Dragan Adamovic

Review of Existing Biomaterials—Method of Material Selection for Specific Applications in Orthopedics

Biomaterials have emerged as a very important material class for wide application in medicine. Intensive research during the last decade strongly indicates that many health-related problems can be efficiently overcome with these new materials. Quality of life has been significantly increased for patients who need reconstructive surgeries, especially in comparison with old solutions. This paper reviews biomaterials in orthopedics that are used either as a support or substitute for bone tissues, from the aspect of their properties and state-of-the-art results in real clinical cases. Limitations and further directions of research are presented. Metal, ceramic and polymer materials, as well as new composites and new material structures, are reviewed, such as biodegradable porous materials and scaffolds. Nowadays, optimal selection of materials is one of the challenges imposed by the presence of many novel materials that can be used in specific applications. A general method of material selection is presented related to the hip stem and permanent metal biomaterials.

Biodegradable Metals as Biomaterials for Clinical Practice: Iron-Based Materials

This review presents the state-of-the-art in the development of iron-based degradable medical implants. Basic properties demanded by the new concept of degradable implants are elaborated, along with the work devoted to understand the underlying mechanism and to improve the properties towards best fitted to the natural tissue. Three application areas are considered: vascular stents, orthopedic implants and tissue engineering scaffolds. Each of these has its own specific demands imposed upon the artificial substitution materials. Biocompatibility is an essential feature that each medical implant must have, but different aspects can be considered depending on the end application. Furthermore, adequate mechanical properties and various characteristics related to the fabrication and in vitro and in vivo testing are presented for pure iron, alloys and composites, as well as joint structures. Corrosion control is a foundation in the development of these materials development and different aspects are also given. Iron-based materials need increased degradation rate because they are still more similar to the permanent implants, due to the slow corrosion process and various methods to overcome this issue have been tried. Porosity and its relation to material structures, mechanical properties, degradation behaviour, magnetic properties, and fabrication technologies, as well as methods of numerical simulations as a supporting tool have been elaborated. Porous structures represent one way to enhance corrosion, while maintaining intact other necessary properties of the biomaterial. Economic impact of the biomaterials sector in general is significant and justifies large investments in research. Iron-based materials for degradable implants are not in clinical practice yet, but the research results achieved so far promise the future applications.

Development of New Composites Made of Waste Materials for Wood Pallet Element

The recycling of waste products and its further use for new products is of the utmost importance nowadays. The quantities of waste product originating from industries involving plastics, paper, wood, textile and metal foils, such as the related automotive, paper, wood and food industries, represent extremely large numbers, strongly indicating the need for efficient waste management. On the other side of things, companies are always looking for ways to lower material costs. The combination of different waste materials can be used for production of new composite materials. This paper will present a brief overview of existing possibilities in the development of new composites completely made of waste materials, as well as further research directions. A preliminary study of material combinations that can provide a composite aimed at load bearing applications is given, for the purpose of replacing elements such as wood blocks in transport pallets. Several combinations of waste material from different industries were studied in a composite structure: paper, cardboard boxes, tetra-pak containers, expanded polystyrene (styrofoam), polyurethane (PU) foam, artificial leather, textile, wood chips and dust. Preliminary compressive tests were performed. The results indicated unsuitable combinations, but also some that provided a stable compact composite which endured high compressive loads. An important result is that such a composite can be made without adding any adhesives. Waste materials from different industries can be efficiently used for new composites, and further study of this is clearly needed.

KONCEPT EKOLOŠKIH TEHNOLOGIJA PLASTIČNOG OBLIKOVANJA METALA U RAZVOJU SAVREMENIH PROIZVODNIH SISTEMA

Tehnologije plasticnog ablikovanja (TPO),u savremenoj industrijskoj proizvodnji dominira u odnosu na ostale tehnologije, prije svega u industrijski razvijenim zemljama.U cilju zastite kako ogranicenih resursa tako i zastiti covjekove okoline, neminovno je usaglasavanje ove tehnologije sa savremenim zahtjevima uvođenja tzv. “cistih“proizvodnih postupaka i tehnologija. U ovom radu dat je savremeni pristup modeliranja sistema TPO sa posebnim osvrtom na tehnologije oblikovanja na zavrsnu formu (Net shape forming, NSF)koje omogucavaju ustedu u materijalu i ekoliski su prihvatljive.Osim ekoloskih aspekata u oblasti TPO, ukazano je na znacaj izbora sredstava za podmazivanje kako sa tehnoloskog tako i sa ekoloskog stanovista. Takođe se, pored navedenih pregleda izucavanja u ovoj oblasti, navode i rezultati sopstvenih istraživanja, sa preporukama za koriscenje ekoloskih komponenti obradnih procesa, u razlicitim postupcima TPO - pri hladnom kovanju, preradi limova i sl.