Volume Ratio Of Filler Research Articles

Synergistic enhancement of dielectric properties of polymer matrix composites by micro‐nano bicomponent ceramics and conductive particles

AbstractBarium titanate (BaTiO3, BT) was co‐doped by solid‐state sintering with niobium pentoxide (Nb2O5) and cobalt trioxide (Co3O4) as dopants. The modified barium titanate containing Nb and Co (BTNC) with larger particle size (0.5–1 μm) and silver powder (Ag) with smaller particle size (25 nm) were co‐filled with polyvinylidene fluoride (PVDF) to prepare (BTNC‐Ag)/PVDF three‐phase composites. The morphology and crystal structure of composites were characterised by scanning electron microscope (SEM) and X‐ray diffraction (XRD), respectively. SEM shows that when the volume ratio of BTNC and Ag in the composite is 4:1, the two fillers have good dispersion in polymer matrix and could intersperse with each other to reduce voids. XRD patterns display that the filling of BTNC and Ag powders was conducive to promoting the enhancement of the diffraction peaks of β phase and γ phase in PVDF. The dielectric properties of the composites are effectively enhanced through the synergistic effect of the micro‐nano bicomponent ceramic BTNC and conductive particles Ag co‐filled polymer PVDF. When the volume ratio of filler (BTNC:Ag = 4:1) to matrix PVDF is 2/1, the dielectric properties of the composite are the best, the dielectric constant reaches 134.1 at 102 Hz and the dielectric loss is 0.04.

Liquid metal-based elastomer heat conduction enhancement enabled by stretching

Liquid metal elastomer composite (LMEC) has high thermal conductivity and low mechanical stiffness compared with that filled with rigid microparticles and presents a wide application prospect in wearable electronics and soft robots. This paper develops a coupled thermal-mechanical simulation model to investigate the thermophysical properties of LMECs, demonstrated by the reported experimental and theoretical results. The impacts of filler deformation capacity and geometry sizes on the heat conduction of the elastomer composite are discussed in detail. The simulation results show that a large strain could enhance the effective thermal conductivity of LMECs, When the liquid metal volume ratio is 40%, the effective thermal conductivity of LMEC with 100% strain (1.2W/mK) is twice as high as that without strain (0.6W/mK). The effects of different fillers on the thermal properties of the composites are investigated. When the strain is 100% and the filler volume ratio is 40%, the effective thermal conductivity of LMEC (1.2W/mK) is much higher than that of copper composite (0.25W/mK) since the liquid metal will deform under a large strain. This work provides some simulation support for the application of LMECs in the fields of biomedicine, thermal management and flexible electronics.

Effect of filler particle characteristics on yield stress and viscosity of fresh sulfur composites

The amount and properties of fillers greatly affect the workability of sulfur composites. In addition, modified sulfur has fluidity only above approximately 115 °C, and its rheology may depend on the temperature. This study aimed to mainly quantify the effects of mixing temperature and filler particle characteristics on the yield stress and viscosity of fresh sulfur composites by applying suspension rheology theory. Sulfur composites containing mineral fillers, such as different blends of fly ash and Portland cement, were examined. The test results revealed that the yield stress of the sulfur composites was influenced by both the type and volumetric ratio of fillers, whereas the viscosity was governed by the specific surface area of filler particles. At 140 °C, the sulfur composites attained a higher yield stress and viscosity than at 120 °C. In addition, the intrinsic viscosity of the sulfur composites was dependent on the filler type and not on its volume ratio. The sulfur composites were well described by conventional yield and viscosity models commonly applied for suspension materials, when the filler volume ratio was less than 30%.

FRACTAL ANALYSIS OF STRUCTURAL AND MECHANICAL CHARACTERISTICS OF AN INTERFACIAL REGION IN EPOXY POLYMER NANOCOMPOSITES

It is shown on the basis of the micromechanical tensile strength model of a polymer composite, that the strength of an interfacial region material in polymer–high modulus filler nanocomposites decreases as its thickness increases, which contradicts the case of adhesion between two polymers, in which the thickness of an interfacial region is linearly dependent on the degree of interfacial adhesion. A fractal model of phase interactions is used to estimate the threshold values of the nanocluster volume ratio of an epoxy polymer matrix and the metal nanoparticles of a filler, with the mechanical stress transfer from the polymer matrix to the filler being weakened upon reaching these values. It is shown that exceeding a threshold value of the filler volume ratio violates the aggregate stability of the filler and reduces the values of the dimensionless parameter of the micromechanical model, which characterizes the degree of interfacial adhesion. With a further increase in the filler volume ratio, the values of this parameter become negative, while the composite strength virtually does not increase.

Cellulose nanofiber/elastomer composites with high tensile strength, modulus, toughness, and thermal stability prepared by high-shear kneading

An aqueous TEMPO-oxidized cellulose nanofiber (TOCN) dispersion and aqueous hydrogenated acrylonitrile-butadiene rubber (H-NBR) latex were mixed with or without applying high shear forces. The TOCN/H-NBR mixtures containing TOCN volume ratios of 0–10.0% were then converted to crosslinked composite sheets with peroxide between the H-NBR molecules by hot-pressing. When the aqueous TOCN/H-NBR mixtures were pretreated with high shear forces, the crosslinked TOCN/H-NBR composites exhibited concomitant high tensile strength, high tensile modulus, high ductility, high storage modulus, and high dimensional stability to temperature. These properties are better than those of H-NBR composites containing single-walled carbon nanotubes or carbon black at the same filler volume ratio. In the crosslinked TOCN/H-NBR comosites prepared with high shear fodrces as pretreatment, electron microscopy images showed that the TOCN elements were homogeneously dispersed in the H-NBR matrix without forming aggregates. Thermal and pulsed NMR analyses of the solvent-extracted residue of the non-crosslinked TOCN/H-NBR composite indicated that characteristic nanostructures formed in the TOCN/H-NBR interfacial phases, which may cause the excellent mechanical and thermal properties of the composite.

Theoretical prediction of dental composites yield stress and flexural modulus based on filler volume ratio

ObjectiveA costly advantageous approach in composites development process is to limit experimental tests by predicting mechanical properties with respect to their filler ratio. Models exist for other fields than dentistry. They have been compared to 3-point bending test experimental results for yield stress, flexural modulus and flexural strength. MethodsFive formulations of the same experimental material were made. They were composed of an organic matrix and different ratios of silanated barium glass particles. The samples were stored in distilled water for 24h at 37°C prior to the 3-point bending test. The Turcsányi model for yield stress was notably investigated, and SEM was used to complete data analysis. ResultsThe yield stress showed reproducible results and a good fit with Turcsányi model with respect to filler ratio. The flexural modulus data are not scattered but did not fit with the existing models. No trend could emerge for flexural strength and strain because of scattering; these properties are more unpredictable. The SEM observations of fracture areas confirm a good matrix-filler interface quality. SignificanceSEM pictures validated the numerical parameter obtained from Turcsányi model. The latter therefore seems to be applicable to dental composites. Firstly, it enables to predict the evolution of the material yield stress without testing all filler ratios. Secondly, this model provides a good way to get micro-information on the matrix-filler interface from macroscopic tests. The discrepancy between flexural modulus results and theory highlighted the necessity to include an “interface quality” parameter in accurate predictive models.

Evaluation of aggregate packing based on thickness distribution of asphalt binder, mastic and mortar within asphalt mixtures using multiscale methods

Aggregate packing is a key factor controlling the durability of asphalt mixtures. Considering the complex system of the aggregate structures, multiscale method was utilized by dividing asphalt mixtures into four scales, including asphalt binder, mastic, mortar and asphalt mixtures. Six asphalt mixtures with different gradation types and nominal maximum aggregate size (NMAS) were prepared and the corresponding mastics or mortars were also designed. Comprehensive image analysis methods, including high-resolution scanning, Scanning Electron Microscope (SEM), and Laser Diffraction Analyzer (LDA), were utilized to obtain the 2D images of asphalt mixtures, mortars and mastics. Then, the distribution curves of the binder within mastics, mastic within mortars, and mortar within asphalt mixtures were calculated and compared. New packing indexes were proposed, such as: expected value (Ebinder) and peak value (Pbinder) of the binder distribution at mastic scale, expected value (Emastic) and peak value (Pmastic) of the mastic distribution at mortar scale, expected value (Emortar) and peak value (Pmortar) of the mortar distribution at mixture scale. By comparing with volumetric parameters, it was found that Ebinder and Pbinder could correlate well with the volume ratio of filler to mastic. Emastic could correlate with the volume fraction of fine aggregate within the mortar, but the Pmastic may also influence by the fine aggregate gradation. The void filled with asphalt (VFA) has weak correlation with both packing indexes, Emortar and Pmortar, which indicates that VFA has limitation for evaluation of the packing properties of asphalt mixtures, and more indexes from the internal structure need to be considered.

Synergistic effect of hybrid stainless steel fiber and carbon nanotube on mechanical properties and electromagnetic interference shielding of polypropylene nanocomposites

This study provides critical insight into the design of nanocomposites and presents both enhanced mechanical and electromagnetic interference (EMI) shielding performance. Polypropylene nanocomposites reinforced with carbon nanotube (CNT) alone, stainless steel fiber (SSF) alone, and a hybrid filler system of SSF and CNT, with 50/50 filler volume ratio but different total filler loadings, were developed via melt-mixing. It was revealed that the hybrid nanocomposites depicted simultaneous enhanced EMI shielding and mechanical performance over single filler composites. The enhanced mechanical and EMI shielding performance of the hybrid nanocomposite was attributed to the bridging of rigid SSFs with flexible CNTs, leading to a robust conductive hierarchical filler network. To characterize and assess the network, standard morphological analysis was performed.

Effects of various factors on the hydrogen isotope separation efficiency of a novel hydrophobic platinum-polytetrafluoroethylene catalyst

The application of platinum supported on polytetrafluoroethylene (Pt/PTFE) as a composite catalyst for the separation of hydrogen isotopes holds much promise but warrants further refinement for improved performance. The objective of the present study was to examine the performance of a new hydrophobic Pt/PTFE catalyst during hydrogen-water exchange-based deuterium separation. The influence of diverse factors such as flow rate, column height, temperature, the volume ratio of filler to catalyst, and flow mode (co-current or counter-current), and so on, on catalytic performance was investigated. The deuterium conversion rate from co-current exchange was superior to that from counter-current exchange. Decreasing the hydrogen flow rate, increasing the feed water flow rate, and decreasing the molar flow ratio of hydrogen to water improved the deuterium conversion rate. In terms of layered filling of the catalyst column, adding more hydrophilic fillers improved the deuterium conversion rate. The characterization results highlight the high catalytic activity of the Pt/PTFE catalyst for hydrogen-water exchange, as well as its high stability in water.

Influence of Resin Viscosity and Filler Volume on Self-Organized Micro Interconnection

The novel selective interconnection using the resin containing low-melting-point-alloy fillers was developed as a high density assembly method of a low-temperature and highly reliable electronic interconnection. By means of the coalescence of fillers and wetting onto the terminal material due to the Laplace pressure of the fillers, self-organization onto the terminals was formed. The influence of the filler volume ratio and resin viscosity on the self-organized interconnecting was investigated by the numerical analysis with a multi-filler dispersion model corresponding to a real process, and was evaluated by using the normalized parameter (self-organization ratio). We clarified the existence of the optimal value of the filler volume ratio. The rate controlling factor transferred from the filler volume to the inflow velocity by the increase of the viscosity.

Bitumen–silica model composites: The role of the filler

AbstractThe storage moduli of bitumen–silica model composites obey a simple relationship: E′ = E′0 + Aϕψ, where ϕ is the filler volume ratio and ψ the bitumen–silica interfacial area for a unit volume of composite. This equation is experimentally varified taking various silicas of different surface areas or chemical surface reactivity. The influence of the interface properties on the mechanical glass transition temperature is also examined.

Mullins Effect in Filler Reinforced Rubber Vulcanizates

In a previous theory expounded by one of the authors on the mechanical and optical analysis of the filler reinforced rubber vulcanizates, the degree of adhesion (1-ζ) was treated as a fixed parameter. When the specimens containing the filler of higher concentration are extended, the degree of adhesion (1-ζ) decreases and the remarkable relaxation (softening) appears in the specimens as shown in Fig. 1.Under the rate theory explained in the paper preceding this report, the hysteresis loops in extension cycles for filler-reinforced vulcanized rubbers are analysed as follows.The present specimens are natural rubber vulcanizates corporated alternately with one of the three species of carbon black, i.e. ISAF (Intermediate Super-Abrasion Furnace), HAF (High Abrasion Furnace), or SRF (semi-reinforcing furnace) and of the two species of non-black, i.e. Hi-Sil (silica) or CaCO3 (calcium carbonate), all these five sorts with various concentrations of X=0 (pure vulcanizate), 0.05, 0.1, 0.15, 0.2, 0.25, (here X denotes the volume ratio of filler to rubber examined). Each specimen was extended to the maximum extension ratio αm=2 for the 1st cycle; for the 2nd, αm=3 and so on. The experimental curves of tension in each extension course, namely αm=2, 3, 4 and 5, are shown in Figs. 2-11. Moreover, the experimental and, theoretical hysteresis curves for αm=3 (48sec) and αm=4 (72sec) in the case of X=0.1 or X=0.2 are shown in Figs. 12-17. Most of the curves for various αm and X are omitted here.It has been proved that according to the above analysis, the hysteresis loops containing the Mullins effect in the filled specimen can be analysed by means of the present theory based on the rate processes, but the details in the phenomena must be expected in future studies. Especially precise examinations of the elementary process in rheology, for instance, about stress relaxation, creep and the rate of recovery and so on, must be made quantitatively and these experiments are now being prepared.