Amounts Of Silica Nanoparticles Research Articles

Microbial Polysaccharide-Based Formulation with Silica Nanoparticles; A New Hydrogel Nanocomposite for 3D Printing

Natural polysaccharides are highly attractive biopolymers recommended for medical applications due to their low cytotoxicity and hydrophilicity. Polysaccharides and their derivatives are also suitable for additive manufacturing, a process in which various customized geometries of 3D structures/scaffolds can be achieved. Polysaccharide-based hydrogel materials are widely used in 3D hydrogel printing of tissue substitutes. In this context, our goal was to obtain printable hydrogel nanocomposites by adding silica nanoparticles to a microbial polysaccharide's polymer network. Several amounts of silica nanoparticles were added to the biopolymer, and their effects on the morpho-structural characteristics of the resulting nanocomposite hydrogel inks and subsequent 3D printed constructs were studied. FTIR, TGA, and microscopy analysis were used to investigate the resulting crosslinked structures. Assessment of the swelling characteristics and mechanical stability of the nanocomposite materials in a wet state was also conducted. The salecan-based hydrogels displayed excellent biocompatibility and could be employed for biomedical purposes, according to the results of the MTT, LDH, and Live/Dead tests. The innovative, crosslinked, nanocomposite materials are recommended for use in regenerative medicine.

Hybrid effect of nanoparticles presence on low‐velocity impact resistance in sandwich panels

AbstractConsidering the massive employment of sandwich panels in multifarious applications, numerous research studies have been conducted on their impact resistance enhancement, one of which, is via simultaneous nanoparticles incorporation including various amounts of silica nanoparticles, clay nanoparticles and carbon nanotubes (CNTs) in to sandwich panels, composed of two glass fiber epoxy composite face sheet and polyvinyl chloride core to render them reinforced. The research objective is to experimentally scrutinize the behavior of nano reinforced sandwich panels under low‐velocity impact test conducted at different energy levels. The damaged areas of the panels were investigated via scanning electron microscopy, the result of which demonstrated that the impact resistance of the sandwich panel can be improved by the integration of nanoparticles. The incorporation of 0.3% of CNT, 1% of nano clay, and 3% of nano silica enhanced maximum contact force by 18.6%, compared to the unreinforced equivalent. Increasing the weight fraction of both CNTs and silica nanoparticles, made contribution to sandwich panels impact resistance increase. The presence of nano clay up to 1 wt% improved the maximum contact force; however, the integration of it into matrix more than 1 wt% led to the reduction of maximum contact force, thus weakened the impact resistance of sandwich panel.

Investigating effects of Nano particles of silica on the properties of self-compacting concrete containing Perlite, Leca, and Scoria light weight aggregates

In this research, effects of silica Nano particles on the important properties of self-compacting-concrete (SCC) containing Leca, Perlite and Scoria light weight aggregates have been investigated. Different amounts of silica Nano particles have been added to the lightweight-self-compacting-concrete (LWSCC) mixtures, and the properties of the LWSCCs at the fresh and also the hardened state have been experimented. The obtained results show that adding the Nano particles of silica decays the performance of the fresh concrete. Nevertheless, adding these particles improves tensile, compressive, and flexural strength of LWSCCs, as well as strength of LWSCCs in acidic medium and decrease water penetrability of LWSCCs.

Investigation of electrical properties of silica-reinforced RTV nanocomposite coatings

This study investigates the effect of various amounts of silica nanoparticles on electrical properties of RTV-SiO2 nanocomposite. The effect of increasing the amounts of filler in the RTV1 polymer matrix on the dispersion and dispersibility of nanoparticles has also been investigated through microscopic images. SEM images demonstrated that surface roughness excessed with increasing filler percentage, so that the non-uniformed distribution of the fillers will occur and the surface morphology will change. Electrical results indicated an increase in dielectric loss factor and a decrease in volume resistance via addition of 1, 3, and 5%wt nano-silica in composites. Also, there was a significant decrease in the dielectric strength by adding 3%wt of nano-silica. However, the dielectric constant and surface resistance did not change. Tracking test demonstrated that the erosion resistance of the sloping surface was greatly improved by increasing the nano-silica content, and this is very important for the application of this specific nanocomposite as a high-voltage insulators coating.

Two-component room temperature vulcanized silicone-rubber (RTV2) properties modification: effect of aluminum three hydrate and nanosilica additions on the microstructure, electrical, and mechanical properties

This study focused on investigating the effect of adding aluminum three hydrate (ATH) and various amounts of silica nanoparticles on electrical, mechanical, hydrophobicity, and flame retardancy properties of the two-component room temperature vulcanized silicone rubber (RTV2). Electrical results indicated the dielectric constant and dielectric loss of the composites were higher than net RTV2, also the composites showed higher volume resistance than net RTV2. However, adding SiO2 nanoparticles and ATH reduced the surface resistivity of the RTV2 from 16.71 (TΩ) to 15.66 (TΩ) in RTV2 + ATH and 15.79 (TΩ) in RTV2 + ATH + 3%SiO2 composites. Evaluation of mechanical properties showed that the elastic modulus in net RTV2 (0.00405 MPa) enhanced to 0.00484 MPa in RTV2 + ATH and 0.0098 MPa in RTV2 + ATH + 3%SiO2. Similarly, hardness of the composites showed a rising trend by increasing the filler content. Also, there was no improvement in hydrophobicity of the composites without SiO2 nanoparticles compared with net RTV2, but adding silica nanoparticles enhanced the hydrophobicity and contact angles in composites. An improvement in flame retardancy of the composite was obtained by a decrease in the torch affected (burned) zone when ATH and silica were incorporated.

Effect of Silica/Graphene Nanohybrid Particles on the Mechanical Properties of Epoxy Coatings

Epoxy resins are used as coating materials, but the practical use of epoxy coatings in industries is limited due to their weak mechanical properties. In the present paper, different amounts of silica nanoparticles ( $$\hbox {SiO}_{2})$$ and graphene nanoplatelets (GNPs) were introduced separately and together into an epoxy coating matrix as reinforcements. Graphene, a newly discovered carbon allotrope, has been found to improve the mechanical properties of the polymer composites in which it is dispersed. Silica particles are also known to improve the mechanical properties of composites. In this study, mechanical, physical and thermal properties of the epoxy coatings are considered as multidimensional by the macro- and microanalyses. The experimental results showed that after the addition of GNPs into the epoxy matrix, the flexibility and impact resistance of the coatings increased by 8.3 and 157.1%, respectively, in relation to neat epoxy. The microhardness increased by 53.8% and penetration depth, which is indicative of the scratch resistance, decreased by 29.7%, with the addition of $$\hbox {SiO}_{2}$$ –GNPs nanohybrid. A remarkable synergistic effect was observed between the GNPs and $$\hbox {SiO}_{2}$$ , which improved the hardness and the scratch resistance of the epoxy coatings.

Mini-emulsified Copolymer/Silica nanocomposite as effective binder and self-cleaning for textiles coating

Mini emulsified Butylacrylate/Acrylonitrile (BA/AN) copolymer-silica nanoparticles (NPs) nanocomposites were used as functional binder. The prepared nanocomposites contained three different amounts of silica NPs 1, 3, 5 wt%. Two different textile fabrics; cotton fabric 100%, and synthetic polyester fabric 100%; were printed using printing paste contain the prepared nanocomposites via silk screen printing technique. The prepared copolymer, silica nanoparticles and their nanocomposites were fully characterized. The printed fabrics were evaluated by investigation their surfaces morphology, color properties, hydrophobic behaviors and UV protection properties.

Diblock-Copolymer-Based Composites for Tire-Tread Applications with Improved Filler Network Topology

We present in this Letter the results of a study focusing on vulcanized poly(butadiene–styrene butadiene rubber) (PB–SBR) diblock copolymers in the microphase-separated state filled with various amounts of silica nanoparticles. It is demonstrated that the microphase separation of PB and SBR blocks is preserved in composites with a silica mass content of ≤60 parts per hundred rubber (phr). The only effect of silica incorporation is a more restricted long-range order of the block copolymer morphology. The most interesting finding is, however, that through mechanical mixing the silica nanoparticles are highly selectively incorporated in the SBR phase up to high filler contents. This opens new opportunities toward a rational design of the filler network in composites with self-assembled elastomer matrixes and results in advantageous mechanical properties for tire-tread applications.

Thermo‐mechanical behavior of poly(butylene terephthalate)/silica nanocomposites

ABSTRACTIn this work, experimental results about poly(butylene terephthalate) (PBT) based nanocomposites filled with various amounts of silica nanoparticles (NPs) are reported. Two different types of filler are used: silica gel NPs, produced through the Stöber method, and a commercial fumed silica, both coated by a PBT shell. Melt‐mixed samples have been thoroughly investigated by scanning and transmission electron microscopy, infrared Fourier transform spectroscopy (FTIR), thermal gravimetric analysis, differential scanning calorimetry, wide and small angle X‐ray diffraction, and dynamic mechanical analysis. A fine and very good dispersion of NPs into the polymeric matrix is revealed through the morphological analysis when Stöber NPs were used as filler with respect to systems including commercial fumed silica particles. This evidence, combined with matrix–filler interactions revealed by FTIR spectroscopy, justifies the enhancement of both storage modulus and glass transition temperature of the former samples in comparison with reference pristine PBT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46006.

In situ synthesis of poly(ethylene terephthalate-co-isophthalate)–SiO2 nanocomposites and their optical properties

In this paper, poly(ethylene terephthalate-co-isophthalate) was prepared and a series of PETI/SiO2 nanocomposites with different amounts of silica nanoparticles was synthesized by in situ polymerization. Optical properties of the resultant nanocomposites were investigated by WGW photoelectric haze meter and UV–Vis-NIR spectrophotometer. Chemical structure and its influence on spherulite size of nano-SiO2 were characterized by Fourier transformed infrared spectra and polarized optical microscopy, respectively. The differential scanning calorimetry results reveal that the addition of nano-SiO2 has an impact on the thermal performance of the nanocomposite. Different proportions of SiO2 were compared and the degree of crystallinity was found to have influence on optical properties of as-prepared nanocomposites. In addition, the results indicate that the low loading levels of SiO2 can improve the optical properties of the composite and an optimum content was selected. Possible reasons for this enhanced role might be the different combination structure of the nanocomposites when the amount of SiO2 varied.

Nitrate permeability of semi‐permeable membranes prepared from binary blends of cellulose triacetate and chitosan

Semi‐permeable membranes of binary polymer blends of cellulose triacetate (CTA) and chitosan (CS) were produced to harvest microalgal biomass for biofuels. Relatively thick membranes of polymer blends containing more than 70% CTA were prepared via solution blending in formic acid. Various characterization methods revealed that both polymers are immiscible at the molecular level at room temperature. However, they were macroscopically compatible and exhibited uniform physical properties due to the molecular interactions between CTA and CS with the same cellulosic backbone containing two linear polysaccharides through a β‐1,4 glycosidic bond. Careful visual inspection revealed that these membranes are transparent and their light transmittance was greater than 90% at all blend compositions. All membranes showed excellent tensile strength at all compositions and the maximum tensile strength was 52.4 MP from the membrane with a CTA/CS weight ratio of 9:1. The permeability of these blend films increased with increasing CS content and the maximum value was 44.28 mg/m2/day. To improve the permeability or transfer rate of the CTA/CS membranes, the porous CTA/CS membranes were also prepared using various amounts of silica nanoparticles. POLYM. ENG. SCI., 58:192–197, 2018. © 2017 Society of Plastics Engineers

Nanosilica reinforced ion-exchange polyHIPE type membrane for removal of nickel ions: Preparation, characterization and adsorption studies

Highly porous styrene/2-ethylhexylacrylate/divinylbenzene polymerized high internal phase emulsion (ST/2EHA/DVB polyHIPE) solid foams reinforced using various amounts of silica nanoparticles (SNPs) were prepared via emulsion templating. The neat and reinforced solid foams were successfully functionalized using sulfuric acid (98%) to introduce the sulfonic groups in the resultant ion-exchange polyHIPE membranes. The effect of SNPs level on the morphology and mechanical properties of the neat and reinforced foams was investigated. The ion-exchange capacity (IEC) of the resulting membranes was measured by titration procedure. The results showed that increasing SNPs level up to 3wt% enhanced IEC from 3.6 to 3.9meqg−1 and improved the water uptake (WU) due to increasing SO3H groups inside the polyHIPE type membranes. The efficiency of 3wt% SNPs reinforced membrane for adsorption of nickel ions was evaluated. The effect of crucial parameters, such as initial nickel concentration, pH of the solution, and membrane contact time, on the removal efficiency was investigated using surface response methodology (SRM) experiment design. Additionally, the adsorption behavior of the membrane was evaluated using different kinetic and isotherm models. The results showed that the adsorption kinetic behavior was in a good agreement with the pseudo-first-order and Elovich model in the low and high nickel concentrations, respectively. Furthermore, the adsorption of nickel ions was fit well on Freundlich adsorption isotherm. The reusability of the reinforced polyHIPE membrane was evaluated for five sorption-desorption cycles.

Deposition of Polyaniline/Silica Nanocomposite Coating on Stainless Steel; Study of its Corrosion Properties

In the present century many efforts have been done to develop efficient methods for corrosion protection of steel in various industries. The use of conducting polymers is one of the new developments in the area. In this study, polyaniline/silica nanocomposite has been coated onto 316L stainless steel via in situ method. The corrosion behaviors of the bare and coated steels have been studied in order to reveal influence of silica nanoparticles (70nm).The prepared coating has been characterized using X-ray diffraction (XRD). The corrosion performance of the coating has been investigated in 1 M H2SO4 solution by using electrochemical impedance spectroscopy (EIS). It was found that protecting effect of coated layer is influenced by amounts of silica nanoparticles.

Synthesis and characterization of s‐histidine‐derived poly (ionic liquid)/silica nanocomposites and their application in the enantioselective hydrolysis of a chiral ester

ABSTRACTIn this study, a new optically active monomer containing two chemically preformed imide rings was synthesized. The monomer was then used to synthesize optically active poly(amide imide)s (OAPAIs) and an optically active polyionic liquid (OAPIL), which were finally reacted with various amounts of silica nanoparticles in an in situ polymerization reaction to produce OAPAI/SiO2 and OAPIL/SiO2 hybrid materials containing sulfonic acid groups. The prepared monomers and the OAPAI and OAPIL nanocomposites were characterized by 1H‐NMR spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, and differential scanning calorimetry. OAPIL/SiO2 served as an excellent catalyst in water as a solvent for the hydrolysis of d,l‐phenylglycine methyl ester with the advantage of a markedly enhanced enantioselectivity and activity. Also, the enantioselectivity was strongly dependent on the SiO2 content in the OAPIL/SiO2 systems; a favorable SiO2 content was 20% (w/w). The enantioselectivity was 95.2% (substrate conversion = 62.3%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39595.

Effect of silica nanoparticles on the bulk flow properties of fine cohesive powders

Silica nanoparticles are often used as flow regulators applied to the surface of fine industrial powder particles, such as toners for electrophotographic (EP) printing devices. In this paper, we have investigated their effect on the cohesion and internal friction of model polymer powders (poly (styrene-co-divinylbenzene) (PS-DVB), d50=7.84μm), whose flow properties are systematically controlled by applying various different types (e.g. size and hydrophilicity) and amounts of silica nanoparticles under a normal consolidation stress of 2kPa using a ring shear tester (RST). The ability of the nanoparticles to reduce the bulk powder cohesion has been confirmed to be dependent on how efficiently they can disrupt the direct contacts between the PS-DVB particles, resulting in a significant reduction of the interparticle adhesion. However, the cohesion increases when the agglomerates of the silica nanoparticles form a flat film structure which causes an increase of the effective contact area. On the other hand, the nanoparticles were found to work better as lubricants when the size of their agglomerates is smaller. Also, the internal friction becomes higher when the silica–silica contacts become dominant, e.g. at higher actual surface coverages, but not as high as that for irregularly-shaped particles. The variation in behaviour between nanoparticles of differing hydrophilicity can be attributed to the ease of breaking down agglomerates on mixing; the cohesion of the PS-DVB powders coated with hydrophobic silica nanoparticles is smaller due to their higher actual surface coverage whilst the internal friction becomes higher.

Characterization and non-isothermal crystallization behavior of biodegradable poly(ethylene sebacate)/SiO2 nanocomposites

Poly(ethylene sebacate) (PESeb) and PESeb/silica nanocomposites (PESeb/SiO_2) were prepared by in situ polymerization from the direct esterification of ethylene glycol with sebacic acid in the presence of proper amounts of silica nanoparticles. The non-isothermal crystallization behavior of PESeb/SiO_2 nanocomposites has been studied using different theoretical equations such as Avrami, Ozawa and combined Avrami and Ozawa equations. It is found that the addition of nanoparticles of SiO_2 influenced the mechanism of nucleation and the growth of PESeb crystallites. Also, the nanocomposites show a higher Avrami value than the neat PESeb, implying a more complex crystallization configuration. Moreover, the combined Avrami and Ozawa equation can successfully describe the crystallization model under the non-isothermal crystallization. The crystallization activation energies, E_a, calculated from ‘‘Kissinger’s equation’’ have shown that the synthesized PESeb/SiO_2 nanocomposites have lower energy than the neat PESeb, reflecting the much lower energy barrier for the rapid heterogeneous nucleation.

Homogeneous dispersion of SiO2 nanoparticles in an hydrosoluble polymeric network

The main difficulty still encountered in the elaboration of polymer/silica nanocomposites is the control of the nanoparticles dispersion homogeneity and the stability of the nanoparticle dispersion in the surrounding substance. The innovative point of this work is the elaboration of hybrid networks in aqueous solution performed with ASE (alkali swellable emulsion) thickeners grafted with silica nanoparticles. The thickening ability of the polymer should favour silica nanoparticles dispersion in fluid matrices. Two ASE copolymers were realised by copolymerisation in emulsion of MA (methacrylic acid) and EA (ethyl acrylate) and/or TFEM (trifluoroethyl methacrylate). The substitution of a part of EA by TFEM gave fluorinated ASE copolymers. Their free acid functions were then coupled with different ratio of amine functionalized silica nanoparticles to afford nanocomposites. The amounts of silica nanoparticles in the copolymers were determined by thermogravimetric experiments. Depending on the silica nanoparticles/copolymer ratio in basic aqueous solutions we achieved stable translucent gel like aqueous suspensions of silica nanoparticles containing 1wt.% of the polymer/SiO2 nanocomposite.

Silica nanoparticles as coupling agents for polypropylene/glass composites

Abstract An evaluation of the fibre/matrix interfacial shear strength was performed by the single-fibre fragmentation tests on polypropylene–glass fibre microcomposites filled with various types and amounts of silica nanoparticles. In particular, both non-functionalized and dimethyldichlorosilane-functionalized silica nanoparticles were added up to a weight content of 7%. Moreover, the effect of various amounts of maleic anhydride modified polypropylene (PPgMA) on the fibre/matrix adhesion was also investigated, including some selected formulations containing both PPgMA and silica nanoparticles. Interfacial shear strength was found to remarkably increase (up to a factor of about 5 for a 7 wt% content of surface treated nanoparticles) with respect to the case of neat polypropylene matrix. The observed effect was explained by considering that silica nanoparticles increase the work of adhesion of polypropylene with respect to glass, as proven by contact angle measurements in different liquids. In addition, silica nanoparticles promoted a remarkable enhancement of both elastic modulus and creep stability of the selected polypropylene matrix.

Surface analysis and anti-graffiti behavior of a weathered polyurethane-based coating embedded with hydrophobic nano silica

In this study, a permanent anti-graffiti polyurethane coating was prepared using concomitant loading of an OH-functional silicone modified polyacrylate additive ranging from 2 to 15mol% and hydrophobic silica nanoparticles from 1 to 5wt%. UV–visible spectroscopy, contact angle measurement and dynamic mechanical thermal analysis (DMTA) analysis were conducted on selected samples to study the weathering performance of samples containing various amounts of silica nanoparticles before and after accelerated weathering conditions. The results showed that higher amounts of additive had inferior effects on the anti-graffiti performance of the coating samples after exposure. However, silica nanoparticles could positively affect the anti-graffiti performance against ageing cycles. This improvement was attributed to lower degradation of samples containing silica nanoparticles and barrier property of nanoparticles against graffiti penetration. The presence of silica nanoparticles did not have any significant effect on the surface free energy of the samples prior and after ageing.

Organic–inorganic nanocomposite bilayers with triple shape memory effect

Various amounts of silica nanoparticles were chemically incorporated into amorphous polyurethanes (PU) of two different molecular weights by sol–gel reactions, and the effects were studied in terms of mechanical, dynamic mechanical, dual, and triple shape memory effects (DSME and TSME) of the nanocomposite films. It was found that the silica particles act as multifunctional cross-links as well as reinforcing fillers and significantly augmented the glassy and rubbery state moduli, yield strength, break strength, glass transition temperature, and dual shape memory properties. A cohesive bilayer of the two films fabricated from an interpenetrating polymer network (IPN) exhibited synergistic mechanical properties in the glassy and rubbery states along with two undisturbed glass transitions by which an intermediate plateau region and TSME were demonstrated.