Silicone Rubber Sheet Research Articles

0307 開水路乱流中の波状面に働く抗力への表面の親水性の影響(OS3-2 流れの抵抗低減,OS3 流れの抵抗低減)

We have carried out experiments to measure velocities of turbulent water flow over two wavy plates on the bottom of a shallow open channel at a high Reynolds number. These plates mimic the folded skin of fast-swimming dolphin. The hydrophilicity of these plates are different. Also, we have measured total drag acting on the test plates by the flow. Wall-shear stress is evaluated from the gradient of mean velocity on the plate surface. The pressure drag is calculated from the difference between the total drag and the friction drag. The friction drag of the wavy plate made of the hydrophilized polycarbonate sheet is 12.1% lower than that of silicone rubber sheet.

Comparisons of Different Elastomer Micro Molds

This paper demonstrates the comparisons of molding with micro molds made of different elastomeric polymers. Micro molds made of pure polydimethylsiloxane (PDMS), 0.3% carbon nanotube (CNT) enforced polydimethylsiloxane (PDMS), 2% carbon nanotube (CNT) enforced polydimethylsiloxane (PDMS) and commercial available high temperature silicon rubber sheet (Avon Group) were studied. Micro moldings using different molding pressures were performed. By comparing the dimensions of micro features produced with different molding pressures, molding accuracies of using micro molds made of different elastomeric polymers are obtained. Results of this study provide valuable information for the development of elastomer micro mold insert for micro injection molding.

Grafting of styrene and 2-vinylnaphthalene onto silicone rubber to improve radiation resistance

Styrene (St) and vinyl naphthalene (2VN) were grafted onto silicone rubber (SR) as “antirads” agents for internal radiation protection. The styrene grafted onto silicone rubber (SR-g-St) sheets were synthesized by the direct gamma radiation method in hexane/ethyl acetate solutions of styrene, and SR-g-2VN in tetrahydrofuran (THF) solutions of 2-vinylnaphtalene at room temperature. The grafting reaction was carried out at doses of 10–100 kGy, at a dose rate of 8.36 kGy h−1. The resistance to irradiation of modified silicone rubber was tested at doses from 100 to 1000 kGy at a dose rate of 8.36 kGy/h. After irradiation of the un-grafted and grafted silicone materials, the crosslinking density, the average molecular weight between crosslinks (Mc), elastic modulus, and thermal properties were studied. The results show that 2-vinylnaphthalene has better radiation protection than styrene, with a protection coefficient of 0.83 compared with 0.80 for styrene. The changes in the properties of silicone rubber due to radiation were examined by infrared (FTIR-ATR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and various mechanical properties.

J022033 培養組織の球圧子押込試験による柔さ計測に関する研究

In this study, in order to measure the softness of cultured tissue, ball indentation tests were performed. As first step, the principle of ball indentation test was applied to the thin silicone rubber sheet (t=0.1mm), which achieved results confirm the validation of the measurement result. Next step, Young's modulus of monolayer cultured nerve cell (PCI2) was measured, and the validation of the measured results was confirmed by comparing with previous studies. The Young's modulus of the cell body is 36.5kPa, and distal, middle and proximal of neuritis are 50.2kPa, 21.8kPa and 51.5kPa, respectively. In addition, Young's modulus of three-dimensional gel-culture system consisting of primary human gingival fibroblasts (GF) and gingival epithelial (GE) cells in collagen gels were measured. The Young's modulus of whole gel and gingival epithelial cells are 3.46kPa and 81.9kPa, respectively. The results were shown the possibility of measuring the Young's modulus of each layer of cultured tissue in the case of laminate structure.

'Diasec' and Other Finishing Techniques - Investigation of Accelerated Light Fading

A study of the accelerated light fading behavior of face-mounted color photographic materials has shown that alterations on the surface of the materials influence their fading characteristics. With the help of spectral density measurements it became apparent that the application of materials such as silicone rubber, adhesive film and acrylic sheeting, but also laminating films, onto the surface of the prints accelerated the degradation of the colorants, especially the yellow dye, in chromogenic materials. In the case of silver dye bleach materials, however, the opposite effect was observed. The influence of the material combination on the stability of face mounted color photographic prints was demonstrated to vary considerably. In order to better assess the inherent damage potential of the materials themselves, these were examined by means of instrumental analysis and measurements of pollutant gasses. Besides off-gassing compounds such as acetic acid and changes in pH caused by aging of the adhesive, face-mounting with a rigid plastic sheet (acrylic glazing) also affected the respective fading behavior of the various materials that were tested.

Sensing micrometer-scale deformations via stretching of a photonic crystal

This paper reports micrometer-scale strain measurements that are enabled through the observed wavelength shift in a stretched surface photonic crystal narrow bandwidth optical reflectance filter. The photonic crystal optical filter is comprised of a 550 nm period, dielectric-coated linear grating structure, which was fabricated on the surface of a thin sheet of silicone rubber. When stretched, the change in grating period induced a change in the wavelength of light coupled into the photonic crystal, which could be measured using a spectrometer. The observed wavelength change was 4.53 nm per 1% strain and was linear up to 3.75% strain. The measurement was affected by temperature fluctuations, which could be compensated. The resolution of the measurement was 78 μɛ.

1210 オプティカルフローに基づく光導波形触覚センサの試作(触覚センサ・触覚ディスプレイ,一般講演)

Three-axis tactile sensing has good advantages on grasping an object of unknown mass and hardness. We developed a new three-axis tactile sensor, which possesses a simple structure to endure large applied force caused by power grasp. Normal force distribution is measured according to gray scale value obtained by image data processing as previous three-axis tactile sensors. Shearing force distribution is determined by linear movement of image data calculated by optical flow. Sensing characteristics of the present sensor is dominated by configuration and material of conical feelers formed on a silicon rubber sheet By mean of LIGA, we obtain a mold of the silicon rubber sheet In evaluation experiments, we applied vertical force and horizontal force to the sensor. Vfe confirmed sensing ability of the present sensor to acquire normal and tangential forces.

Calibration of Silicone Rubber Passive Samplers: Experimental and Modeled Relations between Sampling Rate and Compound Properties

Sampling rates (Rs) for silicone rubber (SR) passive samplers were measured under two different hydrodynamic conditions. Concentrations were maintained in the aqueous phase by continuous equilibration with SR sheets of a large total surface area which had been spiked with polycyclic aromatic hydrocarbons and/or polychlorinated biphenyls. Test sheets made of the same SR but of much smaller surface area were used to measure the uptake rate. Measured Rs values decreased with increasing passive sampler-water partition coefficient (Kpw) according to Rs approximately Kpw(-0.08) under both hydrodynamic conditions. This decrease is not significantly different from modeled values if the uncertainty of the diffusion coefficients in water is included. Modeling also confirmed that uptake of the test compounds under the experimental conditions was entirely controlled by diffusion in the water phase. A model using Rs approximately M(-0.47) is suggested for extrapolation of Rs estimated from the dissipation of performance reference compounds to target compounds in a higher hydrophobicity range.

Negative ion implantation for pattering mesenchymal-stem cell adhesion on silicone rubber and differentiation into nerve cells with keeping their adhesion pattern

Adhesion properties of mesenchymal stem cells (MSC) from a rat bone marrow on silicone rubber (SR) surface modified by carbon negative-ion implantation through a pattern mask have been investigated in order to application in development of an advanced silicone guide tube for nerve regeneration. Then, the MSC cells cultured on C-implanted SR was also tested to their differentiation into neurons. Silicone rubber sheet (SR) was implanted with carbon negative ions. The surface wettability of the SR was improved by the implantation with fluence more than 1 × 10 14 ions/cm 2 for the energy range of 5–20 keV. After samples implanted with carbon negative ions through a patterning mask were sterilized and placed on a culture dish, MSC cells were cultured on them for 10 days with serum culture medium in a CO 2-incubator. The MSC clearly adhered over the C-implanted SR surface along the mask pattern for fluence of 3 × 10 15–1 × 10 16 ions/cm 2, at 10–15 keV. The differentiation into neuron was induced by the method using β-mercaptoethanol proposed by Woodbury et al. The MSC on C-implanted SR completely differentiated with remaining the previous adhesion pattern. The differentiation into neuron was confirmed by neuron specific enolase (NSE).

Influence of Relative Humidity on AC Corona Discharge from Algae Attached on the Silicone Rubber

To make clear the influence of algae growth at the surface of a polymer insulator in a practical transmission line, the characteristics of ac corona discharge from an aggregate algae particle were investigated. The aggregate algae particle was made of Protococcus viridis. Corona onset voltage from an aggregate algae particle was decreased as relative humidity increased. Under the condition of relatively higher relative humidity, luminous channel of corona discharge became more strongly and the number of corona pulses in the current waveform was increased. For an aggregate algae particle contaminated with sea salt including MgCl2, corona onset voltage decreased drastically at relative humidity above 40%. This property would result from deliquescence of MgCl2. Corona discharge was strongly affected by existence of MgCl2 in an aggregate algae particle. Surface resistance of algae attached to the surface of the silicone rubber sheet decreased in fourth figures for relative humidity from 20 to 90%. Therefore, the existence of algae on the polymer insulator inevitably affects the electric property and the surface property of the polymer insulator.

Gene delivery to cells on a miniaturized multiwell plate for high-throughput gene function analysis

The transfectional microarray is a promising tool to conduct high-throughput analysis of gene function. In this study, a miniaturized multiwell plate was prepared by applying a silicone rubber sheet with holes on a gold electrode. The combination of electroporation and a miniaturized multiwell plate successfully achieved spatially controlled gene delivery with absence of cross-contamination between genes. Furthermore, we found that gene delivery efficiency was not dependent on conditions such as plasmid loading, electric field strength, and pulse duration.

Studies on erosion of silicone rubber exposed to partial arc discharges

The effect of electrolyte conductivity on the partial arc discharge development between two electrolyte electrodes on a silicone rubber sheet surface was investigated. Tests were executed by placing the salt-waterlogged glass-filter paper on a silicone rubber sheet to simulate a polluted electrolyte layer, and partial arc discharges with a constant current value of 10 mA were observed. It was found that the formation of an arc channel and a temperature distribution on the sample surface varied with the electrolyte conductivity. In addition, the relation between the electrolyte conductivity and the weight loss due to the heat erosion of specimens was also investigated by a 3D morphological observation and a simulated calculation. The partial arc discharge did significantly not influence on the sample surface erosion under serious polluted conditions. In contrast, the severest erosion appeared under the light pollution with comparatively lower conductivity of the electrolyte electrodes.

Influence of Relative Humidity on Corona Onset Voltage from Algae Attached on the Silicone Rubber Sheet

Influence of Relative Humidity on Corona Onset Voltage from Algae Attached on the Silicone Rubber Sheet

Development of a miniature motor-driven pulsatile LVAD driven by a fuzzy controller

We have been developing a small, lightweight motor-driven pulsatile left ventricular assist device (LVAD) with a ball screw. The motor-driven LVAD consists of a brushless DC motor and a ball screw. The attractive magnetic force between Nd-Fe-B magnets (with a diameter of 5 mm and a thickness of 1.5 mm) mounted in holes in a silicone rubber sheet (thickness 2 mm) and an iron plate adhered onto the a diaphragm of the blood pump can provide optimum active blood filling during the pump filling phase. The LVAD has a stroke volume of 55 ml and an overall volume of 285 ml; it weighs 360 g. The controller mainly consists of a fuzzy logic position and velocity controller to apply doctors' and engineers' knowledge to control the LVAD. Each unit of the controller consists of a functionally independent program module for easy improvement of the controller's performance. The LVAD was evaluated in in vitro experiments using a mock circulation. A maximum pump outflow of 5.1 l/min was obtained at a drive rate of 95 bpm against an afterload of 95 mmHg, and active filling using the attractive magnetic force provided a pump output of 3.6 l/min at a drive rate of 75 bpm under a preload of 0 mmHg. The operating efficiency of the LVAD was measured at between 8% and 10.5%. While the LVAD can provide adequate pump outflow for cardiac assistance, further upgrading of the software and improvement of the blood pump are required to improve pump performance and efficiency.

Passive sampling: partition coefficients for a silicone rubber reference phase

Silicone rubber sheeting can be used as a passive sampling device for hydrophobic organic contaminants in the environment to determine the available concentrations in water and sediments. Reliable sampler-water partition coefficients are required to determine the sampling rates and the dissolved contaminant concentrations in water and in sediment pore water. Log partition coefficients (logK(sr,w)) for silicone rubber-water have been estimated for 32 polycyclic aromatic hydrocarbons (PAHs), 2 deuterated PAH analogues and 32 chlorobiphenyls (CBs) using the cosolvent method, with methanol as cosolvent. Strong linear relationships were found with literature values for the corresponding log octanol-water partition coefficients (logK(ow)) for both CBs and PAHs, confirming that partitioning into the silicone rubber is strongly determined by the hydrophobicity of the compounds, which suggests logK(ow) is a good predictor of logK(sr,w) and that absorption is the main mechanism for accumulation of analytes into the silicone rubber polymer.

Improvement of Bending Motion by Catalyst Addition of Pd-Al<SUB>2</SUB>O<SUB>3</SUB> Powder for an Uni-Morph Soft Device Constructed of Polymer Sheets with and without Powder Dispersion of Hydrogen Storage Alloy

In order to generate the soft bending motion driven by pressure change in hydrogen gas, a soft device was made up and tested. In former research, a unimorph structure was proposed, in which a silicone rubber with LaNi 5 alloy powder distributed was piled up on a pure silicone rubber sheet. Using this structure we succeeded a bending motion of the soft device by applying hydrogen gas pressure. However the mechanical response was slow. To improve the active motion, a catalyst of Pd-Al 2 Ο 3 powder was mixed into the hydrogen storage alloy powder in the rubber. By simple addition of catalyst powder before dispersion into the rubber, we obtained drastically modified responses and displacement in the movement of the device. The catalyst probably accelerated dissociation of hydrogen molecule on the surface of hydrogen storage material particle.

Protein Adsorption Properties on Silicone Rubber Modified by Carbon Negative-Ion Implantation

The adsorption properties of proteins such as laminin (LN), fibronectin (FN) and gelatin on the carbon negative-ion implanted silicone rubber sheet (SR) including their effects of these protein-coated modified SR on patterning nerve-cell culture were investigated. The implantation conditions were fixed at 3x10^15 ions/cm^2 and 10 keV. The concentrations of LN in PBS, FN in PBS and gelatin in de-ionized water (DIW) were 0.5-50, 0.5-10 and 5-10^3 micro g/ml, respectively. The adsorption properties of proteins on SR sheet implanted as a half moon shape were evaluated by XPS. After 4-day in vitro culture of the nerve-like cell of rat adrenal pheochromocytoma (PC12h) on the protein-coated surfaces of SR implanted through the micro-pattern mask with slits of 50-f..l,m width, the phase contrast micrographs show that the suitable protein for patterning the attachment of nerve cell was FN at 1 micro g/ml of concentration, corresponding to high ratio of nitrogen adsorption between implanted and unimplanted regions that was 1.9. As coated with 1 micro g/ml of LN, cells attached over all areas. While coating with 1 mg/ml of gelatin, no cell attached.

Giant Bending Motion of a Soft Actuator Controlled by Hydrogen Gas Pressure

A soft actuator with a giant bending motion controlled by hydrogen pressure for artificial muscles has been innovated. It resembles a bimetal and is constructed with soft silicone rubber sheets for driving and supporting. The LaNi5 hydrogen storage alloy powder is dispersed in the driving sheet. The reversible motion is observed and operated by hydrogenation and degassing. The giant bending motion of over 4000 ppm of strain was observed from 2 min to 3 h of hydrogenation time. The actuator developed shows a giant bending motion as large as that of a typical shape memory alloy.

Behavior of water droplet on electrically stressed polymeric coating surface

This paper describes the behavior of water droplets on an electrically stressed polymer surface and their influence on the surface charge distribution. Tests were done by placing water droplets on the surface of the silicone rubber (SR) and ethylene vinyl acetate (EVA) copolymer sheets with a micropipette, and their behaviors were observed by a high-speed video camera after ac voltage was applied. It was demonstrated that the droplet deformed and vibrated due to the electrostatic force, which caused the droplet to be charged negatively before flashover. However, when a corona discharge occurred at the tip of the droplet where a locally high electric field was built, the charge on the droplet gradually changed to positive with the increase of applied voltage. In addition, the above-mentioned characteristics are different between SR and EVA because of their different surface conditions.

Damping properties of silicone rubber/polyacrylate sequential interpenetrating networks

Silicone rubber/polyacrylate sequential interpenetrating polymer networks(IPNs) were prepared by silicone rubber sheet dipped into the solution composed of different acrylate monomers and benzoyl peroxides(BPOs) for different time at room temperature and then acrylate polymerized at 80 °C for 2 h. The molecular structure and damping properties of sequential IPNs were studied by means of FT-IR and dynamic mechanical analysis(DMA), respectively. The FT-IR spectrum shows that polyacrylate distributes unevenly along the thickness direction of IPNs, i.e. the concentration of polyacrylate decreases from the midst to the surface of the IPNs. The DMA shows that cold crystallization of silicone in the temperature range from −47 °C to −30 °C is reduced and loss factor of IPNs is improved after interpenetrating with polyacrylate. This suggestes that IPNs can be used as damping materials.