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Rubber Compounds (rubber + compound)
Selected AbstractsA Numerical Model for the Optimal Vulcanization of 2D Polar Rubber Compounds Using MicrowavesMACROMOLECULAR THEORY AND SIMULATIONS, Issue 6 2009Gabriele Milani Abstract A numerical model is presented for the optimal vulcanization of 2D extruded polar rubber with microwaves and peroxides. Magnetron power and curing time are used as the input production parameters, and the output mechanical property selected for optimization is the average tensile strength of the item. A 2D thick weather strip is analyzed to validate the model. The electric field is evaluated by means of Yee cells (FDTD approach) and suitably inserted in Fourier's heat transmission law, thus allowing point-by-point temperature profiles to be determined. The temperature is then used to evaluate the degree of peroxidic reticulation, and thus the final tensile strength. A so-called alternating tangent approach based on the bisection method is finally proposed to estimate the optimal magnetron power and curing time. [source] Influence of filler type and content on properties of styrene-butadiene rubber (SBR) compound reinforced with carbon black or silicaPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2004Sung-Seen Choi Abstract Rubber compounds are filled with reinforcing fillers to improve their physical properties. Carbon black and silica have different surface chemistries to each other. Differences in properties of carbon black- and silica-reinforced styrene-butadiene rubber (SBR) compounds were studied. Variation of properties of carbon black- or silica-filled compounds with the filler content was also investigated. The silica-filled compounds without any coupling agent and dispering agent were prepared to investigate the influence of polar materials-adsorption on the silica surface. Viscosity and crosslink density increased with increase of the filler content. Hardness, modulus, tensile strength, and wear property were improved more and more by increasing the filler content. Viscosity of the silica-filled compound was higher than that of the carbon black-filled one. Cure rate of the silica-filled compound became slower as the filler content increased, while that of the carbon black-filled one became faster. Difference in properties between the carbon black- and silica-filled compounds were explained by the poor silica dispersion and the adsorption of cure accelerator on the silica surface. Copyright © 2004 John Wiley & Sons, Ltd. [source] A mathematical hysteretic model for elastomeric isolation bearingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2002J. S. Hwang Abstract An analytical model for high damping elastomeric isolation bearings is presented in this paper. The model is used to describe mathematically the damping force and restoring force of the rubber material and bearing. Ten parameters to be identified from cyclic loading tests are included in the model. The sensitivity of the ten parameters in affecting the model is examined. These ten parameters are functions of a number of influence factors on the elastomer such as the rubber compound, Mullins effect, scragging effect, frequency, temperature and axial load. In this study, however, only the Mullins effect, scragging effect, frequency and temperature are investigated. Both material tests and shaking table tests were performed to validate the proposed model. Based on the comparison between the experimental and the analytical results, it is found that the proposed analytical model is capable of predicting the shear force,displacement hysteresis very accurately for both rubber material and bearing under cyclic loading reversals. The seismic response time histories of the bearing can also be captured, using the proposed analytical model, with a practically acceptable precision. Copyright © 2002 John Wiley & Sons, Ltd. [source] Highlight of a compensation effect between filler morphology and loading on dynamic properties of filled rubbersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Franck Sosson Abstract This investigation highlighted the equivalence between carbon black (CB) loading and structure influences on dynamic mechanical properties in the linear behavior of several filled synthetic rubber compounds. Different morphologies (specific surface area and structure) of CB incorporated at different loadings were formulated to modulate the filler-rubber matrix interphase content, usually named "tightly bound rubber." Both reinforcement level and tightly bound rubber content were measured on each compound by dynamic mechanical analysis (DMTA) and by Soxhlet extraction and thermogravimetry (TGA) respectively. Then, a systematic description of their evolution was made against CB loading and morphology. These evolutions were attributed to the hydrodynamic effect which could be evaluated by the effective filler volume fraction. A new parameter , is defined, representing the effective filler volume fraction for each compound and it was calculated on the basis of experimental parameters. Results show good correspondences between , included both the hydrodynamic effects of the filled carbon black rubbers and dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Processing and mechanical behavior of carbon black graded rubber compoundsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sandeep S. Ahankari Abstract Functionally graded rubber compounds (FGRCs) were prepared by construction based method. The matrix used was natural rubber (NR). Amorphous carbon black (N-330) was used as grading material. The gradation of nanoparticles in a rectangular geometry comprised the variation of particle volume fraction along thickness direction. Its performance was evaluated for structural application through various mechanical and surface properties like tensile strength, modulus, tear strength, elongation at break, hardness, fracture surface by scanning electron microscopy, etc. At the same percentage of nanofiller loading, FGRCs show enhanced properties, i.e., modulus and tear strength (in some grades) compared to uniformly dispersed rubber compounds (UDRCs). Modulus of FGRCs, for a given particular stacking sequence of the layers, increases as much as by 275% compared to UDRCs. The ultimate properties like tensile strength and elongation at break made up for the modulus enhancement that decreases to as minimum as 50 and 80%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Utilization of bowstring hemp fiber as a filler in natural rubber compoundsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008E. Osabohien Abstract The cure characteristics and physicomechanical properties of natural rubber (standard Nigerian rubber) vulcanizates filled with the fiber of bowstring hemp (Sansevieria liberica) and carbon black were investigated. The results showed that the scorch and cure times decreased, whereas the maximum torques increased, with increasing filler loadings for both bowstring hemp fiber and carbon black filled vulcanizates. The tensile strength of both bowstring hemp fiber and carbon black filled vulcanizates increased to a maximum at a 40 phr filler concentration before decreasing. The elongation at break and rebound resilience decreased, whereas the modulus, specific gravity, abrasion resistance, and hardness increased, with increasing filler contents. The carbon black/natural rubber vulcanizates had higher tensile strength, which was about 1.5 times that of bowstring hemp fiber/natural rubber vulcanizates. This superiority in the tensile strength was probably due to the higher moisture content and larger particle size of the bowstring hemp fiber. However, the bowstring hemp fiber/natural rubber vulcanizates showed superior hardness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of rubber matrix type on the morphology and reinforcement effects in carbon black-nanoclay hybrid composites,A comparative assessmentPOLYMER COMPOSITES, Issue 1 2010S. Praveen Carbon black (B),nanoclay (NC) hybrid composites, based on millable polyurethane and brominated isoprene isobutylene rubber (BIIR), were prepared. The carbon black loading was fixed at 20 phr and organically modified sodium montmorillonite clay loading varied from 5 to 20 phr in each rubber compounds. The nanocomposites were prepared in laboratory by mixing two-roll mill. The state of dispersion of the layered silicate was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM results indicated intercalation of PU and BIIR into the silicate interlayers, followed by exfoliation of the silicate layers into the elastomer matrices. However, the level of intercalation and exfoliation varied considerably with the type of elastomer. The reinforcing effects obtained were found to depend strongly on the extent and degree of the dispersion of the carbon black and silicate layers into the rubber matrices. Mechanical and dynamic mechanical properties were evaluated for each composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Short fibers as reinforcement of rubber compoundsPOLYMER COMPOSITES, Issue 4 2002M. A. López Manchado The effect of aramid, glass and cellulose short fibers on the processing behavior, crosslinking density and mechanical properties of natural rubber (NR), ethylene-propylene-diene terpolymer rubber (EPDM) and styrene-butadiene rubber (SBR) has been investigated. Two fiber percentages (10 and 20 phr) were added to the rubber. The results have shown that the above-mentioned fibers, especially aramid fibers, are effective reinforcing agents for these rubbers, giving rise to a significant increase in mechanical properties, such as tensile modulus and strength, and tear and abrasion resistance. Moreover, a significant decrease in the time to reach 97% of curing, t,c (97) is observed, which indicates that the fibers tend to increase the vulcanization rate, regardless of the rubber used. Fibers give also rise to an increase in crosslinking, especially the aramid fibers. [source] Use of carboxylated nitrile rubber and natural rubber blends as retreading compound for OTR tiresPOLYMER ENGINEERING & SCIENCE, Issue 12 2008Kaushik Pal Ore transportation is one of the important unit operations in a mineral industry. In this study, three raw rubber compounds are prepared in three different blend ratios, and four types of raw rubber samples of pure NR with silica reinforced has been collected from the different tire retreading industries. Blend properties largely depend on the blend ratio and on the blending technique. The improvement in the physical properties such as cure characteristics, mechanical characterization, cross-link density, FTIR, thermal characterization, SEM studies, and dynamic mechanical analysis has been studied in those samples. It has been found that retread rubber made with 80 phr XNBR and 20 phr NR has given the better results when compared with the other samples against all the characterization done. It is also seen that rubber made by the researchers are very good in tough, rigid and these are extremely able to withstand for using as a retread rubber for 35T dump trucks tire when compared with the retread rubber made by the tire retreading industries for different mines in India. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Rubber plasticizers from degraded/devulcanized scrap rubber: A method of recycling waste rubber,POLYMER ENGINEERING & SCIENCE, Issue 7 2004Amiya R. Tripathy Seeking a solution to the problem of disposing scrap tires, we attempted to depolymerize or degrade vulcanized rubber scrap such that the resulting pseudo-liquid material could be used as an extender/plasticizer in virgin rubber compounds. As degraded natural rubber (DNR) and degraded styrene-butadiene rubber (DSBR) are polymeric in nature (confirmed from gel-permeation chromatography (GPC) and differential scanning calorimetry (DSC) results), they can be unique substitutes for typical rubber plasticizers (oil). DNR-loaded samples have shown better mechanical property retention after aging and a lower extractable content in acetone than the respective oil-plasticized samples. Solvent swelling in toluene and 100% modulus values indicate that DNR-added rubber vulcanizates undergo a phase adhesion between the rubber matrix and the degraded polymer, as well as incurring extra reinforcement due to particulate carbon black present in the degraded rubber. Polym. Eng. Sci. 44:1338,1350, 2004. © 2004 Society of Plastics Engineers. [source] Chemorheology of model filled rubber compounds during curingPOLYMER ENGINEERING & SCIENCE, Issue 11 2001Jianfen J. Cai The rheological behavior and crosslinking kinetics of model filled rubber compounds during curing were investigated. The effect of chemical composition of monodisperse size particles, prepared by emulsifier-free emulsion polymerization, on dynamic moduli and gelation time of the filled compounds was studied. All filled systems showed much shorter gelation times than the pure matrix in the order PSVP < PS < PMMA , Pure Matrix. The dynamic moduli during curing increased with increasing interactions between particles and matrix. Physical crosslinking, due to either particle clustering or a network of filler particles with an adsorbed polymer layer, made a significant contribution to the overall crosslink density and the gelation of rubber compounds. As a result, the dynamic mechanical properties and curing kinetics of the rubber compounds varied with the chemical nature of the filler particles. [source] Rheological behavior of highly filled ethylene propylene diene rubber compoundsPOLYMER ENGINEERING & SCIENCE, Issue 5 2000M. G. Markovic The rheological behavior of highly filled ethylene propylene diene rubber (EPDM) compounds was studied with respect to the effect of curative system, grafted rubber, shear rate, temperature and die swell using a Monsanto Processability Tester (MPT) to gain an understanding of the molecular parameters that control the surface finish. All systems show pseudoplastic behavior. At a particular shear rate, shear viscosity increases with blend ratio. The dependence of flow behavior on extrusion velocity indicates a surface effect. The extrudate die swell and maximum recoverable deformation are related by a linear relationship, which is independent of sulfur/accelerator ratio, extrusion temperature and shear rates and blend ratio. The principal normal stress difference increases nonlinearly with shear stress. Activation energy decreases with shear rate in most cases. The faster relaxing system produces extrudate of better surface quality. [source] Effects of radiation pretreatments on the rubber adsorption power and reinforcing properties of fillers in rubber compoundsPOLYMER INTERNATIONAL, Issue 7 2001Franco Cataldo Abstract Radiation damage to fillers such as carbon black, graphite and silica induced by high doses of ,-radiation or neutrons dramatically increases their ability to adsorb rubber irreversibly. In fact, the ,bound rubber', ie the amount of non-extractable rubber which remains irreversibly linked to the filler matrix, increases dramatically in radiation-treated fillers. The increased adsorption power of radiation-damaged fillers has been attributed to the formation of a higher concentration of surface defects in the form of trapped free radicals, fullerene-like structures and other kinds of defects. The mechanical properties of rubber compounds filled with radiation-treated carbon blacks show a significant increase in their reinforcing effects, in line with the increased ability to form ,bound rubber'. © 2001 Society of Chemical Industry [source] Effects of rubber type on the curing and physical properties of silica filled rubber compoundsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008Chung Ho Shin Abstract As environmental regulations are getting stricter, tire industries for automobiles have shown much interest in substituting silica for conventional carbon black partially or entirely. To take full advantage of silica as fillers for rubbers, it is essential to find a reasonable rubber system that shows an excellent performance with silica reinforcement. Therefore, in this study, several different rubber compounds comprising the same amount of silica were prepared with several different rubber systems, respectively. The processability, curing characteristics, and mechanical and viscoelastic properties of the rubber compounds were investigated to analyze the performance of the rubber compounds as tire tread materials. Among the rubber compounds studied, SBR1721 compound comprising natural rubber (NR) and styrene butadiene rubber (SBR) with high styrene content was considered the most appropriate for application to tire tread materials. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of a Psychologically Based Management System on Work Motivation and ProductivityAPPLIED PSYCHOLOGY, Issue 3 2000Uwe Kleinbeck Introducing group work as a principle of work organisation to increase productivity in organisations operating in a globalising economy requires new methods of measuring performance in groups. This study describes the introduction of a measurement instrument as part of a participative productivity management (PPM) system in a medium sized factory producing rubber compounds. Using a simple quasi-experimental design, the PPM intervention was found to produce an increase in productivity and was also related to goal clarity, but not to higher group cohesion. It is concluded that PPM helps to increase productivity mainly by increasing task and goal clarity, and that increases in productivity can only be reached reliably when no competing system of performance appraisal exists besides PPM. L'introduction du travail en groupe comme principe de structuration du travail pour ame´liorer la productivite´ d'organisations e´voluant dans une e´conomie globalise´e impose de nouvelles me´thodes pour mesurer la performance dans les groupes. Cet article de´crit l'application d'un instrument de mesure comme e´tant un e´le´ment du syste`me de gestion participative de la productivite´ (PPM) dans une usine de taille moyenne produisant des composants en caoutchouc. En faisant appel a` un plan quasi expe´rimental, l'intervention PPM a ame´liore´ la productivite´ tout en e´tant relie´e a` la clarte´ des objectifs, mais pas a` une meilleure cohe´sion des groupes. On en conclut que la PPM accroit la productivite´ surtout grâce a` une meilleure transparence des objectifs et des tâches, mais que ces gains de productivite´ ne peuvent être obtenus avec certitude si un syste`me concurrent d'e´valuation de la performance fonctionne en paralle`le avec la PPM. [source] | |||||||||||||