Effect of reinforcing carbon black filler on thermally induced crosslinking of polyacrylic acid-epoxidized natural rubber blend

That carbon black filler influences the thermally induced crosslinking between polyacrylic acid (PAA) and epoxidized natural rubber (ENR) is evident from Monsanto rheometric studies, dynamic mechanical analyses, and physical property measurements. Considerable shift in glass transition temperature, as well as broadening of the loss peak due to ENR, along with disappearance of the loss peak due to PAA, indicate that HAF carbon black, at 20 parts per 100 of total polymer, make the immiscible PAA/ENR blend behave as a compatible blend. © 1993 John Wiley & Sons, Inc.     

Dynamic Mechanical and ESCA Studies of Aluminium-Aluminium Bonding by an Epoxidised Natural Rubber-Polyacrylic Acid Blend

A polyacrylic acid (PAA)-epoxidised natural rubber (ENR) blend becomes crosslinked during high temperature moulding and such a blend was found to be a good adhesive for aluminium (Al)-aluminium (Al) bonding. The joint strength can be improved by the incorporation of silica filler into the adhesive up to a loading of 5 phr. However, higher filler loading causes deterioration of the joint strength. Electron Spectroscopy for Chemical Analysis (ESCA) studies of the peeled and then leached Al surface shows that the ENR phase of the blend is primarily responsible for the adhesion with the Al surface. With the increase in filler loading adhesion with Al increases at the cost of crosslinking between the component polymers. This is substantiated by dynamic mechanical analyses of the blends and joints (that is, Al/blend/Al composites). The changes in dynamic mechanical properties of the blends due to Al adhesion could be correlated with the peel strength of the Al/blend/Al joints.     

Effect of HAF carbon black filler on chemorheological behavior of poly(acrylic acid)-epoxidized natural rubber blend

Brabender-mixed blends of poly(acrylic acid) (PAA) and epoxidized natural rubber (ENR) were extruded through the capillary in a Monsanto processability tester, and the capillary pressure versus extrusion time plots were recorded. Constancy in capillary pressure with extrusion time was observed in the case of PAA/ENR blend; but the same blend, filled with HAF carbon black filler, shows a steady increase in capillary pressure with extrusion time. In presence of a free radical acceptor like thiophenol, the rate of capillary pressure rise decreases. Measurements of physical properties, swelling studies, and scanning electron microscopy photomicrography of the extrudates indicates the occurrence of a chemical interaction between physisorbed ENR and chemisorbed PAA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 135–142, 1997     

Maleated Natural Rubber as a Coupling Agent for Recycled High Density Polyethylene/Natural Rubber/Kenaf Powder Biocomposites

Kenaf powder (KP) was incorporated into recycled high density polyethylene (rHDPE)/natural rubber (NR) blend using an internal mixer at 165°C and rotor speed of 50 rpm. The tensile strength and elongation at break of the composites decreased, while the tensile modulus increased with increasing filler loading. The water absorption was found to increase as the filler content increased. The maleic anhydride grafted natural rubber was prepared and used to enhance the composites performance. The addition of MANR as a coupling agent improved the tensile properties of rHDPE/NR/KP biocomposites. The water absorption was also reduced with the addition of MANR.     

Hysteresis and strain-dependent dynamic mechanical properties of epoxidized natural rubber filled with surface-oxidized carbon black

High-temperature molding of a mixture of epoxidized natural rubber (ENR) and intermediate super abrasion furnace (ISAF) carbon black results in strong rubber–filler interaction, the extent of which is greater in the case of the oxidized grade of the carbon black. It has been observed that ENR is bonded to the filler surface through the formation of primary bonds, such as ester and phenolic ether. An extensive filler–filler network formation takes place through the hydrogen bonding between the active groups of the rubber and filler surface. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 723–730, 1998     

Effect of filler loading on cure time and swelling behaviour of SMR L/ENR 25 and SMR L/SBR blends

The effect of filler loading on the cure time (t₉₀) and swelling behaviour of SMR L/ENR 25 and SMR L/SBR blends has been studied. Carbon black (N330), silica (Vulcasil C) and calcium carbonate were used as fillers and the loading range was from 0 to 40 phr. Results show that for SMR L/ENR 25 blends the cure time decreases with increasing carbon black loading, whereas silica shows an increasing trend, and calcium carbonate does not show significant changes. For SMR L/SBR blends, the cure time of carbon black, silica and calcium carbonate generally decreases with increasing filler loading. The percentage swelling in toluene and ASTM oil no 3 decreases for both blends with increasing filler loading, with calcium carbonate giving the highest value, followed by silica‐ and carbon black‐filled blends. At a fixed filler loading, SMR L/ENR 25 blend shows a lower percentage swelling than SMR L/SBR blends. © 2003 Society of Chemical Industry     

Microwave absorbing rubber composites containing carbon black and aluminum powder

Natural rubber (NR), epoxidized natural rubber (ENR), and chlorosulfonated polyethylene (CSM) composites filled with conductive carbon black and aluminum powder have been prepared by using a two‐roll mill. An electromagnetic interference shielding effectiveness of those rubber composites was carried out in the frequency range of 8–12GHz (X‐band microwave). The increase of filler loading enhanced shielding effectiveness of the rubber composites. Conductive carbon black was more effective in shielding than aluminum powder. Binary filler‐filled rubber composites showed higher shielding effectiveness than that of single filler‐filled rubber composites. It has been observed that the shielding effectiveness of these rubber composites could be ranked in the following order: ENR ≥ CSM > NR, whereas the mechanical properties of the rubber composites were in the order of CSM > ENR > NR. The correlation between shielding effectiveness and electrical conductivity as well as mechanical properties of the rubber composites are also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Concentration effect of stearic acid on scorch behavior of epoxidized natural rubber

The effect of stearic acid on Mooney scorch time of epoxidized natural rubber (ENR 25 and ENR 50) and one grade of unmodified natural rubber (SMR L) was investigated in the concentration range of 0.5 to 14.5 phr. Other parameters, namely accelerator systems, temperature, and fillers (carbon black and silica), on the scorch property of ENR 25 in the presence of excess loading of stearic acid were also studied. Results indicate that scorch time increases with stearic acid loading for all the rubbers investigated, the rate of increase being fastest in ENR 50, followed by ENR 25 and SMR L. Mooney scorch time of ENR shows strong dependence on stearic acid loading for delay-action accelerators and at lower temperature of vulcanization. For a fixed filler loading, the dependence of scorch time on stearic acid concentration is similar to that of gum stock. The retardation effect exhibited by excess stearic acid on the vulcanization of ENR may be attributed to complex formation of chelates and the reduction in activation of adjacent double bonds in ENR resulting from interaction between stearic acid and the epoxide group of ENR. © 1995 John Wiley & Sons, Inc.     

Effect of blend ratio on Mooney scorch time of rubber blends

The Mooney scorch times of three rubber blends [epoxidized natural rubber (ENR) 50/SMR L, ENR 50/styrene butadiene rubber (SBR), and Standard Malaysian Rubber SMR L/SBR] were studied in the temperature range of 120–160°C using an automatic Mooney viscometer. N-Cyclohexyl-2-benzothiazyl sulfenamide was used as the accelerator, and the rubber formulation was based on the conventional vulcanization system. Results for the blends investigated indicate that a negative deviation of scorch time from the interpolated value was observed, especially for temperatures lower than 130°C. This observation was attributed to the induction effect of the ENR 50 in the ENR 50/SMR L and ENR 50/SBR blends to produce more activated precursors to crosslinks, thus enhancing interphase crosslinking. To a lesser extent, SMR L also exhibited such an induction effect in the SMR L/SBR blend. At 120°C, maximum induction effect occurred at around a 40% blend ratio of ENR 50 and SMR L in the respective blends. For the filled stock at 140°C, carbon black exhibited less effect on the scorch property of the blends compared to silica. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1301–1305, 1998     

The mastication characteristics of powdered carbon black filled natural rubber during internal mixing

Powdered carbon black filled natural rubber, P(NR/HAF), is a premixture of natural rubber and carbon black in powdered form with good carbon black dispersion throughout the rubber matrix. In this study, the mastication properties of P(NR/HAF) were observed under a wide temperature range (50–110°C) and rotor speed (30–100 rpm) range, using a mixing head attached to Brabender Plasticorder. It was found that P(NR/HAF) showed different mastication characteristic, compared to the traditional internal mastication theories of natural rubber; poor masticating properties of P(NR/HAF) are observed with low rotor speed and high temperature and a ‘‘stable zone’’ with middle rotor speed and lower temperature. The Mooney viscosity of rubber batch under different rotor speed and temperature was almost the same, and mastication properties were unsatisfactory. It was considered that the higher temperature build‐up of the mixing batch of P(NR/HAF) during the early stage of internal mixing results in the special mastication properties. A quadratic mastication model of P(NR/HAF), based on the multivariate regression analysis and stepwise regression analysis, was used to predict the mastication characters of P(NR/HAF) in internal mixer under varied temperature and rotor speed. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

交联网络和填料网络的相互作用对SSBR/BR并用胶性能的影响

以溶聚丁苯橡胶C2557A和顺丁胶BR9000的并用胶为研究对象,通过改变硫磺/促进剂的的用量和炭黑(CB)的用量调整硫化胶中的化学交联网络和填料网络,研究了交联网络和填料网络的相互作用对硫化胶静态和动态性能的影响。结果表明,随着硫磺/促进剂用量的减少和CB用量的增加,混炼胶的焦烧时间和硫化时间逐渐缩短,硫化扭矩差增大;硫磺/促进剂和CB用量相同的硫化胶的Payne效应明显强于混炼胶的,即硫化胶的(G′0-G′∞)值大于混炼胶的(G′0-G′∞)值且随着CB用量的增大而更加明显,说明化学交联网络的形成对填料网络有一定的增强作用。     

Self-vulcanizable rubber blend systems based on epoxidized natural rubber and chlorosulfonated polyethylene: Effect of blend composition,epoxy content of epoxidized natural rubber,and reinforcing black filler on physical properties

Mill mixed blend of epoxidized natural rubber and chlorosulfonated polyethylene forms a self-vulcanizable rubber blend during molding at high temperatures in absence of any vulcanizing agent, which is confirmed by FTIR studies. The extent of vulcanization reaction not only depends upon time and temperature of molding but also on the level of epoxidation in ENR and its proportion present in the blend. Physical properties of the blends are comparable to that of conventional rubber vulcanizates. Such blends can be reinforced by carbon black filler.     

The Effect of Epoxidized Natural Rubber (ENR-50) or Polyethylene Acrylic Acid (PEA) as Compatibilizer on Properties of Ethylene Vinyl Acetate (EVA)/Natural Rubber (SMR L) Blends

The effect of epoxidized natural rubber (ENR) or polyethylene acrylic acid (PEA) as a compatibilizer on properties of ethylene vinyl acetate (EVA)/natural rubber (SMR L) blends was studied. 5 wt.% of compatibilizer was employed in EVA/SMR L blend and the effect of compatibilizer on tensile properties, thermal properties, swelling resistance, and morphological properties were investigated. Blends were prepared by using a laboratory scale of internal mixer at 120°C with 50 rpm of rotor speed. Tensile properties, thermal properties, thermo-oxidative aging resistance, and oil swell resistance were determined according to related ASTM standards. The compatibility of EVA/SMR L blends with 5 wt.% of compatibilizer addition or without compatibilizing agent was compared. The EVA/SMR L blend with compatibilizer shows substantially improvement in tensile properties compared to the EVA/SMR L blend without compatibilizer. Compatibilization had reduced interfacial tension and domain size of ethylene vinyl acetate (EVA)/natural rubber (SMR L) blends.     

The Effect of Filler Loading and Epoxidation on Paper-Sludge-Filled Natural Rubber Composites

The effect of filler loading and epoxidation on curing characteristics, dynamic properties, tensile properties, morphology, and rubber-filler interactions of paper-sludge-filled natural rubber compounds have been studied. Two different types of natural rubber, SMR L and ENR 50, having 0% and 50% of epoxidation and conventional vulcanization were used. Paper sludge was used as a filler and the loading range was from 0 to 40 phr. Compounding was carried out using a laboratory-sized two-roll mill. The scorch time for both rubber compounds decreased with filler loading. The cure time was found to decrease with increasing filler content for SMR L vulcanizates, whereas for ENR 50, the cure time seemed to be independent of the filler loading. Dynamic properties, i.e., maximum elastic torque, viscous torque, and tan delta, increase with filler loading in both grades of natural rubber. Results also indicate that both rubbers show increment in tensile modulus but inverse trend for elongation at break and tensile strength. However, for a fixed filler loading, ENR 50 compounds consistently exhibit higher maximum torque, modulus at 100% elongation, and modulus at 300% elongation, but lower elongation at break than SMR L compounds. In the case of tensile strength, ENR 50 possesses higher tensile strength than SMR L at 10 to 20 phr, but the difference is quite small at 30 and 40 phr. These findings might be associated with better rubber-filler interaction between the polar hydroxyl group of cellulose fiber and the epoxy group of ENR 50.     

Influence of interfacial compatibilizer,silane modification,and filler hybrid on the performance of NR/NBR blends

The effects of epoxidized natural rubber (ENR) as a compatibilizer, silane in situ modification, and filler hybrid on the properties of natural rubber/acrylonitrile–butadiene rubber blends were systematically studied. Phase change with the incorporation of ENR was quantitatively characterized via atomic force microscope quantitative nanomechanics technique. The results show that ENR could greatly reduce the dispersed domain size and increase the interfacial thickness; however, this compatibilizing effect reached the limit when ENR content was 5 parts per hundred rubber (phr). If the content is further increased, the redundant ENR start to gather at the interface and thus form a third phase. The macroscopic dynamic performance measurement was well in accordance with the microscale observation; the blend with 5 phr of ENR presented the lowest heat generation. The results also revealed that silane modification could significantly improve the overall properties, which benefited from better filler dispersal as evidenced by transmission electron microscopy. Finally, the effect of filler hybrid [silica and carbon black (CB)] was studied. It turned out that the blend containing 20 phr silica and 32 phr CB synchronously possessed high wet grip property, low rolling resistance, and high wear resistance, which makes it very promising for the high-performance tire application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47421.     

Abrasion Property of Epoxidized Natural Rubber

The abrasion resistance of two grades of epoxidized natural rubber (ENR 25 and ENR 50) and one grade of styrene-butadiene rubber (SBR) were studied using an Akron abrasion tester. An accelerated sulfur vulcanization system with 2-mercaptobenzothiazole (MBT) as the accelerator is used throughout the study. Carbon black (N 330), precipitated silica, and calcium carbonate were chosen as the fillers. The range of sulfur and filler loadings was from 1 to 5 phr and 10 to 50 phr, respectively. Mixing was done on a two-roll mill. Results obtained show that for all the rubbers studied, the volume loss due to abrasion decreases with increasing sulfur loading and passes through a minimum at about 3 phr of sulfur. This observation is attributed to the changes of cross-link types from monosulfidic to polysulfidic crosslink as sulfur concentration is increased. However, further sulfur loading would cause a “tight” cure, thus increasing the abrasion loss. For sulfur loading less than 3 phr, ENR 25 indicates the highest abrasion loss, followed by SBR and ENR 50. For the filled stock, minimum loss is observed at about 35–40 phr of filler. Reinforcing filler such as carbon black exhibits better abrasion resistance than calcium carbonate, a nonreinforcing filler. The abrasion loss increases at higher filler loading due to the dilution effect of fillers. Ozone plays an important role in the abrasion property of unsaturated rubbers, as reflected by the higher abrasion loss in the presence of ozone.     

Dispersion,temperature and torque models for an internal mixer

Models based on kinetic, thermodynamic and rheological equations have been developed to compute dispersion extent, batch temperature and relative batch viscosity at discrete intervals during a mix cycle in an internal mixer. The calculated relative bulk viscosity can be linked empirically to a measured variable such as rotor torque or power consumption. Solution of the models over successive time intervals allows the computation of complete dispersion, temperature, and torque/power profiles for a mix cycle. The mix models exhibit good fits to experimental torque and temperature curves for mixing natural rubber with carbon black over a wide range of carbon black loadings (0 to 50 phr) for rotor speeds ranging from 40 to 70 RPM in two lab‐scale internal mixers. The models are shown to be suitable for moderately reinforcing (ASTM N660) as well as highly reinforcing (ASTM N121) grades of carbon black. Rate constants for filler dispersion, incorporation and erosion can be extracted from the models and can be interpolated to generate dispersion, temperature and torque curves at new conditions of carbon black loading and rotor speed. The mix models could thus be used for process‐control purposes and for specifying drop targets based on batch properties in addition to the time‐temperature‐energy criteria typically used today. Polym. Eng. Sci. 44:1247–1257, 2004. © 2004 Society of Plastics Engineers.     

Compatibilising effect of carbon black on morphology of NR–NBR blends

Abstract

It is proposed that a non-polar filler can reduce interfacial energies between polar and non-polar polymers. Experiments have been carried out to test this hypothesis using carbon black as the filler in blends of natural rubber (NR) and a nitrile rubber (NBR) with an acrylonitrile content of 45%. Blends of NR–NBR (70/30) were prepared in an internal mixer with varying amounts of carbon black. The dramatic decrease in domain size on addition of carbon black was nonetheless lower than that predicted. Further experiments showed that the amount of carbon black available at the interface for compatibilisation was influenced by preferential incorporation into the lower viscosity elastomer (NBR). Thus, elastomers of similar viscosity should be added to the mixer prior to the carbon black in order to maximise the amount of ‘free’ unwetted carbon black present when the elastomers are blended together. Blending experiments carried out under these conditions resulted in a morphology close to the prediction based on thermodynamic theory.     

Effects of multi‐walled carbon nanotubes and conductive carbon black on electrical,dielectric, and mechanical properties of epoxidized natural rubber composites

The influence of multi‐walled carbon nanotubes (MWCNTs) and conductive carbon black (CCB) on cure, electrical, dielectric, and mechanical properties of epoxidized natural rubber (ENR) composites was investigated. It was found that short MWCNTs (S‐MWCNTs) with low loading significantly affected the cure characteristics in a way similar to high loading of CCB. Moreover, the ENR/S‐MWCNTs composites exhibited high AC conductivity, dielectric constant, and dielectric loss tangent (tan δ ) compared to the ENR/CCB and ENR/L‐MWCNTs (long MWCNTs) composites. In addition, the S‐MWCNTs composites showed the lowest percolation threshold concentration, defined as the lowest loading to form conductive paths in the insulating ENR matrix. This might be attributed to the comparatively high interfacial polarization, with good dispersion and distribution, of the S‐MWCNTs in ENR matrix. These characteristics were confirmed by TEM imaging and by a high bound rubber content, corroborating strong filler–rubber interactions in the ENR/S‐MWCNTs composites. However, the L‐MWCNTs composites showed the lowest electrical and other related properties, despite the highest aspect ratio and specific surface area of this filler. This might be because of the flocculation of nanotubes by mutual entanglement, leading to a poor uneven distribution in the ENR matrix. POLYM. COMPOS., 38:1031–1042, 2017. © 2015 Society of Plastics Engineers     

Effect of carbon black on self‐crosslinking network structure of polychloroprene rubber and epoxidized natural rubber blends

The goal of this research is to improve poor network structure of polychloroprene rubber (CR)/epoxidized natural rubber (ENR) self‐crosslinking blends, which could substitute traditional vulcanizates in some application area. Carbon black (CB)–CR/ENR blends were prepared by reacting CR with ENR in the presence of CB. The structure of CR/ENR blends was characterized by attenuated total‐reflectance Fourier transform infrared spectroscopy (FTIR‐ATR). The effect of CB loading on curing characterization and mechanical properties of CR/ENR blends was investigated, and the interaction among CR, ENR, and CB was studied using differential scanning calorimetry. The effect of CB loading on the Payne effect of CR/ENR was investigated using rubber process analyzer. Scanning electron microscope was used to characterize the morphology of CB–CR/ENR blends. The results showed that CR/ENR blends were obtained by the ring‐opening reaction of epoxy groups in ENR and chlorine groups in CR. Mechanical properties of CR/ENR blends increased with the increase of CB loading. The Payne effect of CR/ENR became more remarkable with increasing CB loading. Morphology study indicated that interfacial compatibility between CR and ENR increased with the increase of CB loading because CB could strengthen the self‐crosslinking network structure of CR/ENR blends. The promoting effect of CB on self‐crosslinking reaction was verified by the assessment of crosslink density. POLYM. COMPOS., 38:463–471, 2017. © 2015 Society of Plastics Engineers