V.V. Tcherdyntsev

Structure and properties of ultra-high molecular weight polyethylene filled with disperse hydroxyapatite

The possibility of preparing composite materials filled with hydroxyapatite on the basis of ultra-high molecular weight polyethylene for use in replacement arthroplasty was studied. The composites were prepared by the combined mechanoactivation of the starting components followed by compaction via thermal pressing. The structures of the resulting composite powder and monolithic composite were investigated by means of differential scanning calorimetry and X-ray diffraction analysis, and the effect of introduced hydroxyapatite on the degree of polymer crystallinity was elucidated. The composites were tested to determine the concentration dependences of their physicomechanical and tribological properties. On the basis of the experimental data, it was concluded that the mechanoactivation processing affords the high-quality polymeric composites, thereby providing the disperse distribution of the filler over the matrix. By a combination of physicomechanical and tribological characteristics, the materials developed can be suggested for the production of articulated joint liners of hip and knee endoprostheses.

Magnetic Properties and Defects of Fe-Ni-Based Magnetic Microwires

We studied the magnetic properties and domain wall (DW) dynamics of Fe_47.4Ni_26.6Si₁₁B₁₃C₂ and Fe_77.5Si_7.5B₁₅ microwires. Both samples present a rectangular hysteresis loop and fast magnetization switching. The linear region of dependence of the DW velocity on the magnetic field in Fe_47.4Ni_26.6Si₁₁B₁₃C₂ sample is considerably shorter. Consequently, we studied the structure of Fe_47.4Ni_26.6Si₁₁B₁₃C₂ sample using X-ray diffraction and atom probe tomography. The results obtained using the atom probe tomography supports the formation of B-enriched precipitates in the interfacial layer and in the metallic nucleus after annealing.

Strength and thermophysical properties of composite polymer materials filled with discrete carbon fiber

The structure and properties of carbon-filled composite materials for tribological applications based on ultrahigh molecular weight polyethylene that are obtained by deformation-induced solid-phase synthesis are investigated. It is shown that the addition of graphite and carbon fiber to a polymer material allows one to improve its tribological and thermophysical properties. An increase in the physical and mechanical characteristics is observed only upon the addition of carbon fiber, while the inclusion of graphite in a matrix polymer gives rise to embrittlement of the material.

Physicomechanical properties of a composite material based on ultrahigh-molecular-weight polyethylene filled with ceramic particles

The effect of the shape of filler particles on the mechanical properties of a composite material based on ultrahigh-molecular-weight polyethylene produced by thermal compacting after preliminary mechanical activation of the initial materials is studied. As a filler, Al2O3 in the form of an ultradispersed powder with a particle size of 200 nm or as 1-μm microspheres is used. The effects of the fillers of both types on the mechanical properties of the composite material is found to be positive and comparable in the concentration range under study (1–10 wt %). The degree of matrix hardening depends on the shape of filler particles.

Polyhydroxybutyrate/Hydroxyapatite Highly Porous Scaffold for Small Bone Defects Replacement in the Nonload-bearing Parts

In the present work, Polyhydroxybutyrate (PHB)/Hydroxyapatite (HA) porous composites (10%, 20%, 30 %, 40%, 50% weight HA) were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical properties with a high content of the bioactive component (HA). Porous PHB/20% HA scaffolds have shown high mechanical properties (compressive strength of 106 MPa and Young’s modulus of 901 MPa). A high volume fraction of interconnected pores (> 50 vol.%) was achieved with pore size of 50 μm - 500 μm. Biocompatibility of porous pure PHB and PHB/20%HA, as its osseointegration were assessed in vitro and after implantation in laboratory animals. PHB/20% HA (−5% ± 0.9%) and pure PHB (−3% ± 1.4%) samples after 24 hours of incubation with human leucocytes showed no significant level of cytotoxicity when p = 0.648 (p-value). In vitro massive adhesion of mouse Multipotent Mesenchymal Stromal Cells (MMSC) to the surface of both porous samples was shown. PHB/20% HA induced more intensive MMSC proliferation compared to pure PHB, which are 31% ± 6.1% and 20% ± 5.7 % respectively when p = 0.039. We observed the resorption (implant surface area was reduced by 49 %) and integration of the porous PHB/20% HA samples into surrounding tissues after 30 days of implantation. The signs of osteoclasts accumulation, neo-angigenesis and new bone formation were observed, which make PHB/20% HA promising for bone tissue engineering.

Quasicrystalline Powders as the Fillers for Polymer-Based Composites: Production, Introduction to Polymer Matrix, Properties

Powders of icosahedral Al65Cu23Fe12 and decagonal Al73Cu11Cr16 quasicrystalline intermetallics were synthesized by the mechanical alloying in combination with subsequent annealing. The conditions of mechanical alloying were purposely chosen to obtain the composite materials filled by dispersed (<3 μm) quasicrystalline particles. A number of silanes were tested for the surface treatment of quasicrystalline particles in order to provide the uniform distribution of quasicrystals over the polymer melt and chemical binding with the polymer matrix and the most efficient silane type was found. The composites based on ethylene-vinyl acetate EVA, polysulphone PSU, and polyphenylene sulfide PPS were produced by the filling with quasicrystalline powders. The study of rheological characteristics has shown that high fluidity of the melt is retained, while uniform distribution of quasicrystalline particles over the polymer is provided. The data of mechanical and physical properties are reported.

Structure and properties of composites based on polyphenylene sulfide reinforced with Al-Cu-Fe quasicrystalline particles

Structural, mechanical, and thermal properties of polyphenylene sulfide (PPS) filled with Al-Cu-Fe quasicrystals particles were studied. It was shown that the introducing of quasicrystalline fillers into the polymer matrix results in the increase in Young’s modulus, hardness, and toughness of the polymer. Quasicrystalline fillers can improve thermal properties of PPS, including heat resistance index, Vicat softening temperature, thermal diffusivity, and thermal conductivity.

Thermal and mechanical properties of fluorinated ethylene propylene and polyphenylene sulfide-based composites obtained by high-energy ball milling

AbstractSolid-state formation method of polyimide (PI) blends based on polyphenylene sulfide (PPS) and fluorinated ethylene propylene (FEP) was elaborated.n Recycled thermoset PI powder was used as reinforcements. FEP/PI and PPS/PI blends were obtained by high-energy ball mill without using compatibilizer. PI content in blends was of 25, 50 or 75xa0wt%. Bulk samples were obtained by sintering at 330xa0°C during 25xa0min, with consequent disposition of sample into hot mold between two cold plates and loading the pressure of 20–35xa0MPa for 10xa0min. Morphology structure and thermal properties of powder blends were studied by tapped density measurements, DSC and XRD analyses. Thermal and mechanical properties of bulk samples were studied by DMA, hardness measurements and compressive tests. Strong chemical interaction between FEP matrix and PI filler was observed, whereas in case of PPS/PI samples nearly no interaction between components was found. Mechanical tests show that optimum filling degree for PPS/PI system is of 25xa0wt% PI, whereas in FEP/PI system it is of about 50xa0wt%.

Structure and mechanical properties of self-reinforced ultra-high molecular weight polyethylene:

Ultra-high molecular weight polyethylene-based self-reinforced composite materials were studied. Surface of the ultra-high molecular weight polyethylene fibers was modified by direct fluorination and nitric acid treatment. Structure and mechanical properties of self-reinforced ultra-high molecular weight polyethylene depending on the content and type of modified fibers were studied. It was shown that self-reinforcing of ultra-high molecular weight polyethylene allows to obtain materials with improved strength–elastic properties. Tensile strength and Young’s modulus of the self-reinforced composite materials are more than three times higher than that of the unfilled ultra-high molecular weight polyethylene.