Porous Rubber Research Articles

Bayesian calibration of constitutive models for polymeric foams

Porous materials are traditionally used for their sound absorption and insulation properties. Over the past decade, more attention has been given to their elastic and damping properties. There is a particular interest in the automotive industry to replace heavy layers (consisting of constrained viscoelastic rubber layers) with felts or foams evidencing high damping capabilities. Hence, characterizing efficiently the viscoelastic properties of porous materials is crucial for quality control and further improvements in product development and fabrication. In this sense, the main contribution of this work is to propose a stochastic strategy to determine the constitutive equations describing the viscoelastic behaviour of foams. Vibration tests are carried out on a two-layer panel containing a free-layer of a foam. A finite element model is developed considering only the viscoelasticity of the porous skeleton, neglecting the influence of the fluid phase. A fractional derivative model is calibrated and validated for two types o foam based on a Bayesian framework. The models indicate that the reconstitute porous rubber presents absolute values of the complex modulus greater than the ones provided by the closed-cell polyurethane foam and its energy dissipation is greater the one provided by the closed-cell polyurethane one.

Durability Evaluation of Polyurethane-Bound Porous Rubber Pavement for Sustainable Urban Infrastructure

Permeable pavements are vital in sustainable urban water management, addressing critical challenges while enhancing environmental resilience. This study focuses on the innovative polyurethane-bound Porous Rubber Pavement (PRP), which possesses high permeability and elasticity due to its unique composition of stone and crumb rubber aggregates with polyurethane binders. PRP’s useful benefits, such as noise reduction, efficient snow/ice management, and others, enhance its appeal, emphasizing the necessity for a thorough investigation into its performance and characteristics, especially in North America. To address these gaps, this paper comprehensively analyzes PRP’s durability and performance, including its strength range, failure criteria, and susceptibility to moisture-induced damage. Various testing methods are utilized, such as evaluating the abrasion loss of the stone aggregate, rutting, stripping due to moisture susceptibility, resistance to degradation from impact and abrasion, and permeability tests. This study evaluates five distinct mix compositions with varied proportions of aggregates and binders. Further, it investigates the effects of different binder types on PRP performance, such as aromatic and aliphatic binders obtained from various sources. Upon the analysis of the comprehensive test results, it was found that the mix characterized by increased rubber aggregates and a high binder content demonstrated a superior performance across various tests for PRP applications. This mix exhibited an enhanced resistance to abrasion, raveling, rutting, and permanent deformation, showcasing its durability and functionality. Additionally, when combined with an aliphatic binder, it displayed an optimal performance even in challenging freeze–thaw conditions, making it a recommended choice for long-term pavement solutions.

An optical-based multipoint 3-axis pressure sensor with a flexible thin-film form.

Multipoint 3-axis tactile pressure sensing by a high-resolution and sensitive optical system provides rich information on surface pressure distribution and plays an important role in a variety of human interaction-related and robotics applications. However, the optical system usually has a bulky profile, which brings difficulties to sensor mounting and system integration. Here, we show a construction of thin-film and flexible multipoint 3-axis pressure sensor by optical methods. The sensor can detect the distribution of 3-axis pressure on an area of 3 centimeter by 4 centimeter, with a high-accuracy normal and tangential pressure sensing up to 360 and 100 kilopascal, respectively. A porous rubber is used as a 3-axis pressure-sensitive optical modulator to omit the thick and rigid focusing system without sacrificing the sensitivity. In addition, by integrating thin and flexible backlight and imager, the sensor has a total thickness of 1.5 milimeter, making it function properly even when bent to a radius of 18 milimeter.

Construction of a reduced graphene oxide/polyvinyl alcohol (PVA)-natural rubber (NR) porous rubber sponge toward solar-driven sustainable water purification

Solar-driven evaporation is an environmentally benign and sustainable technology to address the global water crisis. The abundant and renewable solar energy as its sole input energy, thus leading to zero-carbon emission and minimum environmental impact. Thus, in this work, a hydrophilic reduced graphene oxide (rGO)/polyvinyl alcohol (PVA)-natural rubber (NR) porous rubber sponge was obtained by emulsion ice template and vulcanizing at high temperature. The cross-linked NR rubber and the robust PVA endow rGO/PVA-NR sponge with excellent flexibility integrated outstanding mechanical robustness. The water evaporation rate of the resultant rGO/PVA-NR evaporator can reach up to 2.11 kg·m−2·h−1 under 3 sun illumination. Moreover, benefitting from the multi-scale porous structure and hydrophilicity of the rGO/PVA-NR sponge, water is continuously transported from the bulk water to the evaporation surface in whole evaporation process, ensuring a continuous water supply and salt self-cleaning. Moreover, the results of practical solar-driven interfacial evaporation under outdoor conditions indicated that rGO/PVA-NR evaporator has overall multifunctional purification for inorganic ions and wastewater contaminated with organic dyes. This investigation provides a convenient and environmentally friendly strategy toward developing high-performance solar steaming technologies based on rubber sponge for effective water purification to address the global water crisis.

Construction and Performance Evaluation of Polyurethane-Bound Porous Rubber Pavement (PRP) Trial Section in the Cold Climate

Porous pavements are designed and used in current construction practices to address environmental and safety issues related to wet weather. Porous rubber pavement (PRP) is a novel porous pavement material consisting of recycled crumb tire rubbers, stone aggregates, and polyurethane binders. The higher permeability (up to 45% of air voids) of PRP and its composition offers excellent benefits to the urban hydrological system and environment. Due to its recent outset in the Canadian climate, its properties and performance are not yet investigated. This research investigates PRP’s properties and performance as pavement material through the construction of two trial sections incorporating three newly developed PRP mixes along with a Control Mix. Samples were obtained from the field and tested in the laboratory to determine the mechanical and durability properties, including indirect tensile strength, moisture-induced damage due to freeze-thaw cycles and permanent deformation. A field evaluation was also performed three times: right after construction, three weeks later and after seven months to determine stiffness, frictional properties, roughness and permeability. The results revealed that all PRP mixes exhibited excellent permeability and retained more than 68% of tensile strength after five freeze-thaw cycles. Although PRP showed significantly lower initial elastic modulus than conventional pavement material, ranging between 28 MPa to 59 MPa, in the springtime none of them went below 23 MPa. Material composition, site geometry and subgrade conditions were found to be the main factors influencing the field performance of PRP pavement.

A generalized Ogden model for the compressibility of rubber-like solids.

The aim of this paper is to further demonstrate the advantages and effectiveness of the constitutive formulation proposed by Huang (Huang 2014 J. Appl. Mech. 59, 902-908 (doi:10.1115/1.2894059)). In this formulation, any strain-energy function for an incompressible material can be easily generalized to include the effect of material compressibility, in which only a few material parameters and material functions to be fitted with the experimental data are required. To this end, the Ogden model for incompressible rubber-like solids is chosen as the starting point. By means of this formulation, the generalized Ogden strain-energy function, which takes into account material compressibility, can conveniently be constructed so long as its incompressible counterpart is given. The obvious advantage shown in this paper is that only a few material parameters and material functions are needed, i.e. in addition to the material parameters used in the original Ogden model for incompressible solids, only one material function depending on the volume ratio is involved to characterize the effect of compressibility. Both the material parameters in the original Ogden model and the material function suggested in this paper can be determined by fitting the experimental data for uniaxially tensile test and hydrostatic deformation test of rubbers, respectively. The present model considering compressibility is general since it can be applied to predict the stress-strain responses of rubber-like materials and porous rubbers in various loading conditions. With the present formulation, the applicable range of the celebrated Ogden model can be further broadened, which should be of practical importance for accurately describing the mechanical behaviour of rubber-like solids. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

Development and Applications of a Pressurized Water-Filled Impedance Tube.

In this study, a pressurized, water-filled impedance tube (WFIT) was developed to measure the reflection coefficients of sound-absorbing materials under various hydrostatic pressures. The developed WFIT was calibrated using a two-microphone, three-parameter calibration method (3PCM). The accuracy and repeatability of the measured reflection coefficients for the water–air interface in the WFIT were determined by comparing these coefficients with corresponding theoretical reflection coefficients. The WFIT was then used to measure the acoustic reflection coefficient of a porous rubber specimen on three dates, and the corresponding measurement results exhibited satisfactory repeatability. The aforementioned impedance tube was also used to measure the reflection coefficient of a porous rubber specimen under a hydrostatic pressure of 4 Patm three times on the same day, and one time each on three days, using the same experimental setup and measurement procedure. The results obtained in the aforementioned tests also exhibited satisfactory repeatability. Finally, the WFIT was used to measure the reflection coefficients of porous rubber specimens with various thicknesses under different hydrostatic pressures. The results of this study indicate that the developed WFIT calibrated with the 3PCM can achieve suitable repeatability in the measurement of the reflection coefficients of sound-absorbing materials under various hydrostatic pressures.

Mn-embedded porous rubber seed shell biochar for enhanced removal of copper ions and catalytic efficacy of the used adsorbent for hydrogenation of furfural

Using some metals and their oxides modified biochar adsorbents to purify copper-containing wastewater is effective. However, the degraded reuse performance of waste adsorbents prevented their large-scale application. Thus, in this work, a MnOx-modified porous biochar was firstly obtained by KMnO4 activation of rubber seed shell wastes for Cu(II) ions removal, and then the waste adsorbent was skillfully constructed to Cu-Mn bimetallic catalyst for efficient selective hydrogenation of furfural, realizing the proper disposal of waste adsorbent. The adsorption experiments showed that the optimized Mn-modified biochar (i.e. Mn18%-rssBC) had a good purification capacity for the Cu(II)-containing wastewater with a wide pH range and high strong resistance to some common coexisting ions, and the maximum adsorption capacity of Cu(II) could be up to 200.59 mg/g. The characterization results showed that the oxygen-containing functional groups and a large number of MnOx particles on the surface of Mn18%-rssBC could form stable complexes with Cu(II), making it exhibit efficient and spontaneous multilayer adsorption behavior. In addition, after the reduction of the waste adsorbent, the Cu and Mn species on the surface were uniformly dispersed in the porous carbon in the form of electron-rich nano-polycrystalline aggregates at about 3.5 nm. Under the optimized conditions, the obtained catalyst (i.e., Cu14.3Mn16.5-rssBC) had high catalytic efficiency, which can achieve 100% of furfural conversion and 87.06% of furfuryl alcohol selectivity. In conclusion, this work provided a composite solution for the reuse of copper-containing waste adsorbent, the resource recovery of agricultural and forestry wastes and the efficient transformation of biomass platform compounds.

Study of porous rubber pipes reinforced with waste tire fiber and pineapple leaf fiber for smart irrigation system

Global trend in waste management involves sustainable development for waste utilization according to the concept of circular economy. Wastes from worn-out tires have been known as a world problem and not yet to be resolved successfully. In this work, wastes from worn-out tires, i.e., ground tire rubber (GTR), reclaimed rubber (RR) and waste tire fiber (WTF) were used to produce reinforced porous rubber pipes as irrigation system for smart farming. Comparative study of porous rubber pipes reinforced with natural fibers (pineapple leaf fiber, PALF) was also carried out. The experiment was divided into 2 parts, i.e., porous sheets (model study) and extruded porous pipes. Compound samples were prepared by mixing GTR, RR, and natural rubber (NR) at a ratio of 60:20:20 (by weight) with other additives by using an internal mixer, then shaped into samples by using a compression molding machine (sheets) and a single-screw extruder (pipes). Samples were vulcanized by a hot air oven. Factors affecting sample properties were studied, such as, fiber types (WTF and PALF) and fiber loadings (0-15 phr). Properties of the samples were characterized, such as, mechanical properties, morphology, water permeability rate, and %diameter swell. It was found that tensile strength was increased up to an optimum point. Modulus (at 10% strain, M10) and hardness were increased with increasing fiber loading. However, %elongation at break had a trend to decrease. Morphologies of the composites made from both fibers were insignificantly different in fiber distribution. By adding the fibers, %diameter swell was clearly improved. Pipe samples were also tested in precision smart agriculture system. It can be proven that WTF and PALF can be used to reinforce the porous pipes and used as a watering device for precision irrigation system.

Ultraviolet and Infrared Irradiations Sensing of Gel-Orange Dye Composite-Based Flexible Electrochemical Cells.

The flexible and shockproof rubber-based Al/OD-Gel/Cu electrochemical cell was designed, fabricated, and investigated for the detection of IR and UV irradiations. For this purpose, the transparent gel–orange dye composite was deposited on the porous rubber substrate between aluminum and copper electrodes. It was observed that the gel–orange dye composite was mechanically like a gel: soft and flexible. Electrically, this composite (gel–orange dye) forms a flexible electrolyte. It was found that the impedance of the samples under the effect of infrared irradiation decreased by 2.02 to 2.19 times on changing frequency from 100 Hz to 200 kHz. Accordingly, under the effect of ultraviolet irradiation, the impedance of the samples decreased by 1.23 to 1.45 times on increasing frequency from 100 Hz to 200 kHz. Under the effect of infrared irradiation up to 4000 W/m2, the cell’s open-circuit voltage increased by 1.59 times. The cell’s open-circuit voltage also increased by 1.06 times under the effect of ultraviolet irradiation up to 200 uW/cm2. The mechanism of the absorption of the infrared and ultraviolet irradiations by the OD–Gel composite has been discussed in detail. The fabricated flexible rubber substrate-based Al/OD-Gel/Cu electrochemical cells can be used as a prototype for the development of gel electronics-based devices.

Effect of Humidity and Temperature on the Impedances and Voltage of Al/Gr-Jelly/Cu-Rubber Composite-Based Flexible Electrochemical Sensors.

Here we present the fabrication of graphene and jelly (superabsorbent polymer) electrolyte composite-based shockproof flexible electrochemical sensors (Al/Gr-Jelly/Cu) and their properties under the effect of humidity and temperature. A layer of graphene mixed in jelly electrolyte was drop-casted onto porous rubber substrates between preliminary fixed aluminum (Al) and copper (Cu) electrodes followed by rubbing-in. It was observed that the graphene and jelly mixture was mechanically soft and flexible, similar to jelly. Electrically, this mixture (graphene and jelly) behaved as a flexible electrolyte. It was observed that under the effect of humidity ranging from 47 to 98%, the impedances of the sensors decreased by 2.0 times on average. Under the effect of temperatures ranging from 21 to 41 °C the impedances decreased by 2.4 times. The average temperature coefficient of impedances was equal to −0.03 °C−1. The electrochemical voltage generated by the flexible jelly electrolyte sensors was also investigated. It was found that the initial open-circuit voltages were equal to 201 mV and increased slightly, by 5–10% under the effect of humidity and temperature as well. The short-circuit currents under the effect of humidity and temperature increased by 2–3 times. The Al/Gr-Jelly/Cu electrochemical sensors may be used as prototypes for the development of the jelly electronic-based devices.

Mn-Embedded Porous Rubber Seed Shell Biochar for Enhanced Removal of Copper Ions and its Ingeniously Re-Functionalizing

Mn-Embedded Porous Rubber Seed Shell Biochar for Enhanced Removal of Copper Ions and its Ingeniously Re-Functionalizing

Discharge Characterization and Variability Determination along Shorter Sections of Soaker Hose Pipe for Soil Column Experiment

Unlike other micro-irrigation facilities like a drip, trickle, and sprinklers that emits water at regularly spaced intervals with predefined discharges, porous rubber pipes (soaker hose) has openings of variable sizes that become unevenly spaced with uneven distribution. The latter makes discharge to be variant along its lateral. Shorter sections are used under laboratory column experiments of soil wetting pattern studies and for this reason, laboratory experiments were conducted to evaluate the extent of emission rates variability on short sections of commercial Irrigation Soaker Hose, 16 mm diameter. Three sections of 10 cm length pipes were randomly selected from 15 no's cuts from different parts of the twenty meters length pipe bundle and used to investigate the extent of variability on emission rates characteristics under six different operating pressures. The result was achieved by collecting and measuring water emitted through the pipe sections at pre-determined pressures. The various discharges, coefficient of variation, and pressure-discharge curves of the section of the pipe then determined from the data. The result shows somewhat similar trends on the increase for water collected with an increase in pressures; however, when statistically compared, the discharges among the pipe sections vary. The values of Coefficient of Variation (CV) are less than 10 % as the values CV range from 0.92 % to 5.82 %, which is within a good category, according to ASAE Standard EP405.1 of 0-10%. The findings indicate that, despite variations among the investigated sections, it can use any part as a representative unit in the soil column experiments with reasonable accuracy.

Research on Dynamic Cumulative Damage Effect of Metal Rubber and Stress Wave Propagation Characteristics of Layered Composite Structure

The development of protective materials and structures is of great significance for improving the impact resistance, penetration resistance and spalling resistance of military equipment. At present, the layered composite structure has been widely used due to its good protective performance. In this paper, a special elastic porous material-metal rubber (MR) with excellent cushioning and damping properties was used to prepare high-performance layered composite structures. To begin with, the dynamic mechanical response and the dynamic cumulative damage effect of MR were studied through Split-Hopkinson Pressure Bar (SHPB) tests. Then, the failure form and stress wave propagation characteristics of the layered composite structures were investigated through SHPB tests and finite element method. The results show that repeated impacts can enhance the compactness of MR, thereby increasing the ultimate bearing capacity and energy absorption capacity, which is beneficial for MR to resist repeated impacts. The MR in composite structures can reduce ceramic damage, attenuate stress wave and smooth stress distribution. The titanium alloy on the back of the ceramic will aggravate the damage of the ceramic, and ultra-high molecular weight polyethylene on the back of the ceramic provides cushioning for the ceramic. Therefore, the impact resistance of the composite structure can be improved by adding MR and the reasonable arrangement of materials, and the SiC/UHMWPE/MR/TC4 composite structure has relatively reasonable stress distribution and better protection performance.

The Effect of Vulcanization Accelerator on the Properties of Porous Rubber

This work is devoted to identifying the patterns of influence of the vulcanization accelerator N-cyclohexyl-benzothiazyl-sulfenamide (CBS) on the technological, physico-mechanical, and thermo-physical properties of vulcanizates based on styrene-butadiene rubber. It was found that a decrease in the content of the vulcanization accelerator decreases the maximum torque, and a noticeably longer time is required for optimum vulcanization in the absence of CBS. The thermal conductivity in vulcanizates increases with a decrease in the accelerator concentration due to changes in the structure and molecular mobility of kinetic units. Physico-mechanical indicators increase with a decrease in the concentration of CBS, this is due to a decrease in the apparent density of porous rubbers

ВИКОРИСТАННЯ ГОТОВИХ УЩІЛЬНЮВАЧІВ ШВІВ В ЦЕМЕНТОБЕТОННИХ ПОКРИТТЯХ АВТОМОБІЛЬНИХ ДОРІГ І АЕРОДРОМІВ

Increased requirements for reliability, performance and durability of pavement caused by the increase in vehicle carrying capacity and traffic on the roads. As the domestic and world experience shows, the increasing requirements of the movement are best matched by cement concrete pavements. Stable transport transport performance, high durability give them advantages over pavements built using organic binders. During construction and reconstruction, longitudinal and transverse joints for various purposes are arranged in cement concrete pavements of roads and airfields to prevent deformation and destruction of coating pavements (cracking, chipping of corners and edges of slabs, peeling of the concrete surface layer, the appearance of potholes and sinks, vertical displacement of slabs and their warpage destruction of butt joints and joint fillers). The destruction of pavements, as a rule, takes place in cases where the stresses and deformations arising in the plates exceed the permissible values, as well as in case of failure of the sealing of joints and cracks. Restoring the sealing of expansion joints and cracks are important stages of work to extend the operational life of pavements. A large role on the efficiency of the sealant in the joints and its service life is provided by the deformability of the sealing materials. When choosing a type of sealant, the possible maximum negative and positive air temperatures of the region where the pavements are used are taken into account. Currently, unique sealing materials using polymer compositions have been created. These materials have high technical and operational characteristics and a guaranteed service life of at least 5 years. The sealing or filling of transverse and longitudinal joints in cement concrete pavements is an important factor in ensuring long-term performance of the coating. The experience of using different types of joint sealing materials shows that their proper installation can provide important protective equipment that improves the performance of joints and pavements. In recent years, in foreign practice, the technology of pressing elastic whole or porous rubber profiles into the seam is very often used for sealing joints. In this case, it is possible to carry out work even in wet weather and at low temperatures. Special machines have been developed for the installation of profiles. The article discusses the sealing of transverse and longitudinal seams of cement concrete pavements of roads and airfields with sealing materials, including ready-made seals, the need to use them and study the effect of sealing materials on the design of joints and operational performance of cement concrete coatings in general.

Enhancement of Diversity in Production and Applications Utilizing Electrolytically Polymerized Rubber Sensors with MCF: The Second Report on Various Engineering Applications.

We investigated the proposed hybrid skin (H-Skin) for the requirement of haptic sensibility in rubber using our proposed consummate fabrication process together with a multi-layered magnetic compound fluid (MCF) rubber and stocking-like porous rubber permeated by liquids, which was demonstrated in our previous report. The objective was to assess its applicability to sensing normal force and temperature, as well as fields dominated by shear force. For normal force, we investigated the piezo-electricity and electric current induced voltage, as well as the piezo-resistivity of the MCF rubber sensor under pressure. Additionally, we clarified the viability of measuring the softness and texture of materials using the MCF rubber sensor. For the shear motion, we clarified the characteristics of the friction coefficient using the MCF rubber sensor. The MCF rubber sensor can capture the reactions of paper, cloth, convex- and concave-shaped objects such as plant leaves and metal, and the skin of the human finger. Therefore, it is useful to investigate its texture and biological surfaces. Our obtained outstanding results indicated the feasibility of sensing the surface texture for any material in fields such as paper, fashion, apparel manufacturing, and cosmetic industries, which was impossible until now.

The effect of stabilizers on the properties of porous rubbers

This work is devoted to identifying the patterns of influence of the Lubstab series stabilizers manufactured by LLC NPF Khiminvest on the technological, physicomechanical and thermophysical properties of porous rubbers based on styrene-butadiene rubber with the addition of azodicarbonamide as a porophore. It was found that the addition of the Lubstab 05 stabilizer allowed us to obtain vulcanizates with higher porosity as compared to other samples. A 7% decrease in apparent density as compared to the standard was achieved.

Fabrication of rubber gel as oil absorbent by using water as porosity agent for oil removal

ABSTRACTOil pollution is a crucial issue that has adversed impact not only on the environment but also human beings. As an alternative to all conventional approaches, a porous rubber gel based on liquid natural rubber (LNR) with excellent hydrophobic and wettability properties has been developed using a simple vulcanization reaction. To determine their sorption capability, LNR gel was employed for absorption of various types of oils such as Petrol A, Petrol B, kerosene, diesel, crude oil, and olive oil. The functionality of LNR gel was characterized by Fourier transform infrared spectroscopy and the morphology of LNR gel was observed using a scanning electron microscope. By combining wettability and hydrophobicity, the LNR gel exhibited high oil sorption capacity and selectivity for oil removal from water. The LNR gel was able to absorb oils, especially the low viscosity types. Besides, it can also be reused up to 20 cycles while maintaining its oil sorption performance. The selective absorbent shows the recovery of petrol in the range of 96–99% by squeezing the oil. Thus, LNR gel has great potential as green material for cleaning up oil contaminants on a large scale. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47749.

Clarification of Edge Effect on the Friction Properties of Porous Rubber for Studless Tire

Clarification of Edge Effect on the Friction Properties of Porous Rubber for Studless Tire