Properties Of Rubber Research Articles

Characterization and mechanism of natural rubber composites reinforced by modified calcium sulfate whisker

AbstractThis study concentrated on the mechanical properties of natural rubber (NR) composites [modified calcium sulfate whisker (MCSW)] and the reinforcement mechanism of MCSW on NR. First, anhydrous CSW with an orthogonal crystal system bottom center structure was prepared by hydrothermal method. Subsequently, MCSW was obtained by treating whiskers with inorganic, organic compounds, which effectively coated the surface of the whiskers with an average thickness of 40.85 nm, making the surface change from hydrophilic to hydrophobic. The CSW/MCSW filler was added to the NR under the optimum experimental conditions of 70°C, 12 min, 5 times of rolling, 140°C, and 1 h of curing time. The results showed that the tensile strength, elongation at break, and crosslink density of the NR composites with 15 phr of MCSW added were increased by 80.8%, 9.0%, and 80.2%, respectively, compared with the NR without the filler. The mechanism of MCSW improving the performance of composites was revealed from vulcanization kinetics and interfacial thermodynamics. In this work, a new type of high‐efficiency environmental protection NR filler reinforcing agent was developed.

Construction of a novel halogen-free and phosphorus-free and synergistic flame retardant system with low addition in simultaneously improving the flame retardancy, water resistance and mechanical properties for silicone rubber

To solve the bottleneck problems of flame-retarding silicone rubber (SR), a halogen-free, phosphorus-free and synergistic flame retardant system was prepared by introducing hydrophobic natural product (Gum Arabic, GA) intercalated layered double hydroxide (H-GA@LDH) and multi-walled carbon nanotubes (MWCNT). Prominently, when the total amount of flame retardant is only 7 phr, SR/H-GA@LDH6.0/MWCNT1.0 can reach the limiting oxygen index (LOI) value of 29.4% and UL-94 V-0 rating with the flame retardant index of 2.06. And the LOI value of SR/H-GA@LDH6.0/MWCNT1.0 is decreased by only 1.3% compared with that of SR by 6.9% after water resistance tests. In addition, the peak heat release rate (pHRR) and total heat release rate (THR) of SR composites are decreased by 22.14% and 12.43%. Compared with pure SR, the tensile strength and elongation at break of SR-8 are increased by 115.63% and 23.85%. In this condition, an excellent balance for simultaneously improving flame retardancy, water resistance and mechanical properties has been achieved. Therefore, this paper has provided an effective strategy with halogen-free and phosphorus-free materials for achieving the goal of flame-retarding SR with high performance and breaking the limitation of traditional contaminative and toxic phosphorus-based or halogen-based flame retardants.

The effect of temperature and vulcanisation time on the thermal and mechanical properties of rubber used in tires

ABSTRACT The thermal and mechanical properties of rubber used in tires were measured experimentally. The effect of temperature on the thermal properties and the effect of vulcanisation time on the mechanical properties are analyzed. The specific heat capacity and thermal conductivity both increase with increasing temperature, and the specific heat capacity and thermal conductivity are approximated as linear functions of temperature. The tensile strength, elongation at break and abrasion properties of vulcanizate are significantly affected by the vulcanisation time. As the vulcanisation time increases, the tensile strength first increases and then decreases, and the elongation at break changes with the vulcanisation time on the contrary. The wear volume of tread rubber first decreases and then increases with the increase of vulcanisation time. At the positive vulcanisation time, the tensile strength of the vulcanizate reached the maximum value, while the elongation at break and wear volume reached the minimum value.

Influence of Rubber Powder Movement on Properties of Asphalt Rubber from the Mesoscopic View

Influence of Rubber Powder Movement on Properties of Asphalt Rubber from the Mesoscopic View

Effect of Blowing Agents on Properties of Cellular rubber of Natural rubber / Chloroprene blends

Cellular or sponge rubber can be by expansion of fluid state by gas produced from decomposition of foaming agents [1]. It can be manufactured from various types of rubber and chemicals depending on properties required [2]. Natural rubber can give excellent mechanical properties except for thermal ageing [3]. The objectives of this work were to improve thermal ageing of NR foam by incorporating chloroprene rubber, CR, into NR and foaming NR/CR blends. In order to study the effects of the type of chemical blowing agents on the properties of cellular NR/CR rubber blends, azodicarbonamide (ADC) and oxybisbenzenesulfonyl hydrazide (OBSH) were used as blowing agents and compared. The cure characteristic, mechanical, morphological, and flammability properties of the foams were investigated. The results indicated an increasing chloroprene rubber loading caused the increase in cure time, but decreased in cure rate index. In both cases of foaming agents, the cellular rubbers were found that tensile and tear strength were decreased with CR rubber loading, but the secant modulus and hardness were increased. Compression set was decreased with CR rubber loading. It is also showed that the flammability of NR/CR foam with high CR contents (more than 80%) was better than that with low CR contents. It is also found that using OBSH as foaming agent can produce cellular rubber containing better cell density and cell size distribution than ADC.

Impact of Raw Phenyl Silicone Rubber Parameters on ethod Vulcanized Phenyl Silicone Rubber

Based on the structure of raw phenyl silicone rubber and performance of vulcanized rubber, the properties of raw and vulcanized phenyl silicone rubber are tested in this study. The relationship between raw rubber parameters and the influence of raw rubber properties on the performance of vulcanized rubber are also analyzed. Conclusions are as follows: (1) The viscosity average molecular weight of the raw silicone rubber measured by Ubbelohde viscometer and gel permeation chromatography (GPC) mdiffers relatively greatly, with the result of Ubbelohde viscometer higher than that of GPC. (2) The glass transition temperature of raw silicone rubber is significantly affected by the molar content of phenyl chain (phenyl content) in its structure. In a good linear relationship with phenyl content, it increases as the phenyl content increases. (3) The static glass transition temperature of raw rubber measured by differential scanning calorimetry (DSC) is 0-15 °C lower than the dynamic glass transition temperature measured by dynamic thermo-mechanical analyzer (DMA). (4) Mooney viscosity increases with the increase of the viscosity average molecular weight of raw rubber. (5) As phenyl content rises from 20 % to 40 %, the damping peak loss factor of vulcanized rubber increases from 0.4 to 0.7 and the damping peak temperature increases from -90 °C to -40 °C. (6) As the molar content of vinyl chain (vinyl content) is raised from 0.1 % to 0.6 %, the hardness of vulcanized rubber is boosted from 45 to 65, and the tensile strength decreases from 12 MPa to 6 MPa. (7) With the increase of vinyl content from 0.1 % to 0.4 %, the tear strength of vulcanized rubber decreases from 45 kN/m to 25 kN/m. (8) The vinyl content has an obvious impact on the damping performance of vulcanized rubber at high temperatures. When vinyl content increases from 0.1 % to 0.5 %, the damping property of the vulcanized rubber under high temperature drops from 0.25 to 0.1. (9) The compression set of vulcanized rubber decreases with the increase of vinyl content of raw rubber.

Hydroxyl Boron Nitrid e/Natural Rubber Composites with Enhanced Mechanical and Thermal Conduction Properties: Implications for Heat Dissipative Tires or Conveyor Belts

For its significant technological interest, a systematic investigation on mechanical and thermal conduction properties of natural rubber reinforced by functionalized hexagonal boron nitride nanosheets is highly desirable. We herein first demonstrate a unique synthesis of hydroxyl-functionalized boron nitride nanosheets (OH-BNNSs) via a simple one-pot reduction reaction. This involves negative charging by treating BNNSs with lithium in liquid ammonia and subsequent bubbling of oxygen into dispersion of BNNS salts. Subsequently, a series of functionalized boron nitride nanosheets/natural rubber (NR) composites were fabricated by latex mixing and co-coagulation. Co-coagulating a stable aqueous suspension of OH-BNNSs with natural rubber latex afforded a weblike morphology consisting of platelet networks between the latex particles. Compared to pure rubber, the tensile strength and storage modulus at 25 °C for OH-BNNSs/NR (5 wt %) are increased by 466% and 1 order of magnitude, respectively. Benefiting from the unique structure, the composite at 5 wt % shows a 40% improvement in thermal conductivity relative to pure rubber. This latex-based method provides a facile and effective strategy to design and fabricate advanced functional BNNS-based polymeric nanocomposites with a segregated filler network morphology and considerable property enhancements in direct competition with graphene sheets. The composites could be potentially used in heat dissipative tires or conveyor belts.

Beyond Diels-Alder: Domino reactions in furan-maleimide click networks

The furan-maleimide Diels-Alder chemistry has emerged as an important tool to design thermo-reversible click networks. This not only preserves the strong and robust properties of thermo-sets and rubbers, but also makes it possible to cleave crosslinks at non-degradative temperatures, or in other words to recycle them. In this work a new reaction is reported in furan-maleimide click networks, which is the Double-Diels-Alder reaction (DDA), also known as domino Diels-Alder. This forms extra linkages between Diels-Alder adducts and non-reacted furan groups and evidently leads to stronger materials, but also prevents efficient thermal (re)cycling. This work shows with nuclear magnetic resonance (NMR) characterization, differential scanning calorimetry (DSC) and rheology that the DDA reaction can occur both in intramolecular and intermolecular fashion, but also that it exhibits reversibility just like the regular Diels-Alder reaction. This reaction can be easily overlooked creating what at first sight might be inexplicable reactivity when analyzing the properties of furan-maleimide click networks.

The Effect of Various Fillers on the Properties of Methyl Vinyl Silicone Rubber.

Silicone rubber (SIR) has been widely used in electrical insulation fields, and the introduction of new materials is very important for the performance improvement of SIR composites. In this work, four different fillers, including aluminium hydroxide (ATH), yimonite (YMT), boron nitride (BN) and mica-filled SIR composites were prepared, and the vulcanization behavior, mechanical properties, insulation performance and hydrophobicity of the SIR composites were investigated and compared. Both BN- and mica-filled SIR composites showed excellent insulation performance, while the ATH-filled SIR composite exhibited the best mechanical properties with an elongation at break of 230% and a tensile strength of 2.9 MPa. The SIR/BN composite showed a breakdown strength of 29.2 kV/mm with a 5% failure rate. The addition of YMT deteriorated the insulation performance of SIR but improved the elongation at break and hydrophobicity, with an elongation at break increasing from 115% to 410% and the static contact angle improving from 109.8° to 115.6°.

Experimental and numerical studies of the mechanical properties of nitrile-butadiene rubber exposed to gamma radiation

In this study, the effects of gamma radiation on the mechanical properties of nitrile-butadiene rubber (NBR) samples are examined employing experimental tensile and hardness tests. The NBR is exposed to different doses of gamma radiation (0, 30, 45, 60, 75 and 90 kGy) at room temperature. The obtained results indicate an improvement in the elastic behavior of NBR specimens and a diminution of their plastic behavior with the increase in the absorbed dose. The morphology properties of pristine and irradiated NBR were evaluated by scanning electron microscopy (SEM). A numerical simulation is performed by using five hyperelastic models included in Abaqus: Mooney Rivlin model, Ogden model, Yeoh model, Arruda-Boyce model and Neo-Hookean model. The input data utilized in the conducted simulation are taken from experimental tensile results. The validation of the five hyperelastic models shows that they are stable in tension for both virgin and irradiated samples. The stress-strain curves of both virgin and gamma-irradiated NBR rubber samples are presented and the coefficients of the hyperelastic strain energy function are calculated for all models. The comparison of the simulated results with the experimental measurements demonstrates that the Ogden model provides the best fitting curvature of the stress-strain curves for virgin and irradiated samples. It gives the lowest mean square error. The latter decreases with the rise of the absorbed gamma dose and it is in all cases less than 0.51%. Thus, this model is appropriately applied to better simulate the mechanical behavior of the unirradiated and irradiated NBR. Experimental and numerical results are promising for predicting the behavior of NBR rubber exposed to gamma radiation.

The effects of physical aging on the quasi-static and dynamic viscoelastic properties of Nitrile Butadiene Rubber

The effects of physical aging on the quasi-static and dynamic viscoelastic properties of Nitrile Butadiene Rubber

Differing unsaturation levels of soybean oils impact the properties of peroxide‐vulcanized carbon black‐filled ethylene‐propylene‐diene monomer rubber

AbstractSoybean oils having less unsaturation than conventional soybean oil (SBO) were studied as sustainable plasticizers for ethylene‐propylene‐diene monomer (EPDM) rubber compounds vulcanized with peroxide. In EPDM formulations, part of the petroleum‐based paraffinic oil (PO) was replaced with soy‐derived plasticizers such as high oleic soybean oil (HOSO), partially hydrogenated soybean oil (PHSO), and completely hydrogenated soybean oil (HSO). The mechanical and viscoelastic properties of EPDM rubbers formulated with soy‐derived plasticizers were studied and compared with the properties of PO‐based rubber. Torque rheometry was used to study the vulcanization process and the properties of the vulcanized rubber compounds were evaluated using tensile testing, compression testing, dynamic mechanical analysis, and solvent swelling experiments. The equilibrium swelling test and examination of gel fraction demonstrated the incorporation of soy‐based process aids into the rubber network during vulcanization. It was found that soy‐derived plasticizers could partially substitute for the petroleum‐based plasticizer in EPDM compounds with minimal impact on properties. An additional benefit of the use of hydrogenated SBO is the increase of crosslink density in vulcanized rubber indicating enhanced peroxide efficiency.

Perspective of Use of Rubber Linings in Drum Ball Mills

When developing the designs of rubber linings for drum mills, the authors were guided by the principle of the main priority - creating conditions for improving the technological performance of grinding, along with increasing the service life, using the unique property of rubber - elasticity. Theoretical studies, the results of laboratory tests, confirming the rationale for the design and acceptable operating conditions, as well as the technological indicators obtained as a result of industrial tests for each created design, are presented.

The Properties of Sodium-Hypochlorite-Activated Crumb Rubber and the Influence of Aging on the Rheological Properties of Activated Asphalt Rubber

Asphalt rubber shows good road performance. However, the compatibility and aging problems of asphalt rubber limit its application. The improvement of the solubility of crumb rubber in asphalt was investigated in this research, and the mechanism of its aging effect on the rheological properties of activated asphalt rubber was studied. First, the crumb rubber was activated by using a sodium hypochlorite (NaClO) solution, and the pore characteristics and microstructure of the activated crumb rubber were analyzed. Second, the influence of the crumb rubber’s activation characteristics on the rheological properties of the asphalt rubber before and after aging was analyzed. Finally, the aging mechanism of the activated asphalt rubber was revealed at a microscopic level. The results showed that with the increase in the activation degree, the pore characteristics of the crumb rubber decreased first and then increased. The surface stacking structure of the crumb rubber increased, and a dense gel film gradually formed. The asphalt rubber prepared by the activated crumb rubber had better rheological properties and had a more significant effect under higher stress conditions. This may have been due to the activation of the crumb-rubber surface, forming oxygen-containing functional groups, which, in turn, increased the combination of the crumb rubber and the asphalt. In addition, the activation degree and aging effect of crumb rubber can reduce the large-particle-size molecule (LMS) content of activated asphalt rubber. There is a significant correlation between LMS content and rheological properties, and LMS content can be used to predict the rheological properties of asphalt rubber.

Texture design of microgrooves to improve the tribological properties of wiper blades

Improving the tribological properties of windscreen wipers to achieve high visibility and low wiping noise is crucial for safe and comfort driving on rainy days. This study systematically investigated the effects of microgrooves on the tribological properties of rubber, similar to that used in wiper blades, sliding against glass in the presence of water. It was found that grooves with an orientation angle of 0° were highly beneficial for the wiping process of rubber blades. At low velocities, the grooves reduced the frictional resistance and restrained the propagation of Schallamach waves; however, at high velocities, frictional resistance existed, restraining forced wetting. These findings have significant implications for the development of high-performance windscreen wipers.

Modification of Tyre Rubber Crumb with Wastes of Plant Oil Production

Recovery of fat-and-oil production wastes will reduce the technogenic impact on the environment, as well as involve them in a new production cycle as a secondary material resource. As part of solving this problem, the possibilities of using fat-and-oil production wastes in the production of a tyre reclaim and a modified tyre reclaim are considered. In the course of the studies, the fat-and-oil industry wastes’ sorption characteristics are determined, and in relation to oils in static and dynamic conditions, the spent reagent reclamation ways are determined. The authors obtained a tyre reclaim and a modified tyre reclaim using the fat-and-oil industry wastes (soap stock, diatomite, bleaching clay, and fatty acids isolated from soap stock). In this work, the authors studied the possibility of using the fat-and-oil industry wastes in the formulations of a tyre reclaim and a modified tyre reclaim. Extended physical and mechanical tests of experimental rubbers led to the conclusion that it is most expedient to use the fat-and-oil industry wastes in the formulation of rubber compounds for production of sleeper pads for railroad tracks, since when using a tyre reclaim and a modified tyre reclaim, the indicators of rubber properties practically do not change and comply with control standards.

Effect of Waterborne Polyurethane on Rheological Properties of Styrene-Butadiene Rubber Emulsified Asphalt

To explore the effect of waterborne polyurethane (WPU) on the performance of styrene-butadiene rubber (SBR) emulsified asphalt and broaden the application range of polymer-modified emulsified asphalt, WPU-SBR-modified emulsified asphalt with 0%, 3%, 6%, 9%, and 12% WPU was prepared. The penetration, softening point, ductility, and storage stability tests were used to explore the effect of different contents of WPU on composite-modified emulsified asphalt. Meanwhile, the rheological properties of five modified emulsified asphalts were analyzed by temperature scanning test, multiple stress creep recovery test, and low-temperature bending creep test. The results show that the addition of WPU improved the performance of SBR emulsified asphalt, and the improvement effect varied with the addition amount. With the increase of WPU content, the penetration and unrecoverable creep compliance Jnr of WPU-SBR-modified emulsified asphalt gradually decreased, and the softening point, rutting factor G*/sinδ, and creep recovery rate R gradually increased, indicating that the high-temperature stability of modified emulsified asphalt was enhanced, and when the WPU content was 9%, the best improvement effect was obtained. However, excessive content of WPU will deteriorate the low-temperature performance of WPU-SBR-modified emulsified asphalt, and thus the content of WPU should be appropriately selected in practical engineering applications.

Behaviour of geopolymer concrete at elevated temperature- a comprehensive review

In comparison to conventional materials made of concrete, geopolymer materials are sustainable, durable and strong. Geopolymer used should not only be sustainable but also fire-resistant for the necessary amount of time. The properties of geopolymer materials after high-temperature exposure, such as weight loss, thermal expansion, thermal conductivity, mechanical properties, and microstructure are reviewed and discussed in detail in the current study. In addition, the behaviour of Geopolymer concrete (GPC) at high temperatures with different recycled fibre additions as well as additions of crumb rubber is also examined in this article. The use of recycled fibres made from industrial wastes offers additional advantages, including resource conservation, waste reduction, lower costs of processing than normal fibres, and the removal of waste disposal in landfills. The latter offers a sustainable method for recycling tyres and helps slow down the depletion of natural aggregates. From the literature, it is revealed that at 800–1000 °C, compared to the OPC concrete specimens, the GPC samples had less cracking damage and also substantial spalling was seen in the OPC samples, but not in the GPC samples. GPC with recycled fibres has higher crack-resistant characteristics at elevated temperatures. Meanwhile, in a study at 800 °C, rubberized geopolymer showed more cracks compared to control GPC. This work also provides comprehensive reviews on the type of recycled fibres and rubber aggregates, spalling mechanisms, physical inspection and properties of rubberized geopolymer and recycled fibre-reinforced GPC. It also demonstrated the influence of elevated temperature on the characteristics of recycled fibre-reinforced GPC and rubberized geopolymer after high-temperature exposure.

Influence of Polymeric Microspheres on Rubber Properties for Coating Metal Surfaces

Influence of Polymeric Microspheres on Rubber Properties for Coating Metal Surfaces

Effects of Vinyl Functionalized Silica Particles on Thermal and Mechanical Properties of Liquid Silicone Rubber Nanocomposites

It is very important to develop a new method of preparing high-performance liquid silicone rubber-reinforcing filler. Herein, the hydrophilic surface of silica (SiO2) particles was modified by a vinyl silazane coupling agent to prepare a new type of hydrophobic reinforcing filler. The structures and properties of modified SiO2 particles were confirmed using Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS), specific surface area and particle size distribution and thermogravimetric analysis (TGA), the results of which demonstrated that the aggregation of hydrophobic particles is greatly reduced. Additionally, the effects of the vinyl-modified SiO2 particle (f-SiO2) content on the dispersibility, rheology, and thermal and mechanical properties of liquid silicone rubber (SR) composites were studied for application toward high-performance SR matrix. The results showed that the f-SiO2/SR composites possessed low viscosity and higher thermal stability, conductivity, and mechanical strength than of SiO2/SR composites. We believe that this study will provide ideas for the preparation of high-performance liquid silicone rubber with low viscosity.