation and mechanical resistance must be achieved.•Due to degradation, filler strengthening factor diminishes with Mg content.
ISSN:0928-4931
1873-0191
DOI:10.1016/j.msec.2016.11.037