• Elastomers and Composites
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• v.56 no.4
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• pp.201-208
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• 2021

In this study, the effect of petroleum resin on the mechanical strength, morphology, and vibration damping characteristics of natural rubber (NR) composites was observed. The NR composites plasticized by adding petroleum resin showed decreased hardness and mechanical properties. A morphology analysis indicated that as the amount of petroleum resin increased, carbon black aggregates (or agglomerates) observed at the fracture surface decreased, resulting in an improvement in the dispersibility. In addition, as 20 phr of petroleum resin was added, the effective damping temperature range increased by approximately 11.4%, the hysteresis loss rate increased by 15.2%, and the resilience decreased by 36.6%. Therefore, it was confirmed that the vibration damping characteristics improved with the addition of petroleum resin. This was because the rubber-filler interaction between the NR molecular chain of the NR composite and the carbon black particles improved by the addition of petroleum resin.

• Elastomers and Composites
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• v.42 no.2
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• pp.107-111
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• 2007

Adhesion of NR and BR composites with different initial states of precured or uncured conditions was studied. Adhesion between the NR and BR sheets as well as adhesion between the same rubber sheets was investigated. Adhesion forces of the uncured/uncured specimens were larger than those of the cured/uncured and cured/cured ones. The cured/cured samples and uncured NR/cured BR specimen were fully peeled out by the peel test. When one sheet was broken during the peel test, the sheet having the higher crosslink density was broken irrespective of the rubber types. Adhesion forces of the same rubber sheets were higher than those of the different ones and adhesion force of the cured NR/uncured BR sample was higher than that of the uncured NR/cured BR one. The experimental results were explained with the crosslink density and interdiffusion of rubber chains.

• Elastomers and Composites
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• v.46 no.3
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• pp.237-244
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• 2011

Five natural rubber (NR) composites with different reinforcing systems of unfilled, carbon black, carbon black with silane coupling agent, silica, and silica with silane coupling agent were thermally aged and change of the crosslink densities by the accelerated thermal aging was investigated. The crosslink densities on the whole increased as the aging time elapsed irrespective of the reinforcing systems. The crosslink density changes became noticeable by increasing the aging temperature. For carbon black-filled composites, the silane coupling agent made the crosslink density change to be increased. For silica-filled composites, however, the silane coupling agent made the crosslink density increment reduced at 60 and $70^{\circ}C$ and it hardly affect the degree of the crosslink density change at 80 and $90^{\circ}C$. The activation energies for the crosslink density changes of the carbon black-filled samples increased continuously in a logarithmic fashion, whereas that of the silica-filled one showed a quasi-steady state ranges at aging times of 30-150 days. The activation energy of the unfilled sample increased exponentially with the aging time. The experimental results were explained with sulfur donation from the silane coupling agent, surface modification of the filler by the silane coupling agent, adsorption of curative residues on the silica surface, and release of the adsorbed curative residues.

• Elastomers and Composites
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• v.23 no.4
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• pp.308-323
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• 1988

• Elastomers and Composites
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• v.57 no.4
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• pp.188-196
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• 2022

Styrene-butadiene rubber(SBR) is a copolymer of styrene and butadiene. It is composed of 1,2-unit, 1,4-unit, and styrene, and its properties are dependent on its microstructure. In general, rubber composites contain a single rubber or a blended rubber. Similarly, SBR is used by mixing with natural rubber(NR) and butadiene rubber(BR). The composition of a rubber article affects its physical and chemical properties. Herein, an analytical method for determining the microstructure of SBR using via pyrolysis is introduced. Pyrolysis-gas chromatography/mass spectrometry is widely used to analyze the microstructure of polymeric materials. The microstructure of SBR can be determined by analyzing the principal pyrolysis products formed from SBR, such as 4-vinylcyclohexene, styrene, 2-phenylpropene, 3-phenylcyclopentene, and 4-phenylcyclohexene. An analytical method for determining the composition of SBR/NR, SBR/BR, and SBR/NR/BR blends via pyrolysis is introduced. The composition of blended rubber can be determined by analyzing the principal pyrolysis products formed from each rubber component.

• Environmental Engineering Research
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• v.20 no.4
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• pp.342-346
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• 2015

Haloacetonitriles (HANs) are nitrogenous disinfection by-products (DBPs) that have been reported to have a higher toxicity than the other groups of DBPs. The adsorption process is mostly used to remove HANs in aqueous solutions. Functionalized composite materials tend to be effective adsorbents due to their hydrophobicity and specific adsorptive mechanism. In this study, the removal of dichloroacetonitrile (DCAN) from tap water by adsorption on thiol-functionalized mesoporous composites made from natural rubber (NR) and hexagonal mesoporous silica (HMS-SH) was investigated. Fourier-transform infrared spectroscopy (FTIR) results revealed that the thiol group of NR/HMS was covered with NR molecules. X-ray diffraction (XRD) analysis indicated an expansion of the hexagonal unit cell. Adsorption kinetic and isotherm models were used to determine the adsorption mechanisms and the experiments revealed that NR/HMS-SH had a higher DCAN adsorption capacity than powered activated carbon (PAC). NR/HMS-SH adsorption reached equilibrium after 12 hours and its adsorption kinetics fit well with a pseudo-second-order model. A linear model was found to fit well with the DCAN adsorption isotherm at a low concentration level.

• Elastomers and Composites
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• v.39 no.1
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• pp.51-60
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• 2004

The cure, viscoelastic and mechanical characteristics of organoclay filled NR/BR blends were studied and compared with the properties of carbon black and silica filled NR/BR blends. The nanocomposites with extensive exfoliation state can be fabricated by a solution mixing method. In the composites, the amount of filler content was fixed to 10 phr. Degree of intercalation and exfoliation was characterized by X-ray diffraction (XRD). XRD results indicated exfoliation of the silicate layers into the rubber matrix. While the degree or intercalation and exfoliation is lowered by the conventional mixing method, extensive exfoliation can be obtained by the solution mixing method. It was found that the clay filled NR/BR compound showed better viscoelastic (tan ${\delta}$) and mechanical properties than the carbon black or silica filled NR/BR compounds.

• Elastomers and Composites
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• v.53 no.2
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• pp.67-74
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• 2018

Magneto-rheological elastomers (MREs) are smart materials in which the inherent stiffness and damping properties can be changed by the influence of an external magnetic field. The magneto-rheological (MR) effect depends on the orientation characteristics of the dispersed magneto-responsible particles (MRPs) in the matrix. In this study, natural rubber (NR) and ethylene propylene diene rubber (EPDM) were blended and used as a matrix of an MRE. EPDM was pre-cured before blending with NR. The Mooney viscosity, curing characteristics, and mechanical properties were analyzed with various pre-curing conditions of EPDM and the NR/EPDM blend. The results show that excellent mechanical properties of the NR/EPDM blend-based MRE were obtained when the pre-curing time of EPDM was 60 min. The aging property of the NR-based MRE was improved by the introduction of pre-cured EPDM. Also, the anisotropic MRE showed a higher MR effect than that of the isotropic MRE.

• Elastomers and Composites
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• v.27 no.3
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• pp.183-193
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• 1992

Compared with NR and HNBR compounds, the blend properties of NR/HNBR were studied. The heat, oil and ozone resistance of NR compounds were improved by blending HNBR, and these effects were more clearly revealed with elevating temperatures. For the overall stabilities of the compounds, it was resonable to use the carbon black under the 60phr. In the EV systems, high-saturated NR/HNBR and HNBR compounds showed similar total crosslink density in comparison with NR compounds. Interaction parameters calculated by stress-strain method showed widely varied value.

• Elastomers and Composites
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• v.29 no.2
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• pp.121-130
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• 1994

The physical properties of rubber blend between natural rubber(NR) and ethylene propylene diene terpolymer(EPDM) were investigated as a study of EPDM composite materials. For EPDM/NR blends, the effects of ethylene and diene contents in EPDM, blend ratio, dicumyl peroxide(DCP) curing system on the physical properties, interfacial adhesion force and dynamic crack growth etc. were studied. EPDM/NR blends loaded with carbon black were prepared by mechanical mixing and cured by plate heating cure press. Crosslinking density was measured by swelling method with toluene. The physical properties of all blends were measured with Instron, fatigue to failure(FTF), Demattia flex cracking tester(DMFC), scanning electron microscopy (SEM), etc. As the ethylene and diene contents in EPDM increased, the physical properties, such as dynamic crack growth, adhesion to other component were increased too. Interfacial adhesion force of EPDM/NR blends to dissimilar layer was improved by the use of optimum peroxide curing system.