Fly ash particles and precipitated silica as fillers in rubbers. I. Untreated fillers in natural rubber and styrene–butadiene rubber compounds

In this study, we investigated the effects of untreated precipitated silica (PSi) and fly ash silica (FASi) as fillers on the properties of natural rubber (NR) and styrene–butadiene rubber (SBR) compounds. The cure characteristics and the final properties of the NR and SBR compounds were considered separately and comparatively with regard to the effect of the loading of the fillers, which ranged from 0 to 80 phr. In the NR system, the cure time and minimum and maximum torques of the NR compounds progressively increased at PSi loadings of 30–75 phr. A relatively low cure time and low viscosity of the NR compounds were achieved throughout the FASi loadings used. The vulcanizate properties of the FASi‐filled vulcanizates appeared to be very similar to those of the PSi‐filled vulcanizates at silica contents of 0–30 phr. Above these concentrations, the properties of the PSi‐filled vulcanizates improved, whereas those of the FASi‐filled compounds remained the same. In the SBR system, the changing trends of all of the properties of the filled SBR vulcanizates were very similar to those of the filled NR vulcanizates, except for the tensile and tear strengths. For a given rubber matrix and silica content, the discrepancies in the results between PSi and FASi were associated with filler–filler interactions, filler particle size, and the amount of nonrubber in the vulcanizates. With the effect of the FASi particles on the mechanical properties of the NR and SBR vulcanizates considered, we recommend fly ash particles as a filler in NR at silica concentrations of 0–30 phr but not in SBR systems, except when improvement in the tensile and tear properties is required. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2119–2130, 2004     

Particle size distribution,mixing behavior,and mechanical properties of carbon black (high‐abrasion furnace)–filled powdered styrene butadiene rubber

High‐abrasion furnace black (HAF, grade N330)–filled powdered styrene butadiene rubber [P(SBR/HAF)] was prepared and the particle size distribution, mixing behavior in a laboratory mixer, and mechanical properties of P(SBR/HAF) were studied. A carbon black–rubber latex coagulation method was developed for preparing carbon black–filled free‐flowing, noncontact staining SBR powders, with particle diameter less than 0.9 mm, under the following conditions: carbon black content > 40 phr, emulsifier/carbon black ratio > 0.02, and coating resin content > 2.5 phr. Over the experimental range, the mixing torque τ_α of P(SBR/HAF) was not as sensitive to carbon black content and mixing temperature as that of HAF‐filled bale SBR (SBR/HAF), whereas the temperature build‐up ΔT showed little dependency on carbon black content. Compared with SBR/HAF, P(SBR/HAF) showed a 20–30% mixing energy reduction with high carbon black content (>30 phr), which confers to powdered SBR good prospects for internal mixing. Carbon black and the rubber matrix formed a macroscopic homogenization in P(SBR/HAF), and the incorporation step is not obvious in the internal mixing processing results in these special mixing behaviors of P(SBR/HAF). A novel mixing model of carbon black–filled powdered rubber, during the mixing process in an internal mixer, was proposed based on the special mixing behaviors. P(SBR/HAF) vulcanizate showed better mechanical properties than those of SBR/HAF, dependent primarily on the absence of free carbon black and a fine dispersion of filler on the rubber matrix attributed to the proper preparation conditions of noncontact staining carbon black–filled powdered SBR. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2494–2508, 2004     

Improvement of properties of silica‐filled styrene–butadiene rubber compounds using acrylonitrile–butadiene rubber

Since silica has strong filler–filler interactions and adsorbs polar materials, a silica‐filled rubber compound has a poor dispersion of the filler and poor cure characteristics. Improvement of the properties of silica‐filled styrene–butadiene rubber (SBR) compounds was studied using acrylonitrile–butadiene rubber (NBR). Viscosities and bound rubber contents of the compounds became lower by adding NBR to the compound. Cure characteristics of the compounds were improved by adding NBR. Physical properties such as modulus, tensile strength, heat buildup, abrasion, and crack resistance were also improved by adding NBR. Both wet traction and rolling resistance of the vulcanizates containing NBR were better than were those of the vulcanizate without NBR. The NBR effects in the silica‐filled SBR compounds were compared with the carbon black‐filled compounds. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1127–1133, 2001     

Reclaiming of rubber by a renewable resource material (RRM). III. evaluation of properties of NR reclaim

Sulfur‐cured filled natural rubber (NR) is successfully reclaimed by using a renewable resource material (RRM) and diallyl disulfide (DADS), which is the major constituent of RRM. Reclaiming of NR vulcanizate was carried out at 60°C for 35 min in an open two‐roll mixing mill. Evaluation of the properties of NR reclaim was carried out by mixing it with virgin rubber in various proportions. The cure characteristics and mechanical properties of the virgin NR/ reclaim NR blend were studied. With increase in the proportion of reclaim rubber (RR) in virgin NR/ reclaim NR blend scorch time and optimum cure time decrease. To increase scorch time N‐cyclohexylthiophthalimide as prevulcanization inhibitor (PVI) was added in NR/RR (50/50) blend. It was found that use of 40% NR reclaim with virgin rubber resulted 83% retention of tensile strength of that of the virgin NR vulcanizate. Effect of carbon black loading was studied in NR/RR (50/50) blends. Tensile properties and swelling value of different NR/RR blends were evaluated before and after aging. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1493–1502, 2000     

Studies of reinforcement behavior of unique elastomer‐based nanocomposite gels

Unique nanocomposite (NC) gels were prepared by blending water swollen unmodified montmorillonite clay suspension with natural rubber (NR) and styrene‐butadiene rubber (SBR) latices followed by prevulcanization. These were extensively characterized by dynamic light scattering, solvent swelling, tensile, and dynamic mechanical measurements. Reinforcement behavior of NC gels was investigated by adding NC gels into virgin NR and SBR matrices at various loadings. The distribution and morphology of NC gels in the elastomer matrices was studied by X‐ray dot mapping and high‐resolution transmission electron microscopy. Experimental results indicated tremendous improvement of tensile strength (TS) and modulus of the NC gel‐filled matrices along with noticeable changes in dynamic mechanical and rheological properties. Compared with virgin NR, the TS of 16 phr NC gel‐filled NR system increased by 117%. Similar level of enhancement of TS was also registered for the NC gel‐filled SBR systems. NC gel‐filled systems showed higher shear viscosities and lower die‐swell values compared with their virgin counterparts. Contemporary particulate composite and nanofiller reinforcement models were used to understand the reinforcing behavior of these NC gels. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Carbon black filled powdered natural rubber: Preparation,particle size distribution,mechanical properties,and structures

Carbon black (HAF) filled powdered natural rubber (P(NR/HAF)) was prepared and the particle size distribution, mechanical properties, and micromorphology of P(NR/HAF) were studied. A carbon black–rubber latex coagulation method was developed for preparing carbon black filled free‐flowing, noncontact staining NR powders with particle diameter less than 0.9 mm. A powdering mechanism model was put forward to describe the powdering process, which shows that the key technical points consist in the surfactant with good emulsification properties and the polymer coating resin with good film forming properties. SEM analysis shows that carbon black and rubber matrix have formed a macroscopic homogenization in the P(NR/HAF) particles without contact staining, and carbon black particles are well dispersed in rubber matrix with diameter of about 50–150 nm. P(NR/HAF) vulcanizate showed better mechanical properties than bale natural rubber/carbon black blends (NR/HAF) and simple NR latex/carbon black blends (NRL/HAF), which depends primarily upon the absence of free carbon black, the fine dispersion of filler on the rubber matrix, and the better interaction between carbon black and rubber matrix due to the proper preparation condition of noncontact staining carbon black filled powdered NR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1763–1774, 2006     

Mechanical properties and crosslink density of rare earth‐modified high‐abrasion furnace‐filled powdered natural rubber

High‐abrasion furnace‐filled powdered natural rubber [P(NR/HAF)] has more advantages than traditional HAF‐filled bale NR (NR/HAF) because of its better environmental performance and easier processing quality, but its lower mechanical properties are disadvantageous. To improve the mechanical properties, rare earth‐modified HAF‐filled powdered NR [P(NR/HAF‐Ln)] (Ln = Sm,La,Pr) was prepared by means of coacervation–coprecipitation, using rare earth‐modified HAF as separant and filler. The effect on mechanical properties of P(NR/HAF‐Ln) vulcanizate exerted by the emulsifier/HAF ratio, powdering temperature, Ln/HAF ratio and type of Ln, and HAF content were studied. The results indicated that when optimum formulation, the mechanical properties of P(NR/HAF‐Ln) vulcanizate were better than P(NR/HAF) vulcanizate. In addition, the relationship of the apparent crosslink density and HAF content of P(NR/HAF‐Ln), P(NR/HAF), NR/HAF vulcanizates was also investigated, along with their SEM microphotographs of tensile fracture surface, which indicated that the excellent mechanical properties of P(NR/HAF‐Ln) vulcanizate was attributed to correct amount of Ln that could increase crosslink density and reinforce the interface structure of NR matrix/HAF‐Ln particle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1755–1762, 2006     

废旧轮胎橡胶的常温粉碎及性能研究

采用盘式磨设备对废旧轮胎胎面胶颗粒进行常温粉碎,研究胶粉性能及其对丁苯橡胶(SBR)硫化胶物理性能的影响,并与胎面胶颗粒进行对比。结果表明:常温粉碎胶粉的粒径比胎面胶颗粒降低了一个数量级,形状更加不规则且表面粗糙;动盘和定盘相对转速对常温粉碎胶粉粒径及其分布影响不大,但动盘和定盘间隙影响较大;常温粉碎胶粉的热稳定性比胎面胶颗粒低,且交联密度减小一半以上;与胎面胶颗粒相比,添加常温粉碎胶粉的SBR硫化胶的拉断伸长率有很大提高,但邵尔A型硬度、100%和300%定伸应力以及拉伸强度有所减小。     

废胶粉/SBR共混胶料的流变-形态-力学性能研究

研究了废橡胶胶扮掺混量和粒度对度胶粉/SBR纯胶胶料和废胶粉/SBR炭黑胶料的流变性能和力学性能的影响。根据废胶粉/SBR炭黑胶料和改性胶粉/SBR炭黑胶料破坏断面的扫描电镜照片,对比其撕裂线和扩展线的数量和分布形态,可对胶料的力学性能有所推断,并可观察到胶粉与基质橡胶两相间的界面形态。     

Influence of rubber composition on change of crosslink density of rubber vulcanizates with EV cure system by thermal aging

Variation of the crosslink density of a rubber vulcanizate depending on the rubber composition after the thermal aging was studied with single rubber, biblend, and triblend vulcanizates of natural rubber (NR), butadiene rubber (BR), and styrene‐butadiene rubber (SBR). The efficient vulcanization (EV) system was employed to minimize the influence of free sulfur in the vulcanizate on the change of the crosslink density. Thermal aging was performed at 40, 60, and 80°C for 20 days with 5‐day intervals. The crosslink densities of the vulcanizates after the thermal aging increase. For the single rubber vulcanizates, variation of the crosslink density by the thermal aging has the order: SBR > BR > NR. For the biblend vulcanizates, variations of the crosslink densities of the NR/SBR and SBR/BR blends are larger than that of NR/BR blend. Variation of the crosslink density of the vulcanizate increases by increasing the SBR content in the vulcanizate. Variation of the crosslink density of the rubber vulcanizate depending on the rubber composition was explained by miscibility of the blends, combination reaction of the pendent groups, and mobility of the pendent group. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1378–1384, 2000     

Effect of silanized silica nanofiller on tack and green strength of selected filled rubbers

BACKGROUND: Tack and green strength of filled and gum (unfilled) natural rubber (NR), poly(styrene‐co‐butadiene) rubber (SBR), polybutadiene rubber (BR) and (SBR‐BR) blend with different loadings of reinforcement agent, silanized silica nanofiller (Coupsil 8113), were studied and the results compared and discussed. RESULTS: It was found that silica was fully dispersed in rubber matrix after 13 min of mixing. In addition, with some exceptions for NR and (SBR‐BR) blend, filler loading decreased the tack strength of the studied filled rubbers. Green strength and Mooney viscosity increased with filler loading for all studied filled rubbers but with different rates and amounts. The optimum filler loadings for NR and (SBR‐BR) filled blend were 30 and 10 phr, respectively. Tacks of NR filled rubbers were much higher than those of synthetic filled rubbers. CONCLUSION: It was concluded that filler loading alters substantially the tack and green strength of the rubbers under investigation. Copyright © 2009 Society of Chemical Industry     

Improvement of properties of silica‐filled natural rubber compounds using polychloroprene

Because silica has strong filler–filler interactions, a silica‐filled rubber compound is characterized by a poor dispersion of the filler. Properties of silica‐filled natural rubber (NR) compounds were improved using polychloroprene (chloroprene rubber [CR]). The bound rubber content of the compound increases and the filler dispersion is also improved by adding CR to the compound. Physical properties such as modulus, tensile strength, abrasion, and crack resistance are improved by adding CR. Elongation at break of the vulcanizates containing CR is longer than that of the vulcanizate without CR, although crosslink density of the former is higher than that of the latter. The improved physical properties are attributed to the good dispersion of silica by adding CR. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2609–2616, 2002     

Properties of natural rubber composites reinforced with silica or carbon black: influence of cure accelerator content and filler dispersion

Filler dispersion is a critical factor in determining the properties of filled rubber composites. Silica has a high density of silanol groups on the surface, which lead to strong filler–filler interactions and a poor filler dispersions. A cure accelerator, N‐tert‐butyl‐2‐benzothiazole sulfenamide (TBBS), was found to improve filler dispersion in silica‐filled natural rubber (NR) compounds. For the silica‐filled NR compounds without the silane coupling agent, the reversion ratio generally increased with increase in TBBS content, whereas those of the silica‐filled NR compounds containing the silane coupling agent and carbon black‐filled NR compounds decreased linearly. The tensile strength of the silica‐filled NR vulcanizate without the silane coupling agent increased as the TBBS content increased, whereas carbon black‐filled samples did not show a specific trend. The experimental results were explained by TBBS adsorption on the silica surface and the improvement of silica dispersion with the aid of TBBS. Copyright © 2003 Society of Chemical Industry     

不同粒径胶粉的成分分析及在胎面胶中的应用

通过热重法和红外光谱分析及测定硫含量和粒径分布等方式对用超低温粉碎法制备的不同粒径胶粉的成分进行了分析,并开展了其在商用车轮胎胎面胶中的加工应用研究.结果表明,4种不同胶粉中的挥发分、有机物、炭黑和灰分含量均差别较小,其中有机物质量分数在61％～65％之间,炭黑质量分数在28％～30％之间,含硫质量分数在2％左右,粒径...     

莱茵新Rhenosin TT100在轮胎胎面配方中的应用

研究了莱茵新Rhenosin TT100时NR／BR／SBR胎面胶硫化特性、物理机械性能和发黑与其它配合剂在肢料中的分散性以度耐磨性能的影响。结果表明，谈助剂加入NR／BR／SBR配方中可以明显改善炭黑等配合剂在胶料中的分散性，提高挤出胎面肢断面的致密性，提高了撕裂性能、耐磨性。轮胎实际里程试验表明，采用2份Rhenosin TT100的胎冠肢的轮胎耐磨性优异。     

Possible use of ultra‐fine acrylonitrile butadiene rubber powder as filler in natural rubber vulcanizates

Possible use of ultra‐fine acrylonitrile butadiene rubber powder (UFNBRP) as a filler for natural rubber (NR) was investigated. The UFNBRP was added into NR at various concentrations, and the compound properties were determined. It is found that, with increasing UFNBRP loading, the compound viscosity is increased, whereas both scorch time and optimum curing time are significantly reduced. The results also reveal that UFNBRP has negative effect not only on crosslink density but also on most mechanical properties of the vulcanizate, such as tensile strength, tear strength, compression set, and abrasion resistance. The deterioration of these mechanical properties is thought to arise mainly from the combined effect of large phase size of the dispersed UFNBRP and low interfacial adhesion taking place from the polarity difference between UFNBRP and NR. Interestingly, it is found that, after aging, UFNBRP could promote postcuring phenomenon leading to increases of both relative 100% modulus and relative tensile strength. Oil resistance is also found to improve considerably with increasing UFNBRP loading. This improvement is mainly attributed to the dilution effect, i.e., the higher the UFNBRP loading, the lower the NR portion and, thus, the greater the oil resistance of the vulcanizate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Interfacial Interactions of Silica and Natural Rubber Enhanced by Hydroxyl Telechelic Natural Rubber as Interfacial Modifier

The incompatibility between hydrophilic silica and hydrophobic rubber is an important problem on using silica in nonpolar rubber. In this study, hydroxyl telechelic natural rubber (HTNR) that contains hydroxyl‐terminated groups was introduced into silica‐reinforced natural rubber (NR) in order to improve the bonding strength between rubber and silica. The properties of silica‐reinforced NR compounds and vulcanizates as a function of varying silica contents were evaluated at a fixed HTNR concentration at 8% wt/wt of silica content. The results show that the improvement of silica dispersion and decreasing of filler–filler interactions (Payne effect) were obtained in the NR compounds and vulcanizates with HTNR addition. The enhancements in tensile properties, crosslink density, abrasion resistance, heat build‐up, and thermal properties of the silica‐reinforced NR vulcanizates with added HTNR confirmed that HTNR performed good as interfacial modifier of silica. In the study, the optimum properties of silica‐reinforced NR vulcanizate were achieved at 30 phr silica with 2.4 phr HTNR. However, HTNR still showed poorer efficiency than the synergy between commercial silane coupling agent, bis [3‐(triethoxysilyl) propyl] tetrasulphide (TESPT) and diphenylguanidine (DPG) when used in silica‐reinforced NR vulcanizate. J. VINYL ADDIT. TECHNOL., 26:291–303, 2020. © 2019 Society of Plastics Engineers     

Fracture behavior of crumb rubber‐filled elastomers

The fracture behavior of a crumb rubber‐filled elastomer was observed in optical micrographs. It was found that the failure started from the surface of the unfilled samples. The failure, however, started from a cavity around a crumb in the crumb‐filled samples. This paper suggests that the failure mechanism in the crumb‐filled elastomers (NR, NBR) was based on the microscopic observation of highly strained samples. This paper also considers the failure behavior of two‐component systems: NR/NBR, SBR/NR, and NR/SBR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3137–3144, 1999     

Kinetics of the phase selective localization of silica in rubber blends

The Fourier transformed infrared (FTIR) spectroscopy on the rubber‐filler gel has been used as a tool for the quantitative characterization of the phase selective silica localization in styrene butadiene rubber (SBR)/natural rubber (NR) blends. The so‐called rubber‐layer L was introduced to describe the selective wetting behavior of the rubber phases to the filler. SBR/NR blends filled with silica were the focus of the experimental investigation. NR shows a higher wetting rate than SBR. Silane addition does not affect the wetting of NR but slowdowns the wetting of SBR. With increasing chamber temperature the value of the rubber‐layer L of all mixtures increases owing to the different thermal activated rubber‐filler bonding processes. Using the wetting concept the kinetics of silica localization in the phases of heterogeneous rubber blends was characterized. Because of the higher wetting rate of the NR component, in the first stage of mixing of NR/SBR blends more silica is found in the NR phase than in the SBR phase. In the next stage, silica is transferred from the NR phase to the SBR phase until the loosely bonded components of NR rubber‐layer are fully replaced by SBR molecules. POLYM. COMPOS., 31:1701–1711, 2010. © 2010 Society of Plastics Engineers.     

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