Influence of modified natural rubber and structure of carbon black on properties of natural rubber compounds

Carbon black‐filled natural rubber composites were prepared using various types of natural rubber: unmodified natural rubber, epoxidized natural rubber with two levels of epoxy groups at 25 and 50 mol % [epoxidized natural rubber (ENR)‐25 and ENR‐50], and maleated natural rubber. Two types of carbon black (HAF and ECF) with different structure and surface area were used. The functional groups present in natural rubber and carbon black were characterized by FTIR and ¹H‐NMR. Furthermore, cure characteristics, mechanical, morphological, and electrical properties of composites and gum rubber compounds were investigated. It was found that the presence of polar functional groups in rubber molecules and the different structures of carbon black significantly affected the cure characteristics and mechanical properties. This is attributed to physical and chemical interactions between carbon black surfaces and rubber molecules. It was also found that natural rubber filled with ECF showed the highest Young's modulus and hardness, which is due to the high‐surface area and structure of the ECF causing an increase in the degree of entanglement between rubber chains and carbon black particles. Frequency dependency of the dielectric constant, loss tangent, and AC conductivity was also investigated. An increase in dielectric constant, loss tangent, and AC conductivity was observed in the ENR/ECF composites. High‐carbon black loading level caused network formation of these conductive particles, increasing the AC conductivity of the composites. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

Effect of coal gangue/carbon black/multiwall carbon nanotubes hybrid fillers on the properties of natural rubber composites

The objective of this study was to investigate three kinds of filler with completely different morphology on mechanical properties of natural rubber (NR). Coal gangue (CG) are derived from natural deposits are composed principally by illite and quartz. CG, carbon black (CB), and multiwalled carbon nanotube (CNT) were used as hybrid fillers in NR. CNTs were dispersed into NR latex by ultrasonic irradiation and then the mixed latex were coagulated to obtain the CNTs/NR masterbatch, then mechanical mixing method was employed to prepare the CG/CB/CNTs/NR composites. The addition of CG, CB, and CNTs to NR was varied with the total filler loading fixed at 35 phr. The mechanical properties of NR composites were studied in terms of tensile and dynamic mechanical analysis (DMA). The results showed that the tensile strength and modulus 300% (M300) of all hybrid samples were higher than the composites only loaded CG; and the highest tensile strength of NR loaded with hybrid fillers achieved at sample of loading amount of CG 17.5, CB 15.5, and CNTs 2 phr, whose M300 and elongation at break was obviously higher than that of only CB loaded NR composites; The inclusion CG improves the tensile strength of NR without the sacrifice of its extensibility, while CB and CNTs brings together the enhancement in the ultimate strength and the reduction in the extensibility. DMA results revealed that the existence of CG can improve the dispersion of CB and CNTs in NR matrix. POLYM. COMPOS., 37:3083–3092, 2016. © 2015 Society of Plastics Engineers     

Effect of carbon black loading on curing characteristics and mechanical properties of waste tyre dust/carbon black hybrid filler filled natural rubber compounds

Curing characteristics, tensile properties, fatigue life, swelling behavior, and morphology of waste tire dust (WTD)/carbon black (CB) hybrid filler filled natural rubber (NR) compounds were studied. The WTD/CB hybrid filler filled NR compounds were compounded at 30 phr hybrid filler loading with increasing partial replacement of CB at 0, 10, 15, 20, and 30 phr. The curing characteristics such as scorch time, t₂ and cure time, t₉₀ decreased and increased with increment of CB loading in hybrid filler (30 phr content), respectively. Whereas maximum torque (M_HR) and minimum torque (M_L) increased with increasing CB loading. The tensile properties such as tensile strength, elongation at break, and tensile modulus of WTD/CB hybrid filler filled NR compounds showed steady increment as CB loading increased. The fatigue test showed that fatigue life increased with increment of CB loading. Rubber–filler interaction, Q_f/Q_g indicated that the NR compounds with the highest CB loading exhibited the highest rubber–filler interactions. Scanning electron microscopy (SEM) micrographs of tensile and fatigue fractured surfaces and rubber–filler interaction study supported the observed result on tensile properties and fatigue life. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fracture properties of natural rubber filled with hybrid carbon black/nanoclay

Hybrid carbon black (CB) and nanoclay (NC) in a rubber matrix have provided superior mechanical performances over conventional composites. Yet the fracture and fatigue properties have not been fully explored. In this paper, the mechanical properties of the hybrid-filled natural rubber (NR) were investigated with regard to the tensile strength, fatigue crack growth (FCG) and cut resistance. The ruptured crack tip and the torn surface were studied by using optical microscopy and scanning electron microscopy (SEM), respectively. It was found that the fatigue resistance at large tearing energy and cut strength were enhanced with hybrid filler. Subsidiary cracks were observed at the ruptured tip in rubber with NC. Morphology analysis revealed that the hybrid filler led to a rougher torn surface than rubber with non-hybrid filler. It was proposed that the clay layers constructed a dual phase filler network with CB aggregates. The filler network could cause strength anisotropy in the matrix and introduce more energy dissipation mechanisms to the system, resulting in enhanced fatigue resistance.     

Influence of carbon black and plasticisers on dynamic properties of isotropic magnetosensitive natural rubber

Abstract

The dynamic shear modulus of magnetosensitive (MS) natural rubber composites is experimentally studied, where influences of carbon black, plasticiser and iron particle concentrations are investigated at various dynamic shear strain amplitudes and external magnetic fields within the lower structure borne frequency range. The iron particles embedded in natural rubber are irregularly shaped and randomly distributed; the plasticisers simplify the iron particle blending process, while carbon black reduces the production costs and improves the mechanical properties. The results show that the relative MS effect on the shear modulus magnitude increases with increased plasticiser and iron particle concentration and decreases with increased carbon black concentration. Furthermore, their relative contributions are quantified. Consequently, the study provides a basis for optimising the composition of MS natural rubber to meet a variety of requirements, including those of vibration isolation, a promising application area for MS materials.     

Determination of carbon black fillers in vulcanizates of natural rubber by metathesis degradation

A method for the determination of carbon black fillers in peroxide vulcanizates or sulfur vulcanizates of natural rubber (NR, cis-1,4-polyisoprene) by metathesis degradation with 1-octene was developed using the catalyst WCl₆? (C₂H₅)₃Al₂Cl₃. The carbon black was separated from the reaction mixture by centrifuging and determined by weighing. In this connection, investigations were also performed with the catalyst WCl₆? C₂H₅Al₂Cl₃ which was less suitable for filler determination. The rate of degradation of crosslinked NR with (E)-4-octene was measured. Metathesis reactions of 2-methyl-2-pentene (low-molecular-weight model compound of NR) with 7-tetradecene showed the importance of double bond shift for the degradation of NR.     

Experimental analysis of viscoelastic properties in carbon black‐filled natural rubber compounds

Processability and viscoelastic properties of natural rubber (NR) compounds filled with different carbon black loadings and types were investigated with the use of a steady shear rheometer, namely, the Mooney viscometer, and an oscillatory rheometer, namely, the Rubber Process Analyser (RPA2000). It was found that the type and amount of carbon black strongly influence the viscoelastic properties of rubber compounds. Both the dilution effect and filler transient network are responsible for the viscoelastic properties, depending on the vulcanization state. In the case of uncured compounds, the damping factor of the uncured NR decreases with increasing black loading. This is attributed to the reduction of mobilized rubber content in the compound (or the dilution effect). However, in the case of the cured NR vulcanizates, the filler transient network is the dominant factor governing the damping factor of the vulcanizate. With increasing black loading, the damping factor of the vulcanizate clearly increases. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2197–2203, 2005     

Organo-montmorillonite as substitute of carbon black in natural rubber compounds

The use of octadecylamine modified montmorillonite as substitute of carbon black in natural rubber (NR) compounds is studied. Rubber with 10 parts per hundred resin (phr) of pristine (clay) and octadecylamine modified montmorillonite (organoclay) were compared with 10 and 40 phr carbon black as filler. The modified silicate is analysed by X-ray, FTIR and thermogravimetric analysis. Vulcametric curves show that the organoclay and carbon black accelerate the vulcanization reaction and, furthermore, give rise to a marked increase in the torque, indicating a higher degree of crosslinking as was also confirmed by swelling measurements and DSC. The vulcanisation rate and torque value of the organoclay compound are sensibly higher than the carbon black compound even at high contents (40 phr). Mechanical characterization shows the strong reinforcing effect of both fillers up to 350% in the strength in relation to NR. The mechanical properties of NR with 10 phr organoclay are comparable to the compound with 40 phr carbon black. Moreover, the organoclay improves the strength of the NR without hardly any reduction in the elasticity of the material.     

Effect of pulverized coal/carbon black hybrid fillers on mechanical properties and thermal stability of styrene butadiene rubber composites

Pulverized coal (coal) possesses a layered structure similar to graphite and is a potential reinforcing filler. In this paper, ball milling is used to reduce the particle diameter of coal. The coal is modified with KH-560 to obtain K-COAL and prepared K-COAL/styrene-butadiene rubber (SBR) composites. In addition, carbon black (CB) is modified to obtain CB-Si69, K-COAL and CB-Si69 are added to SBR in different ratios to prepare COAL/CB/SBR composites. The results show that the addition of K-COAL can improve the vulcanization performance, thermal stability, and mechanical properties of SBR composites, but the reinforcing effect is weak. In the COAL/CB/SBR composites, the vulcanization and mechanical properties of the composites gradually increase with the increase of CB, while those of the thermal stability decrease. The tensile strength of the 10 phr COAL/30 phr CB/SBR composite is 24.1 MPa, which is elevated by 1105% and 205% compared with the pure SBR and 40 phr K-COAL/SBR composites, respectively. The composites maintain high elasticity while the tensile strengths are greatly improved, and the mechanical properties are significantly enhanced. In conclusion, this paper provides a reference for the clean utilization of coal and shows new possibilities for finding new fillers to replace CB.     

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

In 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     

Dielectric properties and stress–strain measurements of chloroprene rubber based on different carbon black fillers

A systematic dielectric study of 1 kHz was carried out on chloroprene rubber, mixed with different types of carbon black and different concentrations. The measurements were carried out at room temperature (25°C). It was found that better dielectric properties cannot be achieved when the carbon black concentration exceeds 60% for MT, 40% for SRF, and 20% for both HAF and SAF. In addition, the relation between the dielectric constant ε and the modulus of elasticity E for the different mixes were studied. From this study it was found that, up to certain carbon black volume concentration (depending on the filler type), the modulus equation E_f = E₀ (1 + 0.67φC + 1.62φ²) can be used to relate the dielectric properties ε_f and ε_o of carbon black filled and unfilled rubber compounds. The dielectric measurements were also related to the particle size and the structure of carbon black.     

炭黑补强异戊橡胶和天然橡胶性能之对比研究

用填充炭黑的异戊橡胶（IR）和天然橡胶（NR）分别研究其硫化特性、力学性能、热空气老化性能和动态力学性能。结果表明,异戊橡胶比天然橡胶的硫化速度慢,焦烧时间长。随着炭黑用量的增多,IR和NR的300％定伸应力增大,拉伸强度和拉断伸长率都下降,撕裂强度出现了峰值。炭黑用量增加到40份时,IR的拉伸强度下降最缓慢,耐老化性能最好;而NR随炭黑用量增加,其拉伸强度下降加快,耐老化性能变差。0℃时IR的损耗因子大于NR的损耗因子;60℃时,IR的损耗因子小于NR的损耗因子。     

Hybrid fillers of lignin and carbon black for lowering of viscoelastic loss in rubber compounds

This study investigates novel hybrid fillers for lowering of viscoelastic dissipation in rubber compounds by exploiting non-covalent interactions between lignin and carbon black (CB). Lignin is naturally occurring three-dimensional amorphous polymer consisting of phenyl propane units with hydroxyl, methoxy, and carbonyl substitutions and is capable of producing non-covalent interactions via π–π stacking with CB particles. The hybrid fillers are obtained by precipitating lignin from solutions onto carbon black particles. The fractal nature similar to CB particles and the presence of lignin coating layers on CB particles are confirmed by electron microscopy images. The coating layers are promoted by strong π–π interactions as revealed from Raman spectroscopy and ¹H spin-lattice relaxation data and supported by a drop in zeta potential values. The hybrid fillers show much less networking than CB and reduce the viscoelastic dissipation in model rubber compounds by as much as 10% in comparison to the compounds of only CB.     

Influence of bound polymer on cure characteristics of natural rubber compounds reinforced with different types of carbon blacks

Rubber compounds are reinforced with fillers such as carbon black and silica. The cure characteristics of a filled rubber compound vary with the filler type and content. The influence of the type of carbon black on the cure characteristics of carbon black filled natural rubber compounds is investigated using two types of carbon black (N220 and N550), which are different in primary size and structure. The cure time and cure rate become faster as the carbon black content increases. The crosslink density also increases and reversion resistance is improved with the increase of carbon black content. The cure time and cure rate of the compound filled with N550 are faster than those of the compound filled with N220 at the same level of bound rubber content. In addition, higher crosslink density is also observed in the compound filled with N550 compared to that of the compound filled with N220 at the same level of bound rubber content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2282–2289, 2005     

改性炭黑对天然橡胶/顺丁橡胶并用胶性能的影响

采用3种方法对传统炭黑进行表面改性,考察了改性前后炭黑表面形貌及结构的变化,并采用改性炭黑填充天然橡胶（NR）/顺丁橡胶（BR）并用胶,考察了改性炭黑对并用胶力学性能、硫化特性及动态力学性能等的影响。结果表明,与未改性炭黑相比,细化粒径、调高pH值及木质素改性处理后,炭黑表面的粗糙程度增加;且细化改性炭黑具有更高的比表面积,调高pH值改性炭黑具有更多疏松的二次结构,木质素改性炭黑粒径略有增加。对于炭黑填充NR/BR,用细化粒径及调高pH值方法处理的炭黑进行填充,NR/BR硫化胶的力学性能、耐磨性能及抗湿滑性均得到明显改善,但硫化延迟效应明显;木质素改性后,炭黑填充胶的力学性能、耐磨性能均出现不同程度的降低。     

甲基丙烯酸固态原位接枝改性炭黑对天然橡胶和顺丁橡胶性能的影响

考察了固态原位接枝改性制备的甲基丙烯酸接枝改性炭黑对天然橡胶(NR)和顺丁橡胶。(BR)静态力学性能、动态力学性能的影响。结果表明。甲基丙烯酸改性炭黑比普通商品炭黑填充的NR硫化胶具有更好的静态力学性能;甲基丙烯酸改性炭黑曼有利于降低NR和BR硫化胶的滚动阻力。同时,有利于提高NR硫化胶的抗湿滑性。     

碳纳米管炭黑天然橡胶复合材料的制备与性能研究

碳纳米管以其特殊的结构与优异的性能成为橡胶补强的理想填料。本文中我们采用两种不同牌号的碳纳米管(分别为Flotube 7000、9011)与炭黑N660作为实验原料,制备了碳纳米管/炭黑/天然橡胶复合材料,并对其性能进行了探讨。结果发现：碳纳米管的加入能明显提高复合材料的定伸应力,具有一维取向排列且长径比较大的Flotube 7000(以下简称7000)对力学性能的提高程度最大。且我们将碳纳米管7000、9011分别与炭黑N660并用,对于提高复合材料的导热性能并没有如我们预期的一样存在所谓的“叠加关系”甚至是“协同效应”,而是对于提高复合材料导热有着一定的“负协同效应”。     

Thermal conductivity of natural rubber nanocomposites with hybrid fillers

Natural rubber nanocomposites filled with hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB) were prepared. CNTs were ultrasonically modified in mixture of hydrogen peroxide(H_2O_2) and distilled water(H_2O). The functional groups on the surface of CNTs, changes in nanotube structure and morphology were characterized by Fourier transform infrared spectroscopy(FT-IR), Raman Spectroscopy, and transmission electron microscopy(TEM). It shows that hydroxyl(OH·) is successfully introduced. The surface defects of modified CNTs were obviously higher than those of original CNTs, and the degree of agglomeration was greatly reduced. Thermal conductivity of the composites was tested by protection heat flow meter method. Compared with unmodified CNTs/CB filling system, the thermal conductivity of hybrid composites is improved by an average of 5.8% with 1.5 phr(phr is parts per hundred rubber) of hydroxyl CNTs and 40 phr of CB filled. A three-dimensional heat conduction network composed of hydroxyl CNTs and CB, as observed by TEM, contributes to the good properties. Thermal conductivity of the hybrid composites increases as temperature rises. The mechanical properties of hybrid composites are also good with hydroxyl CNTs filled nanocomposites; the tensile strength, 100% and 300% tensile stress are improved by 10.1%, 22.4% and 26.2% respectively.     

Effect of nano zinc oxide on the cure characteristics and mechanical properties of the silica‐filled natural rubber/butadiene rubber compounds

With the increasing interest in environmental and health issues, legal restrictions, such as European Union (EU) End of Life Vehicle Directives, were strengthened. This led us to incorporate nano zinc oxide (nano‐ZnO), with particle sizes of 30–40 nm and specific surface areas of 25.0–50.0 m²/g, instead of conventional ZnO into natural rubber (NR)/butadiene rubber (BR) compounds to decrease the content of zinc in the formulation. In the unfilled system, only a 20 wt % nano‐ZnO content, compared to conventional zinc oxide content, showed the cure characteristics and mechanical properties of the same level. This was because the increase in the specific surface area of the nano‐ZnO led to an increase in the degree of crosslinking. The effect of nano‐ZnO on the cure characteristics and mechanical properties was more pronounced in the silica‐filled system than in the unfilled system. This was mainly because of the dispersing agent used in the silica‐filled system, which also improved the dispersion of nano‐ZnO. The silica‐filled NR/BR compounds containing 0.3–3.0 phr of nano‐ZnO showed improved curing characteristics and mechanical properties, such as optimum cure time, 100 and 300% modulus, tensile strength, and tear strength compared to the compound with 5 phr of conventional ZnO. The optimum amounts of nano‐ZnO and stearic acid were only 1.0 and 0.1 phr, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of sulfenamide accelerators on cure kinetics and properties of natural rubber foam

The effect of types of sulfenamide accelerator, i.e., 2‐morpholinothiobenzotiazole (MBS), N‐t‐butylbenzothiazole‐2‐sulfenamide (TBBS), and N‐cyclohexyl benzothiazole‐2‐sulfenamide (CBS) on the cure kinetics and properties of natural rubber foam was studied. It has been found that the natural rubber compound with CBS accelerator shows the fastest sulfur vulcanization rate and the lowest activation energy (E_a) because CBS accelerator produces higher level of basicity of amine species than other sulfenamide accelerators, further forming a complex structure with zinc ion as ligand in sulfur vulcanization. Because of the fastest cure rate of CBS accelerator, natural rubber foam with CBS accelerator shows the smallest bubble size and narrowest bubble size distribution. Moreover, it exhibits the lowest cell density, thermal conductivity and thermal expansion coefficient, as well as the highest compression set as a result of fast crosslink reaction. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44822.