Function Of Filler Content Research Articles

Magnetorheological response of Permalloy@ styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene elastomers as a function of filler concentration

AbstractDeveloping advanced magnetorheological elastomers (MREs) with a range of specific characteristics is essential for matching the growing demands from a wide spectrum of applications such as automotive, healthcare, sensors, and actuators. However, the compatibility problems between constituents and the low magnetorheological (MR) effect have limited their performance and integration into actual applications. Here, a novel MRE consisting of styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and Ni‐rich Permalloy (Ni80Fe17Mo3) has been developed with remarkable functional properties. The correlation between the filler concentration and microstructural, mechanical, thermal, magnetic, and MR properties is reported. The incorporation of Ni‐rich Permalloy has a reinforcement effect in the polymer matrix and leads to an improvement of the thermal stability. Further, the saturation magnetization and remanence of the composites increase with increasing filler content. In particular, the saturation magnetization increases from 14.3 to 41.9 A m2/kg, and the remanence from 1.2 to 4.0 A m2/kg when the concentration increases from 20 to 60 wt%. Finally, the MR effect of composites with 20, 40, and 60 wt% filler content is 8%, 15%, and 35%, respectively. A magnetic dipole interaction model is used to discuss the MR effect and a relation between the MR effect and the main parameters affecting it is proposed. Importantly, the obtained MR values are higher when compared with related composites for the same magnetic content, and for the same or similar polymeric matrices, demonstrating the suitability of the developed materials for the fabrication of high‐response functional MR devices.

Preparation and characterisation of polymer blends reinforced with nano-ZnO and study the thermal and electrical properties for industrial applications

Binary blends of unsaturated polyester (70%) and nitrile rubber (NR) (30%) and their composites are prepared. Zinc oxide nanoparticles (ZnONPs) were used as a filler in the hand-lay method. ZnONP weight ratios ranged from 0 to 3 ​wt.%. The ZnONPs were characterised using techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) to examine their crystalline structure and shape. The thermal and dielectric properties of the samples were examined as a function of filler content. Additionally, the theoretical and experimental densities of the nanocomposites were examined using the mixing rule and Archimedes’ principle, respectively. The thermal conductivity and diffusivity values exhibited variations between increasing and decreasing trends as the filler concentrations increased. Among all samples tested, the one containing 2.5% ZnONPs demonstrated the highest thermal conductivity and the lowest diffusivity when compared to the pure blend. As the ZnONP weight ratio increased, the corresponding dielectric constant value rose linearly, while the resistivity decreased linearly. Thermogravimetric analysis (TGA) revealed a significant improvement in the level of char yield and thermal stability of nanocomposites with increasing ZnONP concentration in the matrix.

Silicone rubber composite reinforced by bismuth tungsten oxide as an effective gamma ray protective materials

The workers’ continual exposure to nuclear radiation makes it indispensable to invent and form lightweight materials as flexible radiation shields. So, in this article, silicone rubber SR inlaid with varying filler ratios of bismuth tungsten oxide Bi2(WO4)3 was produced. Mechanical properties, hardness, tensile strength, tensile modulus, and elongation at break, of the SR/Bi2(WO4)3 composites were studied as a function of filler concentration and irradiation dose. The Bi2(WO4)3 filler enhanced these properties. On the other hand, with augmentation of irradiation dose, hardness of the SR/Bi2(WO4)3 composites increased and the other mechanical properties decreased. Under accurate geometry conditions, the gamma ray attenuation coefficients of the SR/Bi2(WO4)3 composites were studied at the energies 661.66, 1173.24, and 1332.5 keV. The attenuation parameters, linear attenuation coefficients mu, experimental mass attenuation coefficients {sigma }_{exp.}, and half value layer HVL results revealed that the attenuation ability of the composite was enhanced with the increase of Bi2(WO4)3 concentration. The results of {sigma }_{exp.} were confirmed through their congruence with the theoretical calculations of mass attenuation coefficients {sigma }_{theo.} Considering the merits of lightweight, high mechanical properties, superior attenuation ability, and appropriate irradiation resistance, the produced SR/Bi2(WO4)3 composite is suitable as durable and flexible gamma ray shields such as anti-radiation coats, gloves, shoes.

2D Fillers Highly Boost the Discharge Energy Density of Polymer‐Based Nanocomposites with Trilayered Architecture

AbstractA new class of trilayered architecture blends polymer‐based nanocomposites with excellent discharge energy densities (Udis) is presented. The preferable energy storage performance is achieved in sandwich structured nanocomposite (PIP) films. The outer polarization‐layers (P‐layer) of the PIP film are composed of Sr2Nb2O7 nanosheets (SNONSs) as well as boron nitride nanosheets (BNNSs) dispersed in poly(vinylidene fluoride) (PVDF)/ polymethyl methacrylate (PMMA) blend polymer matrix (BPM) to provide high dielectric constant, while PVDF/PMMA with BNNSs forms the central insulation‐layer (I‐layer) to offer high dielectric breakdown strength (Eb) of the resulting nanocomposite films. The dielectric performance, Weibull breakdown strength, and energy storage capacity of single and multi‐layer nanocomposites as a function of filler content are systematically examined. The evolution of electric trees is simulated via finite element methods to verify the experimental dielectric breakdown results in single layer nanocomposite films. The PIP film with optimized filler content displays a discharge energy density of 31.42 J cm−3 with a significantly improved charge–discharge efficiency of ≈71% near the Weibull breakdown strength of 655.16 MV m−1, which is the highest among the polymer‐based nanocomposites under the equivalent dielectric breakdown strength at present.

Water Absorption, Thermal and Microstructural Properties of Plastic Composites Developed from Isoberlinia Doka Wood Sawdust and Polystyrene Wastes

In this study, the water absorption, thermal conductivity and microstructural properties of Isoberlinia doka wood sawdust polystyrene composite, synthesised by the hand layup method, were investigated as a function of filler content. It was observed that the thermal conductivity increased with increase in the fibre loading. The thermal conductivity value obtained for the synthesised composite samples was an average of 0.147 Wm−1 k−1. The composites absorbed water until equilibrium was achieved on the 9th day. The maximum water absorbed at equilibrium for the composite with filler concentration of 10, 20, 30 and 40 wt% was 36.46, 40.34, 57.53, 128.65 wt%, respectively. The mass transfer kinetics revealed that water sorption rate increased at higher filler composition due to the increased interstitial pores and gaps that are exacerbated by increased fibre loading. The mass transfer kinetic constants for the composite with filler concentration of 10, 20, 30 and 40 wt% were 0.738, 0.661, 0.996 and 1.155 day−1. Microstructural analysis revealed that the dispersion of wood sawdust particles improved as the fibre loading increased.

Fabrication, characterization, dielectric properties, thermal stability, flame retardancy and transport behavior of chlorinated nitrile rubber/hydroxyapatite nanocomposites

This work focused on the preparation of chlorinated nitrile rubber (Cl-NBR)/hydroxyapatite (HA) nanocomposites by an open two-roll mixing mill. The formation of nanocomposites was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The dielectric properties and flame retardancy of polymer nanocomposites were analyzed with special attention to the loading of HA nanoparticles. Diffusion and permeation properties of petroleum solvents through the prepared Cl-NBR/HA composites were also investigated in detail as a function of filler content, different temperatures and nature of solvent. The incorporation of HA in Cl-NBR has been endorsed by FTIR analysis. The XRD showed the crystalline peaks of HA in the polymer chain. SEM images revealed that the nanoparticles were uniformed distributed in the polymer network with spherically shaped particles. TGA results indicated that the thermal stability of nanocomposites was remarkably higher than the pure Cl-NBR and the thermal stability increases with the loading of nanoparticles. The dielectric study observed a decreasing dielectric constant with increasing frequency, and the maximum property was obtained for 7 phr HA filling in Cl-NBR. The flame resistance of the polymer composites was greatly enhanced by the incorporation of nanoparticles. The diffusion, sorption and permeation constants were found to decreased with increase in HA content. The solvent uptake decreases with the size of the penetrant molecules, and the mechanism of transport of Cl-NBR composite was anomalous in nature. The enthalpy and entropy changes of the nanocomposites were analyzed from the diffusion data. The composite containing 7 phr HA sample showed higher dielectric properties and better solvent resistance properties.

Valorization of post-consumer polythene water sachet and Parinari polyandra shell residue for composites production

Mitigation of the environmental burden associated with indiscriminate disposal of post-consumer low density polyethylene (LDPE) packaging material is receiving attention in recent times. There is a need to search for alternative reuse of the accumulating plastic wastes constituting pollutants in our environment. This work involves the preparation and evaluation of the bio-composite samples from post-consumer low density polyethylene water sachets and parinari fruits shell. Biocomposite samples of filler percentages 10, 20 and 30% were produced. The mechanical properties of the samples were determined as function of filler content and particle size according to ASTM standards and confirmed with SEM. The samples had desirable hardness strength of 4568.9 N/mm2 and desirable biodegradability for 30% filler weight of particle size 4 mm. The biocomposite samples exhibited desirable impact (51.75 kJ/m2), tensile (10.02) and flexural strength (18.23 N/mm2) with the 10% weight samples. The findings in this study suggest that post-consumer LDPE wastes can be valorized by conversion to biocomposites using biomass wastes such as parinari shell as cheap value-addition material, providing a cheap potential waste management method for solving the global plastic waste crisis.

Application of mineral filler in surface layer of three-layer particle board and its effect on material properties as a function of filler content

ABSTRACT Addition of mineral filler in the surface layer of three-layer particle board and its influence on material properties was studied as a function of filler content. Three-layer particle board with a density of 700 kg m−3 and 0, 10, 20, and 40% weight fraction (wt-%) of calcium carbonate filler in surface layers was produced in laboratory scale using urea formaldehyde as resin. The effect of inorganic filler on elastic and strength properties, dimensional stability and formaldehyde emissions was investigated. The results demonstrated that the addition of filler in amounts up to 10 wt-% in surface layers does not significantly affect mechanical properties. Further increase in filler addition above 10 wt-% resulted in a nearly linear decrease in bending properties and increase in water uptake, however did not significantly affect dimensional stability and formaldehyde emissions.

Frontal Polymerization of a Thin Film on a Wood Substrate

Frontal polymerization has been explored as a technique to form two-dimensional thin films (<0.5 mm) on wood. We used trimethylolpropane triacrylate with a thermal free-radical initiator. The viscosity of the resin was adjusted by incorporating fumed silica within the formulation. As filler materials, either calcium carbonate or graphene nanoplatelets was used to evaluate the effect of filler type and content on front propagation. We observed that resin viscosity and film thickness critically affected the qualitative and quantitative propagation of the thermal front resulting in the formation of the coating. A workable coating was formed at a viscosity of 0.6 Pa·s, which was obtained when 3 phr (parts per hundred resin) of fumed silica was used in the resin formulation. Wet film thickness for this resin system was also found to have a limiting value, and full propagation of the front to result in a conformal coating required at least 15 mil (1 mil = 25 μm) of wet film thickness. Filler materials affected film propagation as a function of particle size and thermal properties. While 15 phr calcium carbonate could be incorporated with the resin, only 5 phr graphene nanoplatelets could be loaded within the matrix to ensure complete propagation of the front. Interestingly, for graphene fronts, velocity and temperature reduced systematically as a function of filler content. Filler type and content affected porosity and roughness of the coating, which was quantified by computerized tomography to understand the relationship between porosity and adhesion of the coated film with the wood substrate.

Mechanical properties of wollastonite reinforced thermoplastic composites: A review

AbstractWollastonite is a functional filler that has great potential to be used in thermoplastic composites, replacing more expensive reinforcement such as glass fiber. Wollastonite‐reinforced polymer composite materials have attracted the attentions from research field and industries due to their biocompatibility and reinforcing ability in polymers. Due to the relatively high aspect ratio and hardness, wollastonite is able to improve the tensile and flexural strength of polymer composites. Many researches have been conducted to determine various properties of wollastonite reinforced polymer composites such as mechanical, flammability, thermal, and tribological properties in order to explore their potential in various applications. This review will focus on mechanical properties of wollastonite reinforced thermoplastic composites. Overall, it can be concluded that the properties of wollastonite‐filled polymer composites are the function of filler content, adhesion interactions of wollastonite particles with polymer matrix, size and shape of wollastonite particles. Further research and development are needed to widen its application, and these include the use of nano‐size wollastonite which can be produced synthetically as functional filler in thermoplastics.

Modeling the Thermal Conductivity Inhomogeneities of Injection-Molded Particle-Filled Composites, Caused by Segregation.

Many applications require new materials that have good thermal conductivity, are electrical insulators and can be processed easily and with relatively little energy. A new innovative solution for this problem is thermally conductive composites, which can replace metals in many cases. Many papers have focused on the prediction of their thermal conductivity. At the same time segregation has to be taken into account in the case of composites because it affects the distribution of thermally conductive particles, and thus local thermal conductivities. In this paper, we examined and modeled segregation during injection molding and its effect on thermal conductivity. We injection-molded samples from polypropylene with glass beads of different sizes and analyzed their filler content as a function of the flow path. We described the distribution of the filler with a mathematical model. Using this, we created a new, segregation-dependent model that describes the local thermal conductivity of polymer composites as a function of filler content with great accuracy.

Carbon based polyimide nanocomposites thin film strain sensors fabricated by ink-jet printing method

Carbon-nanotube (CNT) and graphene-nanoplate (GNP) are two popular fillers to fabricate carbon-based nanocomposite devices. In this study, CNT-polyimide (PI) and GNP-PI nanocomposite thin film piezoresistive strain sensors were fabricated on flexible polyimide substrates and their electromechanical properties were characterized. The percolation thresholds were first determined for the two nanocomposites by investigating the volumetric conductivity as a function of filler concentration. Inkjet printing technique was employed to produce the nanocomposite devices with filler concentrations around the percolation threshold. The interdigital electrodes pre-deposited on the substrate were used for the electrical measurement of the devices. The piezoresistive sensitivity of the nanocomposite strain sensors was characterized by uniaxial tensile tests. The optimal compositions of 1.8 wt% CNT-PI and 1.4wt% GNP-PI nanocomposites were suggested for maximum gauge factors of 3.5 and 26, respectively. The temperature coefficients of resistance (TCR) for the fabricated nanocomposite thin film strain sensors were also characterized. The results demonstrate that GNP-PI nanocomposite strain sensors exhibit higher strain sensitivity than the CNT-PI counterpart. Temperature compensation is therefore necessary in practical applications of these nanocomposite strain sensors.

Microwave dielectric properties and Targeted heating of polypropylene nano-composites containing carbon nanotubes and carbon black

The complex dielectric constants of three polypropylene (PP) composite samples were measured at microwave frequency ranges of X (8.2–12.4 GHz) and Ka band (26.5–40 GHz), and as a function of filler content. Three types of carbon filler materials – pristine multiwall carbon nanotubes (p-CNTs), functionalized multiwall carbon nanotubes (f-CNTs), and carbon black (p-CB) were investigated. Attenuation constant for each composite was calculated, based on its measured complex dielectric constant, to highlight the importance of studying frequency dependent performance of composite materials for microwave heating. Most of the reported works for polymer composite heating using microwave power, have been conducted using commercial microwave ovens operating at 2.45 GHz. The results of this investigation for the CNT-composite samples indicate the importance of frequency optimization for creating maximum heat generation. The composite samples were also irradiated using low-power microwave energy at 2.6, 10 and 28 GHz and using a thermographic camera their relative capabilities for producing heat was investigated. The heating results corroborated those of the dielectric property measurements.

Characterization of Highly Filled PP/Graphite Composites for Adhesive Joining in Fuel Cell Applications

In order to evaluate the suitability of graphite composite materials for use as bipolar plates in fuel cells, polypropylene (PP) was melt compounded with expanded graphite as conductive filler to form composites with different filler contents of 10–80 wt %. Electrical resistivity, thermal conductivity, and mechanical properties were measured and evaluated as a function of filler content. The electrical and thermal conductivities increased with filler content. Tensile and flexural strengths decreased with the incorporation of expanded graphite in PP. With higher graphite contents, however, both strength values remained more or less unchanged and were below the values of pure PP. Young’s-modulus and flexural modulus increased almost linearly with increasing filler content. The results of the thermogravimetric analysis confirmed the actual filler content in the composite materials. In order to evaluate the wettability and suitability for adhesive joining of graphite composites, contact angle measurements were conducted and surface tensions of composite surfaces were calculated. The results showed a significant increase in the surface tension of graphite composites with increasing filler content. Furthermore, graphite composites were adhesively joined and the strength of the joints was evaluated in the lap-shear test. Increasing filler content in the substrate material resulted in higher tensile lap-shear strength. Additionally, the influence of surface treatment (plasma and chemical) on surface tension and tensile lap-shear strength was investigated. The surface treatment led to a significant improvement of both properties.

Properties of radiation vulcanised natural rubber latex (RVNRL)–graphene nanocomposites

Graphene-related materials such as graphene oxide (GO)/exfoliated graphene oxide (XGO) and reduced graphene oxide (RGO) recently achieved much interest in nanocomposite research. In this study, we report the synthesis of RGO by a green route, and its efficacy as a potential filler for radiation-vulcanised natural rubber latex (RVNRL) was explored. The synthesised XGO and RGO suspensions were characterised. The mechanical, morphological and electrical properties of the RVNRL-XGO/RGO nanocomposites were evaluated as a function of filler content. The percolation threshold of the RVNRL-RGO composite was 0.1 wt%. Compared with gum RVNRL, significant improvements in tensile strength and elongation at break were obtained for RVNRL-XGO nanocomposites at 1 wt% XGO loading, indicating increased polymer–filler interaction. The morphological results showed aggregation of filler particles at a concentration of 1.25 wt%.

Mechanical and flow properties of blends of polypropylene and powder coating recyclates with and without addition of maleic anhydride

AbstractIn this research, from 10% to 40% by weight of hydrolyzed powder coating recyclates were used as filler in polypropylene (PP). Firstly, PP and filler were dry‐mixed and then, in order to get a homogeneous mixture, were extruded at 180°C. The resulting compounds were cooled and granulated, and by use of an injection molding machine at 180–200°C, standard tensile test bars were produced. Tensile stress, three‐point bending strength, and izod impact strength of these specimens containing different types of filler and different filler concentrations were tested. The results are presented, and the effects of type and content of hydrolyzed powder coating waste on the mechanical properties of polypropylene are discussed. Also, the change in melt flow index of polypropylene as a function of filler content is analyzed. Furthermore, the bonding mechanism of filler and matrix material was examined by electron microscopy.

Simplification and development of McLachlan model for electrical conductivity of polymer carbon nanotubes nanocomposites assuming the networking of interphase regions

This paper simplifies and develops the conventional model suggested by McLachlan for electrical conductivity of polymer CNT nanocomposites. The original model expresses the conductivity as a function of filler concentration, filler conductivity, filler percolation threshold and an exponent. However, this model is developed by considering the roles of interfacial tension between polymer matrix and nanoparticles, tunneling distance between adjacent nanotubes, interphase regions around nanoparticles and waviness of CNT. The experimental results of conductivity for some samples and the analysis of the effects of various parameters on the conductivity evaluate the developed model. The predictions demonstrate fine agreement with the experimental results and the parameters show acceptable roles in the conductivity of nanocomposites. A large tunneling distance significantly decreases the conductivity to zero. Likewise, the higher and slighter surface energies of the polymer matrix and filler, respectively cause an improved conductivity. A thin interphase produces very low conductivity, while a thick interphase and a low waviness improve the conductivity.

Enhanced Dielectric and Mechanical Properties of Natural Rubber Composites Filled with Gold Nanoparticles

In this work, we present the novel robust material, modified natural rubber (NR) composites filled with gold nanoparticles (AuNPs). To investigate its outstanding properties, dielectric, electrical and mechanical properties of NR and modified NR composites filled with gold nanoparticles (AuNPs) were studied. The NR and all composite films were prepared by using solution casting method. The size of the synthetic AuNPs was analyzed by Transmission Electron Microscope (TEM) technique. The dispersion of AuNPs fillers within the NR matrix was investigated by scanning electron microscopy (SEM). Dielectric and electrical properties of NR composites were analyzed as function of filler concentration and frequency in a range of 100-105 Hz, observed with the LCR analyzer. Elastic modulus of all samples was evaluated by a strain gauge set up. It was found that the dielectric constant is inversely related to the frequency. Moreover, the dielectric constant and the electrical conductivity strongly increase in proportional to the AuNPs filler content. In comparison at AuNPs concentration of 0.0010% by weight, it was observed that the dielectric constant of NR composites is eight times larger than the pure NR, while the mechanical properties of the NR composites slightly increase in proportional to the AuNPs. As consequence, the interfacial surface area significantly affects the electrical and mechanical properties of those NR composites.

Electrical Transport Properties of Carbon Nanotube/Polyester Polymer Composites

The electrical properties of polyester/carbon nanotube composites have been investigated within the frequency range of 102 and 106 Hz and temperature from 200 to 360 K. This paper reports the electrical conductivity behavior as a function of filler content, frequency, and temperature. The electrical conductivity of the composites obeys the universal Jonschers’ power law and leads to the parameter ss with values as 0.12< s < 0.93. The impedance data is found to fit well with Mott conditions of variable range hopping conduction. The values of Mott’s temperature, density of states at the Fermi energy, range of hopping, and hopping energy are also presented in this work.

Nanoindentation study on mechanical properties and curing depth of dental resin nanocomposites

Mechanical properties and curing depth of bisphenol‐α‐glycidyl methacrylate/triethylene glycol dimethacrylate‐based dental composites were systematically investigated by site‐specific nanoindentation tests. Effects of filler (20‐nm silica nanoparticle) content on the nanohardness and elastic modulus of the composites were studied in comparison with micromechanics theoretical models. Results showed that the incorporation of the silica nanoparticles at low contents (up to 5.66 vol%) significantly increases the hardness and elastic modulus of the dental composites by up to 65% and 30%, respectively. It was found that the Counto model gave good predictions for the composite modulus as a function of filler content. For the specific composites studied here, the depth of cure increases approximately linearly with the filler content, which may be ascribed to the stronger reinforcement effect of the silica nanoparticles on the dental composites at a higher particle content. These results combined demonstrate the effectiveness of silica nanoparticles as the reinforcement for dental restorative materials even at small volume fractions. POLYM. COMPOS., 40:1473–1480, 2019. © 2018 Society of Plastics Engineers