Fracture Properties and Toughening Mechanisms of Biodegradable Poly(L-lactic acid)/Poly(e-caprolactone) Polymer Blend
DOI:
https://doi.org/10.12974/2311-8717.2018.06.1Keywords:
Bioabsorbable polymer, Polymer blend, Ductile Fracture, Fracture energy absorption.Abstract
PLLA/PCL polymer blends with different PCL contents were fabricated to examine the effect of PCL content on the bending mechanical properties of the blend. Three-point bending tests of beam specimens 5 mm thick were performed at both quasi-static and impact loading-rates, and then bending mechanical properties such as bending modulus, strength and fracture absorbed energy were evaluated. It was found that the modulus and strength decreased as PCL content increased, while the fracture absorbed energy tended to increase with increase of PCL content and was optimized with 15% PCL. Scanning electron microscopy of fracture surfaces and polarizing optical microscopy of tensile damage regions were also carried out to investigate the fracture mechanism of PLLA/PCL blend. It was found that the primary mechanisms involved in the bending fracture of PLLA/PCL blend were initiation of dense craze-like damage and following ductile deformation of the matrix. The model I fracture properties of PLLA/PCL were also evaluated and compared with those of pure PLLA. It was found that the fracture properties were dramatically improved by PCL blending and the primary toughening mechanisms were the aggregation formation of craze-like micro-damages in the process-zone with rough formation of fracture surface.
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