Dual Filler Research Articles

Cyclic uniaxial stress-strain test and rheological behavior of carbon black/metakaolin dual-filler system used in nitrile rubber compounds

Abstract Dual-filler systems may promote synergetic effects to mechanical properties in rubber compounds. The use of metakaolin (M) and carbon black (C) in nitrile rubber (NBR) compounds was studied with respect to rheological and non-obvious mechanical tests. The reaction order of the curing process was not influenced by the filler system, however, carbon black presented a slowdown effect in the vulcanization process. Cyclic uniaxial tests indicated that stress softening was observed even for unfilled compound; however, notably only-carbon black filled compound experienced the highest values for decrease in stress softening after second cycle. Although the polymer chains alone are the main driving force of hysteresis, it was more negatively affected by carbon black than by metakaolin. Moreover, dual filler composites experienced balanced results for stress softening, and other properties as Payne effect and complex viscosity.

Fractionation of direct dyes using modified vapor grown carbon nanofibers and zirconia in cellulose acetate blend membranes

In the textile industry, membrane technology has been widely employed for the exclusion of direct dyes. In this research paper, firstly vapor grown carbon nanofibers (VGCNFs) were functionalized with carboxylates group via piranha oxidation, and then series of CA/PEO-PPO-PEO triblock copolymers were prepared by blending with varying weight percentages of modified VGCNFs and Zirconia (ZrO2). The structural morphologies of membranes were visualized by scanning electron microscope (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM), which exhibits the dispersity of dual fillers in polymer matrix thus improving the microstructure of resultant membranes. The experimental data indicates that the modified VGCNF and ZrO2 nanoparticles were shown increase hydrophilic character. The direct dyes rejection were successfully after filler addition, which were 96% (for Direct Red), 99% (for Direct Blue) and 93% (for Direct Orange). The membranes showed a better antifouling property even after several washing cycles along with improved biofouling property, both of these properties showed a better membrane life. As an outcome, this research could have been a great potential to be used to treat dyes in textile industry.

Synergistic Toughening of Poly(lactic acid)–Cellulose Nanocrystal Composites through Cooperative Effect of Cavitation and Crazing Deformation Mechanisms

In this work, we present poly(lactic acid) (PLLA)–cellulose nanocrystal (CNC) composites with simultaneous improvements in tensile toughness and impact strength using dual CNC-based fillers. The dual CNC-based fillers were designed to toughen PLLA by control of (a) the morphology and (b) the interfacial interactions in the PLLA composites. The first filler, denoted as CNCaq–rD, was comprised of rigid CNC and a rubber layer (rD), which exhibited immiscibility with the PLLA matrix, albeit with weak interactions. The second filler, denoted as CNCaq–rD–PDLA, was comprised of rigid CNC, a middle rubber layer (rD), and an outer layer of PDLA blocks that could form strong interactions with PLLA matrix via stereocomplexation. The dual fillers superbly improved both tensile toughness and impact strength of PLLA through synergistic effects. Incorporating 10% CNCaq–rD and 10% CNCaq–rD–PDLA into the PLLA matrix, the strain at break (a measure of tensile toughness) and impact strength increased by 100-fold and 3-fold,...

A high-density polyethylene container based on ZnO/lignin dual fillers with potential antimicrobial activity

Dual ZnO/lignin hybrid fillers were obtained and subjected to detailed physicochemical and morphological-microstructural analysis. The effectiveness of combination of the components was assessed using Fourier transform infrared spectroscopy. It was shown that the addition of zinc oxide improves the thermal stability of the final hybrid filler. A hybrid material consisting of ZnO and lignin in a weight ratio of 1:5 exhibited very good antimicrobial activity, especially against Gram-positive bacteria (in both of the tested genera: Staphylococcus and Bacillus). In all cases, the action of this material was stronger than that of the positive control, the antibiotic tetracycline. Blow-molded containers made of polyethylene containing 5 wt% of ZnO/lignin with different lignin contents were prepared with a single-screw extruder. The effect of ZnO/lignin hybrid fillers on the properties of a high-density polyethylene container was investigated by means of a uniaxial compression test. Mechanical tests demonstrated a significant twofold increase in the compression force for blends with a ZnO:lignin ratio of 1:5. Additionally, DSC analysis was performed to study the influence of the dual fillers on the microstructure of the blended polyethylene.

Heterostructured filler in mixed matrix membranes to coordinate physical and chemical selectivities for enhanced CO2 separation

Mixed matrix membranes (MMMs) hold great promise in overcoming the tradeoff between membrane permeability and selectivity. The rational design of fillers to well coordinate physical and chemical selectivities remains challenging. Here, we explore a heterostructured filler by in-situ growth of ZIF-8 on LDH surface (ZIF-8@LDH), which was then embedded into Pebax to fabricate MMMs for CO2/CH4 separation. The proximity effect of the heterostructured filler endows MMMs with superior gas separation performance compared with the control MMMs containing single filler ZIF-8, LDH and dual fillers (where ZIF-8 and LDH are separately incorporated). On one hand, ZIF-8 and abundant hydroxyl groups on LDH afford favorable affinity toward CO2, significantly enhancing the physical selectivity of CO2/CH4. On the other hand, the oriented distribution of ZIF-8 on LDH elevates CO2 concentration around LDH and increases the efficiency of CO2 facilitated transport, leading to remarkably enhanced chemical selectivity. Particularly, the optimum separation performance is achieved for MMMs containing 2 wt% of ZIF-8@LDH with a CO2 permeability of 1307 Barrer and a CO2/CH4 selectivity of 31.6. The unique attributes of heterostructured filler may be extended to fabricate a variety of MMMs for high performance molecular separations.

Preparation of Ag coating reduced graphene oxide and its application as a conductive filler to polyacrylate

By taking the advantage of the wide surface area of reduced graphene oxide (rGO), a type of carbon/metal hybrids composed by rGO coated with silver nanoparticles (Ag–rGO) has been synthesized via an easy chemical coating method. Then the Ag–rGO hybrids are filled into polyacrylate (PA) as elelctrically conductive fillers to survey the application of the hybrids in polymer based composites. Compatible research indicates the hybrids could evenly disperse in PA with a Methyl Ethyl Ketone (2-MEK) enviroment for a long period. Property measurements suggest that the Ag–rGO dual fillers have greatly improved the electrical conductivity of PA matrix, enabling the conductive of the Ag–rGO/PA composites to rise more than ten orders while reducing the main bonding performance of the composites. With 10.0 wt% of Ag–rGO hybrids, the composites exhibited optimized electrically conducting and mechanical properties, which were 2.40 × 10−2 S/cm of conductivity, 0.62 KN/m of 180°peel strength and 0.67 MPa of shear strength. The great effect on PA is caused by the electrical conducting of nano-scaled Ag particles and the intermolecular forces between rGO and PA.

Influence of Processing Conditions on the Thermal Stability and Mechanical Properties of PP/Silica-Lignin Composites

Functional silica-lignin dual fillers were obtained via mechanical grinding of the components (Syloid 244 silica and kraft lignin). Of particular importance here is the fact that lignin is a natural polymer and particularly that it is a waste by-product of paper production, whose recycling is highly desirable. The product underwent comprehensive dispersive-morphological and thermal analysis. SiO2-lignin hybrid fillers were also used in polypropylene-based composites, extruded via corotating a twin screw machine with different screw speeds. The thermogravimetric data obtained for the extrudates confirmed that the application of the lignin into PP produces a significant char residue. Addition of silica to lignin via this new hybrid formulation has a positive effect on the thermal stability of PP/silica-lignin composites, which can be seen even when observing the temperature for the maximum rate of weight reduction. Tensile test results show that the addition of silica by means of dual filler incorporation improves the mechanical parameters in comparison with pure PP and PP/lignin composite.

The effects of hybrid fillers on thermal, mechanical, physical, and antimicrobial properties of ultrahigh-molecular-weight polyethylene-reinforced composites

The effects of hybrid filler of zinc oxide and chitosan (chitosan–ZnO) on thermal, flexural, antimicrobial, chemical resistance, and hardness properties of ultrahigh-molecular-weight polyethylene (UHMWPE) composites with varying concentration of zinc oxide (ZnO) and further hybridized by chitosan (CS) were successfully studied. The composites were prepared using mechanical ball milling and followed by hot compression molding. The addition of ZnO to the UHMWPE matrix had lowered the melting temperature (Tm) of the composite but delayed its degradation temperature. Further investigation of dual filler incorporation was done by the addition of chitosan to the UHMWPE/ZnO composite and resulted in the reduction of UHMWPE crystallization. The flexural strength and modulus had a notably high improvement through ZnO addition up to 25 wt% as compared to neat UHMWPE. However, the addition of chitosan had resulted in lower flexural strength than that of 12 wt% ZnO UHMWPE composite but still higher than that of neat UHMWPE. It was experimentally proven that the incorporation of ZnO and chitosan particles within UHMWPE matrix had further enhanced the antimicrobial properties of neat UHMWPE. Chemical resistance was improved with higher ZnO content with a slight reduction of mass change after the incorporation of chitosan. The hardness value increased with ZnO addition but higher incorporation of chitosan had lowered the hardness value. These findings have significant implications for the commercial application of UHMWPE based products. It appears that these hybrid fillers (chitosan–ZnO)-reinforced UHMWPE composites exhibit superior overall properties than that of conventional neat UHMWPE. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

A Study on the Mechanical and Thermal Properties of ENR Filled with Dual Fillers

The effects of dual fillers, carbon black (CB) and mineral filler mixture (MFM) in epoxidized natural rubber (ENR) compound using BR1600 internal mixer were investigated. In this study, the processability of the compound improved and the cure time decreased with partial replacement of CB with MFM. Results also showed that compound filled with partial replacement of 20 phr of CB with MFM exhibited comparable tensile strength value with compound filled with 50 phr CB as single filler. Nevertheless, based on Thermogravimetri analysis (TGA), ENR filled with 50 phr CB gave higher char yield which can ascribe to the better stability of the char layer formed.

Processability Behaviour of Dual Filler Systems Reinforced Epoxised Natural Rubber

Rheological studies of polymers are of great importance in optimizing the processing conditions and in designing processing equipments like injection molding machines, extruders, and dies required for various products. Melt rheological studies give us valuable viscosity data that will be helpful in optimizing the processing conditions. Parameters like melt viscosity as a function of shear rate or shear stress and temperature have become more and more important. Previous study indicated that the flow behaviour of the compound depends on the filler loading. Lesser elastic torque was found with compound containing lower filler content as compared to higher filler content. In this work, effect of dual filler, based on Carbon Black / Silica filled Epoxidised Natural Rubber (ENR) compound was investigated. A total of 80phr of filler content based on passenger tyre tread formulation was used in the experiment. The compounds were prepared by melt mixing in tangential type of an internal mixer. The rheological and the processability properties of the compounds were determined using three different testing instruments namely Capillary Rheometer, Mooney viscometer and Rubber Process Analyzer (RPA). A variation of shear rates (ranging from low to high) was performed, in order to better reflect the actual processing condition in rubber manufacturing. It was found that ENR mix with ratio silica to carbon black 70:10 exhibited the best flow behaviour and processability properties as compared to control and other mixes.

The effect of coupling agents on silicate-based nanofillers/carbon black dual filler systems on the properties of a natural rubber/butadiene rubber compound

Nanofillers have been introduced a few years ago, but their application in elastomers is still a challenge. With the existing rubber processing equipment and constraints of rubber mixing, dispersion of nanofillers is difficult. The processability and performance of compounds containing plate- or tube-like silicates in a blend with conventional fillers, such as carbon black (CB), are investigated, and the effect of surface modification of the nanofillers is studied. Processing is facilitated by the replacement of CB by the nanofillers, but curing efficiency is reduced. The dispersion of the fillers is improved with the addition of nanofillers. The dynamic properties of the cured composite material are affected, giving the composite material lower hysteresis, while the mechanical properties are merely affected by the addition of nanofillers. Additionally, the filler–polymer interaction is increased. The addition of a compatibilizing and coupling agent, a silane, has only a minor effect and does not improve processing and properties significantly for these combined filler systems.

PREDICTION OF ROLLING RESISTANCE FOR TRUCK BUS RADIAL TIRES WITH NANOCOMPOSITE BASED TREAD COMPOUNDS USING FINITE ELEMENT SIMULATION

ABSTRACT Tire rolling resistance (RR) is a key performance index in the tire industry that addresses environmental concerns. Reduction of tire rolling resistance is a critical part of lowering fuel consumption, which could be achieved by changing both design and compound formulation. The major challenge is availability of a suitable software code to evaluate RR of tires using nonlinear viscoelastic properties of rubber. We developed a rolling resistance code and used it to predict rolling resistance of truck bus radial tires with nanocomposite based tread compounds. The energy dissipation in the tire is evaluated using the product of elastic strain energy and loss tangent of materials through post-processing using the rolling resistance code developed in this work. The elastic strain energy is obtained through steady state rolling simulation of tires using commercial software. The loss tangent versus strains at two reference temperatures is measured in the laboratory using a dynamic mechanical thermal analyzer. A temperature equation is developed to incorporate the effect of temperature on loss energy. Good correlation of rolling resistance is observed between simulation and experimental results. Nanocomposites used in this study are prepared based on natural rubber and polybutadiene rubber blends with either organoclay and carbon black or organoclay and silica dual filler system. Carboxylated nitrile rubber, a polar rubber, is used as a compatibilizer to facilitate the clay dispersion in the rubber matrix. Compared with general carbon black or silica tread compounds, substantial improvement of rolling resistance is predicted by finite element simulation with nanocomposite based tread compounds containing dual fillers.

Synergistic Effect of Hybrid Montmorillonite-reduced Graphene Oxide as Dual Filler for Improving the Mechanical Properties of PVA Composites by a One-step Procedure

Synergistic Effect of Hybrid Montmorillonite-reduced Graphene Oxide as Dual Filler for Improving the Mechanical Properties of PVA Composites by a One-step Procedure

Spark Plasma Sintering of Alumina Composites with Graphene Platelets and Silicon Carbide Nanoparticles

This paper reports a study on sintering and characterization of alumina (Al2O3) ceramic composites with graphene platelets (GPLs) and silicon carbide (SiC) nanoparticles. 1, 3, and 5 vol% SiC and 0.38 vol% GPL are mixed with Al2O3 powders and sintered in a spark plasma sintering system. The microstructures and mechanical properties of the composites are investigated. It is found that the composites reinforced with the dual fillers exhibit more uniform and finer microstructures than pure Al2O3 and average grain sizes of the composites decrease with the increasing percentage of SiC. Compared with pure Al2O3, the composites show approximately a 36% increase in hardness, a 40% increase in flexural strength and a 50% increase in fracture toughness. Toughening mechanisms induced by GPLs, such as crack bridging, pullout and crack deflection in the composites, are observed and discussed.

Combined effect of expanded graphite and multiwall carbon nanotubes on the thermo mechanical, morphological as well as electrical conductivity of in situ bulk polymerized polystyrene composites

Synergetic effect of multiwalled carbon nanotube (MWCNT) and expanded graphite (EG) on the properties of polystyrene matrix has been studied extensively. PS/EG, PS/MWCNT, PS/EG/MWCNT nanocomposites were prepared by bulk polymerization method. Thermo mechanical and electrical conductivity were increased with individual or combined addition of MWCNT and EG to the polystyrene. Raman and FTIR study confirmed acid modification of MWCNT. DMTA and DSC analysis revealed PEM (composite of polystyrene with 1wt% expanded graphite and modified MWCNT) composite has the highest storage modulus and glass transition temperature. TGA analysis showed that the incorporation of dual filler enhanced the thermal stability of nanocomposites to a large extent. Dispersion of both the nanofillers was found to be better in presence of each other.

Synergetic effects of radiolytically degraded PTFE microparticles and organoclay in PTFE-reinforced ethylene vinyl acetate composites

This article reports exceptional synergistic effects observed in organic–inorganic dual filler containing ethylene vinyl acetate (EVA) composites. Polytetrafluoroethylene microparticles (PTFEMP) were produced by mechanically grinding radiolytically degraded PTFE; composites of EVA containing PTFEMP and organoclay were prepared in different proportions by melt compounding and their mechanical, melt flow, morphological and crystallographic characteristics were examined. Mechanical properties of ternary composites demonstrated high synergy between fillers, leading to manifold increase in the modulus of dual filler filled composites in comparison to single filler systems. Nielsen model fitted well with EVA/PTFEMP system; however it predicted remarkably low values for EVA/PTFEMP/organoclay system, confirming exceptional synergy between two fillers. Melt viscosity of EVA increased substantially on the addition of either of the fillers. X-ray diffraction studies revealed around 10% intergallery expansion in organoclay, in the composites having high loading of PTFEMP; though the crystallinity of EVA did not change.

MIXING SEQUENCE IN NATURAL RUBBER CONTAINING ORGANOCLAY AND NANO–CALCIUM CARBONATE TERNARY HYBRID NANOCOMPOSITES

ABSTRACT Rubber nanocomposites containing one type of nanofiller are common and are widely established in the research field. In this study, natural rubber (NR) based ternary nanocomposites containing both calcium carbonate and organoclay have been characterized on the basis of morphology, cure characteristics, and physico-mechanical behavior. Natural rubber nanocomposite samples containing modified silicate (Cloisite 15A) and also nano-carbonate calcium were prepared using a laboratory internal mixer. The effect of the mixing sequence on the morphology and mechanical properties of the samples was investigated. Based on results of morphology and mechanical properties, the dual fillers phase nanocomposites (hybrid nanocomposite) perform better in comparison with single filler phase nanocomposites. The reinforcing capability of nano-CaCO3 and organoclay in NR was characterized by means of cure rheometry, morphology, and mechanical properties. NR/single filler phase and two filler phase nanocomposites were prepared by simple melt mixing method. Concentration of nano-CaCO3 and organoclay in NR was 10 and 5 parts per one hundred parts of rubber by weight, respectively. The microstructure and homogeneity of the compounds was confirmed by studying the dispersion of nanoparticles in NR via X-ray diffraction and field emission scanning electron microscopy. A more pronounced effect was achieved by using dual filler based nanocomposites as compared with single filler phase nanocomposites. The obtained results reveal that hybrid nanocomposites have more adequate morphology, rheometery, and mechanical behaviors as well as swelling resistance. The effect of mixing sequence of fillers has been studied in detail. Simultaneous addition of the two nanofillers to the NR compound would lead to better nanocomposite properties compared with other mixing sequences. Also, the results show that the mixing sequence of these nanofillers in NR has little effect on the performance of the nanocomposite.

Dual Filler Effect of Compatibilized Pure and Oil Extended Ethylene Propylene Diene Monomer Nanocomposites

Pure and oil extended ethylene propylene diene monomer nanocomposites were prepared using suitable compatibilizer. Since ethylene propylene diene monomer (EPDM) is non-polar, incorporation of organically modified nanoclay may not lead to better dispersion in the rubber matrix. Hence a polar rubber like epoxidized natural rubber (ENR) can be used as a compatibilizer for dispersing nanoclay in the EPDM matrix. ENR - organically modified nanoclay composites (EC) were prepared by solution mixing. The nanoclay used in this study is Cloisite 20A. ENR-nanoclay composites were incorporated in EPDM and oil-extended EPDM (OE-EPDM) matrices along with carbon black. The morphological studies prove that the nanoclay platelets get intercalated in ENR. Low loading of EC in EPDM and OE-EPDM matrices enhances the dispersion of nanoclay forming partially exfoliated platelets. Curing study shows improvement in torque and faster cure time for the compatibilized EPDM and OE-EPDM nanocomposites containing dual filler system compared to pure and single filler (carbon black) containing rubber compounds. Dynamic mechanical thermal analysis shows high storage modulus and lesser damping characteristics for the dual fillers containing EPDM and OE-EPDM compounds. The same compounds show tremendous improvement in mechanical properties. Scanning electron microscopic (SEM) images of tensile fractured single and dual filler containing rubber specimens show rough and tortuous path of fracture, which may be due to physical interaction between filler and rubber.

Selective dispersion of different organoclays in styrene butadiene rubber in the presence of a compatibilizer

Dual filler (organoclay and carbon black) loaded emulsion polymerized styrene butadiene rubber (E-SBR) based nanocomposites were synthesized by melt blending. Three different organically modified clays (viz. Cloisite 15A, Cloisite 20A and Cloisite 30B) were used for the present study. To disperse different organoclays selectively in the rubber matrix, oil extended carboxylated styrene butadiene rubber (XSBR) was used as a compatibilizer between organoclay and the nonpolar SBR. Wide angle X-ray diffraction analysis (WAXD) and high resolution transmission electron microscopic (HR-TEM) analysis of the nanocomposites revealed that the organoclays were intercalated and delaminated in the elastomer matrix in the presence of carbon black (CB). Different organoclay loaded SBR compounds show improvement in the overall properties such as curing features, mechanical, thermal, abrasion resistance and dynamic mechanical properties compared to the neat SBR. Among the three different hybrid nanocomposites, Cloisite 30B filled SBR compound in the presence of CB show superior properties.

Development of Electrically Conductive Polymers

Conducting composites based on graphite, carbon black and polypropylene have been prepared and the effect of composition on the flexural modulus and electrical conductivity has been studied. The conductivity of polymers containing only one kind of filler did not increase significantly, their modulus of elasticity was the highest for graphite filling, and the lowest for nanotube filling. The conductivity of dual filler hybrids increased significantly due to the synergetic interaction between the two fillers. At lower graphite contents, because of the better dispersion of graphite, the material became more flexible, but at higher carbon black contents the stiffness increased significantly. In the case of triple filler hybrids, if keeping the graphite content at a certain level and varying only the carbon black/nanotube ratio, the conductivity and the flexural modulus varied according to exponential and linear rules respectively.