Sponge Rubber Research Articles

Self-Derived Superhydrophobic and Multifunctional Polymer Sponge Composite with Excellent Joule Heating and Photothermal Performance for Strain/Pressure Sensors.

Flexible strain or pressure sensors have potential applications in electronic skin, healthcare, etc. It remains a challenge to explore multifunctional strain or pressure sensors that possess excellent water repellent and heating performance and hence can be used in harsh environments such as high moisture and low-temperature conditions. Here, a self-derived superhydrophobic and multifunctional polymer composite foam is prepared by adsorption of the Ag precursor in tetrahydrofuran (THF) onto the rubber sponge followed by reduction of Ag+ to Ag nanoparticles (AgNPs). During the Ag+ reduction in hydrazine solution, the swollen rubber sponge by THF is partially precipitated based on the nonsolvent-induced phase separation (NIPS). The NIPS creates a porous structure on the sponge surface and thus a high surface roughness, contributing to the material superhydrophobicity. The precipitated polymer wrapping the AgNPs could enhance the interaction between the individual AgNPs. The obtained conductive sponge composite possesses excellent Joule heating and photothermal performance and can be used as both a strain and pressure sensor. The conductive sponge composite sensor possesses good reliability and durability and can be applied to real-time monitoring of human body movements.

Environment-friendly paper-based flexible pressure sensors with carbon nanotubes and liquid metal

We have proposed and fabricated resistive-type flexible pressure sensors composed of multi-walled carbon nanotube thin films, liquid metal droplets, sponge rubber, and paper. The pressure sensor detects external pressure in the range of tens of kilopascals. The resistance change was found to be approximately 70% when a pressure of 100 kPa was applied. The sensor operation showed good reproducibility under cyclic applied pressure. The simple sensor structure and environment-friendly materials allow the sensor to be easily disassembled into its components, which are reusable and combustible.

Nonlinear vibration of knitted spacer fabric under harmonic excitation

Knitted spacer fabrics can be an alternative material to typical rubber sponges and polyurethane foams for the protection of the human body from vibration exposure, such as automotive seat cushions and anti-vibration gloves. To provide a theoretical basis for the understanding of the nonlinear vibration behavior of the mass-spacer fabric system under harmonic excitation, experimental, analytical and numerical methods are used. Different from a linear mass-spring-damper vibration model, this study builds a phenomenological model with the asymmetric elastic force and the fractional derivative damping force to describe the periodic solution of the mass-spacer fabric system under harmonic excitation. Mathematical expression of the harmonic amplitude versus frequency response curve (FRC) is obtained using the harmonic balance method (HBM) to solve the equation of motion of the system. Parameter values in the model are estimated by performing curve fit between the modeled FRC and the experimental data of acceleration transmissibility. Theoretical analysis concerning the influence of varying excitation level on the FRCs is carried out, showing that nonlinear softening resonance turns into nonlinear hardening resonance with the increase of excitation level, due to the quadratic stiffness term and the cubic stiffness term in the model, respectively. The quadratic stiffness term also results in biased vibration response and causes an even order harmonic distortion. Besides, the increase of excitation level also results in elevated peak transmissibility at resonance.

Damping effects of different shock absorbing materials for tunnel under seismic loadings

Circular tunnels are widely used in infrastructure. Under the action of earthquakes, the destruction of circular tunnels will result in a large number of economic losses and casualties. Therefore, the study on shock absorption of tunnels is important. However, the research has not been sufficient on the effect of the damping layer on seismic response of a circular tunnel in sand. In this paper, the influence of the damping layer on the seismic response characteristics of circular tunnels in sand is studied by large-scale shaking table test. The actual El-centro wave is loaded to the model system in three directions during the tests. The input peak seismic acceleration values are 0.05 g, 0.1 g and 0.2 g. Then the effects of two different damping materials on the dynamic response characteristics of circular tunnels are analysed quantitatively. The test results show that the damping layer reduces the seismic response of the circular tunnel. The response accelerations of the tunnel bottom and crown without damping layer are greater than that with the damping layer, which indicates that damping layer absorbs the energy caused by the seismic motion. When the sponge rubber is used, the circular tunnel dynamic response is more attenuated than that with foam board. In conclusion, the shock absorbing layer can effectively reduce the seismic response of tunnel. As a result, the damage of the tunnel decreases under the earthquake. This study has clarified the isolation mechanism of the shock absorbing materials. It is recommended to use sponge rubber material as the shock absorbing layer.

Manufacturing process and properties of lead-free natural rubber sponge for use in X-ray and gamma ray shielding applications

In this work, light-weighted, flexible, and lead-free X-ray/gamma-ray shielding natural rubber (NR) sponges were developed with the help of a blowing agent, namely Oxybis (benzene sulfonyl) hydrazide (OBSH) (its contents varied from 0, 8 to 16 parts per hundred parts of rubber; phr), and an X-ray/gamma protective filler, namely bismuth oxide (Bi2O3) (its content varied from 0, 100, 300, to 500 phr) in natural rubber (NR) composites. The results suggested that the densities and overall mechanical properties decreased with increasing contents of OBSH, while the increases in B2O3 resulted in the increases in tensile strength and hardness (Shore A), however, initially increases tensile strength and elongation at break but later decreases at 300 and 500 phr. In terms of radiation shielding properties, it was found that the ability to attenuate X-rays and gamma rays improved with increasing Bi2O3 contents. Hence, the overall properties investigated in this work suggested that the developed NR sponges could be used to attenuate X-rays and gamma rays efficiently with additional properties of being light-weighted and highly flexible, which are crucial for safety of radiation-related personnel and users.

Metode Montessori Berbantu Alat Peraga Matematika Berbahan Limbah Karet Spons untuk Mengembangkan Partisipasi Aktif Siswa SD

The purpose of this study is to determine the implementation of Montessori learning methods based on mathematical props made from sponge rubber waste in developing active participation of fifth grade elementary school students. This study uses descriptive qualitative research methods using instruments in form of observation sheets, interview sheets, questionnaire sheets, and documentation. The collected data is analyzed by triangulation. The results showed that Montessori learning based on mathematics teaching aids made from sponge rubber waste can develop active participation of fifth grade students. Active participation of fifth grade students looks better when teachers apply Montessori learning method. This can be seen from the increase in the average value of students' active participation at each meeting. At the first meeting the average value of active student participation was 66.67, the second meeting was 73.91 and the third meeting was 81.52. This study recommends implement the learning methods needed with interesting tools, so that it can increase students’ active participation.

Studying the effect of silica (SiO2) addition on the adhesive properties of polyvinyl alcohol

The work concerned with studying the effect of (SiO2) addition as afiller on the adhesive properties of (PVA). Samples were prepared assheets by using casting method. The mechanical properties showedthat increase in tensile strength from (34MPa) to (68MPa) when(SiO2) added to (PVA). The adhesive strength showed that jointproperties depend upon specific adhesive characteristic of material(PVA) and (SiO2\PVA)composites at different concentrations (1.5%,2.5%, 3.5%, 4.5wt%), the cohesive strength of the adhesive material,the joint design, and adherent type (Sponge Rubber(SR), Naturalleather (NL), Vulcanized Rubber(VR), and Cartoon). The resultsproved the tensile strength increased with (SiO2) ratio, so it can beused as the adhesive material. Shear strength showed an increasewith (SiO2) ratio of sponge rubber, and cartoon adherent, whereas itwas increased up to 2.5% for Natural Leather, and VulcanizedRubber then decreased; That suggested it is most suitable for spongerubber adhesive and cartoon than the other adherents.

Zinc diethyldithiocarbamateに感作された患者に生じた, 化粧用スポンジパフによるアレルギー性接触皮膚炎の１例:～被験物質を湿らせてパッチテストをすることの有用性～

Zinc diethyldithiocarbamateに感作された患者に生じた, 化粧用スポンジパフによるアレルギー性接触皮膚炎の１例:～被験物質を湿らせてパッチテストをすることの有用性～

Judging types of a bent rubber sponge due to insertion task by a two-claw robot hand equipped with a tactile and force sensor system

Judging types of a bent rubber sponge due to insertion task by a two-claw robot hand equipped with a tactile and force sensor system

Study on the Deformation and Stress Analysis of the Sponge/Rubber Adapter

The analysis of adaptors’ deformation and stress is an important prerequisite for the design of the adapters. This paper proposed the mathematical description and analytical method for the sponge cylinder and rubber cylinder under pressure. The analytical formulas on deformation and stress of interference fit between adapters and launchers are deduced. Also, the correctness of the analytical formula is verified by numerical simulation. Furthermore, the effect of precompression and the sponge’s thickness ratio on adapter’s deformation and stress is studied. The following results can be concluded: the results of numerical simulation are basically consistent with that of analytical formula. After installing the adapter into the launcher, the rubber layer will move inward as a whole, then the sponge layer and the rubber layer are subjected to radial and tangential compressive stress. When the precompression is smaller than 0.0075 or larger than 0.0015, the deformation and stress of adapter are approximately in proportion to precompression. If the precompression keeps constant, the deformation and stress of adapter will have extremum when the thickness ratio of sponge equals to a certain value.

Volume-of-Fluid Model for Simulating Vapor–Liquid Phase Change in a Solar Still

In this paper, a volume-of-fluid model is developed to simulate the vapor–liquid phase change in a modified solar still equipped with a porous layer in its basin. The results of the numerical simulation are compared with those of the moist-air model as well as available experimental data to benchmark the accuracy of this model. It was found that the volume-of-fluid model better matches the experimental data than the moist-air model. Finally, the role of a porous layer in improving the rates of evaporation and condensation in a solar still is examined by comparing the results to those of a conventional solar still. There is approximately 39% increase in the productivity when a sponge rubber porous layer with porosity of 0.4 is used in the basin of the solar still.

Development of a dustproof and waterproof snake robot covering the whole body with a sponge rubber tube

Development of a dustproof and waterproof snake robot covering the whole body with a sponge rubber tube

Enhancement of solar still by reticular porous media: Experimental investigation with exergy and economic analysis

In this paper, an experimental study with the exergy analysis are performed to investigate the application of a reticular porous insert in a single slope solar still for performance improvement. Two single slope solar stills containing conventional and modified by inserting a reticular porous layer are fabricated and experimented together. Two stills have the same dimensions. The porous insert was made up by black sponge rubber. All tests were taken in Semnan with geographical coordinates of 35°33′N, 53°23′E, Iran. Hourly water and glass temperatures, productivity, and efficiency of two stills are measured and evaluated experimentally. Moreover, the exergy efficiencies of the solar stills are obtained and presented. Finally, a cost analysis is performed to investigate the modified still economically. It was concluded that the daily total water productions for one day of the experiment are 3263 and 3829 cc/m2 for the conventional and modified stills, respectively. Accordingly, the modified still produces about 17.35% more distilled water in comparison to the conventional one during one day. Finally, the costs per liter per square meter for the modified and conventional stills are 0.0095 and 0.0108 $/L/m2, respectively.

Thermal Insulator Made from Solid Natural Rubber: Part 1 - Formulation of Rubber Compounding, Appropriate Forming Condition and Basic Properties

Closed cell rubber sponge applied as thermal insulator made from solid natural rubber (NR) was prepared by using Supercell DPT as a blowing agent. Rubber chemicals and STR 20, solid NR, were mixed on a two roll mill prior to prepare the specimen by hot press machine. Curing behaviors of the compounded solid NR with various types of sulfur and peroxide vulcanizations were characterized with moving die rheometer (MDR) at 150 and 170°C. Tensile and compressive strengths of the rubber insulator were measured by universal tensile testing machine followed by ASTM D412 and ASTM D395, respectively. Bubble size of the blown up rubber was inspected by an average maximum length of the bubble by using optical microscope. It should be notice from the experimental that all rubber formula both of sulfur and peroxide systems showed loading percentages to completely expand in a mold by about 38 to 48. Rubber insulator blown up with Supercell DPT used by semi-efficient vulcanization (semi-E.V.) unconcealed predominant results among all curing systems so that further investigations of the formulation as heat stuff will be discussed in next paper

Qualitative Experimental research on thermal response of interior finishing material under air-conditioning intermittent running

The response rate of indoor thermal environment is a main factor affecting indoor comfort level greatly under air-conditioning intermittent operation. Interior finishing material can affect inner surface temperature response rate directly as the layer closest to indoor air. According to this situation, in order to explore the thermal response of the different interior finishing material under air-conditioning intermittent running, a experiment is built to analyze the effect of the interior finishing material property on inner surface temperature. Results show that interior finishing property has an significant influence on the thermal response on inner surface temperature. The porous interior finishing material has 20% higher thermal response rate of inner surface temperature than the homogeneous dense materials. Integrating with EPS or rubber sponge in the interior finishing material can improve the thermal response rate of inner surface temperature and the increased response rate can be up to 17.7%~29.6%.

THE DETECTION OF THE NECESSARY CONDITIONS OF EFFECTIVE FUNCTIONING OF THE BALL CLEANING SYSTEM OF THE TUBES OF STEAM TURBINE CONDENSERS. Part 1

A problem of an increase of the power of turbine by improving heat transfer in condensers of steam turbines is considered in the article as a topical one. The analysis of contamination of the internal surfaces of cooling tubes and of the influence of pollution on the process of heat transfer in turbine condensers has been fulfilled. The existing method of cleaning of condenser tubes with the use of porous elastic balls of sponge rubber that is implemented on a number of large thermal power plants and state region power plants of the Republic of Belarus is examined. In the operation of the ball cleaning system a significant drawback has been revealed, viz. a low efficiency of this method due to the failure to comply with preparation the system of circulating water for operation. Also, a certain imperfection of ball cleaning system technology has been determined. One of the prerequisites for the effective functioning of the ball cleaning system is a certain degree of purity of the pipe system of the condenser, characterized by the coefficient of purity. To determine the effectiveness of ball cleaning system a series of experiments on the launching of porous rubber balls in the pipe system of the main and the embedded bunches of the T-250/300-240 UTMZ turbine has been produced. Immediately before the experiments hydraulic cleaning of the tubes of the condenser by a high-pressure installation were carried out. During the experiments, records of the number of downloaded porous rubber balls, of the number of rubber balls captured in a loading chamber, and of the number of rubber balls that remained in a calibration device were kept. A large proportion of default of the balls caused by the presence of residues of the carbonate sediments, that obstruct the movement of porous rubber balls in the tubes of the condenser, was determined. The presence of carbonate deposits in the tubes of the condenser indicates a lack of effectiveness of antiscale treatment of circulating water and of hydraulic method of cleaning tubes of the condenser.

Analysis of the Wrinkle of an Automobile Weather-Strip Seal in Bending

ABSTRACTWeather-strip seals in automotive door systems play a major role in determining the door closing effort, isolating the passenger compartment from water and reducing the wind noise inside the vehicle. The phenomenon of a wrinkle often occurs in weather-strips when they are assembled on the door surfaces which have bent or twisted profiles. Wrinkles in automobile weather-strip seals will affect the closing effort and noise isolation characteristics of the automotive door system. The wrinkle of anethylene-propylene-diene (EPDM) automobile weather-strip seals when bent and the critical conditions for a wrinkle to develop were characterized in this study. The hyperelastic material behavior of the EPDM sponge and EPDM dense rubber in the seal were modeled using the Foam model and Mooney–Rivlin model, respectively. Then a finite element analysis (FEA) model of the automobile weather-strip seal in assembly was developed and analyzed using then on linear FEA software Marc. The deformation of the seal and the thickness decrease in the critical region where it was prone to wrinkle were obtained by this FEA method. Finally the critical criterion of wrinkling was determined by analysis of the reaction forces in the critical region. The proposed analysis method can shorten the product design cycle and decrease the design and trial-product cost considerably.

Examination of the Transferability of Technological key Features of Paperboard Deep Drawing Towards the Application in Fast‐Running Packaging Machines

The deep‐drawing process of paperboard has experienced essential improvement in the recent past; however, the technological advancements have not been transferred to packaging machines yet. Two of the most important issues with regard to the reliable production of high quality 3D shapes are the use of elevated moisture and defined blank holder force profiles. This paper examines a roll preparation method for applying additional water to the paperboard and analyses a spring‐loaded blank holder solution with regard to its achieved accuracy and reliability of the force characteristics. A two‐sided roll application of water on the paperboard using a sponge rubber cover on one of the rolls produces a water intake of up to 12%. The effect of moisture applied by roll preparation is higher compared to conditioning under controlled climate conditions, and the preparation time is reduced to a few seconds. The spring‐loaded blank holder introduced in the paper completely works in position control and avoids the switch over to force control as well as the problem of small position steps, which were necessary during force control. A harmonic oscillation of the blank holder while the material is drawn out of it could not be observed up to an output of 150 cycles per minute. An application of a roll‐based moisturization unit and a spring‐loaded blank holder force in modern packaging machines appears feasible and favourable according to the results of this paper and maintains the capabilities of this 3D forming technology to a large part. Copyright © 2016 John Wiley & Sons, Ltd.

Solid mold investment casting – A replication process for open-cell foam metal production

Abstract Foam metals have always been an interesting material type because of their unique properties and various production techniques. In this study, solid mold investment casting process, which is one of the replication techniques, was used to produce open-cell aluminum foam specimens. Commercial rubber sponge was tested as foam pattern material. Plaster bonded solid molds were prepared in the stainless steel flasks and infiltration of the slurry into the rubber sponge was carried out under vacuum. Following this, pattern removal and mold firing was carried out gradually. Molten A319 casting and A6063 wrought aluminum alloys were cast into flash molds with vacuum assistance (−105 Pa). Sponge pattern and cast foam specimens were examined and compared by stereo microscope and scanning electron microscope (SEM). It is clearly found that rubber sponge is a very suitable pattern material for producing open-cell foam structures.

Effect of Alumina Particles Embedded in Natural Rubber Foams on Cell Morphology and Thermo-Mechanical Properties

Abstract Alumina particles is a ceramic powder used as a dispersed phase or filler to reinforce the mechanical properties and improve thermal properties of natural rubber foams via the vulcanization process at curing temperature 150°C with a two-roll mill. The amount of alumina added in natural rubber foams were varied from 0 to 60 phr on 100 phr of natural rubber in a sulfur curing system. The sodium bicarbonate (NaHCO3) and N,N′-dinitrosopentamethylenetetramine (DNPT) were used as foaming agents. The sponge rubber composite foams were characterized for the microstructure, phase formation, thermal property, particle size distribution, and mechanical property by scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), particle size analyzer, and compression set testing. The fabricated sponge rubber composite foams have distinctive characteristics such as light weight and good mechanical and thermal properties suitable for energy absorption such as thermal, noise, and vibration.