Single Filler Research Articles

Mechanical properties of talc‐ and (calcium carbonate)‐filled poly(vinyl chloride) hybrid composites

AbstractThe main objective of this study was to investigate and compare the mechanical properties of poly(vinyl chloride) (PVC) composites filled with calcium carbonate (CaCO3), talc, and talc/CaCO3. Talc and CaCO3 with different grades were incorporated into the PVC matrix. To produce the composites, the PVC resin, fillers, and other additives were first dry‐blended by using a laboratory mixer before being milled into sheets in a two‐roll mill. Test specimens were prepared by compression molding, after which the mechanical properties of the composites were determined. Single and hybrid filler loadings used were fixed at 30 phr (parts per hundred parts of resin). Talc‐filled composite showed the highest flexural modulus and the lowest impact strength, whereas uncoated, ground, 1‐μm CaCO3 (SM 90) showed optimum properties in terms of impact strength and flexural modulus among all grades of CaCO3. It was selected to combine with talc at different ratios in the hybrid composites. The impact strength of the hybrid composites gradually increased with increasing SM 90 content, but the flexural and tensile properties showed an opposite behavior. Hybrid (10 phr talc):(20 phr SM 90)‐filled PVC composite reached a synergistic hybridization with balanced properties in impact strength, as well as flexural and tensile properties. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers

Friction and Wear of Polymer Composites Filled by Nano-Particles: A Review

Composites formed by adding nano-scale particles to a polymer matrix results in improving electrical, mechanical, and thermal properties of the composite. Good tribological properties can be obtained for polymers filled with nano-scale fillers compared to that filled with micro-scale particles. The friction and wear resistance of these composites is found to increase with increasing filler concentration. It is also possible to use multi-functional fillers to develop high performance composites which cannot be achieved by using a single filler.

Effects of multiple carbon fillers on the rheology of polycarbonate‐based composites

AbstractAdding conductive carbon fillers to insulating thermoplastic polymers increases the electrical conductivity of the resulting composite, which could allow them to be used in electrostatic dissipative and semiconductive applications. Adding fillers often increases viscosity, which can make the material more difficult to process. In this study, three different carbon fillers [carbon black (CB), carbon nanotubes (CNT), and exfoliated graphite nanoplatelets (GNP)] were studied via three different combinations of two different fillers (CB/CNT, CB/GNP, and CNT/GNP). These filler combinations were studied via three 32 factorial designs, which considered the following loading levels: CB: 0, 2, and 5 wt%; CNT: 0, 1, and 5 wt%; and GNP: 0, 2, and 5 wt%. These composites were compounded, injection molded, and tested for electrical conductivity and steady shear viscosity. CB and GNP exhibited classic filler behavior, increasing the composite viscosity with increased filler loading. CNT acted differently, lowering the composite viscosity with increased filler loading. When CB and GNP were combined, the viscosity increase was additive. When CNT was combined with either CB or GNP, the resultant composite had a lower viscosity than the corresponding single filler composite with equivalent loadings of CB or GNP. This viscosity lowering effect of CNT, even at loadings as low as 1 wt%, allows for increased filler loadings of CB or GNP with little impact on processability. Five different formulations (four containing two filler combinations) could be used for electrostatic dissipative applications and seven different formulations (six containing two filler combinations) may be used for semiconductive applications. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers

Development of compatibilized SBR and EPR nanocomposites containing dual filler system

The study described in this paper is an analysis of the role of a compatibilizer for dispersing organically modified nanoclay in styrene butadiene rubber (SBR) and ethylene propylene rubber (EPR) matrices. The normal mixing of non-polar rubbers and organically modified nanoclay may not lead to improved distribution of the nanofiller in the rubbery matrix. Hence, a polar rubber such as epoxidized natural rubber (ENR) can be used as a compatibilizer for dispersing nanoclay in the non-polar rubber matrices. ENR–organically modified nanoclay composites (EC) were prepared by solution mixing. The nanoclay used in this study is Cloisite 20A. The obtained ENR–nanoclay composites were incorporated in SBR and EPR matrices along with carbon black. The morphological studies proved the intercalation of nanoclay platelets in ENR and further incorporation of EC in SBR and EPR matrices leads to partial exfoliation of nanoclay platelets. A curing study demonstrated faster scorch time, cure time and increased maximum torque for the compatibilized SBR and EPR nanocomposites containing a dual filler system compared to the control. Dynamic mechanical thermal analysis showed increase in storage modulus for the SBR and EPR compounds containing dual fillers compared to rubber compounds containing pure and single filler. The same compounds show substantial improvement in mechanical properties. The tensile fractured surface of the rubber compounds containing single and dual filler observed by scanning electron microscopy, (SEM) showed highly rough and irregular fracture paths, which proved the physical interaction between filler and rubber.

Effects of multiple carbon fillers on the electrical and thermal conductivity and tensile and flexural modulus of polycarbonate-based resins

Adding conductive carbon fillers to insulating thermoplastic polymers increases the electrical conductivity of the resulting composite, which could allow them to be used in electrostatic dissipative and semiconductive applications. In this study, three different carbon fillers (carbon black [CB], carbon nanotubes [CNTs], and exfoliated graphite nanoplatelets [GNPs]) were studied via three different combinations of two different fillers (CB/CNT, CB/GNP, and CNT/GNP). These filler combinations were studied via three 32 factorial designs, which considered the following loading levels: CB: 0, 2, 5 wt%; CNT: 0, 1, 5 wt%; and GNP: 0, 2, 5 wt%. These composites were compounded, injection molded, and tested for electrical and thermal conductivity (TC), and tensile and flexural modulus. All of the single fillers caused a statistically significant increase at the 95% confidence level in composite electrical and TC, and tensile and flexural modulus. Many two filler interactions had a statistically significant effect on composite electrical and TC, and tensile and flexural modulus. For example, when CB and CNT are combined into a composite, the composite tensile modulus is higher than what would be expected from the additive effect of each single filler. Five different formulations (four containing two filler combinations) could be used for electrostatic dissipative applications and seven different formulations (six containing two filler combinations) may be used for semiconductive applications.

Effects of Carbon Black–Carbon Nanotube Complex Fillers on the Properties of Isotactic Polypropylene Nanocomposites

In this study, the reinforcing effects of carbon black (CB) and carbon nanotube (CNT) complex fillers on the properties of isotactic polypropylene (iPP) nanocomposites were investigated using various methods. The surface of the CNTs was modified using a linear alkyl chain in order to create a homogeneous CNT dispersion in the iPP matrix. When the CB content that was incorporated in the iPP matrix increased, the thermal and mechanical properties of the iPP/CB nanocomposites were enhanced. Additionally these enhancements in the properties were similarly induced by introducing a small amount of alkylated CNTs (a-CNTs). In contrast, the CB/a-CNT complex filler was more effective for the iPP nanocomposites than the CB or a-CNT single filler in terms of the thermal stability and the electrical properties. However, the mechanical properties of the CB/a-CNT complex filler incorporated iPP nanocomposites were poorer than the only a-CNT incorporated iPP nanocomposites. Additionally, the complex filler did not overcome the nucleation behavior of the a-CNTs in the re-crystallization of iPP.

Properties of Single and Hybrid Aluminum and Silver Fillers Filled High-Density Polyethylene Composites

The electrical and thermal properties of two series of composites, single-filler aluminum (Al) and silver (Ag) and hybrid-filler Al/Ag-filled high-density polyethylene (HDPE) composites, are reported. The composites were prepared by mixing using an internal mixer followed by compression molding. Studies on the electrical properties of single-filler composites showed an insulator-to-conductor transition in HDPE/Ag and HDPE/Al between 45–55 wt% and 55–65 wt% filler loadings, respectively. This is due to the formation of conductive paths that spanned throughout the polymer matrix, as revealed by morphology study. Thermogravimetric analysis results indicated that the degradation temperature of the composites decreased with the incorporation of 15 wt% Al- and Ag-fillers but increased slightly after the addition of 55 wt% of the filler. Investigation on the effect of hybrid composites showed that high-electrical conductivity was achieved, exhibiting percolation phenomenon in HDPE/80Ag20Al and HDPE/70Ag30Al composites where in these composites, 20% and 30% from 55 wt% of Ag were replaced with Al fillers, respectively. Furthermore, thermal stability significantly increased when hybridization was conducted to form the composite.

Study on the viscosity of polypropylene composites filled with different size and size distribution CaCO3

AbstractTwo kinds of different size calcium carbonates are blended and filled into polypropylene in 30 wt%. The melting viscosity of PP composites samples is measured by capillary extrusion rheometer at 230°C. The results show that the melt viscosity of PP composites evidently decreased when that was filled with the blending 325 and 1,500 mesh CaCO3 and the 1,500 mesh proportion in fillers was from 20 to 60 wt%. The viscosity in the low shear velocity decreased more than that in the high shear velocity. The shear viscosity of single filler and filler samples with the size distribution at the different temperature was studied by capillary extrusion rheometer. The results show that the flow activation energy and the flow activation entropy of composites filled with the size distribution filler increased. The change of the flow activation entropy and the model of the efficient arrangement of the structure are used to explain the phenomenon in melting viscosity decrease of PP filled with the size distribution fillers. A structural model of composites that filled with the size distribution fillers was set up. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Thermally conductive and electrically insulative nanocomposites based on hyperbranched epoxy and nano‐Al2O3 particles modified epoxy resin

AbstractNovel epoxy nanocomposites based on a diglycidyl ether of bisphenol A (DGEBA) epoxy, an epoxy functionalized hyperbranched polymer (HTTE) and nano‐Al2O3 were synthesized with the aim of determining the effect of the nano‐Al2O3 particles and HTTE on the structure and properties of epoxy nanocomposites. The mechanical properties, thermal conductivity, bulk resistivity, and thermal stability of the nano‐Al2O3/HTTE/DGEBA ternary composites were evaluated and compared with the corresponding matrix. The improvement in impact properties of these nanocomposites was explained in terms of fracture surface analysis by SEM. The results indicate that the incorporation of nanoparticles and hyperbranched epoxy effectively improved the toughness of epoxy composites without sacrificing thermal conductivity and bulk resistivity compared to the neat epoxy and Al2O3/DGEBA, obtaining a well dispersion of nanoparticles in epoxy matrix and solving the drawbacks for single fillers filled epoxy nanocomposite. Copyright © 2010 John Wiley & Sons, Ltd.

Effect of CaCO<sub>3</sub> Whisker and Polypropylene Hybrid Fiber on Mechanical Properties of Concrete

As the composite of materials, fibers compositing, which can give full play to synergism of each fiber’s reinforcement, will become an inevitable trend. Calcium carbonate whisker is a kind of green environment-friendly fibrous powder filler with high strength, high modulus and excellent thermal stability, which has been proven that it has obviously toughening and reinforcing effects on cement-based materials. In this paper, CaCO3 whiskers composite with polypropylene fiber were added into concrete as reinforcement. Effect of different content of whiskers and fibers on the mechanical properties of concrete was investigated. The results shows that the composite of CaCO3 whisker and polypropylene fiber (PP) has better toughening and reinforcing effects than that of single filler. The strength of whiskers/PPF-reinforced concrete can be obviously improved compared with that of pure concrete, whisker concrete and PPF concrete. These increases could be correlated to the synergism of PPF and CaCO3 whisker, which are different in size, aspect ratio, elastic modulus, and reinforcing role in concrete.

Electrical and thermal properties of polyamide 12 composites with hybrid fillers systems of multiwalled carbon nanotubes and carbon black

Hybrid filler systems of multiwalled carbon nanotubes (MWCNTs) and carbon black (CB) were incorporated into two types of polyamide 12 (PA12) using small-scale melt mixing in order to identify potential synergistic effects on the interaction of these two electrical conductive fillers. Although no synergistic effects were observed regarding the electrical percolation threshold, at loadings well above the percolation threshold higher volume conductivities were obtained for samples containing both, MWCNT and CB, as compared to single fillers. This effect was more pronounced when using a higher viscous PA12 matrix. The formation of a co-supporting network can be assumed. The combined use of CB and MWCNTs improved the macrodispersion of MWCNT agglomerates, which can be assigned as a synergistic effect. DSC measurements indicated an effect of the nanofiller on crystallisation temperatures of PA12; however this was independent of the kind or amount of the carbon nanofiller.

Effect of Silane Treatment on Hybridized Use of Short Cellulose Fibers and Silica Particles for Natural Rubber Reinforcement

セルロース短繊維とシリカ微粒子の添加量を総量で20phrに制御し，得られた天然ゴム系ハイブリッド複合材の引張り特性，膨潤特性，加工特性をそれぞれの強化剤を単独に添加した場合および天然ゴムだけの場合と比較した．その結果，ハイブリッド複合材の引張り弾性率と引張り強さはそれぞれの強化剤を単独で強化した場合の中間的な特性を示すものの，ムーニー粘度などゴムの加工特性を示す指標には複合化した強化剤の効果が大きく現れており，良好な加工特性の向上が認められた．さらに，この複合強化剤の表面をシラン処理すると，引張り特性および加工特性により大きな改善効果がみられた．そこで，EDX，3DマイクロフォーカスX-線CTおよびN-ARC法でこれらの複合強化剤の天然ゴムにおける分散状態に及ぼすシラン処理の効果を検討した．その結果，複合強化剤にシラン処理を施すとそれぞれの強化剤の分散が良くなっていることが確認できた．そして，天然ゴムの強化に対して，セルロース短繊維とシリカとを複合的に用いるだけでなく，複合強化剤にシラン処理を施すと得られる天然ゴム系ハイブリッド複合材の引張り特性や加工性を大きく向上できることが分かった．

Influence Of Tolerances on weld formation and quality of laser-GMA-hybrid girth welded pipe joints

The mechanized GMAW process is currently the most widely used welding process for transmission pipelines and represents the benchmark against which other welding processes have been assessed. Although there have been a number of recent welding procedure developments like twin-wire or double-torch welding that have improved its productivity, the potential for a further increase of its efficiency is exhausted. Alternatively, the Laser-GMA-Hybrid welding of the first pass, offers new possibilities to reduce the number of filler pass welding runs and the necessary equipment substantially. This paper will give an overview about the latest results of the development to qualify the Laser-GMAW hybrid process for pipeline girth welding. The approach of this work was extensive and included the equipment, the edge preparation and the welding process in several positions. Finally, the results were tested under near realistic conditions. Compared to advanced GMAW procedures with a minimum of four runs to complete an 11, 7 mm (0,460″) wall thickness, the number of runs was reduced to one, by combining the hybrid first pass with a single GMAW filler pass weld in the same run.

Effect of filler surface treatment on mechanical properties and thermal properties of single and hybrid filler–filled PP composites

AbstractThe influence of two types of surface treatments (aminosilane and Lica‐12) on the mechanical and thermal properties of polypropylene (PP) filled with single and hybrid filler (silica and mica) was studied. An improvement in tensile properties and impact strength was found for both treatments compared to those of untreated composites. However, the filler with silane coupling agent showed better improvement compared to the filler with Lica‐12 coupling agent. This was due to better adhesion between filler and matrix. Thermal analysis indicates that surface treatments increased the nucleating ability of filler, but decreased the coefficient of thermal expansion of PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Reinforcement of natural rubber with carbon black/nanoclay hybrid filler

Natural rubber (NR) based nanocomposites were prepared by incorporation of a hybrid filler system, organoclay and carbon black (CB), through melt compounding. The hybrid filler exhibited more significant reinforcing effect over the same loading of CB on NR matrix, as revealed by mechanical tests and dynamic mechanical analysis. Wide angle X-ray diffraction, transmission electron microscopy and scanning electron microscopy were used to study the microstructure of NR nanocomposites. Dynamic rheological tests were performed to elucidate the mechanism of reinforcement in order to explain the superior performance of NR containing the hybrid filler. The storage modulus G′ of uncured rubber composites exhibits a three order increase in magnitude for rubber filled with 15 parts per hundred parts of rubber CB and 10 parts per hundred parts of rubber organoclay as compared with gum rubber, leading to a solid-like low frequency behaviour. The findings suggest that the reinforcement is due to a more developed filler network formation in hybrid filler system than that in single phase filler.

Predicting the thermal conductivity of multiple carbon fillers in polypropylene-based resins

In this research, three different carbon fillers (Thermocarb TC-300 synthetic graphite, Ketjenblack EC-600 JD carbon black and Hyperion Catalysis International’s FIBRIL TM carbon nanotubes) are added to a polypropylene matrix to produce single and multiple filler composites with filler concentrations of up to 80 wt% synthetic graphite, 15 wt% carbon black, and 15 wt% carbon nanotubes. The through-plane and in-plane thermal conductivities are measured for these formulations and compared favorably with predictions from the Nielsen thermal conductivity model. Good results are obtained from an empirical in-plane thermal conductivity model for all single filler composites and one multiple filler composite.

In-plane thermal conductivity modeling of carbon-filled liquid crystal polymer-based resins

Adding conductive carbon fillers to insulating thermoplastic resins increases composite electrical and thermal conductivity. In this study, varying amounts of three different carbons (carbon black, synthetic graphite particles, and carbon fiber) were added to Vectra A950RX liquid crystal polymer. The in-plane thermal conductivity of the resulting single filler composites was tested. The results showed that adding synthetic graphite particles caused the largest increase in the in-plane thermal conductivity of the composite. The composites were modeled using ellipsoidal inclusion problems to predict the effective in-plane thermal conductivities at varying volume fractions with only physical property data of the constituents. The synthetic graphite and carbon black were modeled using the average field approximation with ellipsoidal inclusions and the model showed good agreement with the experimental data. The carbon fiber polymer composite was modeled using an assemblage of coated ellipsoids and the model showed good agreement with the experimental data. POLYM. COMPOS., 32:147-157, 2011. © 2010 Society of Plastics Engineers.

Effects of carbon fillers on tensile and flexural properties in polypropylene‐based resins

AbstractA potential application for conductive resins is in bipolar plates for use in fuel cells. The addition of carbon filler can increase the electrical and thermal conductivities of the polymer matrix but will also have an effect on the tensile and flexural properties, important for bipolar plates. In this research, three different types of carbon (carbon black, synthetic graphite, and carbon nanotubes) were added to polypropylene and the effects of these single fillers on the flexural and tensile properties were measured. All three carbon fillers caused an increase in the tensile and flexural modulus of the composite. The ultimate tensile and flexural strengths decreased with the addition of carbon black and synthetic graphite, but increased for carbon nanotubes/polypropylene composites due to the difference in the aspect ratio of this filler compared to carbon black and synthetic graphite. Finally, it was found that the Nielsen model gave the best prediction of the tensile modulus for the polypropylene based composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Thermal and Electrical Conductivities of Carbon Fibers and Carbon Nanotubes Incorporated Polyurethanes Composites

Single filler polyurethane composites with carbon fibers (CFs) and multi-walled carbon nanotubes (MWNTs) were prepared by melt mixing methods and its thermal as well as electrical resistivity characteristics were investigated. The influences of fillers and mixing methods on thermal and electrical conductivity of CF/- and MWNT/polyurethane composites were investigated and the result shows that the addition of carbon fillers improved the thermal conductivity of the polyurethane composites. Higher filler concentration results in better thermal conductivity because better formation of thermally conductive networks along polymer matrix to ensure the thermal was conducted through the matrix and the network along the polymer composites. The presence of carbon additives improves the electrical resistivity of the materials as well. The present study revealed the potential of carbon as agent for better thermal and electrical conductivities and their properties depend strongly on the dispersion and distribution of the fillers in the polymer matrix.

Effect of carbon black/nanoclay hybrid filler on the dynamic properties of natural rubber vulcanizates

AbstractIn this study, natural rubber (NR) nanocomposites based on carbon black (CB) and two poly(ethylene glycol) (PEG)‐modified clay hybrid filler were fabricated. The morphology and mechanical properties were studied. The dynamic properties of NR vulcanizates were investigated over a range of strain amplitude at two temperatures. It was found that NR with hybrid filler exhibits superior mechanical properties over that with CB as single phase filler. The hybrid filler causes a significant alteration in the dynamic properties of rubber. The Payne effect becomes more pronounced in rubber with modified clay. A decrease in loss factor (tanδ) was observed for rubber with hybrid filler also. The results revealed that the inclusion of nanoclay (NC) could induce a stronger and more developed filler network. Because of the anisotropy of the nanolayers, NC would depress the reconstruction of filler network, or lower the reformation rates when broken down under deformation, giving rise to lower tanδ value at broad temperature range as well as strain amplitude. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010