Silica Filler Research Articles

Characterisation and properties of Nanohybrid Dental Composite (NhDC) reinforced with zirconia and alumina

A trial nanohybrid dental composite (NHDC) was developed using silica extracted from biowaste rice. Aim: This study aims to test the effect of mixture of the silica and other filler which is zirconia and alumina, focusing on the characterization and their properties. Nano-silica obtained from rice husk was used as NHDC filler. Methods: Nanosilica white powder, derived from rice husk, was used. There were three groups: Group I, Zr (2%) and Al (3%); group II, Zr (3%) and Al (2%); and group III, Zr (3%). The distribution of filler particles and the chemical structure of filler particles were determined by FESEM images and FTIR test. Then, testing on Vickers hardness (VHN) and fracture strength (FS) of the samples was performed. Results: The distribution of filler particles showed a uniform distribution, and each peak element of the fillers was shown in the FTIR spectrum images. There was significantly increased on VHN and FS after addition of zirconia and alumina. Conclusion: This study concluded that zirconia and alumina strengthen the NHDC properties with addition of zirconia and alumina filler.

SYNTHESIS AND CHARACTERIZATIONS OF NOVEL MISWAK POWDER-BASED DENTAL COMPOSITES

This study aimed to synthesize a novel miswak based dental composite by incorporating miswak powder, chlorhexidine (CHX), and silica fillers in different proportions into a resinous mixture and assess the influence of these fillers on the physical, mechanical, and biological properties of newly developed composites. The stock monomer solution was synthesized using urethane dimethacrylate, triethylene glycol dimethacrylate, and hydroxyethyl methacrylate. Four experimental groups (A, B, C, D) were prepared using 30% stock monomer with 70% filler formulations, while two commercial composites were used as control groups (E, F). The highest value of degree of conversion was shown by Group D, whereas the lowest – by Group A. Compressive strength evaluation showed Group E had the highest value, while the lowest value was recorded for Group B. Furthermore, cytotoxicity assessment showed that all the groups of composites had a biocompatible nature, except Groups A and B, having slight cytotoxicity. Thus, the experimental groups can be used as restorative materials as they exhibited optimum properties.

The effect of nanocellulose and silica filler on the mechanical properties of natural fiber polymer matrix composites

Natural fiber-reinforced polymer matrix composites recently got great attention in biomedical applications due to their inherent characteristics such as biocompatibility, lightweight, and biodegradability. However, natural fiber composites suffer from poor mechanical properties and weak interfacial adhesion. It is well documented that the addition of nanofiller has improved the mechanical properties of different synthetic fibers such as glass and carbon composites. The main objective of this paper is to study nanofillers' effect on the mechanical properties of unidirectional false banana fibers reinforced polymer composites. The filler materials, crystalline nanocellulose fibrils, and crystalline nanosilica particles were extracted from sugarcane bagasse and its byproducts. The composite samples were fabricated by adding the nanofillers in unidirectional natural fibers arranged in four fiber orientations (0°, 0o/90o ±45o, and quasi-isotropic), and their tensile, flexural, compression strength, thermal stability, and void content were measured following ASTM standards. The results revealed that adding nanofillers increased the tensile, flexural, and compressive strengths by 16 % (98.83 Mpa), 11 % (161.60 Mpa), and 23 % (114.62 Mpa), respectively. Similarly, at 0° orientation, the addition of nanoparticles enhances the tensile, bending, and compressive modulus by 30 % (15.43 Gpa), 12 % (13.52 Gpa), and 60 % (42.6 Gpa), respectively. On the other hand, the void content was reduced with the addition of nanofillers. The results also revealed that composites with crystalline nanosilica particle fillers had superior thermal stability compared to crystalline nanocellulose fibril fillers. The overall results of this research give the confidence that nano particle-filled natural fiber composites can be used for bio-based engineering applications, such as prosthetic sockets.

Age resistant low density peroxide cured EPDM rubber insulation for large rocket motors

AbstractNovel methodology introduced to incorporate peroxide in the rubber matrix led to successful development of peroxide cured EPDM insulation based on precipitated silica, a conventional filler. Effect of Silica Filler on the physical, mechanical, thermal, ablative properties and thermal degradation of such an insulation has been recently published. As an outcome of above study, peroxide cured EPDM insulation with 25 PHR of Silica, has been promulgated as potential low density insulation meeting all the requirements of Large Rocket Motor, while having a density as low as 0.997 g/cm3 and Tg as low as −55°C. Effect of aging on mechanical, thermal properties and thermal degradation behavior of low density peroxide cured EPDM insulation has been studied and the findings have been corroborated by FTIR Spectroscopy and morphological Examination by SEM.

Enhanced Mechanical and Thermal Properties in Epoxy-Based Glass Fabric Composites via Nano Silica Integration

ABSTRACT The objective of this study is to improve the mechanical, thermal, and microstructural characteristics of glass fabric composites made of epoxy by adding nano silica fillers. Composites were produced through compression molding, incorporating different concentrations of nano silica (0%, 2.5%, 5%, 7.5%, and 10%). The study encompassed testing the tensile and flexural strength, analyzing thermal properties through TGA and DTA, and characterizing the microstructure using FESEM and FTIR. The findings indicated that composites containing 5% nano silica exhibited the greatest tensile and flexural strengths, enhanced thermal stability, and superior heat dissipation in comparison to composites with different concentrations. The analysis of the microstructure revealed improved distribution of the filler material and decreased voids, resulting in a stronger bond between the matrix and the reinforcement. The findings emphasize the potential of nano silica-enhanced composites in aerospace, automotive, and other engineering sectors. This represents a notable advancement in composite technology for creating strong and efficient materials.

Poly(ether ketone ketone)/hollow silica filler substrates and application for sixth generation communication

AbstractThe influence of density and shape of hollow silicas (silica hollow tubes (SHT) or hollow glass microspheres (HGM)) on dielectric and heat‐resisting characteristics of poly(ether ketone ketone) (PEKK)/SHT and PEKK/HGM films was systematically investigated. The dielectric characteristics of PEKK/SHT or PEKK/HGM films decrease to a minimum, as their SHT or HGM contents approach 8 or 20 wt%, respectively, and the minimum dielectric constant (εr) and dielectric loss (tan δ) of PEKK/SHT or PEKK/HGM films decrease visibly with decreasing SHT densities. By filling with 0.46 g cm−3 mean density of SHT or HGM fillers, the minimum εr and tan δ of PEKK/SHT films are somewhat smaller than those of PEKK/HGM films. The linear coefficient of thermal expansion (LCTE) values of PEKK/SHT or PEKK/HGM films reduce and their onset degradation temperature values increase gradually with increasing SHT and HGM contents. Low εr/tan δ (2.11/0.0022 and 2.2/0.0027 at 1 MHz), LCTE (35.5 × 10−6 and 31.2 × 10−6 °C−1) and excellent heat‐resisting properties favorable for sixth generation (6G) ultrarapid communication are realized for appropriately prepared PEKK/SHT and PEKK/HGM substrate films. The free‐volume‐hole characteristics of PEKK/HGM or PEKK/SHT films approach a maximum as SHT or HGM contents reach an optimum value of 8 or 20 wt%, respectively. © 2024 Society of Chemical Industry.

Influence of non-linear diffusion controlled phenomena on the sorption capability of PEO-Salt-SiO2 composite electrolyte: A study on property optimization

The present research, reports the hygrothermal behavior of poly [ethylene oxide] (PEO) based composite film (500 and1000 μm) containing NH4I and KBr (5–20 wt%) as the mobile phase and non-reactive silica (15 wt%) as the filler. These are termed as PK/NSiO2-series for solvent sorbed and (PK/NSiO2)NS for non-swelled film. The novelty of the research lies in the analyses of non-Fickian solvent diffusion trait of films using python programming. The presence of ions and its variable polarizable nature is found to influence the number density of bonded and free solvent content along with the extend of cross linkage. Introduction of silica is found to enhance the ionic conductivity (about one order higher) of the film irrespective of the type of charge carrier owing to the improved dispersion within the matrix. Non-Fickian diffusion is found to influence the ionic conductivity of P2K20SiO2 (10−5Scm−1 to 10−2 Scm−1) minimizing the degradation to 0.2 %ΔC/1000 h (>1 %ΔC/1000 h, tested for 2000 h) compared to P2N20NSiO2. In contrast, ion migration in P2NSiO2 is guided by Rice and Roth model and being more polarizable ions, the mobility is significant which maximizes the conductivity to ∼10−1 Scm−1. Microstructural study shows heterogenous nucleation to be more pronounced upon addition of silica filler wherein the homogeneity, inter fibrillar interaction and grain growth of spherulites is higher. This tends to extend amorphous regions thereby propagating the ion migration path. The influence of sorption process is studied in terms of electrochemical impedance, dielectric analyses and long term cyclability (20,000 h) in terms of loss tangent.

Elastomeric Compositions of Ethylene-Norbornene Copolymer Containing Biofillers Based on Coffee and Tea Waste.

The development of eco-friendly elastomeric materials has become an important issue in recent years. In this work, thermoplastic elastomer samples of an ethylene-norbornene copolymer (EN) with coffee and tea biofillers mixed with typical fillers such as montmorillonite (MMT), silica (SiO2), and cellulose were investigated. The aim of this research was to determine the effect of fillers on the properties of the materials and to assess their degradability after two ultraviolet (UV) aging cycles (200, 400 h). The scientific novelty of this work is the assessment of the anti-aging effect of simultaneous biofillers-stabilizers based on coffee and tea waste. The surfaces of the obtained polymer compositions were examined using infrared spectroscopy (FTIR-ATR). Contact angles were determined, and surface energy was calculated. The mechanical properties were tested, and the influence of plant fillers and aging on the color change in the materials was analyzed. The combination of coffee with silica, MMT, and cellulose fillers limited the migration of fatty acids and other compounds from the biofiller to the EN surface (FTIR analysis). Based on the aging coefficients K, it was shown that all coffee- and tea-based fillers stabilized the polymer compositions during UV aging (400 h). The results allowed the authors to determine the importance and impact of waste plant fillers on the degradability of the synthetic EN.

Hydrogen permeation behavior and mechanisms in nitrile butadiene rubber composites for hydrogen sealing

As the most widely used sealing component in hydrogen systems, rubber seals are affected by hydrogen over long-term service. Hydrogen molecules can dissolve into rubber materials and diffuse through the material. Studies have shown that adding fillers can enhance rubber's performance, improve its compatibility with hydrogen, and reduce the damage caused by hydrogen diffusion. Therefore, this study integrates experimental hydrogen permeation research with finite element modeling for nitrile butadiene rubber (NBR). The aim is to investigate the influence of filler properties on the microstructure, hydrogen permeation behavior, and hydrogen concentration distribution within NBR. Ultimately, the study elucidates the mechanisms governing hydrogen distribution evolution and permeation in NBR under hydrogen environments. The results indicate that the crosslink density of NBR filled with carbon black (NBR-CB) and silica (NBR-SC) is directly proportional to the filler content. NBR with higher filler content exhibits a lower hydrogen permeation coefficient and superior hydrogen barrier properties. In contrast to silica fillers, carbon black fillers demonstrate strong adsorption and a more pronounced barrier effect against hydrogen molecules, thereby enhancing the hydrogen barrier efficiency. The increase in carbon black's hydrogen solubility (from 2.2 × 10-4 to 16.9 × 10-4 cc(STP)·cm-3(polymer)·cmHg-1) effectively reduces the hydrogen permeation coefficient. In contrast, the rise in carbon black's hydrogen diffusion coefficient (from 0.1 × 10-6 to 4.1 × 10-6 cm2·s-1) exacerbates the overall hydrogen permeation coefficient of NBR-CB, thereby intensifying the hydrogen permeation process.

Effect of Fumed Silica Filler on Rheological and Mechanical Properties of Polysulfide Sealant

Effect of Fumed Silica Filler on Rheological and Mechanical Properties of Polysulfide Sealant

Rheo-Optical Near-Infrared (NIR) Characterization of Styrene-Butadiene Rubber (SBR) Using Two-Trace Two-Dimensional (2T2D) Correlation Analysis.

A rheo-optical characterization technique based on the combination of near-infrared (NIR) spectroscopy and tensile testing was applied for the first time to an actual rubber sample based on styrene-butadiene rubber (SBR) including silica filler. When SBR samples were subjected to mechanical deformation, changes in the NIR spectral features were readily captured. Two-trace two-dimensional (2T2D) correlation analysis was then applied to the sets of NIR spectra to clearly reveal the subtle but pertinent difference between the NIR spectral features of the initial and deformed SBR. The initial deformation of the sample induces greater deformation of the soft butadiene groups than of the hard styrene groups. The inclusion of the silica filler and a coupling agent (CA) essentially develops firm links between the silica and butadiene via the CA to restrict the displacement of the butadiene during the tensile deformation of the system. The development of such linkage requires even more mechanical force to deform the SBR, which, in turn, improves Young's modulus of the rubber system. Asynchronous correlation spectra of SBR with no silica filler revealed that, during the deformation of the SBR, the butadiene groups were initially deformed, and this feature was then replaced by the predominant deformation of the hard styrene groups. On the other hand, this correlation feature became somewhat unclear when a similar analysis was applied to the SBR sample with silica filler, revealing subtle differences in interaction between individual comonomer functional groups distributed randomly along the copolymer chain and CA.

Resistance of Wood Plastic Composites Having Silica Filler to Subterranean Termite

Resistance of Wood Plastic Composites Having Silica Filler to Subterranean Termite

UV-heat dually curable epoxy resin composites with low filler contents and high curing speed

Epoxy resin composites are a type of polymer-based materials with wide application scopes. A mass of fillers was added to improve thermal properties which may degrades mechanical properties at the same time. In addition, the common heat-curing process takes several hours to completely cure. To improve the performance of epoxy resin composites of low-content fillers, we prepare UV-heat dually curable epoxy resin with silicate ester. The overall curing time of UV-heat curing process is about half of the traditional thermal-curing process. The breakdown voltage of epoxy resin modified by silicate ester is up to 181 MV/m, which is increased by 50 % compared to pure epoxy resin. The silicate ester curing agent can react with both epoxy resin and silica fillers and can thus improve the dispersion of the fillers in the matrix and enhance the interaction between fillers and the resin. As a result, the coefficient of thermal expansion (CTE) of the composites was greatly reduced. The CTE of silicate ester-modified epoxy resin composites is 93 ppm/K and 137 ppm/K over the temperature range below and above its Tg, respectively, which is 25 % lower than those of normal epoxy resin composites.

Impact of manufacturing variables on product performance of contraceptive levonorgestrel intrauterine systems

The development of Levonorgestrel Intrauterine Systems (LNG-IUSs) stands as a formidable challenge due to their intricate design and reliance on specialized manufacturing methods. Pharmaceutical manufacturers face a labyrinth of process variables that demand precise identification and comprehension to establish a robust product design to ensure consistent performance. The current manuscript navigates through this complexity, describing a small-scale processing method for LNG-IUSs via addition and condensation curing processes, as well as investigating the influence of key manufacturing variables on LNG-IUS product performance. Different mixing speeds and time exhibited distinct impact on drug content uniformity within the IUS drug-polymer reservoirs. Surprisingly, no variation in drug release rates were observed. Curing temperature and time were the critical processing parameters of IUSs which were dependent on the polymer type (polydimethylsiloxane, PDMS) and drug loading. At lower curing temperatures, crosslinking in PDMS remained relatively unaffected, irrespective of drug loading. By contrast, elevating curing temperatures resulted in a drastic reduction in PDMS crosslinking densities at higher drug loading. This was attributed to increased drug volume fraction within the matrix, impeding optimal prepolymer chain mobility and rearrangement which is crucial for complete crosslinking. Interestingly, rapid curing led to increased PDMS crystallinity, thereby retarding drug release rates while concurrently compromising mechanical properties. PDMS curing chemistry, such as condensation cure (no filler) and addition cure (cured at room temperature), did not affect drug release rates of the LNG-IUSs. In the condensation cure-based LNG-IUS, the formulations prepared without filler had higher drug release rates than those containing silica or diatomaceous earth fillers. Overall, the present study unravels the intricate interplay between PDMS characteristics, processing variables, and product performance, offering fundamental insights into product design and manufacturing of brand and generic LNG-IUS products.

Microscopic Interaction of Oleated Cellulose and Silica in Dual-Filled Elastomers

The quantification of interactions between fillers and filler with elastomers in nanocomposites relies on the combination of different microscopy techniques. Small Angle X-ray scattering is a key method for the identification of the filler network morphology at the nanoscale. Hybrid nanocomposites containing fillers with diverse morphology and reinforcing ability represent considerable complexity thereby justifying ongoing research in this area, as a consequence of the multiple interactions between fillers and also the filler with the elastomer. Therefore, a microscopic structural investigation of a dual-filled elastomer for tire applications is presented. Chemically modified micro-fibrillated cellulose in combination with traditional silica filler dispersed by melt processing in a styrene-butadiene (SBR) random copolymer were investigated. Small-Angle-X-ray Scattering and Scanning-transmission-electron-microscopy (STEM) revealed non-mixing of the two fillers on the silica scale and the predominant formation of individual filler clusters. Through a novel data deconvolution procedure, partial structure functions corresponding to the contribution of each filler to the scattering function were extracted. This approach offers a suitable methodology to identify the compatibility between morphologically different fillers and their mutual effect on the dispersion.

PDMS microspheres as rheological additives for PDMS-based DIW inks

Direct Ink Writing holds vast potential for additive manufacturing with broad material compatibility as long as appropriate rheological properties are exhibited by the material of choice. Additives are often included to attain the desired rheological properties for printing, but these same additives can yield products with undesirable mechanical properties. For example, silica fillers are used to create silicone inks appropriate for printing but yield cured structures that are too stiff. In this work, we investigate the applicability of PDMS microspheres as a rheological and thixotropic additive for PDMS based DIW inks. We utilize a facile oil-in-water emulsion method to reproducibly obtain small (∼5 μm) PDMS microspheres, which are then incorporated into PDMS-based inks. More traditional inks with fumed silica and thixotropic additive were compared with inks containing PDMS microspheres at equal volume loadings to determine whether the PDMS microspheres could impart the desired rheological properties for DIW. Inks including PDMS microspheres exhibited surprising thixotropic effects, which enabled prints with fidelity analogous to traditional ink employing silica filler, while producing mechanically softer prints.

Effects of molecular interactions on the release of small molecules from silicone rubber

AbstractSilicone rubber is a good candidate as a carrier of small molecules in such applications as drug, fragrance and semiochemical delivery. When one matrix is loaded, the molecular interactions between the molecules and the matrix may affect their release rates. For this reason, it is important to investigate the effects of molecular interactions on release to better develop delivery systems with desirable release rates. In this study, the mass transfer and diffusion coefficients of three model molecules (i.e., octanol, octyl acetate, and octyl butyrate) were determined by monitoring their release from silicone rubber sheets loaded using headspace gas chromatography–mass spectrometry. Differential scanning calorimetry was used to characterize the plasticizing effects and Fourier transform infrared spectroscopy was used to characterize the molecular interactions. It was found that the release of octanol conformed to the Fickian diffusion pattern at 1 wt% initial concentration but deviated as the concentration increased due to hydrogen bonding between octanol and the silanol group of the silica filler. When two small molecules were released simultaneously, the effects of one molecule on the diffusion coefficient of the other differed, a result explained by the competing effects of plasticizing and hydrogen bonding.

Utilization of Silica Filler as Reinforcement Material of Polylactic Acid (PLA) in 3D Printing Applications: Thermal, Rheological, and Mechanical Performance.

Glass was introduced as an additive to filaments used for the manufacturing of composite materials, employed by Additive Manufacturing applications. Glass accounts for a large waste electric and electronic equipment (WEEE) percentage, and its recovery and recycling can lead to the production of sustainable composite materials. In this work, poly(lactic acid) (PLA)/commercially available silicon oxide composite filaments were manufactured and their structural, thermal, rheological, and mechanical properties were assessed. Scanning Electron Microscopy confirmed the 1:2 ratio of silicon: oxygen, along with the relatively low adhesion between the filler and the matrix. Differential Scanning Calorimetry presented steady glass transition and melting temperatures of composites, whereas a crystallization temperature of 10% wt. and a crystallinity of 15% wt. composite slightly increased. Rheological analysis showcased that the viscosity of the composite filaments decreased compared to PLA (10-100 compared to 300-400 Pa·s), with a more shear-thinning behavior. Dynamic mechanical analysis exhibited increased elastic, flexural moduli, and flexural strength of composites (up to 16, 23, and 11%, respectively), whereas tensile strength and elongation decreased. The affordability of raw materials (with the future introduction of recycled ones) and the minimal processing steps can lead to the potential scaling up of the study.

Aza-Michael Chemistry for PDMS-Based Covalent Adaptable Elastomers: Design and Dual Role of the Silica Filler

Aza-Michael Chemistry for PDMS-Based Covalent Adaptable Elastomers: Design and Dual Role of the Silica Filler

Effect of demineralized water on the silanization reaction and the performance properties of green tire tread compound

AbstractTire industries seek advancements in technologies ranging from novel constructions to new material systems for fuel efficiency. The chemical formulation of tread compounds and their processing conditions can significantly affect tire performance for key attributes, including rolling resistance, wet traction, and wear resistance. Adding demineralized water (DMW) molecules might enhance the silanization reaction between silane and silica filler surface via improved hydrolysis and condensation, resulting in a better silanization reaction. DMW was sprayed on a silica surface before mixing, incorporated with TESPD silane into S‐SBR/BR tire tread compound, and mixed in an internal mixer. The effects of an increase in the DMW content on compound processability, cure characteristics, filler dispersion, dynamic properties, and mechanical properties were investigated. Adding the water‐treated silica into the compound lowered the heat generation during mixing, lowered the dump temperature, lowered the tan δ (E″/E′) at 60°C, and increased the wet grip property by retaining the abrasion resistance compared with the control. The enhancement of filler dispersion was visualized via scanning electron microscope images. Reaction kinetics concerning the addition of water and the effect of the pH of water on the silanization reaction is also discussed using HPLC analysis.