Rubber Samples Research Articles

An Experimental Study on Behavior of Sustainable Rubberized Concrete Mixes

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.

Polybutadiene rubbers with urethane linkages prepared by a dynamic covalent approach for tire applications

In the context of pneumatic tires, high durability and fuel efficiency reside in a trade-off relationship. This problem may be solved by the introduction of hydrogen bonds into cured rubber, as elastic materials with hydrogen bonds exhibit a different strain dependence of their energy dissipation compared to elastic materials with conventional chemical bonds. Herein, we have applied cross-metathesis reactions between polybutadienes and olefin-containing polyurethanes to the synthesis of novel polybutadienes with urethane linkages as a source of hydrogen bonds in the polymer main chain (PBUs). A series of PBUs with different contents of urethane linkages was synthesized by changing the feed ratios of the polybutadiene and olefin-containing polyurethanes in cross-metathesis reactions, and the resulting PBUs were characterized in order to examine the effect of the hydrogen bonds on the macroscopic mechanical properties. Cured rubber materials prepared from PBUs exhibit higher tearing energy and energy dissipation at high strains compared to conventional control rubber samples, and the tearing energy related to energy dissipation at high strains improves with increasing urethane content. Therefore, the present approach represents a powerful strategy for conciliating durability and fuel efficiency in cured rubbers.

Mechanical Properties, Set and Rebound Resilience Characteristics of Natural Rubber/Ethylene Vinyl Acetate Blend on Various Ratios

AbstractIn this study, natural rubber/ethylene vinyl acetate (NR/EVA) blends are formulated by simple blend using two roll mill. The set properties, both compression and tension, are evaluated as a function of NR/EVA ratios. The ratio of NR/EVA ranges from 100/0 to 95/5, 90/10, 85/15, and to 80/20. Compression and tension set are performed on vulcanized rubber samples at ambient and elevated temperature (100 °C) with constant compression or elongation at 25% of initial value. All tests are carried out for 72 h. Air‐circulated oven is used to conduct testing at elevated temperature. Crosslink density before and after testing is also monitored by equilibrium swelling method. Tensile properties and hardness are also measured to support the discussion. The results show that compression and tension set at ambient temperature tend to increase upon the EVA concentration in the formulation. Set properties are independent of EVA concentration at elevated temperature. Incorporation of EVA decreases the rebound resilience property and thermal aging tends to increase it. The rebound resilience ranges from 31% to 40% for original samples, and from 33% to 43% for aged samples.

Electrical tree in silicone rubber: Roles of silicone grease and switching impulses

This study investigates the characteristics of electrical trees in silicone rubber (SiR) samples after soaking in silicone grease (SG) for various times and exposed to switching impulses. The results show that the tree initiation probability increases from 60 to 100 % after SG soaking for 340 h when the impulse amplitude is 38 kV and the tree fractal dimension increases from 1.16 to 1.45. A similar trend is observed under negative impulse. It is suggested that SG soaking leads to a higher tree initiation probability and a larger tree fractal dimension. In addition, isothermal surface potential decay measurements are employed to obtain the trap parameters of SiR samples. Equilibrium swelling procedures are used to test the crosslinking density. The energy level and density of deep trap both decrease with SG soaking time, which is beneficial for the transport of charge carriers injected from the needle tip and further results in more severe scission of SiR molecular chains. Moreover, the expansion of free volume originating from the broken physical crosslinking structure allows more violent impact ionization of charges to occur, which can also aggravate the scission of SiR molecular chains. Therefore, the decreased tree resistance can be found in SiR after SG soaking. Furthermore, the polarity effects can be observed during the tree initiation and propagation process, which are mainly rooted in the different distribution of hole­type and electron-type traps.

Evaluation of permanent deformation of asphalt rubber using multiple stress creep recovery tests and flow number tests

This study used the Multiple Stress Creep Recovery Test (MSCR) and the Flow number test to analyze the characteristics of asphalt rubber and its use in hot mix asphalt (HMA) regarding to their ability to withstand permanent deformation. MSCR tests were done in three commercial asphalt rubber and in the traditional asphalt binder 50/70. Flow number tests were performed in twenty four specimens of asphalt rubber mixtures and eight specimens of conventional asphalt mixtures. The results of these tests showed that all the asphalt rubber samples had lower compliance values (Jnr) in the MSCR test, which denotes that these modified binders improved the rutting resistance of HMA. This behavior was confirmed with flow number results, since the HMA produced with asphalt rubber had always higher flow number values, when compared to the conventional asphalt mixtures. The analysis of the data showed excellent correlation between Jnr values and FN values.

Investigation of the Climatic Stability of Sealing Rubbers Used in the Technology of the North

The present paper outlines the results of full-scale tests of climatic stability of rubbers based on BNKS-18 (butadiene-nitrile rubber) and Hydrin T6000 epichlorohydrin rubber containing low-volatile and non-toxic phenolic antioxidants. Samples are exposed in an open ground under natural conditions of exposure to climatic external factors of Yakutsk in the Republic of Sakha (Yakutia), as well as in deformed state (by 30%). Such indexes of the samples as conditional tensile strength, elongation at break are measured to determine the resistance of rubbers to aging after the first, third, sixth, ninth, twelfth and eighteenth months of exposing. The results of the study reveal the contribution of CO3 stabilizer in maintaining the stability of the physical and mechanical properties of BNKS-18: rubber containing CO3 has less property changes in the open air. Stafen stabilizer occurred more effective for the rubber based on Hydrin T6000: Over the entire period of full-scale exposure, rubber samples containing it demonstrated the smallest changes in the indicators of elastic-strength properties as compared to the industrial stabilizer 6РРD and other experimental stabilizers.

DC inline plane test of silicone rubber samples with different filler for high-voltage insulation

<span>This paper is about preparation of silicone rubber (SiR) samples with different filler for high-voltage insulation purpose. The fillers used were silica from waste glass, calcium carbonate from cockle shell, silica/calcium carbonate and wollastonite. All the fillers were crushed into powder and undergo internal mixer and hot press as a material preparation. It was expected that the combination of filler with silicone rubber would give better result when experiencing ageing process. The direct current (DC) inclined plane test was used to investigate the tracking and erosion on silicone rubber composites. The tracking length was observed between the top and bottom electrode. Comparison would then be made between the silicone rubbers with different fillers based on the result obtained from the experiment.</span>

Experimental study of spall strength of silicon rubber with microspheres under shock-wave action

In this work, porous media are studied using silicone rubber with glass microspheres as an example. There were investigated three types of silicon rubber samples featuring different concentrations and sizes of microspheres: non-porous silicon rubber, porous silicon rubber with calibrated glass microspheres and porous silicon rubber with glass microspheres having a wide range of sizes. The density of the samples was 0.99, 0.55 and 0.48 g/cm3, accordingly. Investigating spall strength under pulse tension shows that the destruction beginning threshold of the samples in question is quite low. For the non-porous sample, it is around 30 MPa, for the porous ones it is an order of magnitude lower. The spall plate does not come off the sample after the beginning of destruction. The ability of the free surface velocity to change in such a way is typical for materials with a low destruction threshold.

Application of Terahertz Spectroscopy to Rubber Products: Evaluation of Vulcanization and Silica Macro Dispersion

Industrial applications of terahertz (THz) technology are becoming more widespread. In particular, novel evaluation methods for essential rubber products are being developed. THz absorbance spectra of various rubber polymers and reagents enable visualization of filler dispersions and vulcanization reactions. Here, improved visualization of the vulcanization reaction in thick rubber samples is discussed. Silica macro-dispersion is also analyzed because it is a general filler in automobile tires and has been difficult to evaluate with conventional techniques.

An Innovative Procedure for the In-situ Characterization of Elastomeric Bearings by Using Nanoindentation Test

ABSTRACT Control and inspection of the conditions of elastomeric bearings used for seismic isolation purpose is a fundamental activity in ensuring and preserving the performance of a structure. The methods currently used, such as visual inspections, Operational Modal Analysis (OMA), release tests, very often present strong limitations due to their qualitative nature or else to the costs associated with their implementation and functioning. An innovative procedure based on the use of nanoindentation tests is proposed and validated through an experimental campaign. Its main benefits consist in the possibility of quantitatively estimating the current characteristics of elastomeric bearings, in conjunction with low implementation costs and influence on the isolating devices. The innovative procedure consists of coring a very small sample of rubber from a bearing and testing it with a nano-indenter in order to estimate the actual characteristics in terms of shear stress-strain relationships. The experimental tests showed good agreement between the properties calculated with the proposed method and the ones obtained directly through a traditional shear test, making such procedure a promising tool.

Effect of nanoclay on mechanical, thermal and morphological properties of silicone rubber and EPDM/silicone rubber hybrid composites

ABSTRACT The effect of nanoclay on tensile properties is studied by dispersing the different weight percentages (0 wt%, 2 wt%, 4 wt% and 6 wt%) of montmorillonite (MMT) clay in the silicone rubber and hybrid rubber (EPDM/silicone rubber) samples. The thermal properties are also studied by using different instruments such as dynamic mechanical analyser (DMA), differential scanning calorimetry (DSC) and thermogravimetric analyser (TGA). The glass transition temperature (Tg) values obtained from DMA are correlated with DSC, both the values match well. The thermal stability and change in mass of above mentioned materials as a function of temperature are measured using thermogravimetric analysis (TGA). Fourier transformed infrared spectroscopy (FTIR) is used to characterise the grafting of clay in the silicone and hybrid rubbers.

Electrical treeing and partial discharge characteristics of silicone rubber filled with nitride and oxide based nanofillers

This article presents a study on electrical treeing performances with its associated partial discharge (PD) and the influence of filler concentration in silicone rubber (SiR) samples which are filled with silicon dioxide (SiO2) and silicon nitride (Si3N4) as nanofillers for electrical tree growth suppression. There are many researches on electrical treeing in SiR with SiO2 nanofillers but none of the publication have reported on Si3N4 nanofillers for suppression of the electrical tree growth. In this study, the treeing experiments were conducted by applying a fixed AC voltage of 10 kV and 12 kV at power frequency of 50 Hz on unfilled SiR, SiR/SiO2, and SiR/Si3N4 nanocomposites with different filler concentrations by 1, 3, and 5 weight percentage (wt%) and the electrical treeing parameters were observed with its correlated PD patterns. The outcome from this study found that the SiR/Si3N4 nanocomposites were able to withstand the electrical treeing better than the pure SiR or SiR/SiO2 nanocomposites. Furthermore, the increase in filler concentration improved the electrical tree performances of the nanocomposites. This finding suggests the Si3N4 can be used as filler in polymeric insulating materials for electrical tree inhibition. Meanwhile, the PD activity shows increment when the tree progresses thereby indicating correlation in both parameters which can be as key parameter for monitoring unseen electrical treeing in the opaque samples.

Effect of Stabilizer States (Solid Vs Liquid) on Properties of Stabilized Natural Rubbers.

The main objective of this work is to study the effect of hydroxylamine sulfate or stabilizer states (solid vs liquid) on the storage hardening of natural rubber (NR). Several types of natural rubber samples were prepared: unstabilized NR samples and stabilized NR samples: (i) dry NR with 0.2 and 2.0 parts per hundred rubber (phr) of dry hydroxylamine sulfate, and (ii) natural latex with 0.2 and 2.0 phr of liquid hydroxylamine sulfate. The samples were characterized immediately (time 0) and after 12 weeks of storage at room temperature, respectively. We found that the Mooney viscosity, gel content, and Wallace plasticity of NR without a stabilizer increases with storage hardening for 12 weeks. However, two types of stabilized NR samples represent constant values of those three parameters, because hydroxylamine sulfate inhibits network and gel formation in NR. Interestingly, the mixing states (solid vs liquid) between natural rubber and the stabilizer affect the properties of stabilized NR. This could be explained by the better dispersion and homogeneous nature of liquid stabilizers in natural latex (liquid state), and thus the higher loading of the stabilizer in the liquid state. This is important, as the stabilization of NR properties as a function of time is required by rubber industry. This study is a utilization model from theory to application.

Numerical evaluation of complex permittivity of silicone rubber based on Jonscher's law

In this work, the two parts of complex permittivity in the frequency range 1–104 Hz were measured for sheet‐shaped samples of silicone rubber under various aging conditions. After that, fitting equations based on Jonscher's law were used to evaluate both the parts. As a result, it is clearly indicated that the fitting parameters in the equation of are linearly correlated with those in the equation of . This indicates that common information is contained in both and . A possible mechanism is also proposed to explain this phenomenon. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Influence of Nano Silica on the compressive strength and flexural behaviour of Bridge rubberised concrete

Based on the need of light weight concrete used in the bridge construction to reduce loadings on foundation and in the same time maintain enough strength to resist the stresses developed from the structure. Incorporation of recycled rubber from scrap tires in concrete as a partial replacement of course aggregate in production of new type of recycled aggregate lightweight concrete has provided many beneficial effects to both concrete and environments. Many properties of tire rubber concrete are improved compared with normal concrete. However, disadvantage such as reduction in rubber concrete strengths have limited the application of rubber concrete drastically. Therefore, this study presents a new method on producing rubber concrete with comparable compressive strength to Normal concrete strength (without rubber aggregate) by adding Nano silica as a partial replacement of binder (cement). The experimental program includes Four mixes, with one ratio of rubber (10 %,) as a partial replacement of course aggregate by weigh and, one of them is the reference rubberized concrete mix (without NS) and the other three is with three different ratios of Nano silica (0.5%, 1% and 1.5%) from the weight of cement. The experimental program also includes 36 samples were prepared and tested as 6 cubes for compression strength test, three of them in age of 7 days and the other three in age 28 days, and 3 prisms for flexural strength test. The data that obtained from the experimental program indicates that the compression and flexural strength properties of the rubber concrete increases nonlinearly with the increase of Nano silica ratio. The comparison between reference rubber concrete samples (without Nano silica) and other rubber concrete samples (with Nano silica), showed that the compression strength of rubber concrete in age of 7 days increases about (15%, 28% and 43%) for Nano silica (NS) ratio of (0.5%, 1% and 1.5%) respectively The increase in flexural strength was less but still obvious which is about(9%, 15% and 26%) for Nano silica (NS) ratio of (0.5%, 1% and 1.5%) respectively as well. The ultimate strength results of rubberized concrete with NS that obtained from the experimental work was with highest ratio of NS 1.5%.

The effect of non-rubber components on mechanical properties of TESPD silane coupling agent in silica-filled rubber compounds

Silica is reinforcing filler with high polarity, leading to the difficulty to get the homogenous mixing with a natural rubber (NR) compound, which normally becomes silica agglomeration. A silane coupling agent is applied in a silica-filled NR compound in order to enhance compatibility between silica and rubber. Moreover, non-rubber components, especially proteins, are believed to have competition with silane coupling agent during a silanization [1, 2]. In this work, the interaction between the silane coupling agent and silica-filled NR materials was investigated to show the components influencing in the filler-filler and filler-rubber interaction as well as mechanical properties. The rubber types with different non-rubber components such as fresh NR, deproteinized NR (DPNR) and polyisoprene rubber (IR), absence of non-rubber constituents were mixed with bis-triethoxysilylpropyl disulfide (TESPD) and silica by using an internal mixer at high temperature. Payne effect of the unvulcanised rubber samples were characterized to study silica dispersion, respectively. A swelling test was used to determined crosslink density in the rubber samples after a vulcanisation system. In addition, the effect of non-rubber components on mechanical properties of rubbers was investigated to find the relationship between the crosslink density and filler-rubber network.

Confirmation molecular structure of the Hevea rubber molecule and its effects in storage hardening

Lipids are the one of major non-rubber components discovered in natural rubber (NR) latex, which reported to be the significant parameter affecting the properties of NR [1, 2]. Our previous work suggested that lipids are the major factor dominate branching formation in NR [3], which could bring about the change in physical properties of NR during long term storage as called storage hardening (SH) phenomenon. However, lipids found in NR consist of neutral and polar lipids, i.e., phospholipids and glycolipids [3]. The information on types of lipids affecting the storage hardening behaviour in NR have not yet been investigated. Therefore, the aim of this work was to study the relationship between types of lipids on the gel formation in NR under accelerated storage. In the present work, natural rubber was treated by deproteinization, acetone extraction, chloroform:methanol extraction and transesterification for eliminating proteins, neutral lipids, polar lipids and linked lipids, respectively. The molecular structure of the rubber samples and the remaining non-rubber components were analyzed using nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Moreover, the rubber samples were subjected to study the storage hardening behaviour under accelerated condition using phosphorus pentoxide (P2O5).

Elastomer modification by means of ionizing radiation

One of the priorities for improving the performance characteristics of elastomer compositions is their physical modification, which allows to obtain materials with a new set of performance properties. Among the known methods of modifying products based on elastomers, one of the actual methods is radiation modification. It allows you to control the physico-mechanical and elastic-strength characteristics of products. In connection with the foregoing, the development of a technology for the radiation modification of elastomers with the aim of increasing their operational characteristics is relevant. In this work, the effect of ionizing radiation on the thermo-physical and operational properties of elastomeric compositions for the tread of career tires was investigated. It was established that the level of the maximum temperature developed in the samples depends on the degree of vulcanization of the elastomeric compositions. In samples of tread rubber, heat generation is reduced by 2–4 % after treatment with accelerated electrons. In the process of exposure to ionizing radiation, the formation of free radicals and their subsequent recombination occurs. Revealed an increase in crosslinking density in modified specimens. The correlation dependences between the thermophysical properties of elastomeric compositions and the intensity of heat generation in them are established. It was determined that the best thermo-physical properties of polymers with a degree of crosslinking t80. The wear resistance of the modified elastomeric compositions is increased up to 3.5 times.

Effect of Dielectric Parameters and Frequency on Temperature Field of Microwave Curing of rubber compound

This paper aims to predict the heating behavior of rubber samples based on finite element methods using comsol multiphysics software. The effects of frequency and dielectric parameters on the temperature distribution of the stratified and non-layered models were investigated. The dielectric parameters mainly affect the temperature of the temperature field, and the influence on the temperature field distribution is relatively small. The temperature state of the tire surface distributed by different frequencies is not exactly the same. When further studying the influence of frequency on temperature distribution, the combined frequency of 915+2450MHz is selected in the double-waveguide cavity model, and the temperature field distribution is optimal. The power selected at this time is 1000w+1000w. The average temperature of the layered model is higher than that of the non-layered model, and the temperature difference is larger. The research results can provide reference for the research of heating rubber composites in microwave heating systems.

The effect of hydroxylamine sulfate on the storage hardening of natural rubber

Natural rubber (NR) consists of rubber and non-rubber components, which is mostly cis-1, 4-polyisoprene. The main non-rubber components are proteins and phospholipids which are attached at each end of the NR chains. If we store NR for prolong period, the proteins and phospholipids promote formation of a NR network. This causes the gel formation with increasing the Mooney viscosity of NR, and this is called storage hardening. The objective of this work is to study the effect of hydroxylamine sulfate on the storage hardening of natural rubber. Three types of natural rubber sample were prepared: pure NR, NR with 0.2 phr of hydroxylamine sulfate, and NR with 2.0 phr of hydroxylamine sulfate. Samples were characterized immediately (time 0) and after 12 weeks of storage at room temperature. We found that gel content and Mooney viscosity of NR without hydroxylamine sulfate are increased with the storage hardening for 12 weeks. However, both NR samples with hydroxylamine sulfate represent constant viscosity values because hydroxylamine sulfate inhibits the network and gel formation in NR. This is important as the stabilization of NR properties in the function of time is required by rubber industry.