Filler Particle Size Research Articles

Design of Elastomeric Bridge Bearing Pad Compound Formula Based on Hydrogenated Natural Rubber

Laminated elastomeric bearing pad which is commonly produced by natural or chloroprene rubber is functioned as isolation system in bridge or flyover structures. In the research, hydrogenated natural rubber (HNR) was evaluated its feasibility to be used as base elastomer on steel-laminated bearing pad production by designing rubber compound formula. The compounding procedures of HNR applied various vulcanization system and carbon black filler types. The physical and mechanical tests result showed that only hardness parameter could fill the standar quality requirement of commercial elastomeric bearing pad as stated in AASHTO M251 in the range of 50 "“ 70 Shore A scale. The tensile property and compression set value of the HNR vulcanizates were under the requirement. This was due to low rubber-filler interaction and rigidity of crosslink network. The low interaction was more evident with increasing carbon filler particle size. By adjusting semi efficient vulcanization system and used N220 as carbon filler in designing compound formula,HNR was regarded as alternative promosing base elastomer for elastomeric bridge bearing pad manufacture. Nevertheless, it was necessary to improve the procedure to achieve better tesile property and compression set parameter.

Synthesis and characterization of novel nanocomposites with nanofillers particles and their applications as dental materials

Using copolymers materials in the preparation of dental fillings is now more common as a result for needs for more esthetic materials of filling and the international ban on the use of products that contain mercury, amongst others dental amalgams. On the other hand, a disadvantage with the Dental Nanocomposites is that they have a polymerization shrinkage. Particles of the filler are combined in the amongst other components for shrinkage minimization. Filler particle sizes have decreased lately and the majority of Dental Nanocomposites include Nano-particles. New Nanocomposites materials based on 2,2 propyl bisphenyl glycidyldimethacrylate (Bis-GMA) and unsaturated monomers ( Methacrylic acid,Acrylicacid,2,2propylbisphenylglycidyldimethacrylate,Triethyleneglycoldimethacrylate ) with Nano inorganic fillers such as (SiO2,ZrO2 and Hydroxyapatite) were characterized and synthesized for the sake of evaluating the potential applications they have in the field of dentistry, as restoration materials. The initial method was generating and characterizing new dental Nano-composites in presence of Triethylene glycol dimethacrylate (TEGDMA) as crosslinking agent. Composites which contain Bis-GMA and Triethylen glycoldimethacrylate) at the ratio (wt/wt) of 40/20, filled with various Nanofiller amounts (about 4.6%wt) were produced. Photo-polymerization has been induced with camphoroquinone / N,N-dimethylaminoethyl methacrylate(CQ/DMAEMA) present, as a system of photo-initiation. Physicochemical properties, such as volumetric shrinkage (VS), water sorption (WS) and water solubility (WSL) were studied. Characterization is performed with the use of SEM and FTIR spectrum. SEM is utilized for showing the distributions of particle sizes and particle agglomeration of the treated Nanofillers in Nanocomposite. FTIR spectroscopy is initially utilized for identifying qualitative construction of the Nanocomposites. The Thermal stability of all dental Nanocomposites were also studied using the TGA and DSC techniques. The strength and the aesthetic characteristics of resin based Nanocomposite open the possibility of using it for each of the posterior and anterior restorations. Flexural strength, compressive strength, wear resistance and hardness were evaluated. The presented research has the aim of addressing current key utilizations of the practical Nanotechnology in the field of dentistry, most importantly, tooth structure restoration with Resin-based composites (RBCs) which benefit from the Nano-particles.

Kinetic aspects of concentration of solid nanoparticles at the interface in polystyrene–polyethylene mixtures

ABSTRACTThe effect of several mixing process parameters on the concentration of carbon black particles at the interface between the polymer components in polyethylene–polystyrene mixtures was studied. It was established that the process of particle transport from the polymer phase to the interface happens only under the action of shear deformation, but simultaneously acting shear stresses prevent particle concentration. The nanoparticle accumulation at the interface is determined not only by how favored this process is thermodynamically, but also by the parameters of the mixing process. The filler concentration at the interface is facilitated by a reduction in the shear stress, polymer viscosity, filler particle size, and preliminary injection of filler into the polymer component that is less effective at wetting the filler surface. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48585.

Effects of filler particle size and ageing on the fatigue behaviour of bituminous mastics

Fatigue cracking is caused by repeated traffic loads and environmental conditions (temperature, ageing, etc.); it predominantly initiates within the mastic phase in the form of micro-cracks. In this sense, bituminous mastics (comprised of a binder, filler and entrapped air) play a significant role in the anti-fatigue performance of asphalt mixes. In this paper, the effects of filler particle size and ageing on the fatigue behaviour of bituminous mastics were evaluated. Prior to this, the rheological properties of the studied samples were evaluated using physical tests and frequency sweep tests. Moreover, the mastic morphology and filler distribution inside a bituminous matrix were characterized by Scan Electronic Microscope (SEM). The results revealed that ageing had a greater effect than filler particle size on the rheological behaviour of SBS-modified bituminous mastics, especially for mastics containing coarse filler particles. According to the ageing responses derived from log-log fatigue law plots, aged mastics containing coarse filler particles had higher slopes (represented by coefficient B) and lower intercepts (identified by coefficient A) than un-aged mastics. However, opposite fatigue behaviour was observed with fine filler granules, where coefficient B slightly decreased while coefficient A slightly increased after ageing. In addition, mastic morphology and filler dispersion inside a bituminous matrix were characterized by SEM, providing insight to possible relationships between morphological characteristics and fatigue performance.

Evaluation of mechanical and thermal properties and creep behavior of micro- and nano-CaCO3 particle-filled HDPE nano- and microcomposites produced in large scale

The influence of the interfacial area and the particle size of CaCO3 filler particles on the mechanical and thermal properties of high-density polyethylene (HDPE) was studied in this work. The HDPE-based nano- and microcomposites were manufactured by using an industrial compounder system. The tensile, impact, creep, flexural and hardness properties of the filled and unfilled HDPE samples were investigated. The experiment revealed that the addition of both micro- and nanoparticles increased the tensile and flexural modulus of unfilled HDPE. However, it was observed that the addition of these particles did not have a significant effect on the tensile and flexural strength of unfilled HDPE. On the other hand, the presence of these particles decreased the elongation of break of unfilled HDPE. The impact strength of filled HDPE composites decreased slightly with both micro- and nanoparticle contents. The nanoparticle at high stress level (16 MPa) is more effective on the creep behavior of unfilled HDPE than on microparticles. However, microparticles were found to be more effective at low stress levels (8 and 12 MPa). It was found that the particle size has a profound effect on the thermal and physical properties of unfilled HDPE, such as density, melt flow index and vicat softening temperature. The results showed that the size of filler particles has a significant effect on the mechanical and thermal properties of the unfilled HDPE. Therefore, the size selection of constituent materials of nano- and microcomposites is an important consideration because it directly affects the functional performance of particle-filled HDPE nano- and microcomposites.

An investigation on effective thermal conductivity of hybrid-filler polymer composites under effects of random particle distribution, particle size and thermal contact resistance

The thermal conductivity (TC) of polymer composites with randomly distributed hybrid fillers is investigated numerically and theoretically. The effective thermal conductivity (ETC) of such composites is examined under various effects, such as the TC ratios, volume fraction (VF), and particle distribution, particle size, and particularly thermal contact resistance (TCR). The contribution of particle distribution to the ETC were explained comprehensively, which is as a function of projected area and effective length of hybrid fillers. Results indicated that the optimal ETC was affected significantly by particle distribution and particle size at high VF, high TC, low TCR, and largely total particle size of hybrid fillers. However, particle distribution and particle size show not to affect considerably to the value of the optimal TC ratio between two fillers. Particularly, it was confirmed that the TC is generally enhanced when more particles are stacked and concentrated along the thermal flow direction regardless of the effects of TCR. In addition, modified Hashin-Shtrikman model by Ngo's study again shows a good TC prediction even with the TCR effect. These results are very good in practical optimization process to achieve the maximum ETC of composites, thus total cost of composite synthesis can be reduced significantly.

Effect of silica particle size on the microstructure and physical properties of microporous poly(L-lactic acid) produced by uniaxial stretching

Abstract The microporous poly( l -lactic acid) (PLLA) materials were prepared by uniaxial stretching PLLA/20 wt% silica (SiO2) composites. The SiO2 fillers with particle size of 15 nm, 200 nm, 500 nm, 1 μm, 2 μm, and 5 μm were selected to investigate the effect of particle size of fillers on the microstructures and physical properties of the microporous PLLA materials. Micropores were formed due to the debonding at the interface between PLLA and SiO2. The composites with SiO2 particle size of 15 nm, 200 nm, 500 nm, 1 μm, 2 μm, and 5 μm began to debond at 1.4, 1.0, 1.0, 1.0, 0.9, and 0.7, respectively. With the increase of SiO2 particle size, the micropore diameter was enlarged at the same stretching ratio, while the particle number of SiO2 was decreased, however, the porosity was still increased. The mechanical properties, thermal insulation properties, and water vapor permeation properties of microporous PLLA samples were all improved compared with that of undrawn PLLA.

The influence of degree of fragmentation of Pinus sibirica on flammability, thermal and thermomechanical behavior of the epoxy-composites

Abstract In this study, lignocellulosic flour obtained through grinding of Pinus siberica wood (S) was used as a filler for developing epoxy-based (EP) composites characterized by reduced flammability. The influence of filler particle size on flammability, thermal and thermomechanical behavior of the natural composites was discussed in reference to the morphological analysis of final products as well as filler geometrical changes induced by processing. The structural analysis was realized with using 3D tomography. It was found, that introduction of 20 wt% of Pinus siberica wood caused a sharp drop in the heat release rate values, and the lowest results (2.5 times lower compared to EP) was determined for composite with the highest degree of fragmentation. The residue investigation confirmed the influence of particles size on the formation of the swelling structure of char, which effectively inhibits the combustion processes. Moreover, the analysis of gaseous products emitted during the thermal decomposition of composites was performed. The addition of investigated filler caused a decrease in the amount of degradation products, while the quantity of polycyclic aromatic hydrocarbons (PAHs) increased.

Graphene platelets versus phosphorus compounds for elastomeric composites: flame retardancy, mechanical performance and mechanisms

Polymers are widely used but their flammability remains a serious issue causing fatalities and property damage. Herein we present an investigation into the effectiveness of graphene platelets (GnPs) to simultaneously improve the flame retardancy and mechanical properties of ethylene propylene diene monomer rubber (EPDM). EPDM was melt compounded respectively with GnPs and a commercial flame retardant (ammonium polyphosphate, APP) to produce two groups of composites. Although both fillers were well dispersed in EPDM, GnPs significantly improved the mechanical properties of EPDM whilst APP compromised some of the mechanical properties particularly at high fractions. This difference was attributed to the filler particle size and interfacial bonding. Through cone calorimetry testing, 21 wt% char yield was recorded for the EPDM/GnP composite at 12.0 vol%, in comparison with 8 wt% for the EPDM/APP composite. APP was able to lower the peak heat release rate (PHRR) and specific mass loss rate (MLR), but unfortunately it decreased the ignition time and fire performance index (FPI). By contrast, GnPs has been found to increase ignition time by 29% and FPI by 62%, while still achieved the same level of reductions in PHRR and specific MLR, demonstrating clear advantages over APP. During combustion the highly thermally stable GnPs bonded with the viscous, degraded EPDM macromolecules, forming a thick solid char layer which prevented the transport of heat and smoke, contributing to its superior flame retarding performance over APP.

Stability of Dental Composites in Water and Artificial Saliva

The aim of this in vitro study was to evaluate the characteristics of four commercial dental composites: two dual-curing luting resin cements and two indirect composites for crowns and bridges. The novelty of the study consists in the use of combined characterization methods for the investigated materials, namely: after maintaining the samples in the water/ artificial saliva, besides sorption, the surface degradation of the samples was observed after their immersion period; thereafter, the immersion medium was lyophilized and then the percentage of residual monomer found in the medium was determined by HPLC. After 44 days, small concentrations of monomers have been determined in the aqueous/saliva extracts. SEM images show that the samples from each class of material, with a higher content of inorganic filler, exhibit a larger erosion of the surfaces after contact with water compared to the other two samples that show a larger erosion of surfaces after contact with saliva than with water. The surface of the dual-curing resin cement with a higher content of inorganic filler is the smoothest from the samples exposed to saliva, instead the other resin cement is the roughest, as shown by AFM analysis. The overall observation reveals that the samples kept in saliva are rougher than the ones kept in water. Smooth surface materials of both classes of materials ( with a higher content of inorganic filler) have absorbed a higher amount of water / saliva compared to materials with a rougher surface.Water sorption in the composite resins is influenced by the hydrophilicity of the monomers, the nature and size of the inorganic filler particles, and the quality of the matrix / filler interface.

A spatially-varying relaxation parameter Lattice Boltzmann Method (SVRP-LBM) for predicting the effective thermal conductivity of composite material

Functional filler-reinforced composite materials play critical roles in thermal management in various engineering applications. In this study, an in-house coded spatially-varying relaxation parameter Lattice Boltzmann Method (SVRP-LBM) solver has been developed for predicting the effective thermal conductivity (ETC) of simulated composite materials. A randomly dispersed filler generator (RDFG) incorporating Monte Carlo random sampling method has been developed for reconstructing the microstructure of composite materials. The artificial composite materials with functional fillers of different geometries and particle size are studied. The SVRP-LBM is validated against FVM perditions and theoretical models. The spatially-varying relaxation parameters method has been used to reflect materials with different thermophysical properties, including the interfacial contact resistance between the matrix-filler interfaces. It is demonstrated that the lowest relaxation parameters should be around 1.0 in order to achieve a higher accuracy of LBM predictions. The effects of filler geometry and particle sizes on the ETC are also assessed. The shape and orientation of the anisotropic filler have strong effects on the ETC. After the geometry of the filler in the numerical models being adjusted accordingly to the real fillers, the predictions show good agreement with experimental data. All in all, the SVRP-LBM solver has shown good capability and accuracy for predicting the ETC of composite material.

Influence of particle size and particle loading on mechanical properties of silicon carbide–reinforced epoxy composites

In this study, the effect of particle size and particle content of silicon carbide fillers in epoxy matrix on the mechanical properties and microstructure of the developed composites was investigated. Silicon carbide fillers sized to < 45 μm and 90–45 μm were incorporated to epoxy composites to obtain volume fractions of 2, 4, 6 and 8 wt% of SiC. Mechanical properties including flexural strength, compressive strength and hardness tests of the composite samples were performed according to ASTM D790-03 (2003), ASTM D695-15 (2015) and EN 1534 standards. Surface morphology, crack propagation and particulate dispersion were observed using scanning electron microscopes (SEM). The results of the mechanical properties obtained were examined statistically and the results that a strong negative correlation between hardness and flexural strength but the individual correlation between hardness and flexural modulus, compressive stress and compressive modulus were positive. Results also showed that the inclusion of small particulate silicon carbide (< 45 μm) displayed superior mechanical properties in term of flexural, compressive and hardness characterizations at a given volume fraction. Flexural properties of the composite samples decrease with increase in filler concentrations while the compressive strength and hardness increase as particulate loading increase. In terms of microstructure, uniform dispersion of silicon carbide particulates was observed within epoxy matrix with linear crack propagation.

A new permeation model in porous filler–based mixed matrix membranes for CO2 separation

AbstractIn this paper, a novel comprehensive permeation model for mixed matrix membranes (MMMs) is introduced. This model shows the importance of understanding and developing a more reliable model for the permeation behavior of MMMs containing porous filler nanoparticles. A new method is established to provide a more precise/large‐scale three‐dimensional MMMs geometry. The required number of spherical porous fillers in random/nonuniform positions in the polymer matrix is calculated. Interfacial equilibrium constant (K) at the polymer/filler interfaces was adjusted as the concentration ratio of the diffusing penetrants (C2 and C1) at the interface, respectively. In this case, the K values are changed by varying the intended gaseous concentration due to their permeation through the MMM. Hence, its effect on penetrants effective diffusion coefficient was examined. Then, the obtained results were evaluated with similar experimental data, which showed much consistency. Therefore, the accurate calculation method for MMMs permeability was governed for the entire range of the operating pressures in MMMs. The results showed that the permeability of MMMs increases with increasing filler particle size. On the other hand, variations that occur in the MMM permeability at various particle size were much more distinct at higher loadings. Moreover, some well‐known analytical permeation models were used to compare and validate the model's permeability results. It can be concluded that this model provides a method for more precise and realistic design of MMMs as well as to better construe the large number of related experimental data. © 2019 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Clustering effect on permeability spectra of magneto-dielectric composites with conductive magnetic inclusions

Magneto-dielectric composites, promising candidate materials for next-generation microwave communication, require high permeability and low loss, which are closely related to the particle size of the magnetic fillers. However, clustering occurs when particles physically or electrically touch each other, resulting in effective particle clusters that are much larger than the individual particle size. In this paper, we extend the effective medium theory (EMT) to include the clustering effect, which describes a more accurate prediction of the effective permeability of magneto-dielectric composites over wide ranges of both particle concentration and frequency. A Monte Carlo simulation is applied to model the agglomeration of magnetic particles suspended within a polymeric matrix. The extended formula is experimentally verified by the measurement of constitutive parameters, for iron/paraffin composites with various filler concentrations, over the frequency range from 1 MHz to 1 GHz. Considering the clustering effect, the proposed EMT model corrects the overestimation of the traditional EMT models, especially near the percolation threshold where the cluster size grows comparable to the skin depth at a given frequency.

Synthesis and characterization of high-performance epoxy/ Ti3AlC2-reinforced conductive polymer composites

Titanium aluminium carbide powder was reaction synthesized and used as reinforcement in the aircraft grade epoxy matrix (LY556) to develop a high-performance conductive polymer composite. The particle sizes of 4 and 7 µm were employed from 0 to 40 wt.% to improve the mechanical and electrical properties of conductive polymer composites. It was observed that the percolation characteristics were exhibited at a critical threshold of 20 wt.% for both the filler particle sizes. Further, microstructural observations revealed the formation of a conductive network in the conductive polymer composites when the filler content was 20 wt.%. The tensile and flexural properties were increased when the particle size was decreased. Experimental values were then compared with the available analytical models for validation. The mechanical and electrical properties of the conductive polymer composites were optimized by tailoring the filler particle size to 4 µm and particle loading at 20 wt.%. Compared to neat epoxy, the optimized conductive polymer composites have shown a simultaneous increase in strength, stiffness and conductivity performances, which can find applications in aerospace and electronics industries.

Effect of Alternative Fillers on the Properties of Rubber Compounds

The paper is focused on the influence of alternative fillers on rubber compounds properties. Three different types of powder fillers, drinking water treatment sludge (DWTS), perlite and calcium carbonate, were mixed into rubber compound mixtures. The mixtures were composed of STR20, EPDM, zinc oxide, steric acid, paraffin wax, 2-mercaptobenzothiazole (MBT), sulphur, Wingstay L, and filler. The mixtures were mixed in a Kneader type mixer at temperature of 70°C and then continuously mixed using a two-roll mill at temperature of 70°C. The relationships between type and the amount of filler versus properties of rubber compounds were demonstrated. The results showed that tensile and elongation at break of rubber compounds gradually decreased with increasing the amount of filler. Rubber compounds filled with small particle size filler possessed higher tensile strength and elongation at break than those filled with large particle size filler. Values of DIN abrasion loss of rubber compounds prepared under proper mixing condition were not more than 300 mm3. Under appropriate condition, the rubber compounds with DWTS, perlite and calcium carbonate provided sufficiently high shore A hardness (not less than 50 Shore A hardness). Finally, alternative fillers such as DWTS and perlite were expected to replace calcium carbonate in normal formula.

Effects of the morphological characteristics of mineral powder fillers on the rheological properties of asphalt mastics at high and medium temperatures

The primary objective of this study was to investigate the feasibility of the dispersion of fillers dispersion as individual particles and evaluate the effects of the morphological characteristics of filler particles on the rheological properties of asphalt mastics at high and medium temperatures. For a given source and filler, three various filler particle sizes produced from different crushers (i.e., a jaw crusher, an impact crusher and a ball grinding mill) were obtained, namely, F1 (P200-R300: passing a 200-mesh and retained by a 300-mesh sieve), F2 (P400-R500) and F3 (P800-R1000). The binary image particle analysis system was employed to acquire the morphological characteristics of filler particles such as form factor, angularity and surface texture. By applying multiple stress creep and recovery (MSCR) tests at high temperature and time sweep (TS) tests at medium temperature, the rheological properties of asphalt mastics prepared with different filler particle sizes were also investigated. Furthermore, the correlations between the morphological characteristics of filler particles and the high/medium-temperature properties of asphalt mastics were studied by grey relational analysis (GRA) method. Results showed that the proposed new approach to sample preparation was demonstrated to be effective in achieving filler particle dispersion. The GRA demonstrated that the rheological properties of asphalt mastics at high and medium temperatures were significantly affected by the morphological characteristics of the filler particles. Percent recovery (R) and fatigue law fitting coefficients (A and B) were more sensitive to porosity, angularity index, average diameter, aspect ratio and fractal dimension but less sensitive to feature roughness, roundness, convexity ratio, density and specific surface area. In terms of non-recoverable creep compliance (Jnr), the sensibility was apparently reversed, with the reference sequence Jnr presenting less susceptibility to porosity, angularity index, average diameter, aspect ratio and fractal dimension. The GRA results can inform engineers regarding the selection of filler particles that produce asphalt mastics with desired performance characteristics, such as specific rutting resistance and fatigue failure.

The effects of particle size and content on Morphology and Mechanical Properties of Rice Straw and Coal Fly Ash filled-Polypropylene Composites

Polypropylene is a superior type of polymer due to its properties including flexibility, semi-transparent appearance, easily dyed, heat-retaining and hydrophobia. The percentage of recycled polypropylene is minimal which cause environmental pollution. To overcome the environmental problems caused by polypropylene waste, it can be utilized to produce efficient and economically-added product such as thermal insulation composites. The paper is focused on obtaining the technique and operating condition of injection molding to manufacture composite from polypropylene matrix, the influence of composition and particle size of fillers on composite mechanical properties

Study the effects of filler particle size and filler/asphalt ratio on the high and low temperature performance of asphalt mastics

In this study, the conventional and rheological analysis methods are employed to evaluate the effects of filler particle size and filler/bitumen (F/B) ratio on the high and low temperature performance of asphalt mastics. It is found that the addition of mineral fillers can significantly improve the high temperature rutting resistance of asphalt mastics. Meanwhile, it is detrimental to thermal cracking behavior. As the increase of particle size, the percent recovery R, creep stiffness S and m-value increase, while non recoverable creep compliance Jnr decrease. In addition, scanning electron microscope (SEM) imaging analysis shows that the dispersion degree and the morphology of asphalt mastics with various particle sizes have the great differences.

Fatigue Behavior of Inorganic-Organic Hybrid \u201cLunar Cement\u201d

We report the experimental results of fatigue behavior of ultralow-binder-content inorganic-organic hybrid (IOH) based on lunar soil simulant, which may be viewed as a “lunar cement”. Under the same loading condition, the fatigue life of the IOH is superior to typical steel-reinforced concrete, especially when the stress amplitude is relatively high. Fatigue damage mostly occurs in the binder phase, followed by rapid cleavage-like failure. The important material parameters include filler type, filler particle size, and filler-binder bonding.