Properties Of Rubber Research Articles

Effect of alkaline protease content on the structure and properties of natural rubber

AbstractThe solidification technology of natural rubber exerts a significant impact on the properties of natural rubber. The solidification technology of alkaline protease has been highly valued by researchers at home and abroad because of its good solidification effect, excellent vulcanization performance, and low pollution. In this study, the effects of alkaline protease solidification technology and enzyme dosage on the structure and properties of natural rubber were investigated and compared with those of formic acid solidification technology. The solid‐state NMR results showed that increasing the enzyme dosage increased the molecular chain entanglements in the raw rubber. The gel content test results showed that the natural network structures (i.e. gels) increased after the addition of alkaline protease. The test results of the vulcanization characteristics showed that the addition of alkaline protease significantly shortened the positive vulcanization time. The Mw was the largest at an enzyme dosage of 0.07%. The test results for mechanical properties showed that the mechanical properties were best when the enzyme dosage was 0.07%. In addition, as the alkaline protease dosage increased, the Akron abrasion volume of natural rubber decreased, and the Akron abrasion volume was the lowest at an enzyme dosage of 0.07%.

Preparation, characterisation and enhanced fungistatic properties of silicone rubber with different concentrations of CMIT/MIT

Preparation, characterisation and enhanced fungistatic properties of silicone rubber with different concentrations of CMIT/MIT

Effect of Complex Well Conditions on the Swelling and Tribological Properties of High-Acrylonitrile Stator Rubber in Screw Pumps.

The effects of complex well conditions in shale oil wells on the swelling and tribological properties of high-acrylonitrile stator rubber used in screw pumps were investigated in this study. Tests were conducted considering the combined effects of immersion medium, temperature, and duration. The key parameters measured included mass change rate, volume change rate, hardness, elongation at break, tensile strength, surface micro-morphology of the rubber after thermal expansion and swelling, friction coefficient, and wear quantity. The results indicated that in the actual well fluids, the mass change rate of high-acrylonitrile rubber ranged from -1.08% to 1.29%, with a maximum volume change rate of 2.78%. In diesel oil, the greatest mass change rate of the rubber was 4.68%, and the volume change rate did not exceed ±1%, indicating superior swelling resistance. In both actual well fluids and diesel oil, the maximum decreases in hardness were 8.7% and 9.5%, respectively. Tensile strength and elongation at break decreased with increasing immersion temperature, with elongation at break in 80 °C diesel oil decreasing by over 50%, indicating a significant decline in the tensile properties of the rubber. The average friction coefficient of rubber specimens immersed in actual well fluids at three temperatures, as well as in diesel oil at 25 and 50 °C, decreased compared with the high-acrylonitrile rubber without thermal expansion and swelling. However, the average friction coefficient of rubber specimens immersed in diesel oil at 80 °C increased. The wear quantity of the rubber increased following immersion in both media. Additionally, the friction coefficient and wear quantity of the rubber increased with increasing immersion temperatures. The results of the study can offer valuable insights into assessing the durability of properties in high-acrylonitrile stator rubber under complex well conditions.

Impact properties of an end of life tires’ rubber. Numerical validation considering large strain and strain rate conditions

The objective of the authors is to demonstrate that the inclusion of renewed rubber from recycled end of life tires (ELT) can improve the performance of any structural system designed to dissipate impact energy. An interesting application would be its use in road safety barriers. This research starts with the rigorous characterization of the recycled material in order to include it in a viable numerical model. The authors presented, in a previous work (*), the experimental viscoelastic properties of recycled rubber, obtained under impact conditions. Bergström–Boyce (BB) nonlinear viscoelastic model was selected as the most suitable to fit the material behavior. This model is defined by nine material constants that are impossible to obtain, uniquely and directly, considering that only compression test results are available as input data. To overcome this challenge, optimization methods were applied resulting in as many sets of parameters as used optimization methods were considered and, moreover, remarkable differences between constants were observed. Solving this problem is the motivation of the present research: the validation of the optimization method by mean of the numerical evaluation of the obtained sets. The software considered for the numerical evaluation of impact tests (LS-DYNA®) had two slightly different implementations for the BB model: the original, based on the work published in 2009 by Dal & Kaliske and a more recent one implemented by Bergström, based on his works published in 1998 and 2000. This leads to a new question: which is the most appropriate implementation-optimization method for calibrating this material? This paper provides the answer to this question carrying out a complete comparative numerical analysis of all sets by means of explicit dynamics simulations. All calibrations, using the original LS-DYNA® implementation, were in perfect agreement with the experimental results. However, only one optimization method produced acceptable results for the most recent approach. A robust method to characterize recycled rubber from recycled tires using the Bergström–Boyce nonlinear viscoelastic model is presented, despite the experimental limitations (González-Vega et al. 2022).

Influence of preparation parameters on rheological properties and relation analysis of waste rubber modified bitumen mastic

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

Effect of hybrid filler comprising cryptocrystalline graphite and multi‐wall carbon nanotubes on the mechanical and conductive properties of styrene butadiene rubber

AbstractStyrene butadiene rubber (SBR) composites reinforced by cryptocrystalline graphite (CG) and multi‐wall carbon nanotubes (MWCNTs) were prepared. The SBR composite with 50 phr CG content displays superior mechanical reinforcement achieving 20.7 MPa in tensile strength. However, the electrical conductivity enhancement is modest. After incorporating MWCNTs as a secondary filler, the electrical conductivity significantly improved. The results show that the electrical conductivity of the SBR composite reinforced with 10 phr of CG and an additional 5 phr of MWCNTs surpasses that achieved by using 50 phr of CG solely. This enhancement can be attributed to the inherent excellent electric conductivity and high aspect ratio of MWCNTs, with their presence also preventing the re‐agglomeration of CG. Furthermore, within 10–40 phr content of CG, the mechanical reinforcement of CG‐SBR composites is enhanced with the addition of MWCNTs, whereas a minor decline in tensile strength is noted when the concentration of CG above 40 phr. Overall, the SBR composite reinforced with a synergistic combination of CG and MWCNTs is achieved, demonstrating both exceptional mechanical and conductive properties.Highlights Styrene butadiene rubber (SBR) composites with different cryptocrystalline graphite (CG) phr and additional multi‐wall carbon nanotubes (MWCNTs) were characterized. CG‐SBR displays good mechanical property but limited electrical conductivity. Proper ratio of CG/MWCNTs significantly enhances various properties. MWCNTs act as a “bridge” structure connecting isolated CG filler in SBR matrix. MWCNTs network effectively prevents the re‐agglomeration of CG nanosheets.

Effect of acoustic filler on sound insulation properties of millable polyurethane rubber

Effect of acoustic filler on sound insulation properties of millable polyurethane rubber

Rubber devulcanization in the planetary extruder – processing properties and structure

Thermo-mechanical devulcanization of ground tire rubber (GTR) in a planetary extruder was investigated. The processing parameters of recycled rubber were studied based on standardized protocols using a Mooney viscometer and a rubber processing analyzer (RPA). Fourier transform infrared spectroscopy and scanning electron microscopy were used to determine rubber structure. Devulcanization process upscaling limits processing properties of recycled rubber, which for partially devulcanized rubber can be determined only by RPA rheometer.

Preparation of Hydrophobic Modified Silica with Si69 and Its Reinforcing Mechanical Properties in Natural Rubber.

The inherent large number of hydroxyl groups of silica poses strong hydrophilicity, resulting in poor dispersibility in the natural rubber matrix. Here, the silica's surface was hydrophobically modified with [3-(triethoxysiliconyl) propyl] tetrasulfide (Si69) to improve the dispersibility and reinforce the mechanical properties of silica/natural rubber composites. The structure and morphology of modified silica were characterized by Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray electron spectroscopy (XPS), nuclear magnetic resonance spectroscopy and the contact angle. Further, the mechanical properties, dynamic mechanical properties and morphology of silica/natural rubber composites were studied with a universal electronic tension machine, dynamic thermal mechanical properties analyzer (DMA) and scanning electron microscope (SEM). The experimental results show that the Si69 was successfully grafted onto the surface of silica, thereby significantly improving the water contact angle (a 158.6% increase) and enhancing the mechanical properties of modified silica/natural rubber composites.

Utilization of agro waste activated carbons as carbon black replacement in electron beam irradiated styrene butadiene rubber composites

Purpose This study aims to prepare activated carbon (AC) and activated biochar (BC) from sugarcane bagasse (SCB) can be used as carbon black (CB) replacement for styrene butadiene rubber (SBR) composites cured by electron beam (EB) radiation. Design/methodology/approach This study is carried out to investigate the effect of partial replacement of CB (as traditional filler) by AC or BC prepared from low-cost agricultural wastes (SCB) to improve the properties of SBR rubber cured by EB radiation (doses from 25 to 150 kGy). Findings The results indicated that the addition of AC or BC leads to improve the physical and mechanical properties of SBR with increasing irradiation dose [especially at concentration of 10 parts per hundred part of rubber (phr) from BC]. Also in this study, this paper examines how exposure of SBR rubber composites to ultraviolet (UV) radiation changes the mechanical properties for these composites, to do that, the specimens were examined before and after they were exposed to UV radiation for 300 h. The results showed that, the irradiated SBR composites, UV exposure, exhibit better retention in mechanical properties as compared with unirradiated ones, and the samples loaded with CB hybrid with ACs had an increased value of tensile strength (TS) retention as compared with blank sample. Originality/value The importance of this study is that, the production of AC from SCB offers a huge opportunity to overcome the problem of the disposal of SCB.

Effect of recycled agricultural waste on fume emission and physicochemical properties of crumb rubber modified asphalt

Crumb rubber modified asphalt (CRMA) in the application process often produces lots of toxic fumes, and the composition is dominated by total volatile organic compounds (TVOCs) and H2S, which restricts its large-scale use in practical engineering. Therefore, three preferred agricultural wastes namely wood chip powder (WCP), peanut shell flour (PSF) and moxa stick ash (MSA) were added to CRMA to investigate their inhibition effect on CRMA fume in this work, and their inhibition mechanism on CRMA fume emission was discussed. Meanwhile, the influence effect of added agricultural waste on the physicochemical properties of CRMA was further analyzed and the modification mechanism was also explored. The experimental results indicate that the incorporated WCP, PSF and MSA can all inhibit the emission of TVOCs and H2S in CRMA to varying degrees. Compared with CRMA, the TVOCs concentrations of CRMA-WCP, CRMA-PSF and CRMA-MSA are reduced by 36.87 %, 11.72 % and 46.22 % under 190°C, respectively, while the H2S concentrations can be reduced by 53.45 %, 5.03 % and 62.67 %, respectively. The three agricultural wastes contain different mesoporous structures and their inhibition of CRMA fume is dominated by physical adsorption. Moreover, the added WCP, PSF and MSA can also synergize with crumb rubber to strengthen the rutting resistance of asphalt and upgrade the elastic recovery capacity of asphalt under different loads, and the enhancement effect is in the order of WCP > PSF > MSA. In summary, the three agricultural wastes preferred in this research are effective in suppressing the emission of toxic fumes from CRMA while improving its working performance, which can provide a new avenue for fume suppression in CRMA and multi-channel utilization of agricultural waste.

Synergistic Effect of Aluminum Nitride and Carbon Nanotube-Reinforced Silicon Rubber Nanocomposites.

Constructing a synergistic effect with different structural fillers is an important strategy for improving the comprehensive properties of polymeric composites. To improve the comprehensive properties of two-component additive liquid silicon rubber (SR) materials used in electronics packaging, the synergistic effect of granular aluminum nitride (AlN) and tubular carbon nanotube (CNT)-reinforced SR nanocomposites was investigated. AlN/CNT/SR composites with different AlN/CNT ratios were fabricated with two-component additive liquid SR via the thermal curing technique, and the influence of AlN/CNT hybrid fillers on the hardness, strength, elongation at break, surface resistivity, thermal conductivity, and thermal decomposition was investigated in detail. With the incorporation of AlN/CNT hybrid fillers, the comprehensive properties of the obtained AlN/CNT/SR composites are better than those of the AlN/SR and CNT/SR composites. The synergistic thermal conductive mechanism of AlN/CNT hybrid fillers was proposed and demonstrated with the fractural surface morphology of the obtained composites. The obtained AlN/CNT/SR composites show promising applications in electronic packaging, where necessary mechanical strength, electrical insulating, thermal conductivity, and thermal stable materials are needed.

Effect of Inorganic Fillers on Electrical and Mechanical Properties of Ceramizable Silicone Rubber.

Ceramizable silicone rubber (CSR) composed of silicone rubber matrix and inorganic fillers can be transformed into a dense flame-retardant ceramic upon encountering high temperatures or flames. Conventionally, CSR can be sintered into a dense ceramic at temperatures above 1000 °C, which is higher than the melting point of a copper conductor used in a power cable. In this study, the vulcanization process and mass ratio of inorganic fillers of CSR were studied to lower its ceramization temperature to 950 °C. The electrical and mechanical properties of CSRs and their ceramic bulks were studied with various ratios of wollastonite and muscovite. It was found that the CSR samples could be successfully fabricated using a two-step vulcanization technique (at 120 °C and 150 °C, respectively). As a high ratio of muscovite filler was introduced into the CSR, the sample presented a high dc electrical resistivity of 6.713 × 1014 Ω·cm, and a low dielectric constant of 4.3 and dielectric loss of 0.025 at 50 Hz. After the thermal sintering (at 950 °C for 1 h) of the CSR sample with a high ratio of muscovite, the ceramic sample exhibits a dense microstructure without any pores. The ceramic also demonstrates excellent insulating properties, with a volume resistivity of 8.69 × 1011 Ω·cm, and a low dielectric loss of 0.01 at 50 Hz. Meanwhile, the three-point bending strength of the ceramic sample reaches a value of 110.03 MPa. This study provides a potential route to fabricate CSR used for fire-resistant cables.

Mechanical and adhesive properties of RTV silicone rubber blended with silicone polyurethane modified epoxy resin

To enhance mechanical, adhesive, and thermal properties of Room Temperature Vulcanized (RTV) silicone rubber, a silicon-containing polyurethane/epoxy resin modifier (ESiPU) was developed. A three-phase system of polyurethane/epoxy resin/silicone rubber was prepared through blending, modification, and co-curing. FT-IR and 1H-NMR were employed to characterize the chemical structure of ESiPU. Microscopic analysis revealed improved compatibility between modified epoxy resin and silicone rubber. Mechanical testing showed significant enhancements in tensile strength, elongation at break, and adhesive strength, with RTV-20phr exhibiting increases of 236, 266, and 259%, respectively. Thermogravimetric analysis indicated higher initial decomposition temperature compared to pure RTV. At the same time, the char residue at 800 °C increased to 8.67%. TG-IR analysis demonstrated ESiPU’s ability to delay thermal degradation. Contact angle test confirmed improved hydrophobicity. Overall, the developed silicone rubber system exhibits promising mechanical and thermal properties, suggesting potential for aerospace heat protection applications.

Effect of cerium cysteine on the vulcanisation property and thermo-oxidative ageing of natural rubber

Effect of cerium cysteine on the vulcanisation property and thermo-oxidative ageing of natural rubber

Properties and Mechanism of Friction‐Reducing Silicone Rubber Modified with Hyperbranched Polysiloxane

AbstractDuring the utilization of silicone rubber, excessive friction can cause damage to the contact surface and the material itself. Therefore, friction‐reducing modification of silicone rubber has attracted much attention. In this paper, hyperbranched polysiloxanes with different structures is synthesized for friction‐reducing modification of silicone rubber. Infrared spectroscopy, nuclear magnetic resonance spectroscopy, and amine titration tests reveal that hyperbranched polysiloxanes are successfully synthesized by the hydrolytic condensation of 3‐aminopropyltriethoxysilane and their Michael addition with four acrylates with different alkyl chains. The friction coefficients and mechanical properties of silicone rubber are evaluated. Hyperbranched polysiloxanes significantly reduces friction and maintained excellent mechanical properties of silicone rubber. Silicone rubber with butyl‐ester‐secondary‐amino hyperbranched polysiloxane displays the best overall performance, with static and dynamic friction coefficients decreasing by 33.99% and 43.16% compared with that of pure silicone rubber, respectively, and a tensile strength of 10.80 MPa. The friction‐reducing mechanism of hyperbranched polysiloxanes on silicone rubber is investigated by contact angle test and dynamic mechanical analysis. Hyperbranched polysiloxanes migrates to the surface due to the incompatibility of alkyl chains with silicone rubber matrix. Consequently, the shielding effect produced by hyperbranched polysiloxanes on the surface depresses the adsorption activity of silicone rubber surface thereby reducing friction.

Effect of Compound Curing System on Properties of NBR/CM Blends

Abstract The effects of conventional vulcanization (CV), semi-efficient vulcanization (SEV), efficient vulcanization (EV), and equilibrium cure (EC) on the properties of nitrile rubber (NBR)/ chlorinated polyethylene (CM) blends were studied. The results showed that the SEV system had a faster vulcanization rate, larger torque, and larger vulcanization temperature coefficient, and the EC system had reversion resistance and a longer vulcanizing period. The modulus of the SEV system, the tensile strength of the CV system, and the elongation at the break of the EC system were high. The SEV system had good seawater and oil resistance; SEV > EV > CV >EC appeared in G’ and G”. The tanδ of the SEV system was larger than that of the EC system, but the tanδ of CV and EV system was close.

Research on damage behavior of silicone rubber under dynamic impact

Viscoelastic rubber materials are widely used in various vibration reduction structures of military and construction machinery. The complex driving and working conditions make the mechanical structure suffer severe impact, which leading to the damage or lose efficacy of the important viscoelastic elements. In order to reveal the dynamic mechanical properties of silicone rubber after impact, the Uniaxial compression tests of silicone rubber under different high strain rates were carried out with the separated Hopkinson pressure bar (SHPB) dynamic impact experiment, and the original Zhu-Wang-Tang (ZWT) constitutive model was modified by combining logarithmic law and power function law. The dynamic impact simulation model of silicone rubber was established using the modified ZWT-rate-dependent constitutive model, and the dynamic impact damage behavior of silicone rubber was studied under the condition of high strain rate, and the microscopic damage analysis was carried out on the experimental silicone rubber samples by scanning electron microscopy (SEM). The results show that the silicone rubber has obvious strain rate effect and strong deformation resistance at high strain rate. The modified ZWT-rate-dependent constitutive model can be used to obtain the constitutive expression of unified parameters, which can better describe the dynamic mechanical properties of silicone rubber at high strain rates. After dynamic impact compression, a damage line zone appears in the silicone rubber sample. There is a certain rule between the position of the line zone and the loading strain rate and the friction coefficient of the end face, and the silicone rubber is significantly affected by the friction effect of the end face.

Advancement of an Environmentally Friendly and Innovative Sustainable Rubber Wrap Film with Superior Sealing Properties.

Common kitchen wraps like plastic and aluminum foil create significant environmental burdens. Plastic wrap, typically made from non-renewable fossil fuels, often ends up in landfills for centuries, breaking down into harmful microplastics. Aluminum foil, while effective, requires a large amount of energy to produce, and recycling it at home can be impractical due to food residue. A promising new alternative, low-nitrosamine rubber wrap film, aims to reduce waste by offering a reusable option compared to traditional single-use plastic wrap. The film is environmentally friendly, durable, and effective in sealing containers and keeping food fresh or crispy. The raw materials used to make the product were studied, namely fresh and concentrated natural rubber latex. No nitrosamines were found in either the fresh or concentrated latex, which is important as nitrosamines are known to be carcinogenic. The absence of nitrosamines in the raw materials suggests that the universal rubber wrap film is safe for use. In this study, the rubber formulation and properties of rubber used to make rubber wrap film were studied. The content of additives affecting the rubber properties was varied to find the optimum rubber formulation for making rubber wrap films. The rubber formulation with the least amount of chemicals that met the following criteria was selected: tensile strength of at least 15 MPa, elongation at break of at least 600%, and nitrosamine content below 6 ppm. It was found experimentally that the optimum rubber formulation for making a translucent rubber film had 0.7 phr zinc oxide and 1.0 phr sulfur. Performance tests revealed the rubber wrap film's superior sealing capabilities. Its elasticity allows for a tighter fit on containers, effectively conforming to various shapes and creating an optimal seal compared to plastic wrap and aluminum foil. The results of this study provide valuable information for developing a universal rubber wrap film that is safe with low nitrosamines.

Time-varying compressive properties and constitutive model of EPDM rubber materials for tunnel gasketed joint

The stress relaxation of ethylene propylene diene monomer (EPDM) rubber material in a compressed state significantly increases the risk of water leakage at tunnel precast segmental joints. Additionally, EPDM rubber gaskets typically experience a complex precompression strain state, further complicating the prediction of long-term stress relaxation. Therefore, it is imperative to propose a novel constitutive model that realistically reflects the stress relaxation of rubber with arbitrary precompression strain, providing a reference for the long-term waterproof design of shield tunnels. In this study, the time-varying properties of EPDM rubber at material level were studied in detail. At first, a comprehensive set of accelerated aging tests were conducted on EPDM rubber samples with varying precompression strains. The hardening effect of rubber without precompression and the stress relaxation effect of rubber with precompression were explored. The time-varying law and mechanism governing rubber properties under these two effects were analyzed. Subsequently, a conversion relationship between the EPDM rubber test conditions and the actual service time was established. The predicted hardening coefficient for uncompressed EPDM after 100 years is 1.468, whereas the relaxation coefficient for compressed EPDM is 0.359. Comparative analysis revealed that the compression set index do not consider the beneficial effects of hardening, resulting in a 54.1% overestimation of the design water pressure. Finally, the analytical study on the constitutive model of EPDM rubber material was carried out. The error in compression curve for unaged sample obtained from empirical formulas exceeded three times that of the analytical model, underscoring the need to study time-varying constitutive models. An interpolation method was employed to extend the test curve, leading to the development of a new constitutive model that represents the stress relaxation characteristics of EPDM materials under arbitrary precompression strain states. By combining the proposed constitutive model with the timetemperature conversion relationship, the time-varying expressions of the constitutive parameters for relaxation and hardening effects during the service life were derived. In comparison with existing models, the proposed model demonstrates wider applicability, effectively captures the time-varying characteristics of EPDM materials under arbitrary precompression strains, offering an efficient approach for studying the long-term stress relaxation prediction of rubber gaskets in shield tunnels under complex precompression strain states.