Effect of the loading and size of copper particles on the mechanical properties of novel Cu/LDPE composites for use in intrauterine devices

The copper/low-density polyethylene (Cu/LDPE) composites has been developed as a novel intrauterine devices (IUDs) material in our research since the copper-containing IUDs (Cu-IUDs) made of this kind of material can eliminate or lessen the side-effects of the existing Cu-IUDs. In the present study tensile tests were used to characterize the mechanical properties of this novel IUBs material, the Cu/LDPE composites. The influences of the copper particles' loading, varied from 5 to 25 wt.%, and the copper particles' size, 50 nm and 5 mu m, on the Young's modulus, yield strength, tensile strength and elongation at break were investigated. Increasing the copper particles' loading caused an increase in Young's modulus for Cu/LDPE nanocomposite but a decrease in Young's modulus for Cu/LDPE microcomposite, a decrease in yield strength for both Cu/LDPE nanocomposite and Cu/LDPE microcomposite except for an increase in yield strength for Cu/LDPE nanocomposite when the copper nanoparticles' loading is less than 5 wt.%, a decrease in tensile strength and elongation at break for both Cu/LDPE nanocomposite and Cu/LDPE microcomposite. Decreasing the copper particles' size caused an increase in the Young's modulus, yield strength, tensile strength and elongation at break. These changes are attributed to the different dispersion of the copper particles in matrix and the different interfacial adhesion between the copper particles and the matrix caused by the different loadings and sizes of copper particles. Additionally, after the copper particles inside the Cu/LDPE nanocomposite was corroded completely, its mechanical properties are better than those of the original Cu/LDPE nanocomposite due to the releasing of stress concentration caused by the copper nanoparticles. All these results indicate that the Cu/LDPE nanocomposite is much better to act as a Cu-IUDs material than the Cu/LDPE microcomposite does. (c) 2006 Elsevier B.V. All rights reserved.