Addition Of Silica Research Articles

Improving Fibrin Hydrogels' Mechanical Properties, through Addition of Silica or Chitosan-Silica Materials, for Potential Application as Wound Dressings.

Fibrin is a protein-based hydrogel formed during blood coagulation. It can also be produced in vitro from human blood plasma, and it is capable of resisting high deformations. However, after each deformation process, it loses high amounts of water, which subsequently makes it mechanically unstable and, finally, difficult to manipulate. The objective of this work was to overcome the in vitro fibrin mechanical instability. The strategy consists of adding silica or chitosan-silica materials and comparing how the different materials electrokinetic-surface properties affect the achieved improvement. The siliceous materials electrostatic and steric stabilization mechanisms, together with plasma protein adsorption on their surfaces, were corroborated by DLS and ζ-potential measurements before fibrin gelling. These properties avoid phase separation, favoring homogeneous incorporation of the solid into the forming fibrin network. Young's modulus of modified fibrin hydrogels was evaluated by AFM to quantitatively measure stiffness. It increased 2.5 times with the addition of 4 mg/mL silica. A similar improvement was achieved with only 0.7 mg/mL chitosan-silica, which highlighted the contribution of hydrophilic chitosan chains to fibrinogen crosslinking. Moreover, these chains avoided the fibroblast growth inhibition onto modified fibrin hydrogels 3D culture observed with silica. In conclusion, 0.7 mg/mL chitosan-silica improved the mechanical stability of fibrin hydrogels with low risks of cytotoxicity. This easy-to-manipulate modified fibrin hydrogel makes it suitable as a wound dressing biomaterial.

3D printing of HAp/xSiO2 ceramic scaffolds for potential bone graft reconstruction

HAp has drawn great attention in recent years for its similarity to the inorganic component of bone and can be used as a biocompatible implant. However, the application is limited for its poor shape ability and low degradation ability. With the help of Digital Light Processing 3D printing technology, this study proposed a method for the fabrication of bone remodeling scaffolds with high complexity. In addition, this study found that the silica addition will help densify the HAp ceramic and make it transform to a more biodegradable TCP phase at low sintering temperature.

Utility of Chitra-HASi Granules in Cystic Defects of the Maxillofacial Region: A Pilot Study.

Background:Cystic defects that are critical sized or larger require bone replacement strategies. However, due to inherent disadvantages of the various types of grafts, none of the available materials are best suited for these defects. Among the alloplastic materials, hydroxyapatite (HA)-based grafts are the most popular, due to their osteoconductive nature and resemblance to mineral bone. The aim of the study was to assess the utility of the novel material “Chitra-HASi” as a bone substitute in the maxillofacial region.Materials and Methods:In a single-arm, prospective study, patients with radicular and dentigerous cysts were included and the minimum defect size was standardized at 20 × 20 mm or above. The Chitra–HASi material was developed by a wet precipitation technique and adopted for use following multiple in vitro and in vivo studies, confirming its safety and biocompatibility profile. All cysts underwent enucleation, followed by peripheral ostectomy and apicectomy of the teeth involved. The HASi graft was packed inside the cystic defect in a granular form and covered with a mucoperiosteal flap. Panoramic radiographs were taken preoperatively and at 3, 6, and 12 months postoperatively.Results:Twenty-three patients were included in the study, of which only 10 patients could be followed up for 12 months after graft placement. The mean preoperative bone density was found to be 14.9% ± 4.97 (standard deviation), whereas the postoperative 3-month, 6-month, and 12-month densities had a mean difference of −11.3%, −22.9%, and −37.3%, respectively, and the differences were statistically significant. Minor complications such as sinus formation (n = 7) and extrusion of granules (n = 4) were noted, which were managed conservatively. Only two patients required graft removal secondary to infection, leading to a persistent sinus tract.Conclusion:The results of the study suggest that Chitra–HASi granules show potential as an alternative to other bone substitutes. The addition of silica to the porous HA material offers superior strength characteristics and needs long-term evaluation to assess its stability in large cystic defects.

Experimental study on mechanical properties of polypropylene fiber reinforced concrete with silica fume

In this research, the mechanical properties of polypropylene and silica fume are examined with the 0.40% water-cement ratio of M40 grade concrete. The synthetic polypropylene fibers of length 12mm short fibers. in this study, the polypropylene fibers are used up to 0.3% (0%, 0.1%, 0.2%, 0.3%). And the silica fume is being utilized as a substitute for cement with a 4% mass of cement in all the mix proportions. The addition of silica fume to the cementitious matrix strengthened fiber scattering, resulting in a substantial decrease in the absorbency of the polypropylene fiber reinforced concrete(PPFRC). Superplasticizer is also added to these concrete mixes to increase workability. The concrete samples are prepared and cured for 7, 28 days. After completing the curing duration, samples were tested. After That finally, the mechanical properties, as comp. strength, split tensile, bending strength and mode of failure and ultimate load are determined and all proportions of the mix are compared to traditional concrete.

POTENSI PENGGUNAAN PARTIKEL NANOSILIKA DARI ABU SEKAM PADI SEBAGAI BAHAN TAMBAHAN DALAM PEMBUATAN BETON (MINI REVIEW)

In the current era, the increase in infrastructure development correlate with the increased use of concrete. This is because currently, many buildings used concrete. However, concrete is prone to damage due to incomplete processes, for example cracking. Based on several studies that have been reviewed, these problems can be minimized by using silica, both micro, and nano sizes. In general, the silica used comes from quartz sand in the concrete mixture that has been studied. On the one hand, the use of silica is beneficial in the manufacture of concrete, but on the other hand it has a negative impact on the environment. If this is not done prevention, the environment will be more damaged. Therefore, this article looks at the potential of silica from rice husk ash and looks at the characteristics of concrete with silica addition from quartz sand.

Growth pattern of the siliceous skeletons of living Spumellaria (Radiolaria) from the Kuroshio Current, offshore southwestern Shikoku Island, Japan

Experimental culture studies of living radiolarians experience many difficulties because radiolarians are too sensitive to be maintained alive in artificial conditions. We here developed an improved experimental protocol in order to detect newly-formed parts of the polycystine radiolarian skeletons after they were labeled with fluorescent markers. Living samples were collected from surface seawater of the Kuroshio Current offshore from Kashiwajima Island, Kochi Prefecture on the island of Shikoku, Japan. The taxonomic composition of the Kashiwajima radiolarian samples varied markedly across the seasons and sampling sites. Spumellaria were usually abundant in samples collected near Kashiwajima, and had high diversity in shell morphology. Here, we performed experimental studies on living spumellarian radiolarians to clarify their siliceous skeletogenesis. Our culture-based research on spumellarians provided the following results.(A) The pattern of silica deposition on the skeleton of Spongaster tetras tetras varies depending on the growth stage. Three ontogenetic stages were identified: (1) young, (2) progressively-growing and (3) fully-grown. Furthermore, novel varied types of skeletal growth modes were determined as follows: (i) rapid growth on the outermost shell with enlargement of shell size and (ii) internal deposition on skeletal components without change in shell size. From measurements of the growth rate of cultured radiolarians, it is assumed that S. tetras tetras cell has at least a month-long life cycle.(B) Spherical spumellarians have their own shell-forming strategy that permits additional silicogenesis while maintaining the taxonomically-specific shape of their shell; the meshwork of their shell surface consists of polygonal-shaped pore-frames formed by heterogeneous patterns of added silica.Our direct observation with fluorescence markers detected a skeletogenesis process of Haliommilla capillacea possessing a fragile spherical shell. We thus confirm the bridge-growth hypothesis for morphogenesis of the polygonal frame as proposed in previous studies. Spongosphaera streptacantha, having extremely long spines, exhibited a special growth pattern of spine elongation in a centrifugal direction, without a change in width. This was achieved by a particular temporal pattern of silicification characterized by an alternating pattern of patchy addition of new silica on the entire part of each blade from the base to the tip. Moreover, a thin layer of new silica was added by a flowing deposition along the edge of the spine. Based on these culture-based studies using living radiolarians, we conclude that Spumellaria control and maintain a particular shell shape by regulating where silicification takes place on the skeleton, particularly depending on the growth stage.

Thickness controlled SiO2/TiO2 sol-gel coating by spraying

SiO2/TiO2 composite sol-gel coatings can be used in many industrial applications for their self-cleaning and photocatalytic properties. In this study, SiO2/TiO2 composite sol-gel coatings were deposited by spray coating as it allows a better thickness control than dip coating, which is now mostly used. The most critical spray coating parameters were first determined by a fractional factorial experimental design for a TiO2 sol coating. Then, the effect of silica addition in combination with a hydrophobic precursor on the thickness, the water contact angle and the adhesion strength of the coatings was studied.The most critical spray parameters for controlling the thickness of the coating were the reservoir pressure and the height of the spray gun above the substrate, while the atomisation pressure had almost no effect. A thin coating can be obtained by using a great height in combination with a low reservoir pressure.

Mechanical and biological behaviour of porous Ti–SiO2 scaffold for tissue engineering application

The present work reports a cost-effective way of fabricating porous Titanium (Ti)/Silica (SiO2) composite scaffold with tailored pore microstructure through powder metallurgy technique, considering the aspect of implants where low bearing load is required with low elastic modulus. Rice husk (RH) powder of different size range was used as fugitive pore former and sucrose was used as a binder which also acted as a pore former. The porosity of the scaffold was controlled by varying the size and amount of space holder. After sintering, the developed composite scaffold was characterized through SEM, XRD, and EDS. Mechanical and biological testing of the scaffold were performed to determine mechanical and biological properties. The resulting scaffolds have the porosity in the range of 15–34%. The addition of silica from RH increased the compressive strength of the scaffold (116–396 MPa). It was also observed that due to the incorporation of pores in Ti matrix there was reduction in Elastic Modulus of the scaffold which is significantly important for Ti based implant materials. Bioactivity of the scaffold was examined by using SBF solution and it was found that the Ti/SiO2 scaffold has ability to form apatite layer. Antibacterial behaviour and biofilm formation on the surface of scaffold were also studied. Obtained result was compared with the properties of natural bone. It was found that the properties of the developed Ti/SiO2 composite scaffolds are similar to that of natural bone and hence can be suitable for orthopaedic application.

The effect of heat treatment on structure property of (Bentonite - Alumina - Silica) Ceramic

In this work, a ceramic model has obtained from Iraqi bentonite as a base material with limited additions of alumina and silica. The selected material can bear temperatures higher than the bearing temperature of bentonite as it achieved tolerance temperatures (1300°C) based on X-ray diffraction patterns. It was found that the addition of alumina and silica led to the occurrence of basic phases such as mullite, quartz, cordierite and feldspar in percentages that depended on the percentage of addition in the mixture and the firing temperature, which was (1000-1300)°C.

A Study on the Interfacial Compatibility, Microstructure and Physico-Chemical Properties of Polyimide/Organically Modified Silica Nanocomposite Membrane.

Polyimide-silica (PI-Silica) composites are of tremendous research interest as high-performance materials because of their excellent thermal and mechanical properties and chemical resistance to organic solvents. Particularly, the sol-gel method of fabricating such composites is popular for manipulating their properties. In this work, PI-silica composite films are synthesized by the sol-gel method and thermal imidization from the solution mixtures of hydrolyzed tetraethoxysilane (TEOS) (or glycidoxypropyltrimethoxysilane (GPMS)) modified silica and an aromatic polyamic acid (PAA) based on 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA)–p-phenylenediamine (PDA). The phase morphology of composites is found to be controlled by the substitution of TEOS with GPMS. Solid-state NMR spectroscopy is used to confirm the structural components of silica and GPMS-modified silica, whereas FT-IR results confirm the complete imidization of polyimide and composite film and suggest successful incorporation of Si–O–Si bonds into polyimide. The thermal, optical transmittance, and dielectric constant characterizations of pure polyimide and composite films are also carried out. Thermal stability of pure polyimide is found to be increased significantly by the addition of silica, whereas the partial substitution of TEOS with GPMS decreases the thermal stability of the composite, due to the presence of the alkyl organic segment of GPMS. The optical transmittance and dielectric constant of the composite films are controlled by manipulating the GPMS content.

Biodegradable film of black mulberry pulp pectin/chlorophyll of black mulberry leaf encapsulated with carboxymethylcellulose/silica nanoparticles: Investigation of physicochemical and antimicrobial properties

In this study, pectin was extracted from black mulberry fruit pulp and chlorophyll was extracted from black mulberry leaves. The extracted chlorophyll was encapsulated with carboxymethylcellulose (CMC). Black mulberry pectin/chlorophyll of black mulberry leaf encapsulated with carboxymethylcellulose/silica nanoparticles was prepared (Pec/Ch-CMC/SiO2). The physicochemical, mechanical and antimicrobial properties of the prepared films were investigated. SEM, FTIR, TGA and XRD techniques were used to study the structure of the films. According to the results, silica increased the thickness and decreased the moisture and solubility of the films. Increasing the amount of CMC in the capsules used in the film increased the thickness, moisture and solubility of the films. Silica increased the tensile strength of the film and reduced the flexibility of the film, while CMC reduced the tensile strength and increased the flexibility of the film. Chlorophyll and silica greatly increased the antioxidant properties of the film. Encapsulated chlorophyll and silica increased the antibacterial properties of the film against Escherichia coli and Staphylococcus aureus. SEM images showed that by simultaneously adding encapsulated chlorophyll and silica to the pectin structure, almost all gaps in the pectin surface were filled. According to the FTIR spectra, electrostatic interactions between pectin polymer chains with encapsulated chlorophyll and silica were confirmed. According to TGA results, the simultaneous addition of encapsulated chlorophyll and silica to the film increases the thermal stability of the film. According to the results, the pure pectin film has a semi-crystalline structure that the addition of silica and encapsulated reduces its crystalline structure.

Preparation and Characterization of Paraffin/Mesoporous Silica Shape-Stabilized Phase Change Materials for Building Thermal Insulation.

The use of phase change materials (PCMs) is an attractive method for energy storage and utilization in building envelopes. Here, shape-stabilized phase change materials (SS-PCMs) were prepared via direct adsorption using mesoporous silica (MS) with different pore diameters as the support matrix. The leakage properties, microstructure, chemical structure, thermophysical properties, activation energy, thermal stability and thermal storage-release characteristics of paraffin and SS-PCMs were investigated. The results show that the maximum mass proportion of paraffin in SS-PCMs is 70% when the average pore diameter of mesoporous silica is 15 nm, and the phase change temperature and latent heat of the corresponding SS-PCM are 23.6 °C and 135.4 kJ/kg, respectively. No chemical reaction occurs between mesoporous silica and paraffin and the SS-PCMs exhibit high thermal stability. The high activation energy of the paraffin (70%)/MS1 SS-PCM verifies that the shape and thermal properties can be maintained stably during phase change conversions. The time required for SS-PCMs to complete the thermal storage and release process is reduced by up to 34.0% compared with that for pure paraffin, showing a decline in the thermal conductivity of SS-PCMs after the addition of mesoporous silica. Hence, the prepared paraffin/MS SS-PCMs, in particular paraffin (70%)/MS1 SS-PCM, can be used for storing thermal energy and regulating indoor temperature in buildings.

Effect of silica nanoparticles on mechanical and thermal properties of intra-inter ply hybrid laminated composites

Emissions coming out from the automobile accounts for significant universal carbon emission. The reduction in the weight of the vehicle even by a kilogram can lead to a significant reduction in the carbon emissions, the use of natural fibre composites reduces the weight of the vehicle to a larger extent and minimises the problems associated with the disposal of the vehicle after its service life. The main objective of the work is to develop a light weight, comparatively eco-friendly natural fibre hybrid composite reinforced with intraply carbon +E-glass plies and unidirectional sunn hemp mat interplies and nano silica particles and to evaluate its mechanical and thermal properties for possible application in automobiles. The addition of nano silica was varied between 1wt % to 4 wt %. Mechanical properties investigation through (tensile and impact tests) and thermo mechanical investigation through dynamic mechanical analysis (DMA) and heat deflection temperature (HDT) were carried out. Activation energy of the nano composites was determined using Arrhenius model. Failure analysis of the composites was carried out with field emission scanning electron microscopy (FESEM). Mechanical and thermal properties was found to be higher for the intra-interply polymer composite reinforced with carbon+E-glass fibres and unidirectional sunn hemp mats with 3 wt %. nano silica particles addition. The results obtained in this work will be useful in designing comparatively environmentally friendlier composite structures

Experimental Investigations on the Mechanical Properties of Sand Stabilized With Colloidal Silica

Colloidal silica is an innovative stabilizer that is being explored in ground engineering fields. Several experimental investigations were performed to study the effects of colloidal silica stabilization on shear strength as well as hydraulic conductivity of sand. The main aim of the present work is to observe the enhancement in the mechanical properties of colloidal silica-stabilized sand. The paper also aims to explore the optimum pH and corresponding salt content, which provides workable gel time in the field. The primary objective of the present work is to determine the gel time of the colloidal silica solution by adding salt and varying pHs. It was observed that the gel time decreases rapidly as the ionic strength of the colloidal silica solution increases. Sand having relative densities (RD) of 30, 40, and 60% stabilized with four different colloidal silica percentages under a curing period of 3, 7, and 28 days were tested. All test specimens were tested as per standard codal procedures to determine the optimum content of colloidal silica for the enhancement of the mechanical properties of sand. Based on test results, the optimum percentage of colloidal silica at 30% RD, 40% RD, and 60% RD was found to be 12.5%, 11%, and 10%, respectively. Moreover, significant enhancement was observed in the shear strength as well as hydraulic conductivity with the addition of colloidal silica in the sand.

PP/PP-HI/silica nanocomposites for HVDC cable insulation: Are silica clusters beneficial for space charge accumulation?

New potential High Voltage Direct Current (HVDC) cable insulation materials based on nanocomposites are developed in this study. The nanocomposites are produced by blending of polypropylene (PP), propylene-ethylene copolymer (PP–HI) and a modified fumed silica (A-silica) in a concentration of 1 and 2 wt %. The A-silica is successfully modified with (3-aminopropyl)triethoxysilane (APTES) via a solvent-free method, as proven by infrared spectroscopy, thermogravimetry and transmission electron microscope mapping.A-silica in the polymer matrix acts as a nucleating agent resulting in an increase of the crystallization temperature of the polymers and a smaller crystal size. Moreover, the silica addition modified the crystals morphology of the unfilled PP/PP-HI blend. The composite containing A-silica with 2 wt% contains bigger-size silica clusters than the composite filled with 1 wt%. The composite with the higher A-silica concentration shows lower space charge accumulation and a lower charge current value. Besides, much deeper traps and lower trap density are observed in the composite with 2 wt% A-silica addition compared to the one with a lower concentration. Surprisingly, the presence of silica clusters with dimensions of more than 200 nm exhibit a positive effect on reducing the space charge accumulation. However, the real cause of this improvement might be due to change of the electron distribution stemming from the amine-amine hydrogen bond formation, or the change of the chain mobility due to the presence of occluded polymer macromolecules constrained inside the high structure silica clusters. Both phenomena may lead to a higher energetic barrier of charge de-trapping, thus increasing the depth of the charge traps.

Prism coupling technique investigation of optical and thermo-optical properties of polyvinyl alcohol and polyvinyl alcohol/silica nanocomposite films

In this paper, the optical and thermo-optical properties of polyvinyl alcohol (PVA) and polyvinyl alcohol/silica (PVA/SiO 2) nanocomposite films were characterized by using the prism coupler technique. The polymer films were deposited by solution casting method at room temperature. The refractive indices of TE polarization mode, nTE, of all samples were measured at 444 nm, 633 nm, 829 nm, and 1308 nm, respectively. The wavelength dependence of the refractive index is well described by Cauchy’s equation. The effect of polymer molecular weights and the concentration of silica nanoparticles on the optical properties of PVA films was also investigated and discussed. The refractive index of the PVA films was found to increase with molecular weight, whereas it decreases with the concentration of SiO 2 in PVA matrix. The variation of the refractive index of neat PVA and PVA/SiO 2 nanocomposite films with temperature in the range of 30 to 70 °C was determined. Both PVA and PVA/SiO 2 nanocomposites show negative thermo-optic coefficients (dn∕dT) of the order of 10−4 °C−1. Moreover, it was found that the addition of silica in the PVA affect thermo-optic coefficients of the films. The obtained results suggest that PVA is a material with tunable refractive indices and it is suitable for use in optical devices such as optical temperature sensors.

Austenitic Stainless-Steel Reinforcement for Seawater Sea Sand Concrete: Investigation of Stress Corrosion Cracking

Seawater and sea sand concrete (SWSSC) is a highly attractive alternative to normal concrete (NC) that requires huge amounts of fresh water and river sand. However, reinforcements of stainless steel (instead of mild steel that is used in NC) may be required for SWSSC. This article reports investigation of stress corrosion cracking (SCC) of AISI 316 stainless steel (SS) in simulated SWSSC and NC environments, with and without addition of silica to SWSSC and NC, employing slow strain rate testing (SSRT) at 25 and 60 °C. For the purpose of comparison, SCC of SS was also investigated in simulated seawater (SW) solution. SS showed no SCC at 25 °C in any of the test solutions. Indications of SCC were seen in SW at 60 °C, but no features of SCC in SWSSC and NC at 60 °C, as suggested by scanning electron microscopy (SEM) fractographs. While the absence of SCC in SWSSC and NC is attributed to the highly passivating alkaline condition, its absence in SWSSC also indicates the role of alkalinity to predominate the deleterious role of chloride content of SWSSC. However, the addition of silicate to SWSSC or NC triggers transgranular SCC to SS at 60 °C, as evidenced by the fractography.

Development of semi-synthetic catalyst based on clay and their use in catalytic cracking of petroleum residue

Two semi-synthetic clay-based catalysts were prepared. These catalysts were obtained by incorporating lanthanum oxide (Cat1) and chromium oxide (Cat2). They were then tested for catalytic cracking of a heavy petroleum residue (fuel). The two formulations were carried out in the presence of silica to improve their acidity then underwent an acid activation. The catalysts obtained were characterized by various methods (XRD, FTIR, ICP-OES, SEM). The results showed that the incorporation of oxides and the addition of silica improves the structural characteristics of the final products. The support used was a kaolinite rich clay, having a specific surface area of 15.26 m2/g and acidity of 14 meq/g. These values increase, respectively, to 456.14 m2/g and 50 meq/g for Cat1 and to 475.12 m2/g and 57 meq/g for Cat2. The influence of the type of oxide incorporated, the specific surface area, the porosity and the acidity of the catalysts on their catalytic activity was studied. The nature of the oxide used proved to be decisive on the quality of the catalyst. Thus Cat1, prepared with lanthanum oxide, showed the best performance in cracking the petroleum residue achieving a conversion rate of 74.13% compared to 66.53% for cat2.

Silica addition effect on optical properties of halide perovskite-PMMA composite film

The effect of silica (SiO2) addition on optical properties of organometal halide perovskite PMMA composite film was studied. The organometal halide perovskite, MAPbBr3, was synthesis using ligand assisted re-precipitation (LARP) method, and then was compose to PMMA and SiO2 directly to make composite films. The absorbances, transmittances, and photoluminescence (PL) spectrum of the samples were characterised using UV Vis and PL spectroscopy. The result shows that the addition of silica leads blueshift on photoluminescence and absorbance spectra. The blue shift reveals one-dimensional confinement effect in perovskite.

The utilization of plastic waste in a mixed pair of concrete brick walls

Plastic is a daily consumable material due to its easy accessibility and affordability. The high production of plastic waste contributes to the increase risk of hazardous environment which is difficult to be processed and decomposed. One of the solutions is to recycle plastic waste. In this study, the types of High Density of Polyethylene (HDPE) and Polypropylene (PP) were utilized as substation material with 10% of ratio to be mixed in pair with concrete brick walls. The sample study was concrete bricks characterized with dimensions of 40x20x10 cm3 and 15x15x15 cm3. The addition of admixture SikaPayer HC-1ID and silica fume as additive was carried out to improve the performance of testing samples. Samples of concrete bricks were then attached on the wall as a mixed pair with dimension 105x95 cm2, and compression properties were performed. The results showed that visual appearances, content weight, and adsorption ability of two samples were classified as concrete brick type I, and the addition of HDPE and PP to the concrete bricks walls contributed into type II which were able to with-stand load around 2200 and 2800 Psi respectively. The other eminence that was observed from the addition of HDPE and PP was milder weight compared to neat concrete bricks.