HYDROXYAPATITE-GELATIN FILMS - A STRUCTURAL AND MECHANICAL CHARACTERIZATION

Composite films of gelatin and hydroxyapatite were prepared and charac terized by mechanical tests, scanning electron microscopy and X-ray di ffraction investigation. The mechanical properties of the films are gr eatly affected by the presence of hydroxyapatite and change as a funct ion of inorganic phase content. On stretching, the long axis of the co llagen molecular portions align parallel to the direction of deformati on and the gelatin coarse layered structure becomes more evident and o rdered. Furthermore, under deformation the inorganic crystals, which a re embedded in the gelatin layers, seem to squeeze out in the interlay er spaces and assume a preferential orientation parallel to the force trajectories. Thus, as the inorganic phase stiffens the gelatin films, the macromolecular matrix distributes the stress promoting the prefer ential orientation of the apatitic crystals. The results indicate that this experimental approach can be used to prepare composites with ani sotropic properties, which can be modulated through variation in compo sition and mechanical deformation in order to get biomaterials suitabl e to fulfill specific mechanical functions. (C) 1998 Published by Else vier Science Ltd. All rights reserved.