Filler Modification Research Articles

Controlling Surface Modification of Calcium Carbonate Filler and Characteristic of Its Composite Material

Controlling Surface Modification of Calcium Carbonate Filler and Characteristic of Its Composite Material

Adjustment of dielectric performances for polymer-inorganic composites by ferroelectric filler modification with graphene micro-additive

The modification of a ferroelectic filler (barium titanate BaTiO3) with graphene nanoplates deposited from aqueous dispersions is shown to strongly affect the dielectric performances of composites prepared by the incorporation of thus modified filler into cyanoethyl ester of polyvinyl alcohol (CEPVA) as a polymer binder. The increase of graphene content from 0.2 to 1.6 mg/g results in oscillating changes of permittivity and dielectric losses of the composites, whereas the further increase of the additive amount leads to a steady growth of both performances. The observed effects are found to correlate with specific centers on the filler surface responsible for the filler-binder interaction. The deposited graphene amount is optimized to provide a simultaneous significant increase of dielectric permittivity and decrease of the dielectric loss.

Influence of nanofillers on the properties of siloxane elastomers

In this study, the influence of nanosilicon(IV)-oxide (with hydrophobic and hydrophilic functionalized surfaces) on the properties of siloxane elastomers was studied. The elastomers were prepared from vinyl and hydrogen oligosiloxanes, while the nanocomposites were obtained by addition of nanofillers at different concentrations (1, 5, 10 and 20 wt%). The chemical structure of the obtained materials was analyzed by Fourier transform infrared spectroscopy. Transmission electron microscopy confirmed good dispersion of the hydrophobic filler within the polymer matrix, while the hydrophilic filler formed a net on the siloxane sample. Type of the filler modification did not affect hardness of the siloxane hybrid materials, while the samples with the highest content of hydrophobic nanosilica have shown the highest value of tensile strength. Influence of the nanosilica type on thermal degradation of elastomeric materials was investigated by using thermogravimetric analysis, while the influence of the fillers on the phase transition temperature was analyzed by differential scanning calorimetry. Lower compatibility of the hydrophobic matrix and hydrophilic filler caused a decrease in the crystalline melting temperature with the lowest value determined for the sample with the highest filler loading. Increase in the nanofiller content resulted in the improved thermal stability of the obtained hybrid materials.

Effects of Boron and Carbon Added Titanium Filler on Microstructure and Mechanical Properties of Ti-15-3 Alloy Weldments

Microstructural and mechanical properties beta Titanium (β-Ti) weldments can be improved by grain refinement and formation of insoluble precipitates in the weld. This paper reports the effect of Boron (B) and Carbon (C) addition to Ti-15V-3Cr-3Sn-3Al (Ti-15-3) fillers on the microstructural and mechanical properties of Ti-15-3 gas tungsten arc weldments. X-ray diffraction and scanning electron microscopic analysis revealed the presence of β-Ti phase in the weldments prepared without the filler modification, while additional TiB and TiC phases are observed in the weldments prepared with fillers modified with B and C, respectively. B and C addition to the fillers has resulted in the grain refinement of the weldments and the grain size reduction is seen to be higher with the increasing B and C addition. The formation of TiB, TiC and growth restriction effect due to the presence of B and C in the filler resulted in the decreased grain size of the β-Ti weldments. Mechanical properties such as hardness and tensile strength improved as the amount of B and C addition increased. The improvement of mechanical properties is contributed by the grain refinement and the formation of TiB and TiC precipitates in weldments.Â

Enhanced bacteriostatic activity, osteogenesis and osseointegration of silicon nitride/polyetherketoneketone composites with femtosecond laser induced micro/nano structural surface

Poor cell adhesion and osteogenic activity impede the bone regeneration and osseointegration effects of polyetherketoneketone (PEKK) implants. Surface modification and incorporation of bioactive fillers are effective strategies to promote the cellular responses of PEKK implants and their integration with bone tissues. In this study, silicon nitride (SN) microparticles were blended with PEKK to develop bioactive composite implants (SPC). Femtosecond laser was then used to modify SPC surfaces inducing favorable micro/nano structural surface (FSPC). After the laser ablation, irregularly shaped SN microparticles were converted to “petal-like” clusters composed of “pin-like” SN nanoparticles, while the entire surface was covered by SN particles due to the removal of PEKK. The roughness, hydrophilicity, content of surface chemical groups (e.g., -NH2), and protein adsorption capability of FSPC were significantly enhanced compared to SPC and PEKK. Also, the release of biologically active Si ions was increased after the femtosecond laser treatment, inducing a positive microenvironment favorable for cellular activities. Moreover, FSPC exhibited a greater bacteriostatic activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) than SPC. The presence of micro/nano structure also remarkably promoted adhesion, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). In vivo evaluation of the composites in a rabbit femur defect model verified that FSPC could enhance osteogenesis and osseointegration to a greater extent than SPC, evidenced with greater bone-implant contacts and push-out force. These results indicate that the femtosecond laser induced micro/nano structural surface on SN/PEKK implants can significantly promote osseointegration and bone repair. The femtosecond laser exhibits great potential in surface modifying bioceramic/polymer composites. The fabricated FSPC have shown great potential as bone implants in orthopedic applications considering their excellent biocompatibility, bacteriostatic property, osteogenic activity, and osseointegration.

Functionalization of graphite via Diels-Alder reaction to fabricate poly (vinyl alcohol) composite with enhanced thermal conductivity

Surface modification of filler is often utilized to effectively reduce interfacial thermal resistance in thermal conductive materials. In this work, pristine graphite was modified via Diels-Alder reaction with acrylic acid to improve the inertness of graphite (AA@G). FT-IR, Raman and XPS confirmed the reaction onto the surface of graphite. A series of poly (vinyl alcohol) composite loaded with AA@G and graphite was fabricated to investigate the interfacial interaction between matrix and filler. Both XRD and DSC showed that introducing of AA@G would decrease crystallinity of PVA matrix in composite, providing convincing evidence of strong interfacial interaction. Owing to the excellent interfacial interaction, the maximum TC of composite loaded with 30 wt% AA@G reached to 21.3Wm−1K−1, which was 44% higher that of composite loaded with the same mass fraction of graphite (14.1Wm−1K−1). With the synergistic increment in thermal conductive performance, AA@G exhibited extremely high enhanced efficiency of 358% compared with other literature. Also, good thermal stability makes AA@G potential in thermal management system and flexible electronics.

Review on the Use of Nanofillers in Polyurethane Coating Systems for Different Coating Applications

Polyurethane (PU) is the most common, versatile and researched material in the world. It is widely used in many applications such as medical, automotive and industrial fields. It can be found in products such as furniture, coatings, adhesives, construction materials, Paints, elastomers, insulators, elastic fibres, foams, integral skins, etc. because it has extraordinary properties and the facility to tailor-made various formulations according to property requirement using different raw materials which are available. Though the material is having fascinating properties the material is also associated with various problems such as inferior coating properties. Inorganic pigments and fillers are dispersed in organic components and binders to improve different properties of the coating. This paper is intended to review the various nanofillers used in different PU coating systems. It gives a general introduction about the various fillers and it's classification, Mechanism by which the filler enhances the mechanical properties of the materials, various factors which affect the properties of the coatings. Various methods of incorporation of fillers in the coating systems are discussed. Various nanofillers such as SiO2(Silicon Dioxide), TiO2(Titanium Dioxide), AL2O3(Aluminium Oxide), antimony doped tin oxide (ATO), BaSO4(Barium Sulphate), FE2O3(Ferric Oxide) as well as carbon nanotubes, graphene derived fillers and nano-diamonds are discussed in detail. The importance and effect of surface modification of fillers to enhance coating properties are also discussed along with challenges associated with polyurethane coatings and future trends.

Filler modified by a sequential encapsulation and preflocculation method and its effect on paper properties

Abstract Increasing the filler content of sheet tends to decrease filler retention and paper strength properties. To overcome this problem and make better use of fillers, development of new methods on filler modification has never been stopped. In this study, filler modification was carried out by sequentially adding an anionic polyacrylamide, a cationic starch and a cationic polyacrylamide. It is believed that in this process, multiple polyelectrolyte complexes are formed which can not only encapsulate filler particles but also preflocculate the particles. The results showed that, compared to the single preflocculation treatment, the sequential encapsulation and preflocculation (SEP) treatment brought significantly larger particle size and higher surface charge potential of the filler, thus higher filler retention was achieved. When the modified fillers were used for papermaking and paper ash contents were controlled at the same level, the SEP modification was better in improving the tensile index, internal bond strength and tearing index of paper than the single preflocculation method, in addition, it maintained better paper formation, caused insignificant change on opacity of paper. It is believed that this newly developed SEP method is worthy of being applied to industrial scales in making various grades of filled paper.

Hybrid Straw/Perlite Reinforced Natural Rubber Biocomposites

The purpose of the work is to prepare and characterize hybrid fillers of cereal straw - perlite as well as to examine their impact on the functional properties of elastomeric biocomposites. Natural rubber was used as the polymer matrix, vulcanized with a sulfuric crosslinking system. The subject matter of the work included an interdisciplinary knowledge segment in the field of polymertechnology - hybrid biomaterials. The work investigated the effect of physical (mechanical) modification of lignocellulosic filler. The process of milling and homogenization of cereal straw with the addition of perlite was carried out in a planetary ball mill. The properties of biocomposites were examined in terms of two key aspects: The amount of hybrid filler and its ratio (cereal straw to natural mineral). The plate-like structure of natural minerals and the fibrous structure of cereal straw created a two-component filler, which influenced the properties of the produced biomaterials. A significant improvement in barrier, crosslinking density, hardness, mechanical and damping properties has been noted for systems containing hybrid fillers. Moreover, all vulcanizates proved to be resistant to the rmooxidative aging. Furthermore, the straw modificated with perlite formed a more complex structure in the composites, resulting in a stronger reinforcing effect, which was confirmed by dynamic-mechanical analysis (Payne effect).

Method of Modifying of Mineral Fillers for Asphalt Concrete by Calcium Polysulfide

The method of modifying the surface of grains of mineral filler for asphalt concrete with calcium polysulphides is presented in the paper. Calcium polysulfide solution has been proposed for the expansion of the mineral resource base in the production of asphalt concrete aggregates, which breaks down into elemental sulphur and calcium hydroxide in the course of filler modification. The proposed modifier reduces the temperature coefficient for the bitumen-mineral binder by 1.8 times. The structure of the composite of highly filled mixtures based on modified filler has higher properties compared to mixtures based on classical filler: compressive strength at temperature 0°C – up to 33.5 %; Compressive strength at a temperature of 20 °C – up to 84 %; Compressive strength at a temperature of 50 °C – up to 34.3 %.

Perspective on the mechanical response of pineapple leaf filler/toughened epoxy composites under diverse constraints

In view of fiber orientation problem and seminal ecological economics, the present research work is concentrated on the development of ‘commercial adhesive grade’ epoxy composite reinforced with surface-modified low-cost ‘agronomic waste’- based pineapple leaf (PALF) fillers. To overcome the potential adhesion and moisture absorption issues, surface modification of fillers is accomplished with alkaline treatment. The change occurred in the crystal structure and thermal stability of fillers before and after the treatment is quantified using X-ray diffraction and thermogravimetric analysis. The composite samples are subjected to the tensile test with varying strain rate to investigate its effect on the tensile properties and failure behavior of materials. In addition to this, the plane-strain fracture toughness and flexural test have also been carried out to evaluate the composite properties in bending mode with and without the preexisted crack in materials. The dynamic mechanical analysis has also been conducted from room temperature to 150 °C to evaluate the temperature dependence of mechanical properties. The crystallinity of treated filler has been improved by 8 % due to the loss of non-cellulosic components from filler molecules. The highest value of ultimate tensile strength and Young’s modulus are 22 MPa and 570 MPa, respectively. The maximum values of storage modulus of 10 GPa and glass transition temperature of 91 °C were observed for 2.5 % and 12.5 % of filler content, respectively. From these findings, it is envisaged that the balanced tensile and dynamic mechanical properties of PALF–epoxy composites will elucidate their potential applications.

Improving mechanical properties of silicone rubber for use as outdoor insulator sheds by manipulating matrix-filler interfacial compatibility

Interfacial compatibility and particles dispersion are two vital influences for improving mechanical properties of silicone rubber (SR) nanocomposites. To achieve a high level of compatibility with SR-matrix, a series of dispersible nanosilica (denoted as DNS) surface modified with hexamethyldisilazane (HMDS) as well as aluminum hydroxide modified with stearic acid (denoted as m-ATH) were synthesized and used as reinforcement fillers of SR-matrix nanocomposites. Results indicate that the compatibility can be obviously improved by modification of fillers. DNS surface-capped with 0.1 mol l−1 HMDS and m-ATH surface-modified with 0.1 wt% stearic acid exhibit excellent reinforcement effect. Compared with unmodified samples, the tear strength and elongation at break have been improved by 68.5% and 171.2%, respectively. Moreover, the as-fabricated DNS/m-ATH nanocomposite exhibits a tracking-erosion resistance of 1 A 4.5–0.83, a volume resistivity of 1.0 × 1015 Ω·cm and a dielectric constant of up to 3.51, which are all much higher than the standards of high voltage insulator sheds. This indicates that the as-fabricated SR-matrix nanocomposite could be a qualified candidate material for high voltage insulator sheds.

Optimization of modifier deposition on the alumina surface to enhance mechanical properties and cavitation resistance

Composites based on poly(methyl methacrylate), dimethyl itaconate matrix and alumina particles were prepared. Ferrous oxide-doped alumina particles (Al2O3 Fe) and commercial alumina nanoparticles (Al2O3 n) modified with (3-aminopropyl)trimethoxysilane (AM) and methyl esters of linseed oil fatty acids (biodiesel—BD) were used as reinforcement. The mechanical properties of the prepared composites, containing 1, 3 and 5 wt% of surface-modified alumina particles, are compared to a neat polymer matrix. The particles were characterized by single-beam Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The mechanical properties of the composites were determined by micro-Vickers hardness and impact testing. The morphology of the surface of the composites exposed to cavitation was observed through a field emission scanning electron microscope. AFM analysis was used to compare surface features seen using the SEM and to interpret the surface degradation properties. The hardness, cavitation resistance and high-impact energy resistance of the composites are better in the case of AM surface modification of alumina fillers, but biodiesel modified particles have comparable mechanical properties and a stabilized Al–O–Si bond that could be important when a composite is exposed to humidity or a wet environment.

Preparation and characterization of flexible, free‐standing, and easy‐fabricating BaTiO3‐P(VDF‐CTFE) dielectric nanocomposite

AbstractThe flexible and free‐standing nanocomposite films were fabricated by a simple solution‐casting process using BaTiO3 nanoparticles as fillers and P(VDF‐CTFE) 91/9 mol% as polymer matrix. To obtain good wettability between ceramic and polymer, the coupling agent 3‐Aminopropyltriethoxysilane was used to modify the surface of BaTiO3 fillers. A good compatibility of BaTiO3 and P(VDF‐CTFE) was achieved when a small amount of coupling agent was used for the surface modification of BaTiO3 fillers; therefore, the nanocomposites with a dense and uniform microstructure was obtained. It was experimentally found that both dielectric constant and breakdown strength were increased with a suitable amount of coupling agent due to the good compatibility. A dielectric constant of 51 at 1 kHz was obtained with 30 vol% fillers and 2 wt% coupling agent, which was about four times of that for the pure P(VDF‐CTFE) film. When an appropriate amount of coupling agent was coated on fillers, the energy storage density of the composite system was improved. A maximal discharge energy‐storage density of 3.8 J/cm3 was obtained for the nanocomposite film with 5 vol% of BaTiO3 and 2 wt% coupling agent, which is much higher than that of the composites without coupling agent.

Influence of coupling agent on the microstructure and dielectric properties of free-standing ceramic-polymer composites

The influence of a commercial coupling agent on the dielectric properties and microstructure of ceramic-polymer nanocomposites are studied. Free-standing BaTiO3-P(VDF-CTFE) films were fabricated using a simple solution-casting process, and the good wettability between fillers and polymer matrix was obtained by using 3-Aminopropyltriethoxysilane as coupling agent. It is found that the coating of a small amount of coupling agent on the surface of BaTiO3 fillers results in an enhanced dielectric constant, a higher breakdown strength and a larger energy-storage efficiency. When an excessive amount of coupling agent was used, the non-attached coupling agent molecules participated in the complex reactions and result in the aggregation of fillers and the reduction of dielectric constant. It is also found that the surface modification of fillers has a complicated influence on its dielectric behavior which leads to an increase in the dielectric loss of the nanocomposites. When an appropriate amount of coupling agent is coated on fillers, the energy storage density of the nanocomposite is improved due to the enhanced dielectric constant and higher breakdown strength. A maximal discharged energy-storage density of about 4.0 J cm−3 was obtained from the nanocomposite film containing 15 vol% of surface modified BaTiO3 fillers with 1 wt% of KH550, which is about 3 times of that for the nanocomposite without coupling agent.

Thermal Analysis and SEM Microscopy Applied to Studying the Efficiency of Ionic Liquid Immobilization on Solid Supports.

Ionic liquids (ILs) are widely used in elastomer composites, primarily as vulcanization activators or accelerators, crosslinkers, conductive additives, or dispersing agents of fillers. The aim of this work was to study the efficiency of ionic liquid immobilization on filler surfaces using different techniques of thermal analysis and scanning electron microscopy (SEM). Ionic liquid, such as 1-decyl 3-methylimidazolium bromide (DmiBr) was grafted on the surface of silica, calcium oxide, and carbon black to improve the dispersion degree of their particles in the elastomeric matrix. Thermal analysis and SEM microscopy revealed a key role in determining the efficiency of the filler modification with ILs dissolved in acetone. Identifying the weight loss associated with thermal decomposition of DmiBr in modified fillers, allowed the calculation of the efficiency of their modification and compare the surface reactivity of studied fillers with DmiBr. Silica and carbon black exhibited high and comparable ability for interaction with ionic liquid. SEM images showed that particles of DmiBr-modified fillers were quite homogeneously dispersed in the elastomer matrix and exhibited good adhesion to the elastomer.

Low-temperature plasma modification of carbon nanofillers for improved performance of advanced rubber composites

In modern polymer industry, there still is a room for new generations of fillers capable of enhancing the performance of composite materials. Currently, much effort is being put into a process of improving mechanical properties of elastomer materials. In this work, multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) were modified with silane, titanate, or zirconate using plasma treatment, in order to apply them as fillers for styrene/butadiene rubber. Following its modification, filler surface was analyzed: Surface free energy (SFE) was measured with tensiometry, and micromorphology and chemical composition were studied with scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), while elemental composition and bonding were assessed with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Low-temperature oxygen plasma activation of MWCNT fillers leads to a significant increase in the SFE polar component, with the same effect being much weaker for GnP fillers. Grafting silanes, zirconates, and titanates on activated filler surface results in a decrease in SFE polar component—surface oxygen-containing active groups react with silane/zirconate/titanate molecules. Fillers modified in this way exhibit different micromorphology and surface chemical composition what is revealed with the SEM–EDS, ToF-SIMS, and XPS techniques. As the ultimate step, either MWCNT or GnP rubber nanocomposites were manufactured using the modified fillers with their mechanical properties and cross-link density being studied. Filler modification resulted in substantial changes both in composite performance, and in its cross-linking density. In the case of modified filler containing composites, improved tensile strength and elongation at break were observed.

Modification of PCC with agar and its application in papermaking

Modification of filler with polysaccharides such as starch, cellulose and their derivatives by preflocculation is an effective means to overcome the main drawback of mechanical strength decline resulting from filler addition. Agar is a mucilaginous polysaccharide extracted from red algaes and was used to modify precipitated calcium carbonate (PCC) for papermaking in our studies. Results showed that when 0.03% cationic polyacrylamide (CPAM) was used as retention aid, tensile index of handsheets using agar (3%, based on PCC) modified PCC as filler was 29.5% higher than native PCC, whereas filler retention did not change obviously. Optical microscope observation and laser diffraction particle size analysis confirmed that PCC was flocculated and coated by agar after modification. Characterizations of mechanical strength and filler retention of handsheets at different filler content indicated the handsheets can be filled with about 10% more agar modified PCC but to maintain the same strength level.

Improvement of mechanical properties of silica/phenolic composites and abrasive tools by modification of filler using diazonium salt with hydroxymethyl groups

Most important features that influence the properties of composites are the uniform mixing of components and interactions between surfaces of the individual components. Changing the type of interactions on these surfaces has a significant effect on improving the properties of the composites. In this work, we prepared active silica fillers with hydroxymethyl groups on the surface. We proved by Raman spectroscopy uniform distribution of the organic layer on the silica surface. The obtained materials were used as a filler in novolac composites and abrasive tools. Introducing active hydroxymethyl groups onto the surface of the filler allows for covalent bonds between the resin and the modified filler. The mechanical, thermal and thermomechanical properties of the materials were investigated. Flexural strength increased by 68% for novolac composite while 246% for model abrasive tool. Materials with modified silica have a higher cross-linking density. The addition of active filler to the polymer matrix allows to obtain a composite structure with higher stiffness and better damping properties. Therefore, it can be concluded that the use of a modified filler improves the properties of both novolac composites and model abrasive tools.

Highly Controlled Integration of Graphene Oxide into PAN Nanofiber Membranes

A highly improved strategy is established in order to systematically integrate excess exfoliated graphene oxide (GO) as fillers into polyacrylonitrile (PAN) nanofibers via electrospinning. Simple modification of GO surface allowed for their loading efficiency into the nanofibers to surpass the typical limits. Among many features, the hydrophilic and mechanical properties of these membranes were found to be significantly increased compared to the original PAN and bare GO-loaded membranes probably due to the effective reinforcing filler effect caused by the even distribution of the modified GO within the PAN nanofibers. Thus, the simple surface modification of fillers can facilitate the capability of controlling the loading efficiency into electrospun nanofibers which can highly impact the quality and performance of final composite membranes.