Rubber Block Research Articles

A Study on Squeeze Film Between Rotating Porous Rubber Surface and Stationary Impermeable Rigid Surface

The theoretical and experimental study is carried out to investigate the squeeze film phenomena between a cylindrical porous block and an impermeable rigid plate. The porous rubber block is rotated and oscillated sinusoidally in the direction perpendicular to its surface, whereas the rigid plate is stationary. The deformation of the porous rubber block is evaluated with an approximate method, in which the cylindrical rubber block is simplified to be a set of concentric rings and each ring is assumed to be deformed only axially and independently from the neighboring ones. The each ring can be replaced a three-element viscoelastic model. The theoretical result agrees approximately with the experimental result and both results show that a rotational motion slightly decreases the squeeze film pressure and force due to a centrifugal force mainly acting on the film. The effects of the permeability of the porous matrix, the velocity slip at the porous surface and the surface deformation of the porous matrix on the squeeze film characteristics are made clear by comparing the results for the squeeze film between the porous rubber surface and the impermeable rigid surface with those between a pair of impermeable rigid plates.

255 傾斜機能ゴム・ブロックの不均一せん断変形(振動工学II)

255 傾斜機能ゴム・ブロックの不均一せん断変形(振動工学II)

Phase structure and morphology of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers

AbstractSupermolecular structure of isotactic polypropylene/wollastonite/styrenic rubber block copolymers composites were studied as a function of elastomeric poly‐ (styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and the SEBS grafted with maleic anhydride (SEBS‐g‐MA) content (from 0 to 20 vol%) by optical, scanning, and transmission electron microscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry. Wollastonite particles disturbed the spherulitization of polypropylene matrix. Both elastomers affected the crystallization of polypropylene matrix mainly by solidification effect. Although SEBS‐g‐MA encapsulated wollastonite particles more expressive than SEBS forming thus core‐shell morphology in higher extent, scanning electron micrographs indicated more constrained wollastonite particles in fractured surfaces of composites with SEBS elastomer. Moreover, SEBS‐g‐MA disorientated wollastonite particles and affected reorientation of the polypropylene crystallites stronger than SEBS elastomer. POLYM. ENG. SCI., 47:2145–2154, 2007. © 2007 Society of Plastics Engineers

Dynamical research on spherical micro actuator with piezoelectric ceramic stacks drivers

This paper develops a 30 mm × 30 mm × 50 mm spherical micro actuator driven by piezoelectric ceramic stacks (PZT), and analyzes its dynamic performances. First, the space coordinate relationship of the spherical micro actuator and a dynamic model are set up. Second, The Runge-Kutta arithmetic is used to calculate the dynamical parameters of the micro actuator; the SIMULINK module of MATLAB is used to build the dynamical simulating model and then simulate it. Third, an experimental sample of the spherical micro actuator is developed, a micromanipulator is integrated with a micro-gripper based on the sample spherical micro actuator, and the experimental research on the micro assembly is conducted between a micro shaft of Φ180 μm and a micro spindle sleeve of Φ200 μm. Finally, the characteristics of the spherical micro actuator influenced by the mass of the metal sphere of the micro actuator, driving signal frequency, friction coefficient of the contact surface between the metal sphere and the friction block of the micro driving unit are analyzed. The experimental results indicate that the rotation resolution of the micro actuator reaches 0.000 1°, the rotation positioning precision reaches 0.000 5°, and the maximum working frequency is about 1200 Hz. The experimental results validate the back rotation vibration model of the spherical micro actuator. The micromanipulator integrated by the spherical micro actuator can meet the requirements of precise micro operation and assembly for micro electro mechanical systems (MEMS) or other microelements in micro degree fields.

Mechanical properties of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers

AbstractMechanical properties of isotactic polypropylene/wollastonite/styrene rubber block copolymers (iPP/wollastonite/SRBC) composites were studied as a function of elastomeric poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and SEBS grafted with maleic anhydride (SEBS‐g‐MA) content from 0 to 20 vol%. Microphase morphology was stronger influenced by SRBC elastomers than by different wollastonite types. Higher encapsulation ability of SEBS‐g‐MA than SEBS caused more expressive core‐shell morphology and consequently higher notched impact strength as well as yield parameters, but lower Young's modulus. Higher ductility of the composites with SEBS than with SEBS‐g‐MA has been primarily caused by better miscibility of the polypropylene chains with SEBS molecules. Surface properties of components and adhesion parameters also indicated that adhesion at SEBS‐g‐MA/wollastonite interface, which was stronger than the one at the SEBS/wollastonite interface, influenced higher encapsulation of wollastonite particles by SEBS‐g‐MA. POLYM. ENG. SCI., 47:1873–1880, 2007. © 2007 Society of Plastics Engineers

A test method for studying the rolling resistance of rubber compounds

AbstractA test method is described for measuring energy losses in rolling, using the damped oscillations of a pendulum that makes a rigid cylinder roll backwards and forwards across a rubber block (Gent et al. U.S. Patent No. 6,494,076 B1, The Goodyear Tire and Rubber Company, December 17 (2002)). The mechanics of small swings, in which the displacement of the contact patch is smaller than its length, are shown to be different from those governing swings of larger amplitude. Thus, starting with relatively large swings of the pendulum, the amplitude of oscillation decays initially at a constant rate and then changes to a decreasing rate as the swings become small. In principle, the two processes provide separate measures of the energy losses in rolling. The proposed test method may be useful for studying the effects of the surface features of tire treads and road surfaces on tire rolling resistance, in addition to characterizing the dissipative properties of rubber compounds. POLYM. ENG. SCI., 47:1576–1579, 2007. © 2007 Society of Plastics Engineers

Radiation cross-linking of small electrical wire insulator fabricated from NR/LDPE blends

A low voltage, radiation-crosslinked wire insulator has been fabricated from blends of natural rubber block (STR-5L) and LDPE with phthalic anhydride (PA) as a compatibilizer. Physical properties of the NR/LDPE blend ratios of 50/50 and 60/40 with 0.5, 1.0, and 1.5 wt% PA were evaluated. The gel content increased as the radiation dose increased. Tensile at break exhibited a maximum value of 12 MPa at 120 kGy for 1.0 and 1.5 wt% PA of both blend ratios. A higher PA content yielded a higher modulus for the same blend ratio. Blends of 60/40 ratio with 1.0 wt% PA and 0.8 wt% antimony oxide flame retardant gave the highest limiting oxygen index (LOI) of >30% at above 150 kGy. Other electrical properties of the wire insulator were investigated. It was found that an insulator fabricated from a PA content of 1.0 wt% in the NR/LDPE blend ratio of 50/50, after gamma ray cross-linked at a dose of 180 kGy in low vacuum (1 mm Hg), met the Thai Industrial Standard 11-2531 for low voltage wire below 1.0 kV. To comply with the standard for vertical flame test, a more suitable flame retardant was needed for the insulator.

Supramolecular Triblock Copolymers Containing Complementary Nucleobase Molecular Recognition

A novel difunctional alkoxyamine initiator, DEPN2, was synthesized and utilized as an efficient initiator in nitroxide-mediated controlled radical polymerization of triblock copolymers. Complementary hydrogen-bonding triblock copolymers containing adenine (A) and thymine (T) nucleobase-functionalized outer blocks were synthesized. These thermoplastic elastomeric block copolymers contained short nucleobase-functionalized outer blocks (Mn ∼ 1K−4K) and n-butyl acrylate rubber blocks of variable length (Mn ∼ 14K−70K). Hydrogen-bonding interactions were observed for blends of the complementary nucleobase-functionalized block copolymers in terms of increased specific viscosity as well as higher scaling exponents for specific viscosity as a function of solution concentration. In the solid state, the blends exhibited evidence of a complementary A−T hard phase, which formed upon annealing, and dynamic mechanical analysis (DMA) revealed higher softening temperatures. Morphological development of the block copolymer...

고무 블록의 마찰에너지 해석

고무 블록의 마찰에너지에 관한 연구는 고무 마모 연구를 위한 기초 연구이자 마찰과 마모의 관계를 규정짓는 중요한 연구이며, 지금까지의 마모 이론은 대부분 마찰에너지에 근거하여 전개되어 오고 있다. 하지만, 대부분이 실험이나 유한요소 해석에 기초한 연구이며, 해석적 방법에 의한 연구는 많이 이루어지지 않았다. 따라서 본 논문에서는 에너지 방법을 이용하여 재료 물성, 블록의 형상, 수직 및 전단하중, 블록 이동 속도의 함수로 표현되는 마찰에너지를 해석적으로 구하고 그 결과를 시험 결과와 비교 검토하였으며, 이를 통해 마모 특성 해석의 정확도를 높일 수 있는 기반을 마련하였다 The analysis of the frictional energy of the rubber block with contact to the surface is necessary to study the wear for rubber. It is important to define the relationship of the frictional energy and wear, as the most theory of the wear of rubber product is based on the frictional energy of rubber block. To predict the life of the rubber block, the most of research has been focused on the use of the finite element analysis or the actual experiments which need the many time and expensive costs.Therefore, this research is achieved the successful results of the analysis to the frictional energy by analytic method. This frictional energy is function of the material properties, the shape of block, the vertical and horizontal load and the block moving speed. The analytical results are compared with the test results of this paper which can be used for the analysis of the friction behavior for the wear estimation of the rubber products.

Termites live in a material world: exploration of their ability to differentiate between food sources

Drywood termites are able to assess wood size using vibratory signals, although the exact mechanism behind this assessment ability is not known. Important vibratory characteristics such as the modal frequencies of a wooden block depend on its geometry and boundary conditions; however, they are also dependent on the material characteristics of the block, such as mass, density and internal damping. We report here on choice experiments that tested the ability of the drywood termite Cryptotermes secundus to assess wooden block size using a solid wooden block paired with a composite block, the latter made of either wood and aluminium or wood and rubber. Each composite block was constructed to match mass or low-frequency vibratory modes (i.e. fundamental frequency) of the solid wooden block. The termites always chose the blocks with more wood; they moved to the solid wooden blocks usually within a day and then tunnelled further into the solid wooden block by the end of the experiment. Termites offered composite blocks of wood and rubber matched for mass were the slowest to show a preference for the solid wooden block and this preference was the least definitive of any treatment, which indicated that mass and/or damping may play a role in food assessment. This result clearly shows that the termites were not fooled by composite blocks matched for mass or frequency, which implies that they probably employ more than a single simple measure in their food assessment strategy. This implies a degree of sophistication in their ability to assess their environment hitherto unknown. The potential importance of alternative features in the vibrational signals is discussed.

Carlisle Companies Inc.

AbstractRubber Products (MIC: 11.6 SIC: 3011 NAIC: 326211)Carlisle Companies is a holding company. Co.'s Construction Materials segment produces roofing membranes used primarily on non‐residential low‐sloped roofs, related roofing accessories, including flashings, fasteners, coatings and waterproofing and insulation products. Co.'s Industrial Components segment produces bias‐ply, non‐automotive rubber tires, stamped and roll‐formed wheels, industrial transmission belts and accessories. The Diversified Components segment produces heavy‐duty friction blocks, disc linings, braking systems parts; open‐deck construction trailers and commercial; institutional foodservice permanentware and equipment, and wire, cable, connectors and cable assemblies.

Carlisle Companies Inc.

AbstractRubber Products (MIC: 11.6 SIC: 3011 NAIC: 326211)Carlisle Companies is a holding company. Co.'s Construction Materials segment produces roofing membranes used primarily on non‐residential low‐sloped roofs, related roofing accessories, including flashings, fasteners, coatings and waterproofing and insulation products. Co.'s Industrial Components segment produces bias‐ply, non‐automotive rubber tires, stamped and roll‐formed wheels, industrial transmission belts and accessories. The Diversified Components segment produces heavy‐duty friction blocks, disc linings, braking systems parts; open‐deck construction trailers and commercial; institutional foodservice permanentware and equipment, and wire, cable, connectors and cable assemblies.

Axial loading of elliptical-section bonded rubber blocks

Closed-form expressions for the small axial deflection and stress distribution of axially loaded rubber blocks of elliptical cross-section, whose ends are bonded to rigid plates, are derived using a superposition approach. The governing equations and conditions are satisfied exactly, based upon the classical theory of elasticity. Easily calculable expressions are derived for the corresponding apparent Young’s modulus and the modified apparent Young’s modulus in forms analogous to those previously given for blocks of circular cross-section.

Stability of circular-section bonded rubber blocks subjected to compression and bending

Rubber blocks of circular cross-section whose ends are bonded to rigid plates are studied under compression between either flat parallel surfaces or central parallel knife-edges. Implicit expressions are derived exactly in each case for the critical values of the loads at which the blocks begin to bend, based upon the classical theory of elasticity. Convenient very good approximate explicit representations are additionally deduced for these first critical loads. Some typical representative numerical data are compared and presented graphically in both situations.

Small Indentations of Rubber Blocks: Effect of Size and Shape of Block and of Lateral Compression

Abstract Many gaskets and seals consist of a long rubber strip or thin-walled ring, placed on a flat rigid surface and indented by a flat-ended rigid indenter. We have examined their resistance to small indentations by FEA. They are treated as infinitely-long elastic blocks of rectangular cross-section, resting on a rigid frictionless base. The indentation stiffness is calculated for various ratios of indenter tip width to block width and to block thickness, using two restraint conditions on the outer surfaces: frictionless walls (zero outwards displacement), as for a gasket placed in a recess; or stress-free, as for a gasket with no lateral restraint. For an infinitely-wide and infinitely-thick block, the theoretical resistance to indentation is zero. For comparison, the indentation stiffness is calculated for cylindrical rubber blocks of varied radius and thickness, indented by a flat-ended cylindrical indenter. In this case the result for an infinitely-large block is finite. A second study treats indentation of a rubber block, pre-compressed in the surface plane. Biot showed that the indentation stiffness of a half-space becomes zero at a critical compression, about 33% for equi-biaxial compression and 44 % for plane strain compression, for both a neo-Hookean and a Mooney-Rivlin elastic solid. FEA calculations were made of the indentation stiffness of neo-Hookean blocks of various sizes, pre-compressed to various degrees. The results are compared with Biot's result. In an Appendix, the critical degree of compression is calculated for a more realistic strain energy function than either the neo-Hookean or the Mooney-Rivlin approximation.

Artificial muscles based on liquid crystal elastomers

This paper presents our results on liquid crystal (LC) elastomers as artificial muscle, based on the ideas proposed by de Gennes. In the theoretical model, the material consists of a repeated series of main-chain nematic LC polymer blocks, N, and conventional rubber blocks, R, based on the lamellar phase of a triblock copolymer RNR. The motor for the contraction is the reversible macromolecular shape change of the chain, from stretched to spherical, that occurs at the nematic-to-isotropic phase transition in the main-chain nematic LC polymers. We first developed a new kind of muscle-like material based on a network of side-on nematic LC homopolymers. Side-on LC polymers were used instead of main-chain LC polymers for synthetic reasons. The first example of these materials was thermo-responsive, with a typical contraction of around 35-45% and a generated force of around 210 kPa. Subsequently, a photo-responsive material was developed, with a fast photochemically induced contraction of around 20%, triggered by UV light. We then succeeded in preparing a thermo-responsive artificial muscle, RNR, with lamellar structure, using a side-on nematic LC polymer as N block.Micrometre-sized artificial muscles were also prepared. This paper illustrates the bottom-up design of stimuli-responsive materials, in which the overall material response reflects the individual macromolecular response, using LC polymer as building block.

Rubber friction: role of the flash temperature

When a rubber block is sliding on a hard rough substrate, the substrate asperities willexert time-dependent deformations of the rubber surface resulting in viscoelastic energydissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces ofsolids have roughness on many different length scales, and when calculating the frictionforce it is necessary to include the viscoelastic deformations on all length scales. The energydissipation will result in local heating of the rubber. Since the viscoelastic properties ofrubber-like materials are extremely strongly temperature dependent, it is necessary to includethe local temperature increase in the analysis. At very low sliding velocity the temperatureincrease is negligible because of heat diffusion, but already for velocities of order10−2 m s−1 the local heating may be very important. Here I study the influence of the localheating on the rubber friction, and I show that in a typical case the temperatureincrease results in a decrease in rubber friction with increasing sliding velocity forv>0.01 m s−1. This may result in stick–slip instabilities, and is of crucial importance in manypractical applications, e.g. for tyre–road friction and in particular for ABS brakingsystems.

Isoelectric Focusing Sample Injection for Capillary Zone Electrophoresis in a Fused Silica Capillary

An improvement has been made to couple isoelectric focusing (IEF) sample injection and capillary zone electrophoresis in an untreated fused silica capillary. Electroosmotic flow is efficiently prevented by simply using a rubber block at the outlet end of the capillary during IEF sample injection. The experimental conditions that affect the concentration effect are discussed. A concentration enhancement factor of over 100-fold can be easily obtained for two model proteins: lysozyme and ribonuclease A.

New type flexible joint for the Yumeshima Immersed Tunnel

This paper describes a new flexible joint structure called Crown Seal joint for immersed tunnel at Osaka bay. Crown Seal joint can absorb larger deformation between tunnel elements than other types of flexible joints. Crown Seal joint mainly consists of a rubber block and flanges reinforced by plastic fibers. Basic performance of the joint becomes clear by an experiment. From the experiment results, it is confirmed that Crown Seal joint shows that its behavior follows design deformation and keeps neutral position at joint part. This joint can reduce section force and be handled as a pin structure in the seismic design and un-uniform settlement calculation in soft ground. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.

Bending of long, rectangular-section bonded rubber blocks

Readily-calculable explicit closed-form representations are determined for the bending stiffness of, and stresses within, generally loaded bonded rubber blocks of long, rectangular cross-section. They satisfy exactly the stated governing equations and conditions based upon the classical theory of elasticity. From these, more detailed investigations are given for the especially interesting loading cases corresponding to simple bending, cantilever loading and apparent shear. It is observed that the deformed profiles of the side surfaces are not in general parabolic as has been usually assumed previously. In simple bending an improved approximate elementary expression is deduced for the couple needed to create a specified rotation of the loaded end of the block. Similarly, in apparent shear a more realistic simple estimate is derived from the exact expression for the ratio of the true to the apparent shear modulus.