Phr Carbon Black Research Articles

Dynamic Mechanical Behavior, Solvent Resistance and Thermal Degradation of Nitrile Rubber Composites With Carbon Black‐Halloysite Nanotube Hybrid Fillers

In this work, nitrile rubber (NBR) conventional composites containing 70 phr carbon black (CB) is taken for study. New NBR hybrid composites containing 60 phr of CB and varied halloysite nanotube (HNT) loading of 2, 4, 6, 8, and 10 phr were developed. Experimental investigations were carried out to study the synergistic effect of CB and HNT on the dynamical mechanical properties, solvent resistance, thermal stability and degradation kinetics of NBR hybrid composites. Morphological analysis using X‐ray diffraction analysis (XRD) and Field emission scanning electron microscopy (FESEM) revealed the presence of intercalated structures and formation of local CB‐HNT filler network in the NBR matrix. The glass transition temperatures (Tg) of hybrid composites were raised with the addition of HNT which indicates strong interfacial adhesion between NBR–CB–HNT. Dynamic mechanical analysis and solvent uptake studies revealed that replacement of 10 phr CB by 6 phr HNT in hybrid composites improved the storage modulus by 44% at 30°C and solvent resistance by 29%, respectively. Most importantly, the incorporation of HNT could effectively improve the thermal stability of the NBR hybrid composites according to thermogravimetric analysis and oxidation induction time studies. The activation energy of the thermal decomposition of the hybrid composites increased with the addition of HNT. POLYM. COMPOS., 40:E1612–E1621, 2019. © 2018 Society of Plastics Engineers

Graphene / hydrogenated acrylonitrile-butadiene rubber nanocomposites: Dispersion, curing, mechanical reinforcement, multifunctional filler

Elastomers are usually mechanically reinforced with high loadings of carbon black (CB) to achieve the properties demanded; high amounts of mineral flame retardants are used to fulfill fire safety requirements. In this study, multilayer graphene (MLG), a nanoparticle made of only 10 graphene sheets, is applied in low loadings, 3 parts per hundred rubber (phr) to reduce the total amount of filler or boost performance in hydrogenated acrylonitrile-butadiene rubber (HNBR). In the HNBR/MLG nanocomposites, 3 phr MLG replaced 15 phr CB, 3 phr aluminum trihydroxide (ATH), or 15 phr CB + 3 phr ATH. The nanocomposites were prepared via master batch by ultrasonically assisted solution mixing and subsequent conventional two-roll milling. A comprehensive study is presented, illustrating the impact of MLG on curing and mechanical properties; e.g. replacing 2.5 phr ATH with 3 phr MLG increased the Young's modulus by over 60% and hardness by 10%, while improving flame retardancy, and reducing the total heat evolved by 10%. MLG is a multifunctional filler, as demonstrated by various enhancements in terms of the mechanical and flame retardancy properties of the rubber composites.

Mechanical property behavior and aging mechanism of carbon-black-filled EPDM rubber reinforced by carbon nano-tubes subjected to electro-chemical and thermal degradation

Ethylene propylene diene monomer (EPDM) rubber filled with Carbon black (CB) has been mainly used for the rubber hose of a cooling radiator in the internal combustion engine system. Moreover, EPDM aging occurs because of electro-chemical and thermal stresses. In this study, Carbon nanotubes (CNTs) with 0, 2 and 4 parts per hundred grams of rubber (phr) were added to EPDM rubber filled with 75 phr CB to form CNT reinforced CB-filled EPDM rubber. Under conditions of 3 temperatures (60, 80 and 100 °C) and constant voltage (DC 12 V), 3 types of EPDM rubber (CB75, C2CB7 and C4CB75) were immersed in coolant water and aged for 7 days (168 h). This study investigated the effects of CB and CNT concentrations in EPDM rubbers on electro-chemical and thermal degradation behaviors and mechanical properties (tensile strength, elongation at the breaking point and IRHD hardness). A conductive mechanism was also proposed for the addition of CNT and CB.

Synergistic effects of hybridization of carbon black and carbon nanotubes on the mechanical properties and thermal conductivity of a rubber blend system

Abstract The effects of hybridization of multi-walled carbon nanotubes (MWCNTs) with carbon black (CB) and the structure-property relationships of nanocomposites based on hydrogenated nitrile-butadiene rubber/hydrogenated carboxylated nitrile-butadiene rubber blends were extensively studied. MWCNTs used in this work were modified through acid treatment to improve the dispersion of MWCNTs in the rubber matrix and the surface interaction between MWCNTs and matrix. Synergistic interaction between CB and MWCNTs increased the tensile modulus and tear strength of nanocomposites. The effect of MWCNTs on the transport properties invoked an increment in the thermal conductivity of the nanocomposites. A combination of 10 phr (parts per hundred rubber) MWCNTs with 40 phr CB dramatically increased the modulus at 100% elongation, tear strength, and thermal conductivity of the nanocomposite by 66%, 28%, and 36%, respectively, compared with those of nanocomposite filled with 40 phr CB.

The role of carbon nanotubes in promoting the properties of carbon black-filled natural rubber/butadiene rubber composites

Abstract 80/20 natural rubber (NR)/butadiene rubber (BR) blends in which the carbon black (CB) was replaced partially by multi-walled carbon nanotubes (MWCNTs) according to the ratios m (CNTs): m (decreasing amount of CB) = 1: X (X was varied from 1 to 6), was prepared by blending of internal mixer and the two-roll mill at the mill opening of 0.5 mm for 10 times. SEM and TEM were used to investigate the filler networks and the good dispersion of fillers. The compounds containing 5 phr CNTs/27.5 phr CB exhibited the best abrasion resistance which was increased by 12.69% compared that without CNTs. 3D morphology images of wear surfaces and tensile fracture surfaces being similar to the layered map of the geography, which match the abrasion resistance and tensile properties, were observed by 3D measuring laser microscope. The uncured blend with 5 phr CNTs/35 phr CB showed the shortest cure time, the highest modulus and level of crosslink density. Significant improvement in mechanical properties were achieved by incorporating 5 phr CNTs and 35 phr CB, and the tear strength, 100% and 300% modulus of the vulcanizate were enhanced by 36.36%, 61.29% and 31.63% compared with the composite with 0 phr CNTs/40 phr CB, respectively. Additionally, compared with the composite without CNTs, the thermal conductivity of the composites with 5 phr CNTs/35 phr CB is increased by an average of 6.15% at three different temperatures. These considerable reinforcements resulted from the synergistic effect of CNTs and CB.

Studies on Mechanical Properties and Dynamic Performance of SSBR/CB/Silica Composites

Carbon black ( CB ) and silica were used as two-component fillers to enhance the practicability of rubber. In this study, the microstructure, mechanical and dynamic properties of solution-polymerized styrene-butadiene rubber ( SSBR ) vulcanizates filled with carbon black and silica were characterized. 50 phr of total hybrid fillers was used as the base. A series of experiments with different ratios of CB/silica were carried out to determine the best contribution to the performance of SSBR vulcanizates. The studies have shown that when the vulcanizates exhibited the better overall mechanical and dynamic performance with 20 phr silica loading and 30 phr CB loading.

Effects of hybrid filler networks of carbon nanotubes and carbon black on fracture resistance of styrene‐butadiene rubber composites

In this study, influences of hybrid filler networks of carbon nanotubes (CNTs) and carbon black (CB) on fracture resistance of styrene‐butadiene rubber (SBR) composites were well investigated. The spherical CB was partially substituted by fibrous CNTs in two different ways: unequal replacement (1 phr CNTs replacing 4 phr CB) and equal replacement (1 phr CNTs replacing 1 phr CB). The J‐integral tests were employed to evaluate the crack initiation and propagation resistance. The strain amplification and distribution near the crack tip was measured by digital image correlation to explore the fracture resistance mechanism. Results revealed that the fracture resistance was effectively improved by unequal replacement. Meanwhile, for unequal replacement, higher content of CNTs resulted in a weaker strain amplification factor and larger amplification area near the crack tip, which contributed to the improved fracture resistance. However, opposite trends were observed for equal replacement. A synergistic effect in fracture resistance of SBR composites between CB and CNTs was realized for unequal replacement. POLYM. ENG. SCI., 56:1425–1431, 2016. © 2016 Society of Plastics Engineers

Preparation and characterization of hybrid nanocomposites based on NBR/Nanoclay/Carbon black

Acrylonitrile butadiene rubber (NBR)/carbon black (CB)/nanoclay (NC) nanocomposites containing 5 phr NC and 12, 24, and 48 phr CB with resorcinol/hexamethylenetetramine as compatibilizer were prepared in an internal mixer. The possible interacting behavior between NC and CB was studied by transmission electron microscopy, X‐ray diffraction, cure rheometry, dynamic mechanical thermal analysis, and tensile test. The results show an increased cure rate upon incorporation of 5 phr NC to NBR especially in presence of CB. It is also observed that increasing CB content in nanocomposites leads to an extra enhancement in mechanical properties and crosslink density which can be attributed to the synergistic effect between NC and CB due to formation of physical and chemical network. POLYM. COMPOS., 38:E181–E188, 2017. © 2016 Society of Plastics Engineers

Multilayer Graphene/Carbon Black/Chlorine Isobutyl Isoprene Rubber Nanocomposites.

High loadings of carbon black (CB) are usually used to achieve the properties demanded of rubber compounds. In recent years, distinct nanoparticles have been investigated to replace CB in whole or in part, in order to reduce the necessary filler content or to improve performance. Multilayer graphene (MLG) is a nanoparticle made of just 10 graphene sheets and has recently become commercially available for mass-product nanocomposites. Three phr (part for hundred rubbers) of MLG are added to chlorine isobutyl isoprene rubber (CIIR)/CB composites in order to replace part of the CB. The incorporation of just 3 phr MLG triples the Young’s modulus of CIIR; the same effect is obtained with 20 phr CB. The simultaneous presence of three MLG and CB also delivers remarkable properties, e.g. adding three MLG and 20 phr CB increased the hardness as much as adding 40 phr CB. A comprehensive study is presented, showing the influence on a variety of mechanical properties. The potential of the MLG/CB combination is illustrated to reduce the filler content or to boost performance, respectively. Apart from the remarkable mechanical properties, the CIIR/CB/MLG nanocomposites showed an increase in weathering resistance.

Fourier-Transform Rheology of Unvulcanized, Carbon Black Filled Styrene Butadiene Rubber

Rubber materials filled with reinforcing fillers display nonlinear rheological behavior at small strain amplitudes below γ0 < 0.1. Nevertheless, rheological data are analyzed mostly in terms of linear parameters, such as shear moduli (G′, G″), which loose their physical meaning in the nonlinear regime. In this work styrene butadiene rubber filled with carbon black (CB) under large amplitude oscillatory shear (LAOS) is analyzed in terms of the nonlinear parameter I3/1. Three different CB grades are used and the filler load is varied between 0 and 70 phr. It is found that I3/1(φ) is most sensitive to changes of the total accessible filler surface area at low strain amplitudes (γ0 = 0.32). The addition of up to 70 phr CB leads to an increase of I3/1(φ) by a factor of more than ten. The influence of the measurement temperature on I3/1 is pronounced for CB levels above the percolation threshold.

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.

Physical–mechanical properties of carbon black–nanoclay composites of butyl rubber as curing bladder compounds

Partial replacement of carbon black (CB) by organically modified montmorillonite (OMMT) in bladder compounds and synergistic effect between OMMT and CB on required properties were studied. X-ray diffraction results revealed intercalation of rubber into OMMT galleries. Mechanical interaction between rubber and filler, mechanical stability in oxidative aging, resistance to permanent set, reduction in permeation to CO2, and resistance to thermal degradation were all in favour of clay containing composites, especially the compound with 45 phr CB and 4 phr OMMT.

Cut growth and abrasion behaviour, and morphology of natural rubber filled with MWCNT and MWCNT/carbon black

Various amounts of predispersed multi-wall carbon nanotubes (MWCNT) were mixed with natural rubber (NR), with and without carbon black (CB), for preparing MWCNT-filled NR (NC) and MWCNT/CB-filled NR (NH) vulcanizates. All NH vulcanizates contained 30 phr CB and the amount of MWCNT for both NC and NH was varied from 0 to 8 phr. Helium ion microscopy (HIM) and FE-SEM images showed that MWCNT in the NH was dispersed much better than in the NC. Additionally, the well dispersed CB and MWCNT in the NH functioned synergistically in promoting an increase in longitudinal crack growth, leading to enhancement of edge-cut tensile strength (CTS) with increasing MWCNT loading. In contrast, all NC specimens ruptured in a simple lateral direction relating to their lower CTS. Results also revealed that abrasion resistance of the NH was not significantly changed with increasing MWCNT, whereas that of the NC increased. Nevertheless, abrasion resistance of both vulcanizates showed good correlation with the average value of ridge spacing on their abraded surfaces. It was also found that tensile strength of the NH was almost unchanged when the MWCNT loading was increased because the reinforcement by CB predominates over the MWCNT. However, 100% modulus and hardness of both NC and NH increased with increasing MWCNT content.

Characteristics of NR/CB Composites: Preparation Methods and Correlations of Electrical and Mechanical Properties

This work aims to correlate the electrical conductivity and mechanical properties of binary composites made of natural rubber (NR) and carbon black (CB). The samples were prepared using both a wet and dry mixing method before making the composites with a conventional rubber vulcanization process. The dry-mixing method was found to achieve higher electrical conductivity than the wet-mixing method. The composite made by efficient vulcanization (EV) had lower compression set than the composite made by conventional vulcanization (CV) and the compression set increased with an increase of CB. The highest tensile strength of the composite was found at CB content of 20 phr. The percolation threshold concentration of the binary composite was observed at 10 phr CB. Electrical conductivity of the composite depended on sample thickness where thinner samples had higher conductivity than the thick sample.

Correlation of electrical and swelling properties with nano free-volume structure of conductive silicone rubber composites

The present study focuses on finding a correlation between the positron annihilation parameters of silicone rubber polydimethylsiloxane (PDMS) composites loaded with different conductive fillers and their swelling and electrical properties. Four types of conductive fillers have been used in this study, i.e., carbon black (CB), graphite (G), copper, and nickel powders. The investigated swelling parameters for PDMS composites such as the maximum degree of swelling Qm%, the penetration rate, P, and consequently the diffusion coefficient, D, decreased with increasing the filler content due to the reduction of the size of free-volume, which could be observed through a decrease of the probability of ortho-positronium (o-Ps) formation I3, that has been measured by the positron annihilation spectroscopy (PALS). Accordingly, a positive correlation has been found of 76.78% and 61.1% between Qm% and the o-Ps lifetime s3, representing the size of free-volume for the CB and G filled composites, respectively. It is worthwhile, mentioning that the CB filled composites exhibit relatively low values of P, D, and Qm% as compared to the G filled composites due to the difference in the physical properties of the filler, particle size, surface area as well as the tendency of the filler particles to make aggregates. On the other hand, the variation of the diffusion coefficient with the relative fractional free-volume Fr is found in good agreement with the Fujita’s free-volume theory. On the other hand, the electrical conductivity increases with increasing the conductive filler content. Positive temperature coefficient of conductivity (PTCC) behavior is detected, except for the composite containing 20 or 25 phr CB, which showed a metallic behavior. Besides, CB filled PDMS composites exhibit higher electrical conductivity as compared to the composites filled with the other three fillers. The electrical conductivity ln (r) is positively correlated with the probability of free annihilation of positrons at interfaces I2, thus suggesting an increase in the electron density with the filler content. The activation energy of conduction, Ea, decreases with the increase in the loading of conductive filler. Moreover, it was noticed that Ea varies with the filler type, the values of Ea increase as the particle size of the filler increases. Finally, a correlation between the free-volume Vf, determined by PALS with the DC electrical conductivity ln(r) is found to be in accordance with Miyamoto and Shibayma model. POLYM. COMPOS., 00:000–000, 2013. V C 2013 Society of Plastics Engineers

Co-compatibilising effect of carbon nanotubes and liquid isoprene rubber on carbon black filled natural rubber/polybutadiene rubber blend

Bis-(triethoxysilylpropyl)-tetrasulfane functionalised carbon nanotubes (t-CNTs) were used as compatibiliser along with liquid isoprene rubber (LIR) in the natural rubber (NR)/polybutadiene rubber (BR) blend. Their reinforcing and compatibilising effects were evaluated by mechanical, fatigue crack growth resistance properties and blend homogeneity. Scanning electron microscope and transmission electron microscope showed enhanced interfacial adhesion between the binary rubber phases and improved dispersion of the minor phase in the rubber blend respectively with the co-existence of LIR and carbon nanotubes. The tensile strength of the carbon black (CB) filled NR/BR blend reached its optimum when 3 phr CB was replaced with an equal amount of t-CNTs in the presence of 7 phr LIR, while the fatigue crack growth resistance property achieved its maximum in the presence of 3 phr LIR. This interesting co-compatibilisation behaviour of t-CNTs and LIR suggests that t-CNTs have a better effect than CB with the assistance of LIR, which is an effective plasticiser in the NR/BR blend.

Silicone rubber nanocomposites containing a small amount of hybrid fillers with enhanced electrical sensitivity

A conductive silicone rubber (SR) composite, filled with both carbon nanotubes (CNTs) and carbon black (CB) is prepared by a simple ball milling method. Because of the good dispersion and synergistic effects of CNT and CB, the SR composite (SR with 2.5phr CB and 1.0phr CNT hybrid fillers) shows improvement in mechanical properties such as tensile strength and strain to failure. As well, due to the assembly of conductive pathways generated by the CNT and CB, the nanocomposite becomes highly conductive at a comparatively low concentration, with high sensitivity for tensile and compressive stress. Long-term measurement of properties shows that the SR composite maintains the excellent electrical properties under different strain histories. These outstanding properties show that the SR composite has potential applications in tensile and pressure sensors.

Surface morphology, mechanical and tribological properties of blended deproteinized natural and polyisoprene rubbers

The morphology, and mechanical and tribological properties of deproteinized natural rubber with constant viscosity (DPNR) and synthetic cis-1, 4 polyisoprene vulcanizates (IR2200) using ISAF220 carbon black (CB) blends were studied in various ratios: 100/0, 75/25, 50/50, 25/75 and 0/100. Results for different operating test conditions under applied normal load, sliding speed and sliding distance were analyzed. The experimental results showed that the addition of CB (30 phr.) has significantly affected the wear and frictional performance of both DPNR-CV and IR2200 by decreasing the abrasion weight loss by more than 80% compared with the unfilled DPNR and IR2200. Adding 30 phr CB decreases the abrasion weight loss to more than 70%. The surface topography of micro-scales abrasion was characterized by scanning electron microscopy (SEM). Using SEM micrographics, the influence of blend ratios on wear mechanisms and spacing imprinted abrasion patterns was highlighted.

Effect of Mixing Process and Morphologies on the Electrical Conductivity of PA6/EVA/CB Composites

Nylon6 (PA6)/Ethylene-(vinyl acetate) (EVA)/carbon black (CB) composites with different electrical conductivity were prepared in an internal mixer. The factors influencing the electrical conductivity of the ternary composites were investigated, including mixing mode, mixing time and mass ratio of PA6 and EVA, and so on. Among three kinds of PA6/EVA/CB composites, including ones prepared by directly mixing (composites A), EVA and CB were mixed prior to melt-compounding with PA6 (composites B) and PA6 and CB were mixed prior to melt-compounding with EVA (composites C), the mixing time only significantly influenced the electrical conductivity of composites A. Good conductivity of the composites could be realized because the distance between CB particles became closer with the increasing of mixing time. However, the mixing time has no effect on the electrical properties of the composites B and the composites C, due to there were no CB particles migrated phenomenon happened. Scanning electron microscopy (SEM) was used to assess the fracture surface morphologies and the dispersion of the CB particles. The results showed that the dispersion of the CB particles significantly affects the electrical conductivity of the composites. Based on the study of the influence of various mass ratios of EVA and PA6 on the morphologies and electrical properties of PA6/EVA composites filled with 10 phr (parts per hundred resins) CB particles, we suggested that the mass ratio of EVA and PA6 affected the volume resistivity of the ternary composites significantly. In addition, the composites were almost insulation when the mass ratios of EVA and PA6 were 80/20 and 70/30, while the composites became conductivity with the mass ratio of EVA and PA6 higher than 60/40. The PA6/EVA/CB composites which CB particles locate at the interface of EVA and PA6 have the lowest volume resistivity when the mass ratio of two components was 60/40.

Curing Characteristics, Fatigue Life and Morphological Properties of Natural Rubber Nanocomposites with Halloysite Nanotubes (HNTs)/Carbon Black (CB) Hybrid Filler

In this research, natural rubber (NR) with halloysite nanotubes(HNTs)/carbon black (CB) hybrid filler at various filler loading was investigated where the total filler loading used in each compound were 40 phr. The curing characteristics, fatigue life and morphological properties of HNTs/CB/NR nanocomposites were studied. Laboratory two-roll mill was used for mixing process. The results revealed that vulcanizates containing more HNTs in hybrid filler exhibit longer scorch time (ts2) and cure time (t90) for curing characteristics and higher in fatigue life compared to vulcanizates with 40 phr of CB. The images from scanning electron microscope (SEM) confirmed that replacement of carbon black with halloysite nanotubes improved the fatigue life by showing more tearing surface on vulcanizates.