The structure and properties of the carbon non-wovens modified with bioactive nanoceramics for medical applications.

The paper presents the results of the manufacture of carbon fibers (CF) from polyacrylonitrile fiber precursor containing bioactive ceramic nanoparticles. In order to modify the precursor fibers two types of bio-glasses and wollastonite in the form of nanoparticles were used. The processing variables of the thermal conversion of polyacrylonitrile (PAN) precursor fibers into carbon fibers were determined using the FTIR method. The carbonization process of oxidized PAN fibers was carried out up to 1000°C. The carbon fibers were characterized by a low ordered crystalline structure. The bioactivity tests of carbon fibers modified with a ceramic nanocomponent carried out in the artificial serum (SBF) revealed the apatite precipitation on the fibers' surfaces.

Experimental study of mechanical properties of composite carbon screws.

Carbon-carbon composite was used to manufacture carbon screws as possible material for osteosynthesis. The mechanical properties were optimized including the fibre orientation in the composite volume, the effect of the size of the thread and the thread shape. The mechanical properties of the carbon screws were compared with conventional OSTEO steel cortical screws. Two types of carbon specimens were used, varying in fibre orientation along the screw axis. The mechanical properties of the carbon screws including the failure force for one thread and the critical shear stress were determined. The force destroying the connection of the carbon screw with bone was determined. The holding capacity of the carbon screw was compared to the steel screw. The extraction tests demonstrated 50% less holding force than the OSTEO steel screw.

[Use of a new model of keratoprosthesis made from carbon in treatment of dense leukoma after ocular burns]. / Zastosowanie nowego modelu keratoprotezy z kompozytu weglowego w leczeniu ciezkich bielm po oparzeniach rogówki.

Discussed are the results of kerato-prosthetics in 12 cases of severe post-burn leukoma by means of a new model of keratoprosthesis with a carbon bearing. The material for construction of the carrier part of the prosthesis is based on carbon fibres and Polish technology worked up by the Institute of Material Engineering of the Mining-Metallurgic Academy in Krakow.

Mechanical properties of C/C composites processed by wet impregnation and P-CVI methods.

Wet impregnation with phenolic resin and P-CVI methods were used to manufacture C/C composites. The influence of impregnation process of porous 2D carbon fibre substrate with resin and pyrocarbon deposited by CVD technique on mechanical properties of formed composites was studied. The results indicate that using P-CVI method large pores remain in the matrix resulting in lower mechanical strength. This fraction does not undergo any changes during thermal treatment. The flexural modulus of C/C composites depends mainly on the type of reinforcing fibres. The values of moduli measured in composites obtained by both methods do not differ significantly. Comparison of two methods of fabrication of C/C composite show that much better strengths can be achieved by forming the carbon matrix in solid state.

Static and dynamic fatigue properties of carbon ligament prosthesis.

The aim of the present paper was to characterize the static and dynamic mechanical properties of carbon braids used in medicine as prostheses of ligaments and tendons. A computing system (PC software) was used to register and analyze the data of mechanical tests. Tensile static tests (creep testing) were utilized to determine the failure-free value of static force. Fatigue dynamic properties of carbon braids in tensile-tensile cyclic tests including the effect of simulated body conditions were analyzed. The braids were immersed in isotonic solution at 37 degrees C. Fatigue life was markedly lowered in air in comparison with simulated body conditions. For a given value of maximum cyclic force, decreasing the minimum/maximum force ratio decreased the number of cycles to failure. The mechanical approach of fatigue behavior based on approximately maximum fatigue force and number of cycles to failure by analytical expression was given. Energy dissipation due to the hysteresis loop was considered.

[The possibility of using carbon material in surgery of joints]. / Mozliwosci zastosowania materialów weglowych w chirurgii narzadu ruchu.

The experiments consisting in replacement of a dissected anterior cruciate ligament of the knee in rabbits with a bundle of parallel carbon fibers and a braided carbon covered with animal collagen lyophilized dura mater have been performed. Similar experiments have been performed on dogs. The lateral ligaments of the knee were also restored, longitudinally cut menisci and the Achilles tendon were sutured. The produced carbon plate and metal screws were used to fix bone fracture. The positive results of the experiments on animals with the use of carbon fibers of Polish make have proved the possibility of their employment for periarticular ligament reconstruction, suturing, Achilles tendon injuries and juxta capsular meniscus rupture. The union of bone fracture with a composite carbon plate has shown the superiority of "carbon" osteosynthesis over "metal" one. It is believed that carbon materials will be used clinically more widely.