Academic literature on the topic 'Rubber behavior'

As the second largest rubber producer in the world, Indonesia has a very potential opportunity to support the development of rubber base isolation. Various grades of rubber are produced by the local rubber manufacturers starting from the low to high grade rubbers. In the study, the local rubbers were also compared to the rubbers from another developing country, e.g. India. The laboratory test results used to develop the suitable constitutive model for hyperelastic material and then compared to the hyperelastic model of Shahzad et al. Several tests on the local low-grade rubbers have been conducted, namely the uniaxial tensile, planar shear, and equibiaxial tensile tests. From the tests, it can be concluded the behavior of the local low-grade rubber can be fitted with the Ogden model different from the characteristic of rubber tested by Shahzad et al. which was fitted with the Yeoh model.

Rubbers are widely used in various fields as the important sealing materials, such as window seal, door seal, valve, pump seal, etc. The fretting wear behavior of rubbers has an important effect on their sealing performance. This paper presents an experimental study on the fretting wear behavior of rubbers against the steel ball under air conditions (room temperature at 20 ± 2 °C and humidity at 40%). Three kinds of rubbers, including EPDM (ethylene propylene diene monomer), FPM (fluororubber), and NBR (nitrile–butadiene rubber), are considered in experiments. The sphere-on-flat contact pattern is used as the contact model. The influences of the displacement amplitude, normal force, frequency, and rubber hardness on the fretting wear behavior are discussed in detail. White light profiler and scanning electron microscope (SEM) are used to analyze the wear mechanism of the rubber surface. The fretting wear performances of three rubbers are compared by considering the effect of the displacement amplitude, normal force, frequency, and rubber hardness. The results show that NBR has the most stable friction coefficient and the best wear resistance among the three rubbers.

The understanding of the deformation behavior of rubber materials under high strain-rate or high loading-rate conditions will be important in their impact applications adopting significant viscoelastic behavior. Taylor impact test has originally used to determine the average dynamic yield strength of metallic materials at high strain rates, but it also can be used to examine the overall deformation behavior of rubbers representing large elastic deformation by using a high-speed photography technique. Taylor impact tests of rubber materials were carried out in the velocity range between 100~250 m/s using a 20 mm air gun. In order to investigate the overall dynamic deformation behavior of rubber projectiles during Taylor impact test, a 8-Ch high-speed photography system which provides a series of images at each elapsed time was incorporated. Three kinds of rubber materials with different Tg (glass transition temperature) were supplied. The bulging behavior of rubber projectile could be evaluated quantitatively by digitizing images taken. Taylor impact tests at various temperature levels were conducted to predict the bulging behavior of rubbers at high strain rate.

ABSTRACT Ultrasonic devulcanization of tire rubber particles of 10 and 30 meshes by means of a new ultrasonic twin-screw extruder was investigated. The ultrasonic amplitude and devulcanization temperature were varied at a fixed frequency of 40 kHz. The die pressure and ultrasonic power consumption during devulcanization were recorded. The degree of devulcanization was investigated by measuring the cross-link density, gel fraction, and revulcanization behavior. Rubber of 30 mesh exhibited a lower die pressure and higher degree of devulcanization than that of rubber of 10 mesh. Because of the higher level of devulcanization and lower viscosity of devulcanized rubbers at higher amplitudes, the temperature of devulcanized rubbers at the die was reduced with an increase of the ultrasonic amplitude. Generally, the torque at the start of curing and maximum torque on the curing curve measured during revulcanization is higher for rubber of 10 mesh and rubbers devulcanized at a lower temperature. Rheological properties of devulcanized and revulcanized rubbers and mechanical properties of revulcanizates were measured. The complex viscosity of devulcanized and revulcanized rubbers of both meshes as a function of frequency exhibited a power-law behavior, with the power-law index being 0.06 for devulcanized rubbers and 0.02 for revulcanized rubbers. The consistency index of devulcanized and revulcanized rubbers was higher for rubber of 10 mesh; however, both rubbers showed a higher consistency index at a lower temperature. Cole–Cole plots, cross-link density, and gel fraction of devulcanized and revulcanized rubbers, revulcanization behavior, and modulus of revulcanizates separated in two distinct groups based on the level of devulcanization and effect on molecular structure of devulcanized rubber. Revulcanizates with a greater degree of devulcanization exhibited a higher elongation at break, whereas those with a lower degree of devulcanization exhibited higher strength and modulus. Revulcanizates of rubber of 30 mesh exhibited a consistently higher elongation at break. The normalized gel fraction versus normalized cross-link density was described by a unique function independent of the processing conditions and rubber particle size.

The present study examines rubber’s capacity of improving the swell–shrink potential of expansive clays. Two rubber types of fine and coarse categories with different geometrical features were considered. The test program consisted of standard Proctor compaction and cyclic wetting–drying tests. Scanning electron microscopy (SEM) analysis was also performed to identify the soil–rubber amending mechanisms, and to observe the evolution of fabric in response to alternate wetting and drying. Cyclic wetting–drying led to the reconstruction of the soil/soil–rubber microstructure by way of inducing aggregation and cementation of the soil grains. The greater the number of applied cycles, the lower the swell–shrink features, following a monotonically decreasing trend, with the rubberized blends holding a notable advantage over the virgin soil. The tendency for reduction, however, was in favor of a larger rubber size, and more importantly the rubber’s elongated form factor; thus, predicating a rubber size/shape-dependent amending mechanism. The soil–rubber amending mechanisms were discussed in three aspects—increase in non-expansive content, frictional resistance generated as a result of soil–rubber contact, and mechanical interlocking of rubber particles and soil grains. The swell–shrink patterns/paths indicated an expansive accumulated deformation for the virgin soil, whereas the rubberized blends manifested a relatively neutral deformational state, thereby corroborating the rubber’s capacity to counteract the heave and/or settlement incurred by alternate wetting and drying.

In the present work, the processability and fire behavior of parts made by the laser sintering (LS) of polyamide 12/rubber powder blends is studied. In order to evaluate some of the interactions that could take place during LS, three acrylonitrile butadiene rubbers (NBRs) were used, which included two that had different acrylonitrile (AN) contents, and one that had carboxylated rubber. The results show that the flowability of the powders is strongly dependent on the rubber used. For the carboxylated rubber, a good flowability of the blend was observed, whereas the use of rubbers with different AN contents led to significant changes in the powder flowability, with a heterogeneous powder bed, and differences in the porosity as a function of the AN content. Furthermore, the addition of rubbers to polyamide 12 (PA12) entails an increase in the sintering window and, in particular, a change in the melting temperature of PA12 is noticed. Even though some changes in the crystallization and melting temperatures are observed, formulations containing 10 and 20 wt.% of rubbers could be processed using the same process parameters as PA12. Furthermore, the formulations containing carboxylated rubber show improved fire behavior, which is measured by a cone calorimeter, with reductions of about 45 and 65% in the peak of the heat release rate, compared to the PA12. Moreover, almost all of the samples evaluated in this study are classed as “Good” by the Flame Retardancy Index. This result can be partially explained by the formation of an amide linkage between the polyamide and NBR during processing, which could result in increases in the melt viscosities of these samples.

An accurate selection of strain energy function (SEF) plays a very important role for predicting the actual behavior of rubber material in the finite element analysis (FEA). The common method for selecting the SEF is by using the curve fitting procedure. However, the behavior of some typical rubbers, such as low grade rubbers (average hardness value of 47.2), cannot be predicted well by only using the curve fitting procedure. To accurately predict the actual behavior of such specifically nearly incompressible material, a series of FEA were carried out to simulate the actual behavior of four physical testing materials, namely the uniaxial, the planar shear, the equibiaxial, and the volumetric tests. This FEA is intended to examine the most suitable constitutive model in representing the rubber characteristics and behavior. From the comparisons, it can be concluded that the Ogden model provides a reasonably accurate prediction compared to the remaining investigated constitutive material models. Finally, the appropriate SEF, i.e. the Ogden model, was adopted for modeling a low-cost rubber base isolator (LCRBI) in the finite element analysis (FEA). The simple uniaxial compression test of the LCRBI is required for validating that the selected SEF works for predicting the actual behavior of LCRBI.

In terms of recycling and reuse, today's global generation of waste tire well exceeds its consumption. This has resulted in the accumulation of large stocks of toxic rubber waste that raise health and safety risks. The use of waste tire rubber for the construction of the concrete structure was suggested to combat this challenge. This paper explores tests that were performed with samples of waste tire rubber concrete to evaluate compressive strength, flexural tensile strength, modulus of rupture, and impacts resistance. The main parameters investigated were the rubber ratio as a partial volumetric replacement with fine and coarse aggregate. Chip and crumb rubbers were used to replace coarse and fine aggregate respectively in four different amounts by volume (5%, 10%, 15%, and 20%). Even if the inclusion of waste tire rubber in concrete has specific apparent degradations, the potential benefit seems to overlook the adverse effects and also meet the primary significant value of resolution for rubber waste utilization problems. The results show that the substitution of natural fine or coarse aggregates with crump-chip tier rubber will reduce mechanical properties (compressive, flexural and splitting tensile strength), but increase the impacts resistance to 426% and 396% when 20% coarse aggregates and 20% fine aggregates are replaced by rubber respectively. The proposed mix shows an ability to replace 20% of the aggregate (coarse or fine), and the producing, rubcrete, still structural concrete.

Abstract The paper reports that the processing behavior and physical properties of the blends of silicone rubber and fluororubber based on tetrafluoroethylene/propylene/vinylidene terpolymer. The processing behavior of the fluororubber can be improved on blending with low viscous silicone rubber. The results indicate that the processing behavior, mechanical properties, surface energies, and flammability of the blends are controlled by the blend morphology. Surface morphology of the blends show that blends of two rubbers are microheterogeneous and biphasic structure, wherein silicone rubber acts as a continuous matrix with the fluororubber as a dispersed phase.

Analysed the stress-strain test in the pressing direction of metal rubber specimen, the deformation process can be divided into three stages. Used the accumulative method of high step polynomial, the experience formula of metal rubber’s deformation character can be simply and effectively established. With the fabrication and formation technology, the microscopic physics mechanism has been analyzed in these deformation stages.