Papers by Keyword: Wollastonite

Abstract: There are many requirements for biomaterials used in the applications of bone tissue engineering, besides their biocompatibility, they should exhibit acceptable mechanical properties to mimic bone properties. Many research areas in bioactive materials for bone tissue engineering focused on producing new bioactive glass and ceramic compositions containing a trace of inorganic elements (such as Mg, Sr, Cu, Zn) to combine the mechanical properties and bioactivity. In the present study bioglass-MgO composite material has been used to produce Diopside (CaMgSi₂O₆) by the sintering process. The compact samples were made from a mixture powder of (7, 15)wt% MgO and binary bioglass 70Si-30Ca sintered at 1100 ᵒC for 2 hr. The XRD results confirmed the presence of diopside and wollastonite CaSiO₃ in the case of using 7wt.% MgO while the structure was completely diopside at 15 Wt.% MgO. Physical properties, compressive strength, and hardness were investigated, as well as biodegradation behavior and bioactivity in human saliva were inspected. The results confirmed improving the mechanical properties along with increasing MgO as well as proved the ability to form hydroxyapatite on the surface when exposed to human saliva. These findings demonstrated the positive role of MgO in the mechanical properties of 70Si-30Ca bioactive glass besides producing diopside as a good candidate for hard tissue engineering.

Abstract: Recycled nylon 6/thermoplastic poly (ether-ester) elastomer (Hytrel) (R-N6/H) composites filled with various contents of wollastonite (WT) (10, 20 and 30 phr) were prepared using the twin-screw extrusion and injection molding process. In this study, the blend and composite materials were characterized in terms of mechanical and morphological properties. The results showed that the impact strength of the R-N6/H blend was improved with the addition of Hytrel, whereas the tensile strength, tensile modulus, flexural strength and flexural modulus of the R-N6/H blend were decreased. Then, the R-N6/H blend was filled with WT to prepare composites. Interestingly, the incorporation of WT in the R-N6/H blend overcame the inferior properties of recycle blend materials by the mechanical properties enhancing. Despite the good mechanical properties of WT composite materials, they were still affected the elastic properties due to the stiffness characteristic of WT.

Abstract: Enhancement of the room temperature vulcanization silicone rubber (RTV) tracking resistance with various filler loadings of synthesized wollastonite against electrical surface tracking was prepared. The X-ray diffraction (XRD), Scanning electron microscope (SEM), and X-ray fluorescent (XRF) techniques were involved in characterizing the synthesized substances. The test method IEC-60587 standard was employed to evaluate the surface tracking resistance. The results obtained from the XRF technique confirmed that the raw materials could be synthesized for wollastonite, while the XRD and SEM techniques revealed the formation of wollastonite (CaSiO₃) associated with gehlenite (Ca₂Al₂SiO₇). Moreover, it was found that the electrical surface tracking resistance of composite insulation takes a long time to track when the filler loading is increased more than 5 phr.

Abstract: The article shows that synthetic wollastonite, obtained on the basis of a mixture of calcium oxide and silicon oxide, as well as calcium carbonate and silicon dioxide, increases the thermal stability of epoxy materials filled with it. The chemical and atmospheric resistance of epoxy films filled with wollastonite is on average 0.2 – 0.3% lower than that of the base composition, which is probably due to the porosity of both synthetic and natural wollastonite. The phase composition of synthetic wollastonite does not significantly affect chemical resistance of epoxy materials filled with it. The chemical resistance of epoxy compositions, regardless of their composition, is lower in weakly acidic solutions and water, in comparison with weakly alkaline and saline solutions.

Abstract: Evaluation of the antibacterial properties of PVC materials used, in particular, in medicine, is becoming increasingly important due to increased sanitary and hygienic requirements. One of the ways to ensure the resistance of PVC materials to microorganisms is modification with wollastonite, the surface of which is activated by quaternary ammonium salts (QASs). QASs are known for their antimicrobial properties. The results obtained indicate that the basic composition of linoleum is somewhat more resistant to gram-positive bacteria than to gram-negative bacteria. The introduction of wollastonite into the PVC compound formulation increases the resistance to the studied groups of microorganisms. It can be concluded that the surface treatment of Mivoll 10-97 by QAS generally improves the bactericidal properties of the material. The results obtained are consistent with the literature data on the activity of cationic QACs in relation to gram-positive and gram-negative bacteria. Quaternary ammonium salts have the ability to be attracted to the outer surface of the negatively charged bacterial membrane due to the positive charge of their molecules.

Abstract: An effective highly dispersed additive based on the wollastonite Miwoll 05-97 with an average particle diameter of 6.5 microns is obtained. A stable effect of interacting the additive components with Portland slag cement CEM II/A–Ш 42.5H is revealed; it results in improving the strength of fine-grained concrete produced with the raw materials mentioned above. It is established that using water suspension of wollastonite solid particles, highly water-reducing/superplasticizing modifier based on the polycarboxylate ether Master Glenium 430, as a stabilizer of the surface-active substance allows producing an additive with an evener distribution of solid particles in the liquid, and with stable functional properties. A highly dispersed wollastonite-based additive, obtained by ultrasonic dispersion for 10 minutes in the bath-type activator at the frequency of 35 kHz in the aquatic environment with a suspension stabilizer, enables producing the wollastonite-modified fine concrete with a compressive strength of more than 50 MPa, with the 10% additive being 2 times higher than that of the control.

Abstract: The effect of the addition of epoxysilane-treated wollastonite (ETW) to the mechanical and thermal properties of 3D-printed acrylonitrile butadiene styrene (ABS) via fused deposition modeling (FDM) was investigated. The loading of ETW was varied at 1, 3, and 5wt%. The 3D-printed composites were evaluated by scanning electron microscopy (SEM) tensile test, shore D hardness, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of ETW increases the tensile strength, elastic modulus, and toughness of ABS by up to 46.6, 56.2, and 53.7 %, respectively. The shore D hardness increases with increasing ETW. Morphological analysis show that this improvement in mechanical properties is a result of the high aspect ratio of the fillers, the uniform dispersion of ETW in the ABS matrix, and the orientation of ETW particles toward the direction of tensile stress. The glass transition temperature (T_g) of the composites increases and the onset of degradation slightly shifted to higher temperature with an increase in filler loading. The addition of ETW to ABS matrix in FDM 3D printing improved the mechanical and thermal properties of ABS.

Abstract: Biomaterials can be used in several areas of regenerative bioengineering, and is a viable option in the repair of bone injuries. A number of different types of biomaterials have been studied in relation to bone repair. Ceramics such as α-TCP have low fracture toughness compared to natural bone, so reinforcements such as wollastonite whiskers are developed so that they can be used in places with greater overload. This study aimed to evaluate the biocompatibility and bone neoformation of α-TCP plus 10% wollastonite whiskers, in vivo. To obtain the cement, α-TCP powders with or without 10% wollastonite whiskers were added to an aqueous solution containing 2.5% by weight of Na2HPO4 (anhydrous bibasic sodium phosphate). The biomaterial then became a paste, which was molded into the critical 5 mm defect made in the parietal bone of Wistar rats. Ten rats were divided into two groups. The animals from each group were euthanized within 30 days. Calvaries were removed and subjected to histological processing with Eosin and Hematoxylin. The implementation of the whisker biomaterial revealed the formation of intensely vascularized connective tissue in the implemented region; however, animals with the biomaterial α-TCP showed the formation of this tissue around the implemented region. On the other hand, intense bone resorption was observed only in the animals with Wollastonite Whiskers, but new bone formation in both groups. The biomaterial evaluated was shown to be non-cytotoxic, resorbable, and capable of inducing bone neoformation; however, more studies should be carried out to assess the application of this biomaterial in bone injuries.

Abstract: The composition of a highly dispersed additive for concrete based on the natural mineral raw material wollastonite is developed. The properties of the modified fine-grained concrete (FGC) are studied. The three-factor experiment planning made it possible to obtain mathematical dependences of the bending and compressive strength after 3 and 28 days of hardening, density, and water-cement ratio of the fine-grained concrete on such factors as the content of anionic surfactant of naphthalene-formaldehyde type in the composition of the raw material wollastonite being an activator of mechanic-chemical processing, the suspension stabilizer of the pre-activated material, and the content of S-3+wollastonite in powder after mechanic-chemical activation in the suspension. The dependence nomograms are built. The optimal strength parameters of the modified fine-grained concrete with the content of a highly dispersed additive of 5% by weight of cement in its composition, and the wollastonite concentration of 3 g/l in the water medium of the suspension stabilizer S-3 are ascertained. The developed highly dispersed additive allows obtaining fine-grained concrete with the bending strength of 3.1 MPa and the compressive strength of 57.8 MPa.

Abstract: The article analyzes the properties changes of non-autoclave foam on a protein foaming agent with the introduction of dispersed wollastonite and diopside. A decrease in the density of foam concrete (to the grade D300, D400), frost resistance of the material, as well as shrinkage deformations was noted. The optimal technological parameters have been determined, allowing to obtain more stable properties and structure of heat-insulating cement-ash non-autoclave foam concrete. The flow chart of the production of foam concrete of natural hardening in the separate preparation of foam and mortar is presented. The studies were performed at NSTU and NGASU (Novosibirsk) and the NII (Norilsk).