Strong synergistic effects in PLA/PCL blends: impact of PLA matrix viscosity

0470664 - ÚMCH 2017 RIV NL eng J - Journal Article
Ostafinska, Aleksandra - Fortelný, Ivan - Hodan, Jiří - Krejčíková, Sabina - Nevoralová, Martina - Kredatusová, Jana - Kruliš, Zdeněk - Kotek, Jiří - Šlouf, Miroslav
Strong synergistic effects in PLA/PCL blends: impact of PLA matrix viscosity.
Journal of the Mechanical Behavior of Biomedical Materials. Roč. 69, May (2017), s. 229-241. ISSN 1751-6161. E-ISSN 1878-0180
R&D Projects: GA ČR(CZ) GA14-17921S; GA MŠMT(CZ) LO1507
Institutional support: RVO:61389013
Keywords : polymer blends * bone tissue engineering * poly(lactic acid)
OECD category: Polymer science
Impact factor: 3.239, year: 2017

Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(epsilon-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC approximately equal to PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d~0.6 mu m), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering.
Permanent Link: http://hdl.handle.net/11104/0269268