Filler Weight Fraction Research Articles

Estimating the mechanical properties of hydrating blended cementitious materials: An investigation based on micromechanics

The hydration model of Parrot & Killoh (1984) has been extended to blended cements and coupled to a micromechanical scheme similar to that of Pichler & Hellmich (2011) to estimate the Young modulus and the compressive strength of cementitious materials as a function of time. A finite aspect ratio of 7 is introduced to describe the shape of the hydrates and improve the estimate of the early age strength by the micromechanical scheme. Furthermore, accounting for the stress fluctuations in the cement paste partly explains the fact that the compressive strength of a concrete can be lower than that of its cement paste. Finally, the estimated physical properties are compared to numerous experimental measurements from the literature and new experimental measurements on blended cement pastes featuring significant weight fractions of limestone filler, fly ash or silica fume. It is shown that the present model slightly overestimates the dilution effect.

Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites

Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction [10% and 50%]. These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources [241Am, 133Ba, 137Cs, and 60Co]. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652gcm−3 for 50wt% of PbO NPs. Linear attenuation coefficients (µ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.

A comparative study between epoxy/Titania micro‐ and nanoparticulate composites thermal and mechanical behavior by means of particle–matrix interphase considerations

The aim of the present study is to examine and compare the thermal and mechanical properties of epoxy resin/TiO2 particle microcomposites (0.2 μm) and nanocomposites (21 nm). Composite materials consisting of epoxy resin reinforced with different amounts of TiO2 microparticles (1, 5, 10, 15, and 20% wt) and TiO2 nanoparticles (0.5%, 1%, 3%wt) were prepared. The thermal and mechanical properties of the manufactured composites were investigated and compared through differential scanning calorimetry (DSC) and three‐point bending tests (3PB). Lipatov's Theory was then applied on the DSC results, thus leading to the calculation of the particle‐matrix interphase thickness which was correlated to experimental findings. The glass transition temperature (Tg) of the materials was obtained and the effect of the grain size on the measured Tg values was investigated. The data obtained from DSC tests for both micro‐ and nanoinclusions when normalized with respect to the specific surface area of the particles, resulted in a single continuous curve describing the normalized phase transition enthalpy variation with filler weight fraction. POLYM. ENG. SCI., 58:1146–1154, 2018. © 2017 Society of Plastics Engineers

The Effect of Weight Fraction, Silanization and Size of Fillers on the Mechanical Properties of an Experimental SiO2 Dental Composite

Background: This research studied mechanical properties of silica-based nanocomposite as a strong restorative material through flexural test method. Objectives: The purpose of this study was to evaluate the effect of weight fraction, silanization and filler size on the flexural properties of silica-based dental nanocomposite. Methods: The prepared composites were made of light-cured copolymer based on Bisphenol A glycolmethacrylate (Bis-GMA) and Triethylene glycoldimethacrylate (TEGDMA) at proportion of 50:50 which reinforced by silica filler. The effect of silanization and weight fraction of the filler was studied with samples containing 10 wt% (n (10)), 20 wt% (n (20)) and 30 wt% (n (30)) nanosilica filler. Samples silanized with (γ-MPS) were also tested. Flexural properties were evaluated with Three-Point Bending test. Flexural strength of the nano SiO2 based composites were also compared to micro silica glass composites. Flexural data were analyzed with one-way analysis of the variance. Results: The sample with 10 wt% (n (10)) had equal strength as the sample with 30 wt% (n (30)) nanosilica filler. Modulus of the sample n (30) was higher than the other samples, but its toughness was significantly lower. Silanization had not expected positive effect on the flexural properties. Conclusions: Adding low amount of nanosilica improved mechanical properties of the resin composite. Silanization of the particles enhanced workability of the paste, but mechanical properties decreased significantly. Reduction in the size of the filler to nano scale caused better flexural strength in comparison to micro glass silica composites.

Ternary hybrid nanoparticles of reduced graphene oxide/graphene-like MoS2/zirconia as lubricant additives for bismaleimide composites with improved mechanical and tribological properties

To develop low friction coefficient and high wear resistance composites, the ternary hybrid nanoparticles consisting of reduced graphene oxide (rGO), graphene-like MoS2 and ZrO2 with active amino groups (NH2-rGO/MoS2/ZrO2) were successfully prepared through a facile and effective one-pot hydrothermal method. Subsequently, the bismaleimide (BMI) composites with different weight fraction of fillers were fabricated to enhance the mechanical and tribological properties of BMI resin. The results demonstrate that the layers of MoS2 in the filler can significantly decrease and just a little content of fillers can remarkably improve the mechanical and tribological properties of BMI resin. In particular, the average friction coefficient and volume wear rate of the BMI composite containing 0.4wt.% NH2-rGO/MoS2/ZrO2 can reach the lowest value of 0.15 and 1.5×10−6mm3/(N·m), respectively. The excellent friction-reducing and wear-resistance performances are mainly attributed to the good synergistic effect among the rGO nanosheets, graphene-like MoS2 and ZrO2.

Synthesis and characterization of poly1-hexene/silica nanocomposites

SiO2 nano particles, with particle size of 12 nm, were first modified by substituting surface OH groups with O-hexyl moiety. Then, poly1-hexene/modified-SiO2 composites with various nano-SiO2 weight fractions were prepared by three different methods: in situ, solution, and melt methods and designated as PH-SiO2/Insitu, PH-SiO2/Sol and PH-SiO2/Melt, respectively. PH-SiO2/Insitu samples showed highly uniform particle dispersion up to 30 wt. % of silica while in PH-SiO2/Sol and PH-SiO2/Melt samples agglomeration of the silica nanoparticles occurred for filler contents ≥5 wt. % (i.e. 5, 10, 20 and 30 wt%). In the synthesized composites, the storage modulus significantly increased as high as 20.7 times when compared with neat poly1-hexene. Maximum decomposition temperature (Tmax) and char yield at 600 °C increased with increasing silica level. Rheological results showed that Gʹ> Gʺ over the frequency range, illustrating the elastic behavior of the composite samples. In fact, samples showed the characteristic of a non-Newtonian fluid with a strong shear thinning effect in which η* increased with increasing filler weight fraction. From the results, it can be expected that modified silica could replace silica nanoparticles in polyolefin nanocomposite reinforcement.

Effects of MWCNTs Size on Melt Flow Properties of Polypropylene Composites During Capillary Extrusion

The influence of multi-walled carbon nanotubes (MWCNTs) size including average diameter and length-diameter ratio on the melt flow behavior of polypropylene composites were investigated by means of a capillary rheometer in a temperature ranging from 190 to 230 °C and under apparent shear rates varying from 100 to 4000 s−1. It was found that the melt shear flow approximately obeyed the power law; the values of the melt shear viscosity increased with an increase of the filler weight fraction, while decreased with increasing the average diameter of the MWCNTs; the dependence of the melt shear viscosity on temperature roughly obeyed the Arrhenius equation; the relationship between the melt shear viscosity and the MWCNTs weight fraction was almost linear; the sensitivity of the melt apparent shear viscosity to the MWCNTs weight fraction was weakened with increasing the MWCNTs average diameter.

Recycling of metal sludge wastes for thermal conductive filler via sintering and surface modification

In this work, the waste metal sludge was used to thermal thermally conductive filler after sintering and pulverization. The thermal conductivity of a composite containing metal sludge is only 0.93 W m−1K−1for 60 wt% of filler, which is lower than that of conventional thermally conductive composites containing ceramic fillers at the same filler weight fraction. However, the differences between the thermal conductivity values of the filler materials are reduced when compared at the same volume fraction, due to the high density of the metal filler. Moreover, the thermal conductivity values were similar after surface modification of the filler particles using a silane coupling agent. Hence, the surface modification of metal oxide particles from sludge wastes is a promising method for producing a filler material with reasonable thermal conductivity values compared to conventional ceramic fillers. In addition, this method contributes to reducing an environmental pollution and the production costs of various electronic devices.

Non-isothermal crystallization properties of polypropylene composites filled with multi-walled carbon nanotubes

The influence of the filler size and content on the crystallization behavior of polypropylene (PP) composites filled with three multi-walled carbon nanotubes (MWCNTs) with different sizes was investigated by means of a differential scanning calorimetry (DSC). It was found that the values of the onset crystallization temperature, crystallization peak temperature and end crystallization temperature increased with increasing MWCNT weight fraction and with decreasing filler average diameter; the value of the crystalline degree of the composites increased slightly with increasing filler weight fraction. The values of the crystalline degree of the composites filled with MWCNTs with wide length-diameter ratio and small specific surface area were the lowest when the MWCNT weight fraction was lower than 4%, which can be attributed to weak interaction between the matrix and inclusions due to small specific surface area. Moreover, the total crystallization rate of the composites filled with a small amount of the MWCNTs could be significantly increased.

Improvement of Wear Resistance of UHMWPE by Adding Solid Lubricating Fillers

For estimating effectiveness of adding solid fillers for composites with ultra-high molecular weight polyethylene matrix tribotechnical characteristics of UHMWPE mixture with graphite, molybdenum disulfide and polytetrafluoroethylene were investigated under dry friction, boundary lubrication and abrasion. The optimum filler weight fraction was determined in terms of increasing wear resistance. Permolecular structure and surface topography of wear tracks for UHMWPE composites with different weight fraction of the fillers was studied. The mechanisms of wear of polymeric composites “UHMWPE-graphite”, “UHMWPE-PTFE” and “UHMWPE-MoS2” under dry sliding friction and abrasive wear are discussed.

Valorisation of macroalgae industrial by-product as filler in thermoplastic polymer composites

Poly(lactic acid) composites filled with algae industrial by-product were prepared using melt-mixing process at filler weight fractions of 20, 30 and 40wt%. Algae by-products were after the extraction of alginate (AW) and mixed with diatomaceous earth (DE). The composition and morphology of both fillers were analysed. Composites’ mechanical properties and thermal degradation were investigated as a function of filler type and content. The addition of DE-filler at 40wt% resulted in the increase of Young’s modulus by 20% compared to the neat PLA. The presence of small DE particles improved stress distribution and led to stronger composites as compared with AW-filled. Cold crystallization of PLA was induced by small algae particles. Thermal degradation of all composites started at lower temperatures compared with neat PLA. A glow-wire test was carried out to evaluate the effect of inorganic matter on the ignition of the material.

Viscoelastic behaviour and modelling of nano and micro TiO2 powder-epoxy resin composites

Epoxy resin composites reinforced with different weight fractions of TiO2 micro-particles 0.2μm in size (1%, 5%, 10%, 15%wt) and of TiO2 nano-particles 21nm in size (0.5%, 1%, 3%wt) were manufactured. The quasi-static mechanical properties of both nano-composites and micro-composites were investigated and compared through tensile testing. The experimental results were predicted and the degree of matrix-particle adhesion and particle dispersion were evaluated, by the Property Prediction Model (PPM) developed by the first author. The composites were also subjected to creep-recovery tests as well as to relaxation tests in order to investigate their viscoelastic behaviour. The experiments were carried out at different filler-weight fractions and loading conditions. Non-linear viscoelastic behaviour was observed in all cases and appropriate models were applied in order to describe, and/or predict the viscoelastic behaviour of all materials tested. A fair agreement between experimental results and theoretical predictions was observed for both viscoelastic and static results.

Scale effects in tribological properties of solid-lubricating composites made of ultra-high molecular weight polyethylene filled with calcium stearate particles

Friction properties being influenced by scale effects are simulated in the paper by the example of polymer composite material made from Ultra High-Molecular Weight Polyethylenes (UHMWPE) filled by calcium stearate (C36H70CaO4). Of interest are the composites whose mechanical properties and tribotechnical characteristics do not depend monotonically on filler (inclusions) weight fraction. In order to describe the influence of scale effects onto frictional properties the model based on Reiss averaging (model of "weak phase") is employed. It is also suggested that when gradient elasticity theory is applicable the formal analogy between effective friction coefficient for surface heterogeneous structures and effective mechanical properties (compliances) for heterogeneous material can take place. Theoretical dependence to describe nonmonotonic change of effective friction coefficient versus filler concentration was obtained for the polymer composites under study. The suggested expressions might be useful for the sake of properties prognosis of antifriction polymeric materilas.

Impact and flexural properties of PP/CaSiO3 composites

The effects of filler surface treatment and content on the impact fracture toughness and flexural properties of polypropylene (PP) composites filled with wollastonite (CaSiO3) were investigated. The results showed that the introduction of the filler could toughen and reinforce the PP; the influences of the filler surface treatment on the toughness and strength were significant; the values of the Izod V‐notched impact strength and the Charpy V‐notched impact strength of the composites increased with increasing the filler weight fractions; the values of flexural modulus increased with increasing the filler weight fractions; the flexural strength increased when the filler weight fraction was lower than 10% and then varied slightly. This toughening effect should be attributed to the stress concentration because of strip shape of the filler and to block the development of the notched cracks in the matrix, improving the notched sensitivity to the impact fracture of the PP composites. This study should be helpful to understand the mechanisms of CaSiO3 reinforcing and toughening PP resin. POLYM. COMPOS., 39:398–404, 2018. © 2016 Society of Plastics Engineers

Thermal properties and thermal stability of PP/MWCNT composites

The effects of the filler size and content on thermal properties and thermal stability of polypropylene (PP) composites filled with four different sizes of multi-walled carbon nanotubes (MWCNTs) were investigated through thermogravimetric analysis. The results showed that the values of the decomposition temperature increased with increasing weight fraction and length–diameter ratio of the filler, while increased with decreasing filler diameter. The values of the residues increased approximately linearly with increasing filler weight fraction. The values of maximum mass loss rate decreased roughly with increasing filler weight fraction, while the influence of the filler diameter and length–diameter ratio on the maximum mass loss rate was insignificant. The thermal stability improvement might be attributed to the barrier function of the MWCNTs. This study provides a basis for further development of MWCNTs reinforced polymer composites with desirable thermal properties for potential application as energy materials.

Investigation on microstructural, mechanical and electrochemical properties of aluminum composites reinforced with graphene nanoplatelets

In present study, the microstructure, mechanical and electrochemical properties of aluminum–graphene nanoplatelets (GNPs) composites were investigated before and after extrusion. The contents of graphene nanoplatelets (GNPs) were varied from 0.25 to 1.0wt.% in aluminum matrix. The composites were fabricated thorough powder metallurgy method, and the experimental results revealed that Al-0.25%GNPs composite showed better mechanical properties compared with pure Al, Al-0.50%GNPs and Al-0.1.0%GNPs composites. Before extrusion, the Al-0.25%GNPs composite showed ~13.5% improvement in ultimate tensile strength (UTS) and ~50% enhancement in failure strain over monolithic matrix. On the other hand, Al-0.50%GNPs and Al-0.1.0%GNPs composites showed the tensile strength lower than monolithic matrix. No significant change was observed in 0.2% yield strength (YS) of the composites. However, the extruded materials showed different trends. The 0.2%YS of composites increased with increase in GNPs filler weight fractions. Surprisingly, UTS of composites with 0.25 and 0.50% GNPs was lower than monolithic matrix. The failure strain of the baseline matrix was enhanced by ~46% with 0.25% graphene nanoplatelets. The superior mechanical properties (in terms of failure strain) of the Al-0.25%GNPs composite maybe attributed to 2-D structure, high surface area and curled nature of graphene. In addition, the corrosion resistance of pure Al and its composites reinforced with 0.5 and 1.0wt% GNPs was also investigated. It was found that the corrosion rate increased considerably by the presence of GNPs.

Dielectric, mechanical and electro-stimulus response properties studies of polyurethane dielectric elastomer modified by carbon nanotube-graphene nanosheet hybrid fillers

The typical nano-carbon materials, 1D fiber-like carbon nanotubes (CNTs) and 2D platelet-like graphene nanosheets (GRNs), that have attracted tremendous attention in the field of polymer nanocomposites due to their unprecedented properties, are used as conducting filler to induce a considerable improvement in the mechanical, thermal and electrical properties of the resulting graphene/polymer nanocomposites at very low loading contents. This study deals with the preparation and electro-stimulus response properties of polyurethane (PU) dielectric elastomer films with such 1D and 2D nanocarbon fillers embedded in the polymer matrix. The various forms of carbon used in composite preparation include CNT, GRN and CNT-GRN hybrid fillers. Results indicate that the dielectric, mechanical and electromechanical properties depend on the carbon filler type and the carbon filler weight fraction. Here, it has been also established that embedding CNT-GRN hybrid fillers into pristine polyurethane endows somewhat better dispersion of CNTs and GRNs as well as better interfacial adhesion between the carbon fillers and matrix, which results in an improvement in electric-induced strain. Therefore, the nanocomposites seem to be very attractive for microelectromechanical systems applications.

Graphene nanoplatelet-fly ash based geopolymer composites

Geopolymers show high quasi-brittle behavior because of their ceramic-like characteristics. Recent findings have indicated that graphene can be used as an additive to improve the mechanical properties of composites. In this study, we report the effect of the addition of graphene nanoplatelets (GNPs) on the microstructure and mechanical properties of a fly ash based geopolymer. The GNPs are relatively homogeneously distributed in the matrix of all composites. However, overlapping and agglomerate formation of GNPs was detected by FESEM. The results showed that the compressive and flexural strength of the geopolymer improved by 1.44 and 2.16 times, respectively, when adding 1% GNPs. The introduction of a GNP filler, even at low filler weight fractions, increased the toughness, stress and strain at the first crack and rigidity. Moreover, the wettability decreased with an increase in GNP content.

Comparative studies on physico-mechanical properties of composite materials of low density polyethylene and raw/calcined kaolin

The paper describes the preparation of the composite materials of low density polyethylene (LDPE) as the base mixed separately with raw kaolin and the same calcined at 800 °C under the same variation in weight percentage using single-screw extruder and a mixing machine operated at a temperature between 190 and 200 °C. Some of the mechanical and physical properties such as Young's modulus, elongation at break, shore hardness and water absorption were determined at different weight fractions of filler (0, 2, 7, 10 and 15%). It was found that the addition of filler increases the mechanical properties. Absorption test was done in water at different immersion times for different composites. The degree of water absorption of composite materials was found to decrease with increasing wt% of kaolin filler (0–15%) according to Fick's law. Calcined kaolin produces better mechanical properties than raw kaolin.

Functionalized Composite Coatings Based on Filled Powder Paint Processed in Planetary Ball Mill

Key stages for providing functional properties to polymeric coatings based on powder paints in order to reduce the rate of electromagnetic radiation due to treatment in planetary ball mill were studied. While varying the time of the treatment, as well as the filler weight fraction, the properties of powder mixtures, as well as the structure and properties of the coatings were investigated. Functionality of the coatings was achieved through adding shielding filler (the powder of Cr17Ni2steel) into powder paint and their subsequent treatment in a planetary ball mill.