Info

Diameter (nm)

Fig. 6. Hydrodynamic particle size distribution of (a) un-HAp/EAA (40% w/w) (b) cn-HAp/EAA (40% w/w). EAA, poly(ethylene-co-acrylic acid); HAp, hydroxyapatite; un-HAp, untreated-HAp; cn-HAp, phosphonic acid treated-HAp.

Greater deformation in the polymeric phase in the composite has been observed in the case of composites having less nanoparticle content. With an increase in the nanoparticle content, the elastic deformation is resisted, followed by an increase in modulus. The percent elongation to failure of the nanocomposite is decreased significantly with addition of n-HAp particles and has continued to decrease with an increase in the amount of n-HAp particles, which has been summarized in Table II. Limin Sun et al,41 have reported HAp/polymer composite prepared by the flame-sprayed technique, which has shown poor improvements in mechanical properties as a consequence of poor adhesion between particle-polymer interfaces. In the present study, we have developed an HAp/polymer nanocomposite with sufficient improvement of mechanical properties, having a strong interfacial bonding between particle and polymer matrix with good dispersion of nanoparticle. The adhesion between the n-HAp particle and the polymer matrix is therefore very much effective with regard to stress transfer under tensile loading using p-aminophenyl phosphonic acid as a coupling agent.

IV. Summary and Conclusions

A HAp/EAA nanocomposite with uniform dispersion of p-aminophenyl phosphonic acid-coated n-HAp particles has been synthesized successfully following a solution-based method with significant improvement in mechanical properties. FTIR and thermal analysis have indicated the presence of a strong interfacial bonding between phosphonic acid-coated n-HAp particles and EAA matrix. A shift in XRD peaks of HAp and EAA after composite formation has indicated the

Table II. Mechanical Properties of un-HAp/EAA and cn-HAp/EAA Nanocomposites un-HAp/EAA

cn-HAp/EAA

Fig.7. Tensile stress-strain curves of (a) un-HAp/EAA nanocomposites with various w/w proportions of n-HAp as a filler (b) cn-HAp/EAA nanocomposites with various w/w proportions of n-HAp as a filler. EAA, poly(ethylene-co-acrylic acid); n-HAp, nano-hydroxyapatite; un-HAp, untreated-HAp; cn-HAp, phosphonic acid treated-HAp.

Fig.7. Tensile stress-strain curves of (a) un-HAp/EAA nanocomposites with various w/w proportions of n-HAp as a filler (b) cn-HAp/EAA nanocomposites with various w/w proportions of n-HAp as a filler. EAA, poly(ethylene-co-acrylic acid); n-HAp, nano-hydroxyapatite; un-HAp, untreated-HAp; cn-HAp, phosphonic acid treated-HAp.

presence of compressive and tensile stresses at the particle-polymer interface due to mismatch of the thermal expansion coefficient between HAp and EAA, which further contributes toward the improvement in the mechanical properties of the un-HAp/EAA

cn-HAp/EAA

n-HAp

Tensile

Young's

Elongation

Tensile

Young's

Eiongatiot

loaded

strength

modulus

of break

strength

modulus

of break

(w/w)(%)

(MPa)

(MPa)

(%)

(MPa)

(MPa)

(%)

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