Addition Of Silica Nanoparticles Research Articles

Preparation of poly‐d,l‐lactide based nanocomposites with polymer‐grafted silica by melt blending: Study of molecular, morphological, and mechanical properties

AbstractPolylactide was first designed for the pharmaceutical and medical fields. Unfortunately, polylactide, especially poly‐d,l‐lactide (PDLLA), presents too low mechanical properties for a wide range of applications. The addition of silica nanoparticles should reinforce the mechanical strength of PDLLA. In order to improve silica/polymer interactions, this study focused on the preparation of polymer chain grafted silica using two grafting methods. The first strategy relied upon the ring opening polymerization ofd,l‐lactide on initiating silica surface (ie, “grafting from”). The second approach considered a sol‐gel synthesis process in presence of Si‐OR terminated polylactide chains to promote grafting of these chains on new silica particles (ie, “grafting to” method). Only “grafting from” silica successfully led to a nanoscale dispersion into the polyester matrix for silica content up to 5 wt%. A 3 wt% content of this silica allowed improving Young modulus of 106.0% and ultimate tensile stress of 63.7% compared to the PDLLA control.

Hollow silica reinforced magnesium nanocomposites with enhanced mechanical and biological properties with computational modeling analysis for mandibular reconstruction

The present study investigates Mg-SiO2 nanocomposites as biodegradable implants for orthopedic and maxillofacial applications. The effect of presence and progressive addition of hollow silica nanoparticles (0.5, 1, and 1.5) vol.% on the microstructural, mechanical, degradation, and biocompatibility response of pure Mg were investigated. Results suggest that the increased addition of hollow silica nanoparticles resulted in a progressive increase in yield strength and ultimate compressive strength with Mg-1.5 vol.% SiO2 exhibiting superior enhancement. The response of Mg-SiO2 nanocomposites under the influence of Hanks’ balanced salt solution revealed that the synthesized composites revealed lower corrosion rates, indicating rapid dynamic passivation when compared with pure Mg. Furthermore, cell adhesion and proliferation of osteoblast cells were noticeably higher than pure Mg with the addition of 1 vol.% SiO2 nanoparticle. The biocompatibility and the in vitro biodegradation of the Mg-SiO2 nanocomposites were influenced by the SiO2 content in pure Mg with Mg-0.5 vol.% SiO2 nanocomposite exhibiting the best corrosion resistance and biocompatibility when compared with other nanocomposites. Enhancement in mechanical, corrosion, and biocompatibility characteristics of Mg-SiO2 nanocomposites developed in this study are also compared with properties of other metallic biomaterials used in alloplastic mandibular reconstruction in a computational model.

Enhancement of mechanical behavior of FRP composites modified by silica nanoparticles

To enhance the mechanical behavior of fiber-reinforced polymers (FRPs), the mechanical properties of epoxy and vinyl ester resin and two types of FRP modified by silica nanoparticles at 1, 2, 3, and 4 wt% are investigated herein. Fracture toughness tests of the casting resin were conducted, and scanning electron microscopy (SEM) was performed to identify the fracture surface and toughening mechanism. Damage mechanisms of resin with nanoparticles were analyzed and differences owing to varying nanoparticle contents were identified. Impregnated fiber roving with modified resin was studied for enhancements in tensile strength and stiffness. Results showed that the addition of silica nanoparticles to the epoxy/vinyl ester resin improved the mechanical properties, which reached the maximum at the nanoparticle content of 3 wt%. The tensile, flexural, and impact strengths of the epoxy resin increased by 26%, 6%, and 49%, respectively, compared with the control epoxy resin. Furthermore, the corresponding enhancements of the vinyl ester resin are 17%, 17%, and 94%. At the same particle content, the fracture toughness of the epoxy and vinyl ester resins are increased by 12% and 20%, respectively. SEM of the fracture surface reveals a relatively rough surface with tortuous cracks, thereby resulting in a higher fracture toughness of the modified resin. The tensile strength of the impregnated basalt fiber roving made of the modified vinyl ester resin increased, and results show an 18% increase at the particle content of 3 wt%. Meanwhile, the adoption of epoxy resin with silica nanoparticles resulted in the basalt and impregnated carbon fiber roving achieving higher tensile strength and stiffness compared with those without nanoparticles.

Investigation of nanoparticle-polymer interaction in bio-based nanosilica-filled PLA/NR nanocomposites: molecular dynamics simulation.

Molecular dynamics (MD) simulation, by employing the COMPASS force field, was utilized to investigate structural and thermal characteristics as well as interfacial interactions between components of nanocomposite consisting of poly(lactic acid) (PLA)/natural rubber (NR)/nanosilica, abbreviated as PSxN, where 1 ≤ x ≤ 7 and it represents the parts of SiO2 nanoparticles added to the PLA/NR (PN) blend. Analysis of the obtained results including density (ρ), fractional free volume (FFV), glass transition temperature (Tg), interaction energy (Einteraction), and radial distribution function (RDF) of these nanocomposites was performed. Comparing Einteraction of nanocomposites with that of the PN blend showed that the interactions between the chains of the two polymers are highly dependent on the added amounts of silica nanoparticles, so that by adding silica to the PN blend to obtain PS1N and PS3N nanocomposites, the amount of Einteraction was reduced to a smaller positive value, which indicates the tendency of the nanocomposite's components to interact with each other. By further addition of silica nanoparticles to have PS5N and PS7N nanocomposites and then by analysis of the RDF results, it was found that the nanoparticles were not well dispersed in these two nanocomposites and they were accumulated in the NR rubbery phase. Therefore, the percolation threshold for silica loading on the PN blend is at most 3 parts (x = 3). These results as well as the other obtained simulation results were compared with the available experimental data, and the agreement observed between them approved the simulation procedure and validated the obtained results.

Highly toughened poly(lactic acid) (PLA) prepared through melt blending with ethylene-co-vinyl acetate (EVA) copolymer and simultaneous addition of hydrophilic silica nanoparticles and block copolymer compatibilizer

In this study, a highly toughened PLA was prepared through physical melt-blending with EVA at the presence of hydrophilic nanosilica and SEBS-g-MA block copolymer compatibilizer. The effect of nanosilica and compatibilizer on the morphology, mechanical properties, and linear rheology of the PLA/EVA blends was also investigated. According to TEM images, nanosilica was selectively located in the PLA matrix while some were placed on the interface between the two polymers as was also predicted by thermodynamic and kinetic analysis. Upon the addition of nanoparticles, the interfacial adhesion between the phases was enhanced and the average droplet size decreased. Interestingly, incorporation of SEBS-g-MA induced morphological changes as the spherical EVA droplets turned into a cylindrical shape. DSC results indicated that blending with EVA copolymer resulted in the reduction of crystallization of PLA matrix; however, the crystallinity increased at the presence of nanoparticles up to 5 wt%. The addition of compatibilizer considerably hindered the crystallization of the PLA phase. PLA/EVA blend containing optimum levels of nanosilica exhibited considerably enhanced tensile toughness, elongation at break, and impact strength. On the other hand, the simultaneous addition of nanoparticles and SEBS-g-MA led to synergistic toughening effects and the compatibilized blend containing nanosilica exhibited excellent impact toughness. For instance, the elongation at break of the compatibilized PLA/EVA blend containing the optimal content of nanosilica was increased from 7% to 121% (compared to neat sample). The notched Izod impact strength was also increased from 5.1 to 65 kJ/m2. Finally, the microstructure of the blends was assessed by rheological measurements.

Effects of Silica Nanoparticle Addition on Physical and Mechanical properties of Sugar Palm Fibers Reinforced Cement Composite Concrete

This study examines the effect of nanosilica addition to the physical and mechanical properties of sugar palm fibers (SPFs) reinforced cement composite concrete. The composite concrete ingredients are SPFs as the filler, cement and nano-silica as the matrix, CaCl2 as the catalyst, and water. Testing and fabrication of the composite concrete were performed according to the standard of ASTM C 1185 and ASTM C 1186. The results obtained show that, in general, the addition of nanosilica improves the quality of the composite concrete. A positive effect is attained by adding nanosilica to its optimum amount. The excessive addition of nanosilica reduces the quality of the composite. The composite's mechanical property that is negatively affected by the addition of the nanosilica is the elasticity, in which more nanosilica added stiffer the composite.

Synthesis and application of mesoporous silica nanoparticles as gas migration control additive in oil and gas cement

Cement failure has been widely reported to be one of the major causes of many catastrophic accidents in the oil and gas industry. Lack of cement integrity and strength has been associated with the potentially harmful gas migration from the reservoir into the wellbore. In this study, the potential application mesoporous silica nanoparticles as gas migration control additive for oil and gas cement was evaluated. Here, mesoporous silica nanoparticles were prepared using micelle templating sol-gel method and its performance as the additive was assessed against the commercial micro- and nano-sized silica particles. Based on the result, it is revealed that all of the cement samples prepared with or without additives exhibited sufficient rheological properties for field application. Nonetheless, results showed that silica nanoparticles addition would result in a slight increase in viscosity and yield point reduction of the cement slurry. Further investigations suggested that silica nanoparticles could also accelerate the hydration process due to their ability to provide a large surface area for nucleation reaction and the formation of C–S–H seeds. As a result, this would lead to the creation of a denser and stronger cement structure, which exhibits low porosity and permeability features. According to the result, the most optimum formulation was achieved when the cement was mixed with 0.0132 wt% of a mesoporous silica nanoparticle, with the compressive strength value of 6.67 MPa and the values of porosity and permeability of 8.94% and 2.47 × 10−17 m2 (0.025 mD), respectively.

Elongational behavior of silica nanoparticle-filled low-density polyethylene/polylactic acid blends and their morphology

We investigated the rheological behavior of linear low-density polyethylene (LLDPE)/polylactic acid (PLA) blends in the presence of modified and non-modified silica nanoparticles in extensional flow. Characterization methods were used as Fourier transform infrared spectroscopy, scanning electron microscopy, and rheometric measurements under shear and uniaxial extensional flows. The rheology behavior of LLDPE significantly was changed by the addition of PLA and silica nanoparticles. Extensional results showed that the elongational viscosity of the blends intensified by the incorporation of silica nanoparticles. Strain hardening was observed for LLDPE containing 2 wt.% of the unmodified silica nanoparticles, which disappeared by enhancement of the unmodified silica from 2 to 8 wt.%. Furthermore, elongation thinning was observed for the filled blends at high loading, which was more sensitive to the strain rate by increasing of PLA. Surface modification of silica was demonstrated in different elongational behavior. Indeed, a fracture took place by loading the modified silica nanoparticles in LLDPE; however, the intensity of this behavior dramatically increased for filled blends with a high loading of modified silica.

Improving the thermal conductivity of water by adding mono & hybrid nano-additives containing graphene and silica: A comparative experimental study

Effect of addition and hybridization of Graphene (G) and Silica (SiO2) nanoparticles on thermal conductivity of water, was experimentally studied. Initially, XRD, FTIR and FESEM tests were performed to specify phase and structural analysis and microstructural-observation of nano-materials. After that, nano-materials were dispersed and homogenized in distilled water by magnetic stirrer and ultrasonic vibrator, using the two-step method. The stability of graphene and silica nanoparticles in the base fluid at different pH values was examined. Thermal conductivity of three types of nanofluids, G/Water, SiO2/Water and G-SiO2/Water, at different volume fractions (φ) of 0.05–1% and temperature (T) range of 25-50 °C was measured. For predicting the thermal conductivity of G-SiO2/water hybrid-nanofluid, a two-variable correlation with R-Squared = 0.99 was extracted from experimental data by curve fitting method. The most and the least thermal conductivity enhancement attributed to G/water and SiO2/water mono-nanofluids respectively; while thermal conductivity enhancement between these two values and closer to the greater value associated with G-SiO2/water hybrid-nanofluid. By comparing the thermal conductivity results of the three present types of nanofluids, G-SiO2/Water hybrid-nanofluid would be a good choice as a high thermal and cost-effective nanofluid for thermal equipment.

Low Velocity Impact, Fatigue and Visco-elastic Behaviour of Carbon/E-glass Intra-ply fibre-Reinforced Nano-silica Toughened Epoxy Composite

This current research dealing the effect of adding high stiffness carbon fibre along with E-glass fibre and addition of nano-silica particles as a toughening agent in epoxy resin. The main aim of this research is to improve the damping, storage modulus and fatigue behaviour of glass-epoxy composite by using carbon fibre and nano-silica particles. The intra-ply glass and carbon fibre were prepared using handloom method with uniform weft and warp. The proposed composites were prepared using hand layup method followed by post-curing at 120οC. The low-velocity impact test results revealed that the composites made with intra-ply carbon glass fibre along with 2 vol% of nano-silica offered maximum resistance against penetration. Similarly, the fatigue behaviour revealed that the presence of 1 vol% nano-silica and carbon fibre provides the highest life cycle of 30150 counts. The visco-elastic properties of glass-carbon intra-ply fibre with 2 vol% of nano-silica composite possess storage modulus of 9.5 GPa. The scanning electron microscope images revealed more shear cups in the fractured matrix, which indicates improved toughness of the epoxy matrix.

Improving the insulating and physical characteristics of HV porcelain dielectric materials using nano-silica

The high-voltage electrical porcelain insulator plays an important role in the electrical power industry. The effect of silica nanoparticles (NS) addition on the electrical and physical properties of porcelain insulators sintered at different temperatures was investigated in the present study. Kaolin, feldspar, and quartz (in the form of silica sand) were used as economical raw materials to prepare porcelain insulator samples. Different additions of silica nanoparticles (0–15 wt%) were used. The porcelain specimens were compressed under 50 MPa pressure and treated at different sintering temperature (from 1100 to 1400 °C). The morphology and microstructure of the raw materials and some selected specimens were investigated using scanning electron microscope. Phase composition of some selected samples was identified using X-ray diffraction, to evaluate the thermal, structural, and microstructural changes by increasing the concentration of silica (0–15 wt%). The dielectric properties were evaluated by measuring the AC breakdown strength, the relative permittivity (er) and dielectric loss (tan δ) at different frequencies at room temperature. A finite element method axi-symmetrical model of the samples with the help of FEMM 4.2 package is used to evaluate their breakdown strength. The results revealed that the physical and dielectric properties of porcelain samples enhanced by increasing the sintering temperature. The porcelain samples admixed with 10 wt% silica nanoparticles and sintered at 1300 °C present the maximal density (3.57 g/cm3), minimal water absorption (0.0173%) and minimal porosity values (0.043%) as well as a good insulating characteristic.

Fire and mechanical properties of DGEBA-based epoxy resin cured with a cycloaliphatic hardener: Combined action of silica, melamine and DOPO-derivative

The effect of the addition of additives such as melamine (Mel), silica nanoparticles and a phosphorus-based compound, i.e. 3-(6-oxidodibenzo[c,e][1,2]oxaphosphinin-6-yl)propenamide (DA), on the fire and mechanical performance of a bisphenol A diglycidyl ether (DGEBA)-based epoxy resin cured with isophoronediamine has been investigated. A UL 94-V0 classification was achieved for epoxy resin containing DA at 2 wt% of phosphorus loading. However, addition of silica nano particles was necessary to avoid melt dripping. The incorporation of DA and Mel to the epoxy resin promoted a remarkable reduction (48% to 70%) in the heat release rate (HRR) values, a significant delay (up to 47%) in the ignition time in cone calorimetry experiments, and thus an increase (~75%) in the time to flashover. Evolved gas, thermal and fire analysis was used to propose the combined mode of action of DA, Mel and silica in the fire performance improvement of the epoxy system. Tensile and three-point bending flexural tests showed that the addition of DA increases the rigidity of the resin, resulting in a strong increase in the Young's modulus (up to 34%) and in a slight reduction in fracture strength, elongation break and toughness which is typical for non-reactive additives.

Modification of aqueous graphite suspensions for use in gelcasting

Fabrication of carbonaceous bulk bodies via colloidal aqueous routes has some problems. So it was intended to fabricate carbonaceous bodies through the gelcasting method. Effective parameters of this process (stability of graphite in water-based solutions studied in different solid loadings, pH values, and tween 80 additive) have been investigated. Also, other methods for modifying rheological behavior like surface oxidation and adding nano-silica particles have been considered. It has been seen that with the use of graphite as the carbon source in quantities equal to 45 and 50 wt%, proper suspension can be made and stability of the suspension improves with adding 2.5 wt% nano-silica particles and 6 wt% twin 80. For preparing these suspensions, the addition of nano-silica particles in the mentioned quantity is essential. Based on experiments, above-mentioned parameters cause higher mechanical strength in comparison with carbon lack bodies with identical parameters. Microscopically experiments show polymeric network constructed in raw bodies.

Mechanistic study on silica nanoparticles-assisted guar gum polymer flooding for enhanced oil recovery in sandstone reservoirs

Nanoparticles-assisted polymer flooding has attracted the attention of researchers for its enhanced rheological properties and stability of the chemical slugs. The present work deals with the rheological properties of guar gum with and without silica nanoparticles in the temperature range from 25 °C to 75 °C. It is found that the viscosity of guar gum solution increases significantly with increasing concentration of silica nanoparticles. Imbibition experiments were performed with waxy crude oil-saturated sandstone cores using 2000 ppm brine, 4000 ppm guar gum solution, 0.2 wt% silica nanoparticles in distilled water, and 4000 ppm guar gum containing 0.2 wt% silica nanoparticles as test fluids for understanding the mechanism of wettability alteration in the presence of silica nanoparticles and guar gum. Mixture of 0.2 wt% silica nanoparticles and 4000 ppm guar gum shows higher oil recovery (∼36 % original oil-in-place) compared to other test solutions in imbibition experiments. Contact angles between crude oil and sandstone rock were measured in presence of 2000 ppm brine, 0.025 wt% silica nanoparticles in water, and guar gum (2000 ppm)-silica nanoparticles (0.025 wt%) mixture. Guar gum containing silica nanoparticles are effective in changing the contact angle towards water-wet state (Contact angle ∼115°) from oil-wet state (contact angle ∼72°). No significant phase change is observed during the phase behavior experiment except for light emulsion formation. Finally, core flooding experiments were conducted with guar gum, silica nanoparticles solution, and mixture of silica nanoparticles and guar gum for additional oil recovery to verify the effectiveness of the chemical slugs. Results showed that the addition of silica nanoparticles to guar gum solution improves the effectiveness of guar gum polymer by recovering 44.3 % of original oil-in-place. A comparative study was also conducted to show the performance of silica nanoparticles-assisted guar gum solution for additional oil recovery. Most of the research works have focused on the application of silica nanoparticles-induced polyacrylamide and xanthan gum chemical slugs in enhanced oil recovery. However, laboratory study based on the application of silica nanoparticles-induced guar gum solution in additional oil recovery adds some interesting findings to the literature compared to the existing information.

Nanosilica filled EPDM/Kevlar fiber hybrid nanocomposites: Mechanical and thermal properties

Hybrid nanocomposites have been evolving as promising materials that can be utilized for various applications. The present work deals with the fabrication of nanosilica reinforced EPDM/Kevlar fiber hybrid nanocomposites. Tensile strength, elongation-at-break, density of the developed EPDM/KF hybrid nanocomposites were evaluated and compared. The ability of the hybrid nanocomposite to resist the temperature conduction has been probed with thermal conductivity measurement and their stability in thermal atmosphere was studied with thermogravimetric analysis. The results demonstrated that nanosilica reinforced EPDM has shown significant enhancement for the tensile strength (upto109%) and modulus. And the thermal conductivity of EPDM has been further lowered with the silica nanoparticles addition, maintaining a lower density. The strategic methodology adopted in our study utilizes a low consumption of nanomaterial which can evocatively communicate the thermal insulation system.

Removal of Pb(II) Ions from Aqueous Solutions by Spherical Nanocomposites Synthesized Through Immobilization of Paecilomyces lilacinus in Silica Nanoparticles Coated with Ca-Alginate

In the present study, a novel microbial nanocomposite "Paecilomyces lilacinus-silica nanoparticlescalcium-alginate beads" (P. lilacinus-SN-Cal-Alg) were synthesized and their high efficiency for removing Pb(II) ions was demonstrated in aqueous solution. P. lilacinus-SN-Cal-Alg beads before and after the adsorption of Pb(II) were characterized by FT-IR, SEM-EDS, and XPS analyses. The adsorption capacity of Pb(II) by P. lilacinus-SN-Cal-Alg beads was analyzed in aqueous solution. For comparison, the adsorption capacity of Pb(II) by another type of microbial composites, namely, P. lilacinus-Cal-Alg beads, without addition of silica nanoparticles, was also studied in parallel. Lastly, the equilibrium data in adsorption process were examined by both Langmuir and Freundlich isotherm models to evaluate adsorption mechanism. The results showed that an excellent removal efficiency of Pb(II) in aqueous solution (85.54%) was obtained at initial concentration of 200 mg/L by using the P. lilacinus-SN-Cal-Alg beads. Meanwhile, they exhibited the better adsorption capacity for Pb(II) than P. lilacinus-Cal-Alg beads. The adsorption process by P. lilacinus-SN-Cal-Alg beads was best described by the Langmuir model indicating that monolayer adsorption of Pb(II) ions takes place on the beads surfaces and showed that its maximum adsorption capacity was 282.49 mg/g.

Ability of Trichoderma harzianum in carbon fiber and silica nano particles formulation to control Fusarium oxysporum in vitro

Basal rot disease caused by Fusarium oxysporum f. sp. cepae is one of the major diseases that cause yield loss on shallot. Utilization of biocontrol agents can be applied as an environmentally safe control method. The antagonistic microorganism that has the potency to control fusarial diseases is Trichoderma harzianum. A carrier is required in preparing a formulation of this antagonistic fungus as a biocontrol delivery system (BDS). Carbon fiber was proven suitable as a carrier of some antagonistic bacteria. A formulation can also be supplemented with plant micronutrient. Addition of silica nano particles (Si NPs.) in the formulation did not reduce the viability of the antagonistic bacteria. An experiment was carried out to determine the ability of T. harzianum in the formulation with carbon fiber and Si NPs. to suppress the in-vitro growth of F. oxysporum. The experiment was arranged in the completely randomized design with 5 treatments and 5 replications. The treatments were challenging F. oxysporum by T. harzianum in different composition of formulation on potato dextrose agar. The compositions consisted of T. harzianum + 0.5% Si NPs., T. harzianum + 1% Si NPs., T. harzianum + 0.5% Si NPs. + 5% carbon fiber, T. harzianum + 1% Si NPs. + 5% carbon fiber, and T. harzianum only (control). The results showed that each treatment with T. harzianum in the formulation of carbon fiber + various concentrations of Si NPs. was able to suppress the in vitro growth of F. oxysporum by 58.39-60.92%. The BDS with carbon fiber and Si Nps. did not significantly reduced the ability of T. harzianum to antagonize F. oxysporum. The control treatment of single T. harzianum caused the highest suppression on the growth of F. oxysporum, up to 60.93%..

Electrospun SiO2/PVDF copolymer composite nanofiber: effect of SiO2 content on nanostructure, morphology, and thermal property

A separator is an important part of lithium-ion batteries. Nanofiber separator is one promising material to improve the performance of lithium-ion batteries. SiO2/cPVDF composite nanofiber was successfully synthesis by the electrospinning process. SiO2 nanoparticle, cPVDF, and N-N DMAc were used to synthesis composite nanofiber. SiO2 content influences nanostructure, morphology, diameter and thermal property of nanofiber. Nanofiber separator prepared with the optimum condition of flow rate 0,004 mL/min, voltage 22 kV, and the distance to collector 13 cm. Structure of nanofiber separator was analyzed with ATR-FTIR. FTIR vibration band peak at 1057.8 cm−1 839.4 cm−1 and 761.3 cm−1 were related to Si-OH functional group, a distinctive β phase crystal and α phase crystal, respectively. The average diameter of cPVDF nanofiber, SiO2/cPVDF (0.5%) nanofiber, SiO2/cPVDF (0.75%), and SiO2/cPVDF (1%) were 648.3 nm, 320.6, 347.1, and 388.8 nm, respectively. Effect of addition of silica nanoparticles decreased the average diameter nanofiber. Electrospun SiO2/cPVDF composite nanofiber also showed different thermal behavior under different gases conditions in TGA study, and it is observed that the nanofiber separator could stand until near 400°C before the main chain’s degradation occur. XRD and DSC analysis showed that increasing of SiO2 content decreased crystallinity of nanofiber composite. Water contact angle experimental results of SiO2/cPVDF composite nanofiber revealed an improvement of hydrophobicity with the addition of SiO2 on nanofiber composite.

Preparation and mechanical properties of acryl/glass cloth composite materials with low light dispersion

The aim of this study was to prepare transparent acryl/glass cloth composite materials with low light dispersion and high mechanical properties (modulus and strength) by using E-glass cloth and photo-curable acrylate monomers. The influences of the refractive index of the matrix, and the addition of comonomers and silica nanoparticles treated with silane coupling agent on the transparency, wavelength dependence of transmittance, and tensile properties of the composite materials were investigated. The acryl/glass cloth composite material prepared with E-glass cloth and 2,2-bis[4-(acryloxy diethoxy) phenyl] propane (ABPE4) indicated high transmittance at 600 nm, while the transmittance at 400 nm was reduced due to the scattering at the interface of the matrix and the glass fibers because the refractive index difference was large at shorter wavelengths. The usage of a comonomer with a lower refractive index than ABPE4 was an effective way to decrease the refractive index mismatch between the matrix and the glass fibers, and the transparency of the resulting composite material was improved. Moreover, the mechanical performance of the acryl/glass cloth composite material was increased by adding comonomer with a high affinity for glass cloth to matrix. The addition of silica nano particles treated with a silane coupling agent to the matrix was also a useful method for not only improving the transparency, but also improving the mechanical performance, because the nano particles on the fiber surface reduced the refractive index difference and increased the surface area and bonding strength at the interface of the matrix and the fibers.

Characterization of a bacterial cellulose-silica nanocomposite prepared from agricultural waste products

Bacterial cellulose (BC) has attracted considerable scientific interest and can be modified, making it more widely useful in composites with guest nanoparticles. In this study, silica nanoparticles obtained from rice husks were used to prepare BC-silica composite aerogels (CAs) via a sol-gel method. Various amount of silica nanoparticles (3, 6, 9 and 12% w/v) dissolved in 2.5 M NaOH were used as a precursor for inclusion into BC. Subsequently, it was employed to form a SiO2 gel skeleton in a BC matrix by adding 2 M H2SO4, as a catalyst. Increasing levels of silica nanoparticles led progressively lower transmittance values of BC-silica CAs. SEM images revealed a surface morphology of spheroid particles with little agglomeration. The XRD diffraction peaks were gradually covered by a broad peak of silica as increasing silica content. Similarly, FTIR spectroscopy results also indicate the presence of silica in proportion to its content. Furthermore, addition of silica nanoparticles improved the thermal properties using TGA analysis, shifting the decomposition temperature of BC up to 550 °C and retaining of BC weight at least 60% with the BC sample with 3% of silica. This unique characteristic implies that silica had a stabilizing effect on polymeric cellulose. These results demonstrate an economical and environmentally friendly preparation of BC-silica CAs that can benefit material applications.