Wollastonite Fibers Research Articles

Addition of Wollastonite Fibers to Calcium Phosphate Cement Increases Cell Viability and Stimulates Differentiation of Osteoblast-Like Cells.

Calcium phosphate cement (CPC) that is based on α-tricalcium phosphate (α-TCP) is considered desirable for bone tissue engineering because of its relatively rapid degradation properties. However, such cement is relatively weak, restricting its use to areas of low mechanical stress. Wollastonite fibers (WF) have been used to improve the mechanical strength of biomaterials. However, the biological properties of WF remain poorly understood. Here, we tested the response of osteoblast-like cells to being cultured on CPC reinforced with 5% of WF (CPC-WF). We found that both types of cement studied achieved an ion balance for calcium and phosphate after 3 days of immersion in culture medium and this allowed subsequent long-term cell culture. CPC-WF increased cell viability and stimulated cell differentiation, compared to nonreinforced CPC. We hypothesize that late silicon release by CPC-WF induces increased cell proliferation and differentiation. Based on our findings, we propose that CPC-WF is a promising material for bone tissue engineering applications.

Application of Alkali-Activated Agro-Waste Reinforced with Wollastonite Fibers in Soil Stabilization

AbstractThis study addresses the feasibility of using palm oil fuel ash (POFA) as a precursor in alkali activation reactions, as well as mineral wollastonite microfibers as discrete reinforcement. ...

Selection of brake friction materials using hybrid analytical hierarchy process and vise Kriterijumska Optimizacija Kompromisno Resenje approach

Selection of proper formulation is one of the most challenging tasks in the design and development of brake friction materials. Improper selection often leads to premature component or product failure during working. This article develops an evaluation approach based on VIKOR (Vise Kriterijumska Optimizacija Kompromisno Resenje) strengthened with AHP (Analytic Hierarchy Process) to choose an optimal friction material formulation according to several performance defining criteria, which are probably conflicting. Friction materials based on the variation of Kevlar–lapinus and lapinus–wollastonite fibers are fabricated and characterized for their physical, chemical, mechanical, and tribological performance. The tribological performance was evaluated on a Krauss type friction tester following R‐90 norms as per ECE (Economic Commission for Europe) regulations. Experimental results in‐terms of friction performance, fade performance, wear performance, friction stability, recovery performance, friction variability, friction fluctuations, and disc‐temperature rise were considered as criterions for performance optimization. The weight of importance for each criterion was determined by AHP, while VIKOR is employed to rank the alternatives. The results show that the formulation with 27.5/2.5 wt% of lapinus/Kevlar fiber combination exhibit optimal properties. POLYM. COMPOS., 39:1655–1662, 2018. © 2016 Society of Plastics Engineers

Multiscale characterization of carbonated wollastonite paste and application of homogenization schemes to predict its effective elastic modulus

This paper describes the multiscale characterization of the carbonated wollastonite paste using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), and statistical nanoindentation (SNI, also known as ‘grid indentation’) methods as well as micromechanical homogenization models. Wollastonite (CaSiO3) fibers are commonly used as filler in ceramics or plastics. However, wollastonite can also be regarded as non-hydraulic binder material since upon carbonation it forms a heterogeneous matrix with mechanical properties similar to those of the conventional hydrated cement pastes. Carbonation reaction of wollastonite results in the formation of two main products: calcium carbonate (CaCO3) and amorphous silica gel (SiO2). The SEM/EDS microanalysis performed on this system revealed that the average calcium to silica (Ca/Si) atomic ratio of the silica gel phase was around 0.40. Three individual carbonated wollastonite paste samples, each representing a different degree of carbonation were selected for nanoindentation tests. The obtained elastic moduli for silica gel, calcium carbonate, and unreacted wollastonite grains were, respectively, 41.7 GPa, 67.3 GPa, and 134.7 GPa. The micromechanical homogenization models were then utilized to predict the effective (also referred to as ‘homogenized’) elastic moduli of the carbonated wollastonite paste. The predicted values of the effective elastic moduli of carbonated wollastonite pastes were found to be in the range of corresponding values for hydrated high to ultra-high performance cement pastes. Additionally, the values of the effective elastic moduli of the carbonated wollastonite pastes were observed to increase with the increase in the degree of carbonation.

Quantitative 2D Restrained Shrinkage Cracking of Cement Paste with Wollastonite Microfibers

AbstractPlastic shrinkage cracking in restrained cement pastes reinforced with wollastonite particles of micro and submicron sizes was studied using a quantitative two-dimensional (2D) cracking experiment. A series of blended paste mixes with portland cement and different grades of wollastonite fibers were developed and tested under low vacuum conditions. Testing parameters included four grades of wollastonite with aspect ratio in the range of 3∶1–20∶1 and average particle size ranging from 33 to 2,000 μm at 15% cement replacement. Wollastonite beneficially altered the shrinkage cracking morphology by arresting crack growth, wherein crack lengths and widths were reduced by a factor of two, and the area by a factor of three when compared with the control specimens. However, the initial evaporation rate, early age diffusivity, and cumulative moisture loss increased. Influence of the microfibers in controlling early age drying were related to the porosity of the microstructure using mercury intrusion porosim...

Preparation and Evaluation of Polyester Hybrid Composites Reinforced with Carbon Fibre/ Wollastonite Fibers

Preparation and Evaluation of Polyester Hybrid Composites Reinforced with Carbon Fibre/ Wollastonite Fibers

Crack-free silicate bioceramics from preceramic polymers

As a case study, the present paper illustrates an innovative processing method employing a preceramic polymer containing different fillers, which can be used to manufacture various ceramic components for biomedical applications. Crack-free wollastonite (CaSiO3) ceramics were successfully produced, with high phase purity, after heating at 900°C in air starting from a silicone resin containing CaCO3 micro-sized particles as ‘active filler’. As ‘passive filler’, wollastonite preceramised powders as well as commercially available wollastonite fibres were added. Their presence reduces the gas evolution occurring due to the decomposition of the calcium carbonate active filler and the polymer-to-ceramic conversion, reducing the stresses that generate in the component during heating. The resulting samples exhibited improvements in terms of the morphology and the mechanical strength, with respect to samples not containing any passive fillers, without significant modification of the final phase assemblage.

Effects of wollastonite on the properties of medium-density fiberboard (MDF) made from wood fibers and camel-thorn

The effects of wollastonite fibers on the physical and mechanical properties of medium-density fiberboards composed of wood fibers with up to 10 % camel-thorn chips were studied. Approximately 30 % of the wollastonite fibers were less than 100 nm while the remainder were less than 1 μm. Wollastonite fibers significantly improved most of the physical and mechanical properties while addition of camel-thorn produced more variable effects on panel properties. Up to 10 % camel-thorn could be added to panels without negative effects. A combination of 10% camel-thorn and 5% wollastonite fibers produced panels with the best properties.

Assessment of braking performance of lapinus–wollastonite fibre reinforced friction composite materials

Brake friction materials comprising of varying proportions of lapinus and wollastonite fibres are designed, fabricated and characterized for their chemical, physical, mechanical and tribological properties. Tribological performance evaluation in terms of performance coefficient of friction, friction–fade, friction–recovery, disc temperature rise (DTR) and wear is carried out on a Krauss machine following regulations laid down by Economic Commission of Europe (ECE R-90). The increase in wollastonite fibre led to an increase in density and hardness whereas void content, heat swelling, water absorption and compressibility increased with the increased in lapinus fibre. The performance coefficient of friction, friction–fade behaviour and friction–stability have been observed to be highly dependent on the fibre combination ratio i.e. coefficient of friction, fade and friction–stability follow a consistent decrease with a decrease in the lapinus fibre content, whereas the frictional fluctuations in terms of μmax−μmin have been observed to increase with a decrease in lapinus fibre content. However, with an increase in wollastonite fibre content in formulation mix, a higher wear resistance and recovery response is registered. The worn surface morphology has revealed topographical variations and their underlying role in controlling the friction and wear performance of such brake friction composites.

Mechanical properties of micro and sub-micron wollastonite fibers in cementitious composites

Effect of mineral wollastonite micro and sub-micron fibers on the mechanical properties of cement-based systems are studied using compressive strength and notched beam flexural tests. A series of blended paste and mortar mixtures with silica fume and wollastonite particles of different morphology and size were developed and tested. Testing variables included four grades of wollastonite fibers or platelets with average particle size ranging from 33 to 2000μm, with aspect ratios varying from 3:1 to 20:1, and cement replacement levels of 5%, 10%, and 15%, by mass. Non-linear fracture mechanics concepts used indicate considerable effect of wollastonite reinforcement on the fracture resistance of the cementitious matrix. Uniaxial compressive strength tests showed a 30% increase due to 10% cement replacement with wollastonite and silica fume. Flexural strength was enhanced by 40% and fracture toughness by as much as 150% at the optimal dosage of wollastonite fibers. Morphology of fractured surfaces was studied using SEM to correlate the mechanical properties with internal micro-structure. It was observed that at optimal dosage, wollastonite fibers promote classical toughening mechanisms such as crack bridging and crack path deflection.

Combined effect of selected mineral fibres and tobacco smoke on respiratory tract in rats.

The rats were inhaling amosite and wollastonite fibres at two concentrations (30 and 60 mg/m3) one hour every second day and cigarette smoke of 3 cigarettes per day (with the exception of Saturdays and Sundays). They were sacrificed after 6 month of exposure. Bronchoalveolar lavage (BAL) was performed and selected inflammatory and cytotoxic parameters were examined. Amosite: inflammatory parameters were the most changed after 60 mg/m3 in both groups with or without smoking; the cytotoxic parameters were strongly influenced by smoking. Wollastonite (asbestos substitute) inhalation confirmed lower inflammatory and cytotoxic effects on all examined animal groups in comparison with amosite.

Rheological characterization of polymers fiber composite

The use of reinforced polymer composites has continued to show substantial growth due to desirable cost and performance characteristics, especially related to mechanical properties. Wollastonite and glass fibers are materials that can be used to improve polymer performance. Its vast array of applications suggests potential usage in various fields of work (e.g., plastics, friction materials paintings, coating, and construction products), but there is not much data available in the literature related to rheological properties of fiber reinforced polymers. In this work, a study of shear and extensional properties of composite materials containing wollastonite and glass fibers is performed using rotational and extensional rheometry. Suspensions containing different concentrations of wollastonite and glass fibers, in Newtonian and viscoelastic matrices are investigated. Results are obtained for different concentrations and temperatures. It is observed that even the addition of low fiber concentration can affect both shear and elongational properties, leading to different final products characteristics. POLYM. COMPOS. 34:1269–1278, 2013. © 2013 Society of Plastics Engineers

Electrical property and characterization of nano-SnO2/wollastonite composite materials

Nano-tin oxide was deposited on the surface of wollastonite using the mixed solution including stannic chloride pentahydrate precursor and wollastonite by a hydrolysis precipitation process. The antistatic properties of the wollastonite materials under different calcined conditions and composite materials (nano-SnO2/wollastonite, SW) were measured by rubber sheeter and four-point probe (FPP) sheet resistance measurement. Effects of hydrolysis temperature and time, calcination temperature and time, pH value and nano-SnO2 coating amount on the resistivity of SW powders were studied, and the optimum experimental conditions were obtained. The microstructure and surface properties of wollastonite, precipitate and SW were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), specific surface area analyzer (BET), thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier translation infrared spectroscopy (FTIR) respectively. The results showed that the nano-SnO2/wollastonite composite materials under optimum preparation conditions showed better antistatic properties, the resistivity of which was reduced from 1.068×104Ωcm to 2.533×103Ωcm. From TG and XRD analysis, the possible mechanism for coating of SnO2 nanoparticles on the surface of wollastonite was proposed. The infrared spectrum indicated that there were a large number of the hydroxyl groups on the surface of wollastonite. This is beneficial to the heterogeneous nucleation reaction. Through morphology, EDS and XPS analysis, the surface of wollastonite fiber was coated with a layer of 10–15nm thickness of tin oxide grains the distribution of which was uniform.

Formation and preliminary in vitro evaluation of a zinc polycarboxylate cement reinforced with neat and acid‐treated wollastonite fibers

Zinc polycarboxylate dental cement is known to form both molecular and mechanical bonds with native tooth materials. However, its relatively weak mechanical properties limit its applications. Wollastonite fibers, with different aspect ratios, were blended with ZnO, prior to its mixing with polyacrylic acid, at weight percentages up to 25%. Setting time, density, compressive strength, and Young's modulus of the formed composites were determined. Composition and morphology of the composites were determined by XRD, IR, and SEM before and after treatment in simulated body fluids. A slight delay in the setting time of the composites was observed. An overall improvement in the compressive strength and modulus of these composites was observed up to 5 wt % of wollastonites, followed by a decrease with increasing the proportion of wollastonite in the composites. Immersion of these composites in SBF solutions resulted in the formation of apatite deposits on the surfaces of the reinforcing fibers.

Angiogenic effect induced by mineral fibres

Due to the toxic effect of asbestos, other materials with similar chemical–physical characteristics have been introduced to substitute it. We evaluate the angiogenic effect of certain asbestos substitute fibres such as glass fibres (GFs), ceramic fibres (CFs) and wollastonite fibres (WFs) and then compare angiogenic responses to those induced by crocidolite asbestos fibres (AFs). An in vitro model using human endothelial cells in small islands within a culture matrix of fibroblasts (Angio-Kit) was used to evaluate vessel formation. The release of IL-6, sIL-R6, IL-8, VEGF-A and their soluble receptors, sVEGFR-1, sVEGFR-2, was determined in the conditioning medium of Angio-Kit system after fibre treatment. ROS formation and cell viability were evaluated in cultured endothelial cells (HUVEC). To evaluate the involvement of intracellular mechanisms, EGFR signalling, ROS formation and nuclear factor-κB (NFκB) pathway were then inhibited by incubating HUVEC cells with AG1478, NAC and PDTC respectively, and the cytokine and growth factor release was analyzed in the culture medium after 7 days of fibre incubation. Among the mineral fibres tested, WFs markedly induced blood vessel formation which was associated with release of IL-6 and IL-8, VEGF-A and their soluble receptors. ROS production was observed in HUVEC after WFs treatment which was associated with cell cytotoxicity. The EGFR-induced ERK phosphorylation and ROS-mediated NFκB activation were involved in the cytokine and angiogenic factor release. However, only the EGFR activation was able to induce angiogenesis. The WFs are potential angiogenic agents that can induce regenerative cytokine and angiogenic factor production resulting in the formation of new blood vessels.

Development of glass fiber, wollastonite reinforced polypropylene hybrid composite: Mechanical properties and morphology

Hybridization with small amounts of mineral fibers makes these glass fiber composites more suitable for technical applications. This study focused on the performance of injection molded short wollastonite fiber and chopped glass fiber reinforced hybrid polypropylene composites. Results showed that hybridization of glass fiber and wollastonite was found to be comparable to that of polypropylene glass fiber composites. Analysis of fiber length distribution in the composite and fracture surface was performed to study fiber breakage fracture mechanism. The simultaneous compounding of polypropylene with two fillers was done to obtain a hybrid composite. The mechanical properties of hybrid, injection molded, chopped glass fiber/wollastonite/polypropylene composites have been investigated taking into account the effect of hybridization by these two types of fillers. This system is expected to have considerable mechanical properties, good surface finish and low cost. It has been found that the tensile, flexural, and impact properties of the filled polypropylene were higher than those of unfilled polypropylene. The hybrid effects of the tensile strength and modulus were studied by the rule of hybrid mixtures (RoHM) using the values of single fiber composites.

Influence of surface treatment on hybrid wollastonite-polyethylene composite resins for rotational moulding

The purpose of this research was to develop a reinforcing material for polyethylene-based composite manufacture by rotational moulding. Wollastonite, sisal fibres and PE are premixed by blending and compounding with a single screw extruder and then granulated to particles with diameter about 0.5 mm prior to rotational moulding, for which the mixture is placed in a mould that is heated from the outside to 250 °C for a period of about 10 min. Aminosilane was used as a surface treatment for wollastonite. It was found that incorporating wollastonite microfibres improved the tensile properties of the system. When wollastonite fibres were coated with aminosilane, the impact strength and processability were enhanced greatly. Sisal fibres were added to improve the impact properties. Scanning electron microscopy revealed good adhesion between the coated fibre reinforcement and the polyethylene matrix at the fracture surface. The mechanism of this phenomenon is discussed.

Thermophysical properties of ethylene–vinylacetate copolymer (EVA) filled with wollastonite fibers coated by silver

A new type of thermally conductive fibers based on silver coated wollastonite was prepared and characterized. The fibers were used for the preparation of elastic, highly thermally conductive polymeric composites based on ethylene–vinylacetate copolymer (EVA). It was shown that silver coated fibers significantly improved the thermal conductivity of composites despite the low silver volume content. The experimental results were discussed and compared to various theoretical models. The specific heat and the specific density of the composites were also characterized and reported.

Electrical, mechanical and adhesive properties of ethylene-vinylacetate copolymer (EVA) filled with wollastonite fibers coated by silver

New type of electrically conductive polymeric composites was prepared using ethylene-vinylacetate (EVA) matrix filled with silver-coated wollastonite (W-Ag) fibers. The electrical, mechanical and adhesive properties of the composites are reported in this paper. The electrical percolation threshold was found about 8 vol.% and the highly electrical conductivity value (1.8 × 10 5 S m −1) is reached for 29 vol.% of filler fraction. The mechanical and adhesive properties of these composites were also discussed and correlated with some models.

Shrinkage study of textile roller molded by conventional/microcellular injection-molding process

One of the advantages of microcellular conventional injection molding over conventional injection molding is that the shrinkage of the part can be reduced. This project investigated the effect of the process parameters on the shrinkage of the textile roller by conventional/microcellular injection-molding process. Polybutyleneterephthalate (PBT) materials with 30 wt.% glass and Wollastonite fiber were used. The results showed that the shrinkage by microcellular injection molding is less than that of conventional injection molding. Glass fiber filled PBT has more shrinkage than Wollastonite fiber filled PBT due to the non-uniform cell size of the glass fiber filled PBT.