Effect Of Filler Size Research Articles

Application of personal non-lead nano-composite shields for radiation protection in diagnostic radiology: a systematic review and meta-analysis

composites with micro- and nano-metal fillers has attracted the attention of researchers for radiation shielding applications. Lead toxicity and heaviness have oriented extensive research toward the use of non-lead composite shields. The present study aimed to systematically review the efficiency of the composite shields of various micro- and nano-sized materials as composite shields have been considered in radiation protection and diagnostic radiology. In addition, a meta-analysis was performed to determine the effects of filler size, filler type, shield thickness and tube voltage on dose reduction. The relevant studies published since 2000 were identified via searching in databases such as Google Scholar, Medline, Web of Science, Scopus, and Embase. In total, 51 articles were thoroughly reviewed and analyzed. Heterogeneity was assessed using the χ2 and I-square (I2) tests, and a fixed effects model was used to estimate the pooled effect sizes. The correlations between the subgroups were determined separately using meta-regression analysis. According to the results, the bismuth shield dose reduced from 22% to 98%, while the tungsten shield dose increased from 15% to 97%. The rate also increased from 6% to 84% in the barium sulfate shields. The combination of two metals resulted in higher attenuation against radiation, with the nano-shields exhibiting higher attenuation compared to the micro-shields, especially in low energies. Moreover, the meta-analysis indicated that the fixed effects pooled estimation of dose reduction was 89% for shield thickness (95% CI: 79-100; P 100). The single-metal personal shields made of bismuth powder had better performance than tungsten and barium sulfate. In addition, the combined metals in a shield showed more significant attenuation and dose reduction compared to the single-metal shields.

Filler size effect in graphite/paraffine wax composite on electromagnetic interference shielding performance

Graphite exhibits electromagnetic wave attenuation and high electrical conductivity. In this study, we analyzed the electromagnetic interference shielding effectiveness (EMI SE) performance and electric conductivity of composites fabricated by varying the size (mean size: 6–100 µm) of graphite fillers and explained resulting attributes through the relative permittivity and geometrical characteristics of the filler. When the graphite/paraffine wax composite was fabricated using large-sized graphite (KS150), the spacing between the graphite fillers became widened, enabling electromagnetic waves to leak through the gap. The analysis results indicated that KS150 graphite exhibited an EMI SE performance of under 10 dB when the filler content was 30 wt%. However, when the content was increased to 50 wt%, the EMI SE performance improved sharply to 40 dB. In contrast, when the composite was filled with small-sized graphite (KS6), having a high ratio of surface to volume, the EMI SE performance was greater than that with the largesized graphite at low loading. The results related to the EMI shielding performance of graphite-filled composites revealed that the size of the filler greatly affects the EMI SE. The composite using KS75 showed an EMI SE performance of 53.0 dB and electrical conductivity of 2,000 S/m.

Structure-Rheology-Property relationships in double-percolated Polypropylene/Poly(methyl methacrylate)/Boron nitride polymer composites

Double-percolated thermally conductive polymer composites comprising of polypropylene (PP), poly (methyl methacrylate) (PMMA), and boron nitride (BN) were successfully produced by melt compounding. The effects of BN platelets sizes on morphology and thermal conductivity (TC) were investigated by mixing three different sizes BN, namely 16, 30 and 180 μm with PP and PMMA. The obtained results demonstrate that for all the sizes, BN platelets were either in the PMMA phase or at the interface, and the ternary composites with high filler loadings showed enhanced TC compared to the corresponding binary systems. It is shown that smaller BN platelets led to finer morphology, which caused more interfaces and consequently more phonon scattering and lower TC of the system. Finally, we show for the first time that there is a direct scaling between particle size, mechanical properties and TC. This work proved the advantage of using double-percolated structure to improve TC of polymer composites and provided a better understanding of the filler size effects on the morphology and TC of ternary systems.

Effect of filler size and loading on thermo-mechanical degradation of polypropylene-ethylene/wollastonite composite

This study is to understand the side effect of wollastonite fillers in polymer compounding that caused different levels of thermo-mechanical degradation (TMD) during extrusion. Wollastonite has a needle-like structure with different ratio of L/D; it compounded with the polypropylene-ethylene copolymer (PPcoE) using a twin-screw extruder. The effect on the TMD of PPcoE was determined by analysing the by-products within the extrudates via FTIR. The rheology of PPcoE composite was measured using a capillary rheometer, and the thermal stability of composite was studied using TGA. In this study, TMD is classified as two levels: chain scission and oxidisation. The wollastonite filler were found to accelerate the TMD mechanism and generated oxidised products during extrusion. The reduction of filler size effectively minimised the chain cleavage of PPcoE matrix, also come with improvement in thermal stability. However, increasing the filler loading had a dominant effect of inducing more chain cleavage on the polymer matrix.

Enhancing thermal conductivity in graphene-loaded paint: Effects of phase change, rheology and filler size

High thermal-conductivity coatings have garnered much attention in fields such as the automotive and aerospace industries. Commonly used filler-loaded coatings are limited either by the high viscosity of the coating paint or by the intrinsic properties of the filler. In this study, we used graphene as a high thermal conductivity filler to enhance the properties of paint used in the automotive industry. The effects of filler size on the thermal conductivity and viscosity of stable liquid dispersion (paint) are studied and modeled in graphene nanoplatelet-loaded paint (2.47 vol%), which exhibits enhanced thermal conductivity of 160% (1.6 vs. 0.6 W (m K)−1 for the neat commercial paint) and low viscosity. Furthermore, the filler with the optimum performance (in the paint) is studied in solid state, where it elicits a 720% enhancement in thermal conductivity (14.4 vol%).

Effects of Nanoparticles’ Size and Shape on the Thermodynamic Properties of PI/SiO2 Nanocomposites

In this paper, the effects of SiO2 size (ranging from 5.7[Formula: see text]Å to 7.50[Formula: see text]Å) and shape (spherical, cylindrical and rod) on the interface structure and the thermodynamic performance of polyimide (PI)/SiO2 composites were investigated by molecular dynamics simulation. Also, whether the nanofiller with isocyanate propyl triethoxysilane (ICTOS) can highly enhance interaction in PI/SiO2 (bonded PI/SiO[Formula: see text] was investigated by experiment. To enhance the interfacial intensity efficiency, the coupling agent ICTOS was used to modify the surface of the silica nanoparticle. The results showed that the size and shape of SiO2 not only affect the interfacial number of hydrogen bonds and the interfacial area, but also impact on the glass transition temperature of the composites. As the radius of the embedded nanosilica increased, the bonded energy and [Formula: see text] gradually decreased, showing a prominent filler size effect. At the same time, the [Formula: see text] of spherical-type system was significantly greater than the nanosystems of other shapes. This is because as the number of surface atoms and superficial area of the spherical filler are higher than the nanofillers of other shapes, the combination between spherical-type silica and the PI chains is more compact than those between cylindrical and rod-like silica and the PI chains. The contributions of different nanofillers to the filler size dependency of [Formula: see text] of the nanocomposites can be elucidated by comparing the interfacial interaction and net structure between the PI matrix and silica which exhibit prominent filler shape and size dependency. Finally, the results were confirmed by the nonbonded interaction energy and reduced radial distribution function (RRDF), and the highly interaction interface is found to bring about a greater reinforcing effect.

Is Deterioration of Surface Properties of Resin Composites Affected by Filler Size?

Purpose To investigate the effect of filler size on surface gloss and roughness of resin composites using a glossmeter and 3D noncontact surface topography, respectively, before and after tooth-brushing abrasion. Materials and Methods Seven model resin composites and one commercial were tested in the study. All materials were first polished, and then the surface gloss and 2D and 3D roughness parameters were recorded. Materials are then subjected to abrasion in a tooth-brushing simulator. Roughness parameters were recorded after 10,000 cycles, and after 20,000 cycles, both roughness and gloss were recorded. One-way ANOVA and Bonferroni post hoc test (p < 0.05) were used to analyze data. Conclusion Filler size is strongly correlated to gloss and surface roughness retention.

Filler size effect in an attractive fibrillated network: a structural and rheological perspective.

The effect of the filler size on the structural and mechanical properties of an attractive fibrillated network composed of oxidised cellulose nanofibrils (OCNF) in water was investigated. Silica nanoparticles with a diameter of ca. 5 nm (SiNp5) and and ca. 158 nm (SiNp158) were chosen as non-interacting fillers of the OCNF network. These filler sizes were chosen, respectively, to have a particle size which was either similar to that of the network mesh size or much larger than it. Contrast matched small angle neutron scattering (SANS) experiments revealed that the presence of the fillers (SiNp5 and SiNp158) did not perturb the structural properties of the OCNF network at the nanometer scale. However, the filler size difference strongly affected the mechanical properties of the hydrogel upon large amplitude oscillatory shear. The presence of the smaller filler, SiNp5, preserved the mechanical properties of the hydrogels, while the larger filler, SiNp158, allowed a smoother breakage of the network and low network recoverability after breakage. This study showed that the filler-to-mesh size ratio, for non-interacting fillers, is pivotal for tailoring the non-linear mechanical properties of the gel, such as yielding and flow.

Electrical tree formation in polymer-filler composites

Insulating fillers are often mixed with polymer dielectrics in order to improve dielectric breakdown strength. However, filler-loaded dielectric films show higher variability, which limits their large-scale utility and application. In this paper, we present a computational framework for predicting the spatial distribution of electrical tree formation in a polymer dielectric in the presence of insulating fillers. The framework is based on the numerical solution of Poisson's equation inside the dielectric film and the application of the Monte Carlo model for finding the electric breakdown path. The simulation results explain several puzzles associated with the breakdown of polymer-filler dielectrics, such as (1) the improved breakdown strength with insulating filler mixing, (2) high degree of variability in breakdown measurements, and (3) effects of filler size, shape and position on the breakdown. In addition, the proposed framework not only provides the physical understanding of the breakdown process but also inspires new design concepts to improve the breakdown strength of the polymer composite.

Unprecedentedly high thermal conductivity of carbon/epoxy composites derived from parameter optimization studies

Efficient removal of heat accumulation from electronic devices has been considered an important issue because it is prone to induce reduced lifetime, heat shock, ignition, and malfunction during their operation. To that end, optimized epoxy composites, which are fabricated by dispersing a mesogen-containing polymer compatibilizer (BPIB)-applied multi-layered graphene nanoplate (MGNP) filler into a mesogen-containing epoxy (DGEBP) matrix (BPIB-MGNP/epoxy), are designed toward high thermal conductivity at the low filler loading content. Various effects on its thermal conductivity, including size, thickness, and dispersion of fillers along with the crystalline property of epoxy, are systematically investigated by comparing with their intermediate counterpart materials. The extended micromechanics model, which was modified using a power law from its initial one, was employed to address the filler size effects on its thermal conductivity as well as an exponential increase of thermal conductivity with increasing filler loading content. Thickness effects of carbon fillers are examined by comparing GNP/epoxy composites with single-layered graphene filler-based epoxy composites. The effects of dispersion properties of the fillers in the epoxy composites are also investigated using the theory prediction plot based on the extended micromechanics model. The comparison between experimental and theoretical prediction led us to study crystalline properties of the BPIB-MGNP/epoxy composites because it was unexpected and beyond the theoretical traces. An Ashby plot is prepared to evaluate the state of our results by comparing them with the reported state-of-the-art composite performances.

Poly(propylene fumarate)/magnesium calcium phosphate injectable bone composite: Effect of filler size and its weight fraction on mechanical properties.

This study aimed to produce a composite of poly(propylene fumarate)/magnesium calcium phosphate as a substitutional implant in the treatment of trabecular bone defects. So, the effect of magnesium calcium phosphate particle size, magnesium calcium phosphate:poly(propylene fumarate) weight ratio on compressive strength, Young's modulus, and toughness was assessed by considering effective fracture mechanisms. Micro-sized (∼30 µm) and nano-sized (∼50 nm) magnesium calcium phosphate particles were synthesized via emulsion precipitation and planetary milling methods, respectively, and added to poly(propylene fumarate) up to 20 wt.%. Compressive strength, Young's modulus, and toughness of the composites were measured by compressive test, and effective fracture mechanisms were evaluated by imaging fracture surface. In both micro- and nano-composites, the highest compressive strength was obtained by adding 10 wt.% magnesium calcium phosphate particles, and the enhancement in nano-composite was superior to micro-one. The micrographs of fracture surface revealed different mechanisms such as crack pinning, void plastic growth, and particle cleavage. According to the results, the produced composite can be considered as a candidate for substituting hard tissue.

Experimental study on the effect of filler size on the denitrification of SBBR process in low temperature

In order to study the effect of filler size on the treatment of low temperature wastewater by SBBR process, three groups of SBBR reactors were established. They used cubic sponges with side lengths of 1, 1.5 and 2cm as filling fillers, respectively. The denitrification effect of the three fillers was compared under the conditions of stable water temperature of (10±1)°C, HRT of 10h and reactor filling rate of 16%. The results showed that the removal of NH4+-N and TN in the reactor with the filling size of 1cm was the best, and the removal rates were 96% and 80%. The NH4+-N and TN removal rates of the reactors filled with the other two sizes of fillers were all below 80% and 70%. The membrane biomass measurement of the reactor showed that the smaller size of the filler has a larger specific surface area, which was beneficial to mass transfer and microbial growth and enrichment, thereby promoting the denitrification of low temperature wastewater.

Tribological behavior of unsaturated polyester hybrid composites containing wood flour and carbon nanotubes

The dry-wear behavior of hybrid composites comprising of multi-walled carbon nanotubes (MWCNTs) and wood flour (oil palm kernel shell powder) within an unsaturated polyester matrix was investigated in this paper. The results revealed that the incorporation of wood flour -even at little as 10 wt% filler content- significantly improved the tribological behavior of the composite. This improvement in tribological behavior was attributed to the transfer of a soft layer of wood flour on the worn area during the wear process, which acted as a self-lubricating material. Investigation of the effect of filler size revealed that composites containing smaller filler sizes exhibited higher values of friction coefficient (µ) and specific wear rate (Ws). This reduction attributed to the creation of a surface with a lower surface roughness (Ra) at the worn area which resulted in a larger number of contacts between counterpart surfaces. In addition, increasing in the normal load resulted in a considerable increment in the values of µ and Ws. Filler treatment with hot alkali solution (1 to 9 wt% concentration) showed that both µ and Ws reached their minimum values at 5 wt% alkali concentration due to improved interfacial bonding between the filler and matrix. Finally, a relatively small amount (0.2 wt%) of well-dispersed MWCNTs within the wood flour polyester composite was found to be capable of improving the tribological behavior of such hybrid composites.

Joining of SiO2 ceramic and TC4 alloy by nanoparticles modified brazing filler metal

Nano-Al2O3 particles modified AgCuNi filler was adopted to braze the SiO2 ceramic and TC4. The effects of filler size as well as the brazing temperature on the interfacial microstructure and mechanical property of the joints were investigated. Nanoscale filler reduced the phases dimension and promoted the homogeneous distribution of microstructure, obtaining a higher joint strength when compared to microscale filler. The increase of brazing temperature made the accelerating dissolution and diffusion of Ti, which promoted the increase of thickness of Ti4O7 + TiSi2 layer adjacent to SiO2 ceramic and diffusion layer zone nearby TC4 alloy. The hypoeutectic structure was produced in the brazing seam due to the high Ti content. The maximum shear strength of ∼40 MPa was obtained at 950 °C for 10 min.

Development of mechanical properties in dental resin composite: Effect of filler size and filler aggregation state

The aim of this work was to study the effect of filler size and filler aggregation state on the mechanical properties of dental resin composites evaluated at filler loadings between 20 wt% and up to 76.5 wt%. Non-aggregated silica nanoparticles (SiNPMPS) (80 nm), doughnut-shaped silica nanoclusters obtained by spray drying (SDSiNPMPS) (3.5 μm) and amorphous barium-alumina borosilicate microparticles (BaAlBoSiMPS) (1.0 μm), functionalized by 3-methacryloxypropyl trimethoxysilane (MPS), were the fillers incorporated into resin matrix dental composites composed of triethylene glycoldimethacrylate (TEGDMA), urethane dimethylacrylate (UDMA), bisphenol A polyethylene glycol diether dimethacrylate (Bis EMA), and bisphenol A glycidyl methacrylate (BisGMA) (0.3:0.7:1:1 weight ratio, respectively). The mechanical properties developed in the resin composites were correlated with the formation of percolated-like particle networks, as observed by scanning electron microscopy (SEM), and volume fraction percolation thresholds (ϕc) calculated from a percolation model. Resin composites with non-aggregated SiNPMPS showed an apparent percolation threshold ϕc = 0.15 (i.e. 27 wt%); above this filler concentration and up to a volume fraction of particles (ϕP) of 0.24 (i.e. 40 wt%) there was an increase in the flexural modulus and the compressive strength of the resin composite. However, a further increase in filler concentration diminished all its mechanical properties due to a decrease in the particle-matrix adhesion strength, demonstrated by the increase in surface roughness and fracture steps as observed by SEM images. On the other hand, a resin composite filled with doughnut-shaped silica nanoclusters (SDSiNPMPS) showed an apparent percolation threshold ϕc = 0.41 (i.e. 60 wt%); increasing filler loading over this concentration generated an improvement in its mechanical properties, except the flexural strength also due to a decrease in the particle-matrix adhesion strength. The resin composites obtained with amorphous individual BaAlBoSiMPS microparticles (1.0 μm) and BaAlBoSiMPS microparticle aggregates (ca. 40.0 μm) showed an apparent percolation threshold ϕc = 0.41 (i.e. 64 wt%) that promoted an improvement in all their mechanical properties. SEM image of BaAlBoSiMPS resin composite at high filler loading (≥ 60 wt%) showed a decrease in fracture steps and no presence of voids, indicating a better adhesion between amorphous BaAlBoSiMPS particles and the polymeric matrix, which explains the improvement of mechanical properties. Resin composites filled exclusively with silica doughnut-shape nanoclusters or amorphous BaAlBoSiMPS microparticles could develop mechanical properties similar to or even better than those obtained by mixing nanofillers with spherical nanoclusters, which are commonly used in commercial resin composites.

Filler size effect on fracture behavior of milled-fiber composites

Quasi static flexural and fracture tests are conducted on anhydride rich epoxy system reinforced with three different sizes of milled glass fibers, 1/32”, 1/8” and 1/4”. The matrix is prepared by mixing DGEBA resin and MTHPA hardener in equal ratio by weight whereas the 16 μm diameter slender fillers are reinforced at 3% volume fraction. It is observed that the flexural modulus and fracture toughness increase monotonically with increase in the slender filler size whereas the flexural strength of composites decreases with increasing filler lengths. The largest fillers enhance the flexural modulus and fracture toughness of neat epoxy system by ~ 1.3 and ~ 3 times, respectively. It is suggested that in the presence of large slender fillers, fiber fracture is the dominant toughening mechanism whereas the smaller size fibers are subjected to pull-out in the fracture process

Recycled Natural Rubber Latex Gloves Filled CR Rubber: The Effects of Filler Size and loading

The effect of (rNR-G) as a filler with different size and loading on curing characteristics (scorch time, cure time, minimum and maximum torque) and physical properties (swelling test, crosslink density and hardness test) on rNR-G/CR (chloroprene) were investigated. Two sizes of fillers (fine size and coarse size) were utilized with different loadings (0, 5, 10, 15, 20 and 25 phr) for each size. The results indicated, the optimum cure characteristics for the (rNR-G)/CR compounds were at 5 phr for the fine size, meanwhile, for the physical properties, the hardness increased with the increasing of filler loading, and gave higher values in the case of fine size.

Polypropylene Filled With Glass Spheres in Extrusion‐Based Additive Manufacturing: Effect of Filler Size and Printing Chamber Temperature

AbstractA challenge in extrusion‐based additive manufacturing of polypropylene (PP) filled with spherical particles is the combination of decent processability, excellent warpage control, and the retention of the tensile strength of neat PP. This study addresses this issue by adopting two approaches. Firstly, different size fractions of borosilicate glass spheres incorporated into PP are compared. Secondly, the temperature of the printing chamber (TCh) is varied. The effects of these features on the thermal, crystalline, morphological, tensile, impact, and warpage properties of 3D‐printed parts are examined. Smaller glass spheres (&lt;12 µm) are found to be superior to larger fractions in all investigated aspects. Notably, the corresponding composites show higher tensile strengths than neat PP. An increase inTChresults in a more homogeneous temperature distribution within the printing chamber and promotes annealing during printing. Consequently, the dimensional accuracy of printed parts is improved. Additionally, β‐crystals and larger spherulites are formed at a higherTCh.

Effects of Filler Size on the Mechanical Properties of Polymer-filled Dental Composites: A Review of Recent Developments

Effects of Filler Size on the Mechanical Properties of Polymer-filled Dental Composites: A Review of Recent Developments

Synergistic effects of filler size on thermal annealing-induced percolation in polylactic acid (PLA)/graphite nanoplatelet (GNP) nanocomposites

Two graphene-based nanofillers of different sizes were melt mixed with polylactide acid (PLA). Composite films based on graphite nanoplatelets (GNPs) with the largest lateral size showed superior electrical conductivity and a lower percolation threshold after melt-compounding and hot-pressing at room temperature. However, upon annealing in the melt, composites based on GNPs with the smallest lateral size displayed significantly improved electrical conductivity and a decrease in percolation threshold as a result of dynamic percolation while composites based on large GNPs showed hardly any change in conductivity and percolation threshold. Hybrid filler systems based on 5 wt% GNP with variable small/large GNP filler ratios displayed synergistic effects in the formation of a conductive network during thermal annealing, and an optimum filler ratio of 50/50 was found to achieve the highest conductivity after annealing. This annealing-induced increase in particle connectivity for composites based on 5 wt.% hybrid small/large GNPs was also reflected in rheological measurements by the manifestation of a plateau in the storage modulus at low frequencies after annealing while such phenomenon was not observed for nanocomposites solely based on either small or large GNPs at similar loadings.