2005 Fiscal Year Final Research Report Summary
NANO-STRUCTURE AND FRACTURE PROPERTIES OF BIOABSORBABLE COMPOSITE MATERIALS
| Project/Area Number |
16560074
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TODO Mitsugu KYUSHU UNIVERSITY, Research Institute for Applied Mechanics, Associate Professor, 応用力学研究所, 助教授 (80274538)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKAWA Kazuo KYUSHU UNIVERSITY, Research Institute for Applied Mechanics, Professor, 応用力学研究所, 教授 (00151150)
TAKENOSHITA Yasuharu KYUSHU UNIVERSITY, Faculty of Dental Science, Associate Professor, 大学院・歯学研究院, 助教授 (50117157)
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| Project Period (FY) |
2004 – 2005
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| Keywords | bioabsorbable / poly (lactic acid) / hydroxyapatite / poly (s-caprolactone) / nano structure / fracture toughness / polymer blend / 相溶性 |
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| Research Abstract |
Hydroxyapatite (HA), primary constituent of bone, poly (lactic acid) (PLLA, PLA), bioabsorbable polymers and poly (ε-caprolactone) (PCL) were used to fabricate biocompatible and bioabsorbable composite materials. The fracture properties of the composites were evaluated, and their fracture micro-mechanisms were investigated using microscopes. The results obtained are as follows :
(1)Fracture property of HA/PLLA : Effect of shape and size of HA particle on the fracture property and mechanism of HA/PLLA composite was investigated, and it was found that micro-particle (the diameter is about 5μm) optimizes the fracture property of HA/PLLA. The primary mechanism of the toughening effect by the micro-particle is localized plastic deformation of PLLA around HA particles due to local stress concentration induced by debonding at HA/PLLA interfacies.
(2)Fracture property of PLLA/PCL : Brittleness of PLLA can be improved by blending ductile PCL phase. Fracture properties of PLLA is dramatically impr
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oved and maximized with addition of 15wt% of PCL. It was also found that spherical structure of PCL is formed in the blend system. The size of the spherical structure increases with increase of PCL content. The toughening mechanisms are energy dissipation mechanisms such as craze-like damages in crack-tip region and ductile deformation of entangled structure of PLLA and PCL bundles.
(3)Fracture property of HA/PLLA/PCL : As a new bioabsorbable material, HA/PLLA/PCL was successfully developed, and it was found that the fracture property of HA/PLLA/PCL can be optimized with 5wt% of PCL. Further addition of PCL tends to decrease the fracture property of the composite system because of enlargement of spherical structure of PCL phase separation.
(4)Fracture property of PLA/PCL/LTI : The phase morphology of PLA/PCL was improved by blending LTI. The size of spherical structure of PCL as phase separation can be dramatically reduced due to the LTI addition. Fracture property of PLLA/PCL/LTI was found to be much better than that of PLLA/PCL.
(5)Fracture property of PLLA/PCL/PLLA-CL : PLLA-CL copolymer, a polymeric biomaterial, was used to modify the phase morphology of PLLA/PCL blend. It was successfully proved that the fracture property of PLLA/PCL/PLLA-CL is better than that of PLLA/PCL. Less
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