Cure characteristics,morphology, and mechanical properties of ethylene–propylene–diene–monomer rubber/acrylonitrile butadiene rubber blends

Blends based on ethylene–propylene–diene monomer rubber (EPDM) and acrylonitrile butadiene rubber (NBR) was prepared. Sulfur was used as the vulcanizing agent. The effects of blend ratio on the cure characteristics and mechanical properties, such as stress–strain behavior, tensile strength, elongation at break, hardness, rebound resilience, and abrasion resistance have been investigated. Tensile and tear strength showed synergism for the blend containing 30% of NBR, which has been explained in terms of morphology of the blends attested by scanning electron micrographs. A relatively cocontinuous morphology was observed for 70 : 30, EPDM/NBR blend system. The experimental results have been compared with the relevant theoretical models. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of curing systems and polysulfonamide pulp on the curing characteristics,mechanical properties,and swelling behavior of ethylene–propylene–diene elastomer composites

The effects of three curing systems and polysulfonamide (PSA) pulp on the curing characteristics, mechanical properties, and swelling behavior of ethylene–propylene–diene elastomer (EPDM) composites were investigated. The maximum torque value and the optimum curing time were highest for EPDM composites cured with a peroxide system, and they were closely followed by those cured with a sulfur system. In comparison with those cured with peroxide and phenolic resin systems, EPDM composites cured with the sulfur system showed higher mechanical properties and dimensional stability. With increasing PSA pulp content, the maximum torque value of the EPDM composites increased, whereas the optimum curing time of the composites decreased. The orientation percentage of the PSA pulp in the EPDM composites was maximum at 30 phr pulp, as determined from green strength measurements. In the longitudinal direction along which the pulp was oriented, the EPDM composites showed higher tensile strength as well as lower elongation and swelling ratios. Also, with increasing PSA pulp content, the tensile strength of the EPDM composites decreased up to 10 phr pulp and subsequently increased, whereas the elongation and swelling ratio of the EPDM composites decreased linearly. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dynamic mechanical properties of styrene‐butadiene composites reinforced by defatted soy flour and carbon black co‐filler

Carboxylated styrene‐butadiene (SB) composites reinforced by a mixture of defatted soy flour (DSF) and carbon black (CB) were investigated in terms of their dynamic mechanical properties. DSF is an abundant renewable commodity and has a lower cost than CB. DSF contains soy protein, carbohydrate, and whey. Aqueous dispersions of DSF and CB were first mixed and then blended with SB latex to form rubber composites using freeze‐drying and compression molding methods. At 140°C, a single filler composite reinforced by 30% DSF exhibited roughly a 230‐fold increase in the shear elastic modulus compared to the unfilled SB rubber, indicating a significant reinforcement effect by DSF. Mixtures of DSF and CB at three different ratios were investigated as co‐fillers. Temperature sweep experiments indicate the shear elastic moduli of the co‐filler composites are between that of DSF and CB composites. Strain sweep experiments were used to study the fatigue and recovery behaviors of these composites. Compared with the DSF composites, the recovery behaviors of the 30% co‐filler composites after the eight consecutive deformation cycles of dynamic strain were improved and similar to that of 30% CB composite. Strain sweep experiments also indicated that the co‐filler composites have a greater elastic modulus than the CB reinforced composites within the strain range measured. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The effects of filler content on cure and mechanical properties of dichlorocarbene modified styrene butadiene rubber/carbon black composites

A study has been carried out on the curing characteristics and mechanical properties of carbon black filled dichlorocarbene modified styrene butadiene rubber (DCSBR). Processing characteristics such as optimum cure time and maximum torque increases with increasing of the concentration of carbon black in DCSBR whereas scorch time decreases. The mechanical properties and resistance of the vulcanizate towards thermal, flame and oil resistance have been carried out. Variation of bound rubber content of carbon black filled DCSBR and the influence of the extracting temperature on the bound rubber content was investigated and its activation energy was calculated from the Arrhenius plot. The reinforcing nature of the filler was assessed from stress strain and swelling data. The enhancement in mechanical properties was supported by data on the increased content of crosslink density in these samples obtained from swelling and stress strain analysis. The results of the studies indicate that carbon black can be used as a good reinforcing filler for DCSBR.     

Characterization and mechanical properties of exfoliated graphite nanoplatelets reinforced polyethylene terephthalate/polypropylene composites

Recently, graphene and its derivatives have been used to develop polymer composites with improved or multifunctional properties. Exfoliated graphite nanoplatelets (GNP) reinforced composite materials based on blend of polyethylene terephthalate (PET), and polypropylene (PP) compatibilized with styrene–ethylene–butylene–styrene‐g‐maleic anhydride is prepared by melt extrusion followed by injection molding. Characterization of the composites' microstructure and morphology was conducted using field emission scanning electron microscopy, transmission electron microscopy (TEM), X‐ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). Tensile and impact strengths of test specimens were evaluated and the results showed maximum values at 3phr GNP in both the cases. Morphological studies showed that the GNPs were uniformly dispersed within the matrix. Results from XRD analysis showed uniformly dispersed GNPs, which may not have been substantially exfoliated. FTIR spectroscopy did not show any significant change in the peak positions to suggest definitive chemical interaction between GNP and the matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40582.     

New gasoline and gas barrier from plasticized carbon black reinforced butyl rubber/high‐density polyethylene blends

The effects of the high‐density polyethylene volume fraction on the curing characteristics and network structure of rubber blends have been studied in terms of the torque, scorch time, optimum curing time, Mooney viscosity, number of elastically effective chains, viscosity, interfacial tension, glass‐transition temperature, scanning electron microscopy, internal friction, sound velocity, acoustic attenuation, polymer–solvent interaction parameter, swelling index, and gel fraction. The applicability of the blends for gasoline barriers has been examined through the changes in the electrical resistance and volumetric swelling in gasoline versus time at room temperature. The transport mechanism of the solvent through the crosslinked butyl rubber/high‐density polyethylene blends is governed by Fickian diffusion law. The transport coefficients, namely, the diffusion coefficient, intrinsic diffusion, and permeation coefficient, have been computed. The experimental data for the permeation coefficient are in good agreement with the values calculated by Maxwell's model and far from those of Robeson's model. In addition, some thermodynamics parameters, namely, the standard entropy, standard enthalpy, and standard Gibbs free energy, have been estimated as functions of the high‐density polyethylene concentration of the butyl rubber blends. Furthermore, the applicability of butyl rubber/high‐density polyethylene composites for Freon gas barriers and antistatic charge dissipation has been examined. Finally, the mechanical properties, such as the tensile strength, hardness, stiffness, and elongation at break, of butyl rubber composites with different high‐density polyethylene concentrations have been evaluated. The increase in the mechanical properties is due to the increase in the crosslinking density and the interfacial adhesion of the blend. This proves that these new blends have important technological applications as gasoline and Freon barriers and for antistatic charge dissipation with good mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1237–1247, 2006     

Improved mechanical properties of NR/EPDM blends by controlling the migration of curative and filler via reactive processing technique

Simple blending of natural rubber/ethylene–propylene–diene rubber (NR/EPDM) generally results in inferior mechanical properties because of curative migration and their differences for filler affinity. In this work, the 70/30 and 50/50 NR/EPDM blends prepared by reactive processing techniques were investigated and compared with the simple, nonreactive blends. The reactive blend compounds were prepared by preheating EPDM, containing all curatives to a predetermined time related to their scorch time prior to blending with NR. For the 70/30 gum blends, four types of accelerators were studied: 2,2‐mercaptobenzothiazole (MBT), 2,2‐dithiobis‐ (benzothiazole) (MBTS), N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS), and N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS). When compared with the simple blends, the reactive blends cured with CBS and MBTS showed a clearly improved tensile strength whereas the increase of tensile strength in the blends cured with TBBS and MBT was marginal. However, a dramatic improvement of ultimate tensile properties in the reactive 50/50 NR/EPDM blends cured with TBBS was observed when compared with the simple blend. For the N‐550‐filled blends at the blend ratios of 70/30 and 50/50, the reactive‐filled blends prepared under the optimized preheating times demonstrated superior tensile strength and elongation at break over the simple blends. The improved crosslink and/or filler distribution between the two rubber phases in the reactive blends accounts for such improvement in their mechanical properties. This is shown in the scanning electron micrographs of the tensile fractured surfaces of the reactive blends, which indicate a more homogeneous blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study of carbon black distribution in BR/NBR blends based on damping properties: Influences of carbon black particle size,filler, and rubber polarity

Effects of filler and rubber polarity on the distribution of filler in butadiene/nitrile rubber (BR/NBR) blends were investigated, using the dynamic mechanical thermal analysis technique. As 30-phr filler is added, the reduction in heights of damping peaks (tan δ_max), attributed to the dilution effect, was observed. It was also found that the BR phase in the blends, compared to the NBR phase, is more preferential for small- and large-particle size carbon blacks to reside, probably because of the lower viscosity and lower polarity of the BR phase. The addition of silica instead of carbon black leads to an increase in filler migration to the NBR in the 20/80 BR/NBR blend, which is attributed to the strong silica–NBR interaction. In addition, an increase in NBR polarity promotes carbon black migration to the BR phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3198–3203, 2001     

In situ formed internal water channels improving water swelling and mechanical properties of water swellable rubber composites

In this study, electrospun nanofibers of poly (vinyl alcohol) (PVA) and styrene–butadiene–styrene triblock copolymer (SBS) were employed in conventional water‐swellable rubber (WSR) to design WSR composites with improved water swelling and mechanical properties. With the introduction of PVA nanofibers, considerable improvement in elasticity, strength, and water‐swelling behavior was observed. After immersion, PVA nanofibers dissolved within the composite to in situ form water channels to connect isolated super‐absorbent polymers (SAPs). Those water channels led to an increase in water uptake by the WSR composite. Furthermore, the secondary water‐swelling behaviors of the WSR composite showed a remarkable increase in swelling rate as well as in mechanical properties. The addition of SBS nanofibers had a marked impact on the mechanical properties of the WSR composite. Their roles became more pronounced after water immersion. The proposed enhancement mechanism is also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44548.     

Cure characteristics,morphology, mechanical properties,and aging characteristics of silicone rubber/ethylene vinyl acetate blends

Silicone rubber/ethylene vinyl acetate (SR/EVA) rubber mixes with different ratios were prepared by using dicumyl peroxide (DCP) and benzoyl peroxide (BP) as curing agents. The vulcanization characteristics such as cure kinetics, activation energy, and cure rate of the blends were analyzed. The effects of blend ratio and curing agents on the mechanical properties such as stress–strain behavior, tensile strength, elongation at break, tear strength, relative volume loss, hardness, flex crack resistance, and density of the cured blends have been investigated. Almost all the mechanical properties have been found to be increased with increase in EVA content in the blends particularly in DCP‐cured systems. The increment in mechanical properties of the blends with higher EVA content has been explained in terms of the morphology of the blends, attested by scanning electron micrographs. Attempts have been made to compare the experimental results, from the evaluation of mechanical properties, with relevant theoretical models. The aging characteristics of the cured blends were also investigated and found that both the DCP‐ and BP‐cured blends have excellent water and thermal resistance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1069–1082, 2006     

Combined effect of VA content and pH level of filler on properties of EPDM/SmBO3 and EPDM/ATO composites reinforced by three types of EVA

This study investigates the interaction of vinyl acetic (VA) content of ethylene‐vinyl acetate (EVA), pH level of Samarium borate (SmBO₃), and Sb‐doped SnO₂ (ATO) on reinforcement of peroxide‐cured ethylene‐propylene‐diene rubber (EPDM)/SmBO₃ and EPDM/ATO composites. It was found that EVA could both reinforce mechanical properties of EPDM, and enhance fluidity of gum during processing. During vulcanization, the interaction of VA groups and pH value of filler particles can influence the crosslink density of EPDM composites. In alkaline EPDM/SmBO₃/EVA, VA groups could hydrolyze to produce polyvinyl alcohol and reduce pH level of medium by consuming OH⁻. When dispersed in acidic EPDM/ATO/EVA, VA groups could generate polyunsaturated bonds and acetic acid during vulcanization. The double bonds could react with dicumyl peroxide (DCP) and then boost crosslink efficiency of EPDM composites. Moreover, acetic acid and reduction of pH value could make DCP decompose into ions, and lower crosslink density of EPDM composites. In addition to the contribution of crosslink density, EVA could crystallize in EPDM composites to reinforce EPDM composites. Electric properties of EPDM were also affected. Surface and volume resistivity of EPDM composites decreased with the rise of VA content. As for EPDM/SmBO₃/EVA composites, the growth of VA groups could boost dielectric constant and loss, decrease dielectric strength, due to the enhancement of polarity and reduction of crosslink density. In terms of EPDM/ATO/EVA composites, the EPDM/ATO/EVA14 possesses the highest dielectric constant and loss, and the lowest dielectric strength, because of the competing effect of VA content and crosslink density. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Utilization of peanut shell powder as a novel filler in natural rubber

This work focuses on the use of peanut shell powder (PSP) as filler in natural rubber (NR). Peanut, one of the food crops in the world, generates large amounts of waste namely peanut shell. Modified and unmodified PSP-NR composites with varying particle size and dosages were prepared by an open mill mixing technique. The processing characteristics and the curing behavior of the composites were determined by Monsanto Rheometer. The technological performance was done by analyzing the tensile strength, tear strength, and hardness of the vulcanizates. The swelling studies were carried out to observe the crosslink density, rubber-filler interaction, and the reinforcing nature of the filler on NR. The observed variation in mechanical properties has been supported by the fractography of the composites obtained by Scanning Electron Microscopy. The result of the study shows that the PSP is most effective filler in NR at 10 parts per hundred (phr) loading. Filler reinforcement ability of modified PSP is more when compared with unmodified PSP; therefore, modified PSP-NR composites shows better physicomechanical properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Morphology and mechanical behaviors of rigid organic particles reinforced polycarbonate

For the purpose of promoting mechanical properties of bisphenol-A polycarbonate (PC) reinforced by rigid organic styrene–acrylonitrile copolymer (SAN) particles, styrene/acrylonitrile/glycidyl methacrylate terpolymer (SAG) was synthesized and applied as compatibilizer for PC/SAN blends. It is found that the phase morphology of PC/SAN/SAG blends is closely related with their mechanical properties. Large continuously distributed SAN phase or spherical dispersed SAN particles with average diameter over 2 μm tend to trigger premature tensile failure of blends due to stress concentration. The incorporation of SAG can simultaneously reinforce and toughen PC/SAN blends by controlling the size and distribution of the dispersed SAN particles. For the blends with fixed PC/SAN ratio, the elongation at break and fracture energy are markedly improved when SAN domain size is reduced by adding appropriate amount of SAG. Typically, for blends with a PC/SAN ratio of 75/25, adding 3 wt% SAG will cause the average diameter of SAN particles to reduce from 2.35 ± 1.20 to 0.74 ± 0.25 μm, meanwhile up to 95% increment in elongation at break and 115% increment in fracture energy is achieved.     

Structural,rheological, and mechanical properties of PA6/SAN/SEBS ternary blend/organoclay nanocomposites

The aim of this study was to investigate the effect of nanoclay addition on the morphological and mechanical properties of PA6/SAN/SEBS ternary blend. Two different nanoclays with different modifiers and two different mixing sequences were used to investigate the role of thermodynamic and kinetic, respectively, in the nanoclays localization. XRD, SEM, TEM, melt rheology, tensile and Izod impact tests were used to characterize the nanocomposites. Results of characterization of nanocomposites showed that clay localization is a very influential parameter to determine the type of morphology and, consequently, mechanical properties of ternary/clay nanocomposites. It was demonstrated that presence of nanoclay in the matrix results in the increase of stiffness, while localization of nanoclay at the interface improves the toughness and tensile strength. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41969.     

A study on mechanical and thermal properties of silicone rubber/EPDM damping materials

Silicone rubber (SR) and ethylene‐propylene‐diene monomer (EPDM) blends were prepared for damping application. The mechanical and thermal properties of the blends are studied. With the increasing content of EPDM, the tensile strength is decreased but elongation at break is increased. By blending with EPDM, tan δ (at 35 to 200°C) of SR is enhanced. However, thermogravimetric analysis results showed the decrease in thermal stability. Scanning electron microscopy study showed the good filler dispersion of the blends with some large silica particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cure characteristics,mechanical, thermal,and coloring properties of natural rubber/dye‐loaded shell powder composites

To explore the application of shell powder (SP) in rubber, a dye‐loaded SP (DSP) bio‐filler based on SP and Congo red was incorporated into natural rubber (NR). The adsorption experiments demonstrated that the maximum monolayer adsorption capacity of Congo red onto SP was 69.3 mg/g. The effect of aluminate coupling agent and DSP was investigated by evaluating the cure characteristics, mechanical, thermal, and coloring properties of NR/DSP composites. It was suggested that the optimum amount of aluminate coupling agent was 2 wt %, and the best tensile strength (24.80 MPa) of vulcanizates was achieved at the DSP content of 20 phr, while other mechanical properties such as tear strength kept increasing with the addition of DSP. Furthermore, the improved thermal stability and uniform color distribution of the NR composites was obtained. The results indicate that DSP is promising to become a low‐cost filler and pigment for rubber materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45750.     

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

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

Structural,mechanical, thermal,and electrical properties of carbon black reinforced polyester resin composites

Carbon black (CB) reinforced polyester resin (PR) composites (CPC) have been fabricated from mechanical mixtures of liquid PR and CB powder having 0–50 wt% CB contents and cured with 1% of methyl ethyl ketone peroxide at room temperature under a pressure of 50 MPa. The samples have been examined by the Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD) technique, scanning electron microscopy (SEM), mechanical test, micromechanical test, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) and electrical test. FTIR spectra confirm the physical and chemical bond formations between CB and PR. XRD shows a very partial crystalline structure in cured PR and hexagonal structure in CB particles. SEM exhibits a clear dispersion of CB particles in PR matrix at lower loading and aggregates at higher loading. With the increase of fillers, while the tensile and flexural strengths of CPCs decrease, the Young's and tangent modulii increase by 80 and 100%, respectively. These increments are found consistent with the theoretical values. The degree of physical crosslinking between CB and PR as well as the aspect ratio of CB in CPCs are found to increase with the increase of filler. A remarkable increase in microhardness of about 61% at 50 wt% CB content is observed. The TGA represents that the thermal degradation temperature for pure PR is 373°C and that for CPC is 393°C. The dielectric constant of CPCs decreases with increasing frequency, whereas the ac‐ and dc‐ conductivities of CPC are found to increase with CB content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40421.     

丁腈橡胶／氯化丁基橡胶共混物的性能研究

研究了丁腈橡胶／氯化丁基橡胶共混物的低温性能和耐热性能。结果表明．选用TMTD／CZ／ZnO作共硫化体系,共混物体系两相的相容性较好;在并用比例为70／30时,与纯NBR相比,共混物Tg下降5.5℃,失重5％热分解温度提高38.4℃,且耐油性变化很小,适宜制备高低温性能较好的耐油橡胶制品。     

Studies on blends of polychloroprene and polybutadiene rubber containing phosphorylated cardanol prepolymer: Melt rheology,cure characteristics,and mechanical properties

Melt rheology, cure characteristics, and mechanical properties of blends of polychloroprene (CR) and polybutadiene rubber (BR) in the presence and absence of phosphorylated cardanol prepolymer (PCP) were studied. The melt rheology parameters of the blends over a wide range of shear rates and temperatures were studied using a capillary rheometer (Rheoflixer SWO). The plasticizing effect of PCP in the blends was indicated by reduction in apparent melt viscosity and activation energy for melt flow. Good compatibility between the blend components (CR and BR) in the presence of PCP was evidenced by the lower values of principal normal stress difference. The self crosslinking behavior of the blends in the presence and absence of PCP was studied at different temperatures, using a Brabender Plasicorder and the kinetic parameters of crosslinking were evaluated. The cure characteristics of blends of CR and BR containing different dosages of PCP (0–10 phr) in a semi efficient vulcanization system were also studied at temperatures ranging from 150°C to 180°C, using an oscillating disk rheometer. The increase in tensile modulus, tensile strength, and tear strength of the vulcanizates in the presence of 5 phr of PCP is presumed to be an indication of reinforcement resulting from accelerated cross linking reaction as evidenced by higher chemical crosslink density index. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3195–3200, 2006