X-ray Microtomographic Study of Nanoclay-Polypropylene Foams

In the present paper X-ray microtomography technique has been applied to investigate internal, three dimensional structure of clay/polypropylene nanocomposite foams. Several sets of foam samples were prepared using the improved compression moulding technique that allows controlling independently the cells‘ size, cells‘ shape and density of foams. Then the X-ray images were acquired followed by an application of image processing steps and final reconstruction of foams microstructure. Volume distribution of cells has been extracted from three dimensional images and related to processing parameters. Since not only the size but also the shape of cells influences a load bearing capacity of foams, the sphericity parameter has been selected as a relative quantifier of cells shape. The sphericity parameter has been also related to different processing parameters.

Study on the mechanical properties of Cu/LDPE composite IUDs

BACKGROUND

The copper/low-density polyethylene composite (Cu/LDPE composite) intrauterine devices (IUDs), which can eliminate or lessen the side effects of existing IUDs, have been developed in our laboratory. As a novel type of copper-containing IUDs, it is not clear whether the mechanical properties of the Cu/LDPE composite IUDs can meet the need of clinical use or not. Therefore, the mechanical properties of the Cu/LDPE composite IUDs have been studied in the present article.

STUDY DESIGN

The influence of copper particle content and size on the mechanical properties of the Cu/LDPE composite IUDs was analyzed firstly to provide guidance for the material composition design of the Cu/LDPE composite IUDs, and then the BaSO(4)/LDPE composite, which has been applied as a framework of the existing copper-containing IUDs in clinical use for decades, has been used as reference to judge whether the mechanical properties of the Cu/LDPE composite IUDs can meet the need of clinical use or not. However, the mechanical properties of IUDs cannot be characterized directly. Therefore, the mechanical properties of both the Cu/LDPE composite IUDs and the framework of the existing copper-containing IUDs were investigated by means of tensile test using standard tensile samples, and the fracture surface morphology of the tensile samples was characterized by scanning electron microscopy (SEM).

RESULTS

Both the elongation at break and the tensile strength decrease with increasing of copper particle content and increase with increasing of the copper particle size, while the elastic modulus shows an opposite tendency. The tensile strength and elastic modulus of both the Cu/LDPE microcomposite IUDs and the Cu/LDPE nanocomposite IUDs with 25 wt.% of copper particles are higher than those of existing copper-containing IUDs (TCu220C; its framework is made of the BaSO(4)/LDPE composite with 20 wt.% of BaSO(4)).

CONCLUSIONS

The content and size of the copper particles have significant effect on the mechanical properties of Cu/LDPE composite IUDs. The mechanical properties of both the Cu/LDPE microcomposite IUDs and the Cu/LDPE nanocomposite IUDs with 25 wt.% of copper particles were superior to that of existing copper-containing IUDs, indicating that the novel Cu/LDPE composite IUDs can satisfy the requirement of mechanical properties in clinical application.