Limits...
Mechanical properties of dispersed ceramic nanoparticles in polymer composites for orthopedic applications.

Liu H, Webster TJ - Int J Nanomedicine (2010)

Bottom Line: The mechanical properties of the resulting PLGA composites with well-dispersed ceramic (either titania or HA) nanoparticles were investigated and compared with composites with agglomerated ceramic nanoparticles.Results demonstrated that well-dispersed ceramic nanoparticles (titania or HA) in PLGA improved mechanical properties compared with agglomerated ceramic nanoparticles even though the weight percentage of the ceramics was the same.Specifically, well-dispersed nanoceramics in PLGA enhanced the tensile modulus, tensile strength at yield, ultimate tensile strength, and compressive modulus compared with the more agglomerated nanoceramics in PLGA.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI, USA.

ABSTRACT
Ceramic/polymer composites have been considered as third-generation orthopedic biomaterials due to their ability to closely match properties (such as surface, chemistry, biological, and mechanical) of natural bone. It has already been shown that the addition of nanophase compared with conventional (or micron-scale) ceramics to polymers enhances bone cell functions. However, in order to fully take advantage of the promising nanometer size effects that nanoceramics can provide when added to polymers, it is critical to uniformly disperse them in a polymer matrix. This is critical since ceramic nanoparticles inherently have a strong tendency to form larger agglomerates in a polymer matrix which may compromise their properties. Therefore, in this study, model ceramic nanoparticles, specifically titania and hydroxyapatite (HA), were dispersed in a model polymer (PLGA, poly-lactic-co-glycolic acid) using high-power ultrasonic energy. The mechanical properties of the resulting PLGA composites with well-dispersed ceramic (either titania or HA) nanoparticles were investigated and compared with composites with agglomerated ceramic nanoparticles. Results demonstrated that well-dispersed ceramic nanoparticles (titania or HA) in PLGA improved mechanical properties compared with agglomerated ceramic nanoparticles even though the weight percentage of the ceramics was the same. Specifically, well-dispersed nanoceramics in PLGA enhanced the tensile modulus, tensile strength at yield, ultimate tensile strength, and compressive modulus compared with the more agglomerated nanoceramics in PLGA. In summary, supplemented by previous studies that demonstrated greater osteoblast (bone-forming cell) functions on well-dispersed nanophase ceramics in polymers, the present study demonstrated that the combination of PLGA with well-dispersed nanoceramics enhanced mechanical properties necessary for load-bearing orthopedic/dental applications.

Show MeSH

Related in: MedlinePlus

Microscopic fracture appearances of PTCd (well-dispersed nano-titania in PLGA composites) after tensile tests. The fracture cross-section is shown in (a). The top surfaces of PTCd near the fracture cross-section are shown in (b,c,d). Original magnifications are 400 X for (a) and 50 kX for (b,c,d). Magnification bars are 100 μm for (a) and 200 nm for (b,c,d).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2865024&req=5

f10-ijn-5-299: Microscopic fracture appearances of PTCd (well-dispersed nano-titania in PLGA composites) after tensile tests. The fracture cross-section is shown in (a). The top surfaces of PTCd near the fracture cross-section are shown in (b,c,d). Original magnifications are 400 X for (a) and 50 kX for (b,c,d). Magnification bars are 100 μm for (a) and 200 nm for (b,c,d).

Mentions: Figures 10 and 11 shows microscopic fractures on the PTCd (well-dispersed nano-titania/PLGA composites) after tensile tests. Figure 10a shows the fracture cross-section of the PTCd. Figure 10(b,c,d) shows the top surfaces of PTCd near the fracture cross-section. Figure 11 shows the bottom surfaces of the PTCd near the fracture cross-sections. The de-bonding of the ceramic phase from the polymer matrix was also observed for PTCd, as shown in Figures 10(b,c) and 11(b,c,d). The silver streaks, however, were not observed on the top surface of PTCd. The microcracks and nanopores were present on the top surfaces in Figures 10(b,d). Crack initiation, propagation, and branching were observed in Figures 10d and 11a.


Mechanical properties of dispersed ceramic nanoparticles in polymer composites for orthopedic applications.

Liu H, Webster TJ - Int J Nanomedicine (2010)

Microscopic fracture appearances of PTCd (well-dispersed nano-titania in PLGA composites) after tensile tests. The fracture cross-section is shown in (a). The top surfaces of PTCd near the fracture cross-section are shown in (b,c,d). Original magnifications are 400 X for (a) and 50 kX for (b,c,d). Magnification bars are 100 μm for (a) and 200 nm for (b,c,d).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2865024&req=5

f10-ijn-5-299: Microscopic fracture appearances of PTCd (well-dispersed nano-titania in PLGA composites) after tensile tests. The fracture cross-section is shown in (a). The top surfaces of PTCd near the fracture cross-section are shown in (b,c,d). Original magnifications are 400 X for (a) and 50 kX for (b,c,d). Magnification bars are 100 μm for (a) and 200 nm for (b,c,d).
Mentions: Figures 10 and 11 shows microscopic fractures on the PTCd (well-dispersed nano-titania/PLGA composites) after tensile tests. Figure 10a shows the fracture cross-section of the PTCd. Figure 10(b,c,d) shows the top surfaces of PTCd near the fracture cross-section. Figure 11 shows the bottom surfaces of the PTCd near the fracture cross-sections. The de-bonding of the ceramic phase from the polymer matrix was also observed for PTCd, as shown in Figures 10(b,c) and 11(b,c,d). The silver streaks, however, were not observed on the top surface of PTCd. The microcracks and nanopores were present on the top surfaces in Figures 10(b,d). Crack initiation, propagation, and branching were observed in Figures 10d and 11a.

Bottom Line: The mechanical properties of the resulting PLGA composites with well-dispersed ceramic (either titania or HA) nanoparticles were investigated and compared with composites with agglomerated ceramic nanoparticles.Results demonstrated that well-dispersed ceramic nanoparticles (titania or HA) in PLGA improved mechanical properties compared with agglomerated ceramic nanoparticles even though the weight percentage of the ceramics was the same.Specifically, well-dispersed nanoceramics in PLGA enhanced the tensile modulus, tensile strength at yield, ultimate tensile strength, and compressive modulus compared with the more agglomerated nanoceramics in PLGA.

View Article: PubMed Central - PubMed

Affiliation: Division of Engineering, Brown University, Providence, RI, USA.

ABSTRACT
Ceramic/polymer composites have been considered as third-generation orthopedic biomaterials due to their ability to closely match properties (such as surface, chemistry, biological, and mechanical) of natural bone. It has already been shown that the addition of nanophase compared with conventional (or micron-scale) ceramics to polymers enhances bone cell functions. However, in order to fully take advantage of the promising nanometer size effects that nanoceramics can provide when added to polymers, it is critical to uniformly disperse them in a polymer matrix. This is critical since ceramic nanoparticles inherently have a strong tendency to form larger agglomerates in a polymer matrix which may compromise their properties. Therefore, in this study, model ceramic nanoparticles, specifically titania and hydroxyapatite (HA), were dispersed in a model polymer (PLGA, poly-lactic-co-glycolic acid) using high-power ultrasonic energy. The mechanical properties of the resulting PLGA composites with well-dispersed ceramic (either titania or HA) nanoparticles were investigated and compared with composites with agglomerated ceramic nanoparticles. Results demonstrated that well-dispersed ceramic nanoparticles (titania or HA) in PLGA improved mechanical properties compared with agglomerated ceramic nanoparticles even though the weight percentage of the ceramics was the same. Specifically, well-dispersed nanoceramics in PLGA enhanced the tensile modulus, tensile strength at yield, ultimate tensile strength, and compressive modulus compared with the more agglomerated nanoceramics in PLGA. In summary, supplemented by previous studies that demonstrated greater osteoblast (bone-forming cell) functions on well-dispersed nanophase ceramics in polymers, the present study demonstrated that the combination of PLGA with well-dispersed nanoceramics enhanced mechanical properties necessary for load-bearing orthopedic/dental applications.

Show MeSH
Related in: MedlinePlus