Carbon Silica Dual Phase Filler Research Articles

The Effects of Carbon-Silica Dual-Phase Filler on the Crosslink Structure of Natural Rubber.

Carbon–silica dual-phase filler (CSDPF)/natural rubber (NR) vulcanizate was prepared by mechanical blending, followed by a hot-press vulcanization. The dispersion of CSDPF in the NR matrix and the effects of CSDPF on the filler–rubber interaction and structure of the rubber network were studied. Scanning electron microscope results showed that CSDPF dispersed uniformly; however, there were some aggregates of CSDPF when loading too many fillers. With an increase in CSDPF, the interaction between CSDPF and NR chains increases, which was detected by bound rubber in the CSDPF/NR compound. The spectra of solid-state nuclear magnetic resonance revealed that CSDPF could promote the formation of poly-sulfidic crosslink in the rubber vulcanization network. Further, the molecular chain movement ability of vulcanizates decreases according to the spin–spin relaxation of 1H nuclei in CSDPF/NR compounds. The crosslink density of vulcanizate increases, while the chemical crosslink and physical crosslink in the vulcanization network also increase according to the tube model.

Surface modification of rice husk–based carbon–silica dual‐phase filler by ethanol‐assisted milling and its reinforcing on natural rubber

AbstractSilica carbon black (SiCB) was used as a natural carbon–silica dual‐phase filler (CSDPF) containing both biochar and silica, which was obtained by pyrolysis of rice husks. The reinforcing performances of SiCB were limited by the large particle size and poor surface activity. In this work, the size and distribution of the SiCB particles were modified by ethanol‐assisted milling (S/E), and increase in oxygen‐containing groups enhanced the surface activity of SiCB and promoted the grafting of silane coupling agent (Si69). The filler–rubber interfacial interactions were enhanced when the Si69‐grafted SiCB (S/E‐X, X means the amount of Si69) was used as filler for natural rubber (NR). Compared with the SiCB‐filled NR (SiCB/NR), the S/E‐3‐filled NR (S/E‐3/NR) showed 44%, 19%, and 27% improvement in the tensile strength, tear strength, and stress at 300% strain, respectively, and the reinforcing properties have reached the level of commercial carbon black (N774). This study provides a novel way for surface modification of CSDPF and improves the application of rice husk–based materials in rubber composites.

Characterization of hybrid fillers based on carbon black of different types obtained by impregnation

The paper presents the investigations on obtaining dual phase fillers with preset silica content running a successful impregnation of two completely different types of conventional carbon black with silicasol. The hybrid fillers studied were characterized by atomic absorption spectroscopy and inductively coupled plasma–optical emission spectroscopy. The total pore volume, the average pore diameter, the specific surface area, the oil absorption number, and iodine adsorption of the fillers were also investigated. The distribution of both phases within the hybrid filler obtained and their interpenetration were investigated with scanning transmission electron microscopy-energy dispersive X-ray spectroscopy. The hybrid products obtained were investigated as reinforcing fillers of natural rubber-based composites. The results obtained show that the suggested impregnation with silicasol of conventional carbon black is a perspective method for preparation of carbon-silica dual phase fillers. The method provides an easy control over the quantitative ratio between the two phases. The fillers thus prepared do not change significantly the curing and mechanical characteristics of the vulcanizates, but improve their thermal aging resistance. The isolation of the carbon black aggregates by the silica phase, and the interpenetration of the two phases is a prerequisite to obtain elastomer composites of good mechanical and microwave properties suitable for producing of microwave shielding devices.

Impacts of filler covalent and non‐covalent modification on the network structure and mechanical properties of carbon–silica dual phase filler/natural rubber

The carbon–silica dual phase filler (CSDPF) was modified by bis (3‐triethoxy‐silylpropyl) tetrasulphane (Si69) and 1‐allyl‐3‐methyl‐imidazolium chloride (AMI), respectively. The natural rubber (NR) vulcanizates filled with modified CSDPF were fabricated through mechanical mixing followed by a high‐temperature cure process. The impacts of filler surface modification on the curing characters, crosslinked junctions, network structure, and mechanical properties of NR vulcanizates were investigated. The results showed that the Si69 interacted with CSDPF through covalent bond, while the interaction between AMI and CSDPF was hydrogen bond. Both modifications increased the cure rate of CSDPF/NR compounds as well as the crosslinked degree, compared with those of pristine CSDPF/NR compound. The modifications improved the dispersion of CSDPF in NR matrix. The covalent modification by Si69 caused a limited movement of NR chains in the CSDPF surface, which contributed to a greater tensile modulus of Si69‐modified CSDPF/NR. However, the higher content of mono‐sulfidic crosslink and the poorer content of strain‐induced crystallization in the NR matrix led to a slight increase of tensile strength and tear strength of Si69‐modified CSDPF/NR, compared with those of CSDPF/NR. The tensile modulus of AMI‐modified CSDPF/NR had a lower value due to a faster polymer chain motion on the CSDPF surface. However, the tensile and tear strength of AMI‐modified CSDPF/NR increased significantly because of the increase of mono‐sulfidic crosslink, strain‐induced crystallization, and the existed hydrogen bond between CSDPF and NR. Copyright © 2015 John Wiley & Sons, Ltd.

Effect of carbon–silica dual phase filler obtained by impregnation method on the properties of SBR-based composites

Styrene butadiene rubber (SBR)-based composites have been reinforced with carbon–silica dual phase fillers. The new type of reinforcing fillers have been obtained by an impregnation method used for introduction and deposition of a second silica phase over the surface of carbon black particles. The mechanical properties of SBR-based composites (applicable for passenger tread compounds) have been investigated. It has been found that the modulus at 100% of elongation and tensile strength of the composites reinforced with the dual phase fillers have increased considerably in comparison to those of the composites containing standard carbon black.

The mechanism of carbon–silica dual phase filler modified by ionic liquid and its reinforcing on natural rubber

The carbon–silica dual phase filler (CSDPF) was modified by ionic liquids (ILs): 1‐allyl‐3‐methyl‐imidazolium chloride (AMI) and 1‐butlyl‐3‐methyl‐imidazolium hexafluorophosphate (BMI). The modified CSDPF was then incorporated into natural rubber (NR) through mechanical mixing. The interactions between CSDPF and ILs were investigated using differential scanning calorimetry (DSC), Fourier‐transform infrared spectroscopy (FTIR), and Raman spectroscopy. The bound rubber of NR compounds, the mechanical properties, and dynamic properties of NR vulcanizates filled with ILs modified CSDPF (ILs‐CSDPF/NR) were measured. The results showed that the AMI interacted with CSDPF through both hydrogen bonds and van der Waals forces, while the interaction between BMI and CSDPF was merely weak van der Waals force. The modification of CSDPF by ILs could improve the tensile strength, tear resistance, and fatigue life of NR vulcanizates. The AMI‐CSDPF/NR gave the superior mechanical and dynamic properties among the NR vulcanizates with the highest bound rubber content and the most homogeneous filler dispersion, which was displayed in scanning electron microscope (SEM) images. POLYM. COMPOS., 36:1721–1730, 2015. © 2014 Society of Plastics Engineers

Synergistic effect of carbon black and carbon-silica dual phase filler in natural rubber matrix

In this article, the synergistic effects of carbon black (CB) and modified carbon–silica dual phase filler (MCSDPF) on the properties of natural rubber (NR) were investigated. MCSDPF was prepared by modifying carbon–silica dual phase filler (CSDPF) with bis(3-triethoxysilylpropyl)tetrasulphane (Si-69). Fourier transform infrared spectroscopy and thermogravimetric analyzer analyses revealed that Si-69 was successfully grafted to CSDPF. NR-based compounds containing various combinations of MCSDPF and CB were prepared through a mechanical mixing. Investigations of mechanical properties, ageing resistance, abrasion resistance, dynamic mechanical properties, and morphology of tear fractured surface of MCSDPF/CB/NR vulcanizates were conducted. Our study shows that adding MCSDPF led to significant improvement in the tear resistance, fatigue life, and elongation at break of MCSDPF/CB/NR vulcanizates. Optimum stoichiometric combination of MCSDPF and CB inside the NR matrix was derived (ratio of MCSDPF and CB in wt% = 15/50), which showed synergistic effects of MCSDPF upon CB that was ultimately reflected in their tensile strength, wet skid resistance, and rolling resistance. POLYM. COMPOS., 35:1466–1472, 2014. © 2013 Society of Plastics Engineers

COMPARISON OF STRUCTURE AND PROPERTIES OF TWO STYRENE–BUTADIENE RUBBERS FILLED WITH CARBON BLACK, CARBON–SILICA DUAL-PHASE FILLER, AND SILICA

ABSTRACT Heat buildup, wet skid resistance (WSR), wear resistance (WR), and cutting and chipping resistance (CCR) of carbon black (CB), carbon–silica dual-phase filler (CSDPF), and silica-filled two kinds of styrene–butadiene rubber (SBR) were investigated. For the same SBR systems, the composite filled with silica exhibited the lowest heat generation and highest WSR performance, whereas it showed the worst WR and CCR among the three composites. The CSDPF-filled composite obtained a balanced overall performance. Rubber processing analyzer (RPA) strain sweep results showed that the CSDPF-filled composite exhibits the lowest Payne effect, which is related to filler networking in the rubber matrix. Solid-state 1H low-field NMR demonstrated that the sequence of the filler–rubber interaction of the composites was CB > CSDPF > silica. Bis-(3-(triethoxysilyl)-propyl)-tetrasulfide increased the cross-link density of the silica-filled composite. For the composites with different fillers, the lower filler network structure and higher cross-link density result in the lowest heat generation of silica-filled composite, and the strongest filler–rubber interaction leads to the best WR and CCR performances of the CB-filled composite. Filled SBR5025 composites exhibited better WR, lower heat buildup, and worse CCR than filled SBR1712 composites with the same filler.

Characterization of Filler-rubber Interaction, Filler Network Structure, and Their Effects on Viscoelasticity for Styrene-butadiene Rubber Filled with Different Fillers

For styrene-butadiene rubber (SBR) compounds filled with the same volume fraction of carbon black (CB), precipitated silica and carbon–silica dual phase filler (CSDPF), filler-rubber interactions were investigated thru bound rubber content (BRC) of the compounds and solid-state 1H low-field nuclear magnetic resonance (NMR) spectroscopy. The results indicated that the BRC of the compound was highly related to the amount of surface area for interaction between filler and rubber, while the solid-state 1H low-field NMR spectroscopy was an effective method to evaluate the intensity of filler-rubber interaction. The silica-filled compound showed the highest BRC, whereas the CB-filled compound had the strongest filler-rubber interfacial interaction, verified by NMR transverse relaxation. The strain sweep measurements of the compounds were conducted thru a rubber process analyzer; the results showed that the CSDPF-filled compound presented the lowest Payne effect, which is mainly related to the weakened filler network structure in polymer matrix. The temperature sweep measurement, tested by dynamic mechanical thermal analysis, indicated that the glass transition temperature did not change when SBR was filled with different fillers, whereas the storage modulus in rubbery state and the tanδ peak height were greatly affected by the filler network structure of composites.

Effect of Fillers on Wet Skid Resistance of Tires. Part II: Experimental Observations on Effect of Filler-Elastomer Interactions on Water Lubrication

Abstract It was demonstrated previously that on the worn surface of vulcanizates during wet skid tests, carbon black is covered by rubber whereas silica particles are at least partly exposed. In this report, the experimental results of the effects of carbon black and silica on wet skid resistance measured by various test methods and under different conditions are explained based on the “Three Zone Concept” of the contact area of tread compounds with the track surface during sliding or rolling. The three zones are water film squeezing, transition and traction zones. In the first two zones, where hydro-dynamic and micro-elastohydrodynamic lubrication mechanisms are dominant, silica is beneficial for wet friction. In the traction zone, where friction is governed by boundary lubrication, carbon black is preferred. Under test conditions where the water squeezing and transition zones are more developed, such as at high speed, lower temperature, smoother track surface, lower load, higher slip angle, and ABS brake, the silica shows better performance, but otherwise where the traction zone is larger, carbon black gives higher wet skid resistance. Accordingly, a new carbon-silica dual phase filler CSDPF 4210 that is characterized by high surface coverage with silica has been developed. With this material, the wet skid resistance of a passenger tire on a car with ABS at high speed and smooth road surface is significantly improved.

Relaxation behavior of carbon silica dual phase filler reinforced chlorobutyl vulcanizates

AbstractDynamic mechanical analysis and dielectric relaxation spectra of carbon silica dual phase filler reinforced chlorobutyl vulcanizates were used to study their relaxation behavior as a function of temperature (−60°C to +100°C) and frequency (100–106 Hz). Strain‐dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.07–5%. The nonlinearity in tan δ and storage modulus was explained based on the concept of filler–polymer interaction and the interaggregate attraction (filler networking) of carbon black. The dynamics of chlorobutyl chain segments in the composites was explained on the basis of their connectivity. The segmental relaxation of the polymer chains in the presence of filler and crosslinking has been explained, based on conformational transitions occurring at high frequencies. The ‘percolation limit’ of the filler in the composites was found to be in the range of 30–40 phr loading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4320–4327, 2006

Effect of fillers on the relaxation behavior of chlorobutyl vulcanizates

AbstractThe effect of addition of fillers (carbon black (CB), carbon silica dual phase filler (CSDPF), and nanoclays) on the relaxation behavior of chlorobutyl vulcanizates has been studied. The primary relaxation (α‐transition, the glass transition) was studied by dynamic mechanical analysis as a function of temperature (−60 to +100°C) and positron annihilation life time spectroscopy (−70 to +110°C). Irrespective of the filler and its loading, all the composites showed the glass transition temperature in the range of –29 to –33°C, which was explained on the basis of relaxation chain dynamics of polyisobutylene in the vicinity of fillers. The secondary relaxation (α* or β relaxation) was studied using dielectric relaxation spectra in the frequency range of 100–106 Hz. Nanoclays had a profound influence on the secondary relaxation, whereas CSDPF and CB had a marginal effect. The nonlinear strain dependent dynamical parameters were also evaluated at double strain amplitudes of 0.07–5%. The nonlinearity in tan δ and storage modulus has been explained on the concept of filler–polymer interactions and the interaggregate attraction (filler networking). The “percolation limit” of the fillers in the composites has been studied by DC conductivity measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3161–3173, 2006

Bound rubber in chlorobutyl compounds: Influence of filler type and storage time

Bound rubber (BdR) is considered as a measure of the filler–polymer interaction in rubber compounds. The variation of the BdR content with storage time was studied in chlorobutyl compounds filled with fillers like carbon black, carbon–silica dual phase filler (CSDPf), silica, and nanoclays. The effect of the addition of a silane coupling agent on the BdR in carbon black and silica filled compounds was also studied. The BdR content increased with storage time in all compounds. The increase in BdR was higher during the initial 15 days of storage. Thereafter there was only a marginal increase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 715–720, 2006

Surface activity studies on carbon-silica dual phase fillers using flow microcalorimetry and multiple probe temperature programmed inverse gas chromatography

Carbon–silica hybrid particles (or carbon silica dual phase fillers (CSDPF)) are used as high performance fillers for elastomers and were originally developed to combine the best aspects of carbon black and silica in one package. In this work a range of such fillers with differing silicon content have been analysed, together with a range of carbon black and silica samples, using flow micro-calorimetry (FMC) and multiple probe temperature programmed inverse gas chromatography (MPTPIGC). The probe set for FMC comprised: ethyl acetate, pyridine, tributylamine; and propan1-ol. The linear increase in both heat and level of adsorption (from dry heptane) of all the probes within the CSDPF silicon content range investigated indicated that the interactions in the FMC were with the silica phase of the CSDPFs. FMC data for a variety of silica reference samples clearly indicates that the linear increase in adsorption activity does not continue beyond ca. 15% w/w silicon. MPTPIGC data obtained using a range of saturated and unsaturated linear and cyclic hydrocarbons together with benzene and pinacolone showed no clear relationship to silicon content. In fact the retention characteristics of CSDPF resembled those of carbon black more than silica. Differences in the carbon phase of the CSDFS and carbon blacks could be resolved using MPTPIGC. This study therefore highlights the complimentary nature of FMC and MPTPIGC in surface analytical studies of fillers.

Modification of Dual Phase Filler by Electron Beam Irradiation: Physical Characterization

Abstract Electron beam modification of carbon black (N220) and carbon-silica dual phase filler affects the microstructure of carbon black. This is confirmed from X-ray diffraction studies. The scanning electron microscopy /energy dispersive X-ray analysis reveals surface oxidation, which is further corroborated from nitrogen and iodine adsorptions. Transmission electron microscopy studies show the aggregation of fillers upon electron beam irradiation. Linear fractal dimension calculated by image analysis increases upon irradiation, due to the formation of filler aggregates.

New Generation Carbon-Silica Dual Phase Filler Part I. Characterization and Application to Passenger Tire

Abstract A new carbon-silica dual phase filler (CSDPF) 4000 has been developed for passenger tire application. Analytically, this filler is featured by higher levels of silica at the surface of the aggregate and higher silanol contents compared with the CSDPF 2000 family of products introduced previously. From the compounding point of view, this new dual phase filler shows higher polymer-filler interaction on the carbon domains and lower filler-filler interaction relative to the conventional fillers used in tire tread compounds. The new filler shows significant improvement in wet skid resistance over the earlier products. When this filler is employed in passenger tire tread compounds, the tradeoff among rolling resistance, wear resistance and wet skid resistance of the tire can be significantly improved compared with conventional fillers.

Surface characterization of electron beam modified dual phase filler by ESCA, FT-IR and surface energy

Electron beam modification of carbon black (N220) and carbon-silica dual phase filler has been carried out at room temperature. The increase in oxygen to carbon ratio (O/C) determined by using Electron spectroscopy for chemical analysis (ESCA) is observed. Fourier transform infra-red spectroscopy (FT-IR) studies detect a new peak at 801 cm−1 upon electron beam irradiation, which is due to Si-C stretching in the case of modified dual phase fillers. The absence of the peak at 3400 cm−1 and the presence of the peak at 1720 cm−1 due to aliphatic ester stretching confirm the presence of trimethylol propane triacrylate (TMPTA) on the surface. Similarly, the absence of peak band at 3400 cm−1 confirms chemical interaction of triethoxysilylpropyl tetrasulphide (Si-69). A decrease in dispersive component (γsd) and an increase in polar component (γsp) of the surface energy corroborate surface oxidation.

Carbon—Silica Dual Phase Filler, a new Generation Reinforcing Agent for Rubber: Part IX. Application to Truck Tire Tread Compound

Abstract The application of carbon-silica dual phase fillers (CSDPF) to natural rubber compound was investigated. It was found that these new fillers give significantly better overall performances in comparison with the conventional fillers—carbon black and silica. In a typical truck-tread compound, due to its high polymer—filler interaction and lower filler—filler interaction, the CSDPF E shows a comparable laboratory abrasion resistance and more than 40% reduction in tan δ at 70 °C, a parameter for rolling resistance, compared to compound filled with its carbon black counterpart, N1 10. These properties can, to a certain degree, be further improved by the addition of a small amount of coupling agent, bis(3-triethoxysilylpropyl)tetrasulfane (TESPT). In the case of wet skid resistance measured using the British Portable Skid Tester, the data show that CSDPF gives better performance than the conventional fillers, with and without coupling agent.

The role of silica and carbon–silica dual phase filler in a novel approach to the high temperature stabilisation of natural rubber based composites

A variety of solutions to the problem of high temperature stabilisation of natural rubber (NR)/carbon–silica dual phase filler (CSDPF) composites have been compared. Enhancement in stabilisation performance was observed when a small amount of silica (5.5 phr) was added to a carbon black filled (50 phr) formulation containing a conventionally added stabiliser system (polymerised 1,2-dihydro-2,2,4-trimethylquinoline and N-(1,3-dimethylbutyl)- N′-phenyl- p-phenylene diamine). However, the most successful approach was the formation of a novel filler-coupled stabiliser which was based on poly(hydromethyl siloxane) grafted with N-phenyl-1,4-phenylenediamine (PPDA). The stabilisation performance was followed via monitoring of loss in tensile strength as a function of ageing time.

Carbon—Silica Dual Phase Filler, A New Generation Reinforcing Agent for Rubber: Part VIII. Surface Characterization by IGC

Abstract The surface characteristics of carbon—silica dual phase filler (CSDPF) were investigated by inverse gas chromatography (IGC) at infinite dilution. It was found that due to its unique surface microstructure, the dispersive component of the surface energy γsd of CSDPF is considerably higher than those of carbon black and silica. Among CSDPFs, the surface energies increase with increasing surface area. The adsorption energies of a series of hydrocarbon probes and polar compounds were also measured with IGC. Relative to conventional fillers, the higher adsorption energies of hydrocarbon probes on dual phase fillers as well as their higher γsd, suggest a stronger interaction with hydrocarbon polymers. This is consistent with observations on bound rubber measurement. The overall polarity of CSDPF and the specific or polar component of the surface energy of CSDPF were estimated from specific free energies of adsorption of polar compounds. The polarity of this new filler, while being similar to that of its carbon black counterpart, is substantially lower than the polarity of precipitated silica. This would result in a high compatibility of this dual phase filler with hydrocarbon rubber, leading to lower filler—filler interaction and better microdispersion.