淀粉/炭黑/丁苯橡胶复合材料的抗疲劳性能

采用乳液共混法,用少量淀粉等量替代炭黑,制备淀粉/炭黑/丁苯橡胶(SBR)复合材料,研究了淀粉用量对复合材料抗疲劳性能的影响。结果表明,当丁苯胶乳为100份、炭黑与淀粉的总量为50份时,淀粉最佳替代量为5～8份,在此条件下复合材料的抗疲劳性能大幅度提高;淀粉/炭黑/SBR复合材料的抗疲劳性能与硫化胶的抗切割性能、裤形撕裂强度以及损耗因子有一定的相关性。     

Synergistic effects of hybrid carbon nanomaterials in room‐temperature‐vulcanized silicone rubber

This work examines nanocomposites based on nanofillers and room‐temperature‐vulcanized silicone rubber. The carbon nanofillers used were conductive carbon black (CB), carbon nanotubes (CNTs) and graphene (GE). Vulcanizates for CB, GE, CNTs as the only filler and hybrid fillers using CNTs, CB and GE were prepared by solution mixing. The elastic modulus for CNT hybrid with CB at 15 phr (4.65 MPa) was higher than for CB hybrid with GE (3.13 MPa) and CNTs/CB/GE as the only filler. Similarly, the resistance for CNT hybrid with CB at 10 phr (0.41 kΩ) was lower than for CB (0.84 kΩ) at 20 phr and CNTs as the only filler. These improvements result from efficient filler networking, a synergistic effect among the carbon nanomaterials, the high aspect ratio of CNTs and the improved filler dispersion in the rubber matrix. © 2016 Society of Chemical Industry     

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     

Synergistic effects of carbon nanotubes and carbon black on the fracture and fatigue resistance of natural rubber composites

The quasi‐static fracture and dynamic fatigue behaviors of natural rubber composites reinforced with hybrid carbon nanotube bundles (CNTBs) and carbon black (CB) at similar hardness values were investigated on the basis of fracture mechanical methods. Mechanical measurement and J‐integral tests were carried out to characterize the quasi‐static fracture resistance. Dynamic fatigue tests were performed under cyclic constant strain conditions with single‐edged notched test pieces. The results indicate that synergistic effects between CNTBs and CB on the mechanical properties, fracture, and fatigue resistance were obtained. The composite reinforced with 3‐phr CNTBs displayed the strongest fatigue resistance. The synergistic mechanisms and dominating factors of quasi‐static and dynamic failure, such as the dispersion state of nanotubes, hybrid filler network structure, strain‐induced crystallization, tearing energy input, and viscoelastic hysteresis loss, were examined. The weakest fatigue resistance of the composite filled with 5‐phr CNTBs was ascribed to its strikingly high hysteresis, which resulted in marked heat generation under dynamic fatigue conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42075.     

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.     

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

Abstract

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.     

Crack growth resistance of natural rubber reinforced with carbon nanotubes

Carbon nanotubes (CNTs)/natural rubber (NR) composites are prepared through ultrasonically assisted latex mixing combined with a two-roll mixing process, and their crack growth behavior is examined to evaluate their fatigue properties. CNTs/NR shows a reinforcement of crack growth resistance compared to unfilled NR. The measurements of the tearing energy and the hysteresis loss show that CNTs/NR exhibits more energy dissipation than NR. Also, strain-induced crystallization (SIC) around the crack tip of CNTs/NR and NR composite was examined at different fatigue strains. CNTs positioned at the crack tip led to a crack branching at low fatigue strain, which is responsible for the improvement of the crack growth resistance of CNTs/NR. However, the inclusion of CNTs renders NR higher crystallinity and larger crystallization zones in front of the crack tip at high fatigue strains, which allows more energy dissipation during crack growth. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48447.     

Influence of the filler type on the rupture behavior of filled elastomers

This work is devoted to the rupture behavior of elastomers filled with carbon black (CB) or silica. Two elastomers have been studied: one which crystallizes under strain, natural rubber (NR), and another one which does not crystallize, styrene butadiene rubber (SBR). The study of the crack propagation of Single Edge Notched specimen (SENT) during stretching at different speeds focuses on the crack initiation and crack deviation phenomenon. This deviation is of main importance in the materials crack resistance as it leads to a large increase in the energy needed for rupture. The deviation in filled or unfilled NR is controlled by crystallization, which is a slow process. In unfilled SBR, deviation is controlled by polymer chain orientation, which is hindered by relaxation mechanisms. The introduction of fillers promotes strain amplification, and strain anisotropy in the crack tip region of the notched samples, and therefore crack deviation. In term of energy density at break of the SBR composites, the SBR filled with silica treated with a covering agent is the most efficient. Thus, a weak interface between the silica and SBR promotes better rupture properties. When comparing Silica and CB filled NR, the highest strain energy to rupture is also obtained with silica. This might be due to the weaker filler‐matrix interface for silica. Thus, these results evidence the kinetic aspect of the rupture, and of the mechanisms it involves: the polymer relaxation, the crystallization (for NR), and the filler‐matrix interaction and decohesion, all of them being strongly interrelated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crack growth behavior of natural rubber influenced by functionalized carbon nanotubes

In this work, the silane coupling agent bis‐(triethoxysilylpropyl) ‐tetrasulfide (TESPT) is used to modify the carbon nanotubes. After modification, carbon nanotubes can be well dispersed in the natural rubber (NR) matrix and form a strong and flexible network. Based on the original real‐time crack tip morphology monitoring, crack propagation and scanning electronic microscopy tests, it is revealed that modified carbon nanotubes filled NR samples (NR/F‐CNTs) have better crack resistance. It is found that modified carbon nanotubes can resist the cavitation process during cyclic loading. Crack tip morphology monitoring tests indicate that the crack tip of NR/F‐CNTs is rougher and the ligaments are thinner and densely distributed. A crack branching phenomenon is also observed. It proves that F‐CNTs increase the energy consumption of NR during cyclic loading. It is concluded that the F‐CNTs used in this work improve the crack resistance of NR in two ways: the one is cavitation resistance and the other is the increase of energy consumption for crack propagation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44527.     

Effect of conductive carbon black on electrical conductivity and performance of tire tread compounds filled with carbon black/silica hybrid filler

For green tires, carbon black (CB) is partially replaced by silica (SiO₂) in the tread formula in order to improve wet grip (WG) and fuel saving efficiency (FSE). However, such replacement inversely affects electrical conductivity of a tire resulting a greater potential for static shock or electrostatic ignition. This work aimed to improve electrical conductivity of the tread compound by partially replacing either CB or SiO₂ by 0–12 phr of conductive carbon black (CCB) (with replacing ratio of 2:1) and investigating the effect of such replacement on the tire performance. Although the partial replacement of CB or SiO₂ by CCB increased the magnitude of transient filler network resulting in the negative effects on heat build-up, WG and FSE of the tread vulcanizates, it significantly improved electrical conductivity. Surface resistivity decreased sharply when CB or SiO₂ was replaced by 3 phr of CCB, revealing the point of percolation threshold. In addition, the partial replacement of CB or SiO₂ by CCB did not cause significantly change of both hardness and tensile properties. At any given CCB loading, the SiO₂ replacement provided greater surface conductivity and higher abrasion resistance with lower WG and FSE than the CB replacement.     

Studies of nanocomposites based on carbon nanomaterials and RTV silicone rubber

The mechanical and electrical properties were investigated for nanocomposites based on carbon nanotubes (CNTs) and conductive carbon black (CB). Solution room‐temperature‐vulcanized silicone rubber was used as a matrix. Vulcanizates based on CNTs and CB was prepared by solution mixing. With the addition of 2 phr of CNTs to the rubber matrix, the Young's modulus increased by 272% and reached as high as ～706% at 8 phr, whereas the modulus increased only 125% for CB specimens at 10 phr. Similarly, the electrical properties at 5 phr content of CNT were ～0.7 kΩ against ～0.9 kΩ at 20 phr CB. The Kraus plot from equilibrium swelling tests shows that the high properties for CNT specimens are due to high polymer–filler interfacial interactions, the small particle size that improves the distribution of the filler in a highly exfoliated state, and high electrical connective networks among the filler particles. These improvements can especially influence medical products such as feeding tubes, seals and gaskets, catheters, respiratory masks and artificial muscles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44407.     

Effect of external loads on damage detection of rubber‐toughened nanocomposites using carbon nanotubes sensory network

Multiwalled carbon nanotubes of 0.2% weight fraction are used as a sensory network for detecting and characterizing the damage of particulate epoxy composites under shear loading conditions. Three different weight fractions of carboxyl‐terminated butadiene acrylonitrile copolymer rubber [10 parts per hundred of epoxy resin (phr), 20 phr, and 30 phr] are used for toughening a thermoset epoxy composite. The electrical response of the specimens is measured, nearest the central shearing plane, using a four‐circumferential ring probe technique in conjunction with a high‐resolution data acquisition system. A collection of the electromechanical response results are reported with respect to the shear strain. The resistance changes observed under shear loading are related to nonlinear deformation mechanisms, void initiation, and growth around rubber particulate. With increasing rubber content, the strength of the material decreases and a greater drop in resistance is recorded as a result of decreased distance between neighboring carbon nanotubes (CNTs) due to declustering and straightening of molecular chains of host matrix. In the end, a comparison for 30 phr composites under shear loading with that of tensile and compression loading conditions is presented. For initial deformation, there is no change in resistance under shear loading condition; however, the significant resistance change can be noticed under both tension and compression. The specimen under shear loading conditions experiences smaller decrease in resistance when compared with both tension and compression. However, the decrease in resistance is higher for compression due to higher decrease in distance between neighboring CNTs. POLYM. COMPOS., 37:360–369, 2016. © 2014 Society of Plastics Engineers     

Compressive residual thermal stress induced crack deflection in carbon nanotube-doped carbon/carbon composites

Introducing carbon nanotubes (CNTs) by electrophoretic deposition (EPD) is a promising method to improve the strength and toughness of carbon/carbon (C/C) composites. Herein, a new reinforcing mechanism called “compressive residual thermal stress (RTS) induced crack deflection” has been reported. Concretely, CNTs, with different loading content, were introduced by EPD method. Results showed that the CNT content had little influence on CNT-induced matrix refinement. However, the strength of the CNT-doped C/C composites increased with the rising content of CNTs and cracks could only deflect when the CNT interface reached a certain thickness. A theory based on compressive RTS induced crack deflection was built to interpret this discrepancy. Tensile stress existed at the interface in pure C/C composites, while compressive stress occurred and increased with the rising thickness of the CNT interface, which were verified by finite element analysis and Raman test. Calculation revealed that compressive stress exceeded 30 MPa at the crack tip could make the crack deflection happen more easily since it released more strain energy than penetration.     

炭黑/黏土/丁苯橡胶纳米复合材料的性能

研究了用1份(质量,下同)或2份黏土替代5份或10份炭黑对炭黑/黏土/丁苯橡胶纳米复合材料性能的影响。结果表明,用少量黏土非等量替代炭黑后,复合材料的物理机械性能变化不大;复合材料的耐磨性能随炭黑用量的减少而降低,耐屈挠疲劳性能随黏土用量增加而提高。当炭黑与黏土的填充量分别为45份和2份时,复合材料的物理机械性能和动态生热与填充50份炭黑时相当。     

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.     

Reinforcement of rubber using radial single-walled carbon nanotube soot and its shock dampening properties

A soot composed of radial single-walled carbon nanotubes (r-SWCNTs), in which 70 nm length nanotubes are grown radially around the core metal particles, and nanohorn-like carbons (NHCs) was used as reinforcement for a styrene-butadiene rubber (SBR). The fracture stress of r-SWCNT soot (38 phr)/SBR was 6.3 MPa at 60% strain. Furthermore, the hardness value of r-SWCNT soot (38 phr)/SBR was 94, which is 1.38 times larger, and larger than carbon black/SBR. Additionally, the resilience of r-SWCNT soot/SBR with 38 phr filler content was markedly lower than 20% in comparison with standard carbon black filler. These results indicate that r-SWCNT soot/SBR possesses excellent kinetic energy absorbing properties.     

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.     

Effects of the vulcanizing reagent addition on the properties of CNTs/SBR powder composites

Vulcanizing reagent (VR) suspensions with different sulfur additions were mixed with CNTs suspensions and SBR latex, and then powder CNTs/SBR (PSBR) composites were prepared by spray‐drying process. Investigations showed that VR additions have significant influences on the properties of CNTs/PSBR composites. With the increment of VR additions, glass transition temperature (T_g) of the composites increased gradually, and reached the maximum when the sulfur addition was 4.0 phr, and then it would decrease if the sulfur addition continued to rise. The elongation at break of the vulcanizates decreased linearly. The tensile strength and hardness reached the maximum when the sulfur addition was 4.0 phr, and almost kept constant when the addition continued to rise. Yet the tear strength reached the maximum when the addition was of 2.5 phr, and then decreased slightly when the addition exceeded 4.0 phr, which was corresponding to the structure designability of the composites affected by the sulfur aggregates in the matrix. Under different temperatures, when the vulcanizing temperature was 150°C, the vulcanizing speed was proper, vulcanizing time was prolonged, and the vulcanizing security was intensified. Compared with the vulcanization of carbon black/PSBR composites, more sulfur additions are needed in the vulcanization of CNTs/PSBR composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of carbon nanotubes grown temperature on the fracture behavior of carbon fiber reinforced magnesium matrix composites: Interlaminar shear strength and tensile strength

The design of an interfacial structure is particularly important for load transfer in composites. In this paper, different amounts of carbon nanotubes (CNTs) were grafted onto the carbon fiber (CF) surface by adjusting grown temperature using injection chemical vapor deposition (ICVD). The prepared CF preform grafted with CNTs (CNTs-CF) were used to reinforce magnesium alloy by squeeze casting process. The microstructures were analyzed by means of optical microscope (OM) and scanning electron microscope (SEM), and the interlaminar shear strength (ILSS) and tensile strength of the composites were determined by double-notch shear test and tensile test. The results indicated that moderate ILSS was more conducive to improving the tensile properties of carbon fiber reinforced magnesium matrix (C_f/Mg) composites. Compared with C_f/Mg, the tensile strength of composite with CNTs increased by about 80%. For C_f/Mg composites grafted with CNTs, CNTs had the effects of delaying crack propagation and increasing energy consumption by the pull-out and bridging mechanism, which were the main reasons for improving the strength. The analysis of shear fracture surface showed that the crack propagation path can be optimized by adjusting the amounts of grafted CNTs. The presence of CNTs affects the stress distribution and consequently the crack initiation as well as the crack propagation.     

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

Abstract

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.