Rubber Contact Research Articles

Charactérisation par chromatographie sur couche mince des composés benzothiazoliques et du β-sitostérol cédés par les seringues non réutilisables

A thin-layer chromatographic study of 2-mercaptobenzothiazole, 2-(methylthio)benzothiazole, 2-(2-hydroxy-ethylthio)benzothiazole, 2-hydroxybenzothiazole, zinc 2-mercaptobenzothiazolate, mercaptobenzothiazole disulfide, and beta-sitosterol with three developing solvents and eleven spray reagents is reported. A simple method is described which highlights the leaching of 2-mercaptobenzothiazole and 2-(2-hydroxy-ethylthio)benzothiazole from the rubber plunger-seals of disposable syringes: contact of rubber with bidistilled water, extraction of this liquid with chloroform, chromatography on silica gel with the solvents previously studied and spraying with N-chloro-2,6-dichloro-p-benzoquinone monoimine. The method may also be used to discriminate those syringes sterilized with ethylene oxide, the only ones able to leach 2-(2-hydroxy-ethylthio)benzothiazole, from those sterilized by irradiation. Owing to the beta-sitosterol traces leached, it may also be used to investigate whether the plunger-seals are made of natural rubber. The toxic effects of the compounds leached are briefly reported.

シリコーンゴムコンタクトレンズ表面に対するプラズマ重合の応用とその効果

プラズマ重合法を利用してシリコーンゴムコンタクトレンズ表面を親水化し, コンタクレンズへの適応性の検討を行った. プラズマ重合装置は13.56MHzの高周波電源及び容量負荷方式の外部電極を採用し自製した. モノマーとしては水ぬれに関する試験及び表面性状観察からビニルピロリドンを選択した. 最適重合条件は電力40W, 真空度1.0～2.0Torr及び時間60秒であった. 室温乾燥, 水中煮沸, 摩擦などに対する重合層の耐性試験で良好な結果が得られた. 350名695眼について装用実験を行い, 水ぬれに伴う問題例はわずかに12名16眼であった. ただし, 涙液成分によるレンズ汚染が数例発生し, 今後の課題と考える. 一応, ビニルピロリドンを用いてプラズマ重合したシリコーンゴムコンタクトレンズ親水化表面はコンタクトレンズ表面として優れたものであることが確認された.

ベルト研削加工面に及ぼすと粒切れ刃高さ分布と弾性変位量の影響

A simulation of abrasive belt grinding process was carried out. In abrasive belt grinding, the height distribution of grain cutting edges changes with the advance of grinding time and the elastic deformation of contact wheel is the cause of the displacement of grain cutting edge position. So, the influence of the height distribution and elastic displacement of the grain cutting edges were investigated by the simulation. As a result of that, the mechanism of residual depth of cut and the finished surface roughness were analyzed theoretically in cylindrical plunge grinding. The obtained main results are as follows. (1) Residual depth of cut and finished surface roughness increase as the height distribution of grain cutting edges becomes wide. (2) In the case of using a rubber contact wheel, the displacement of grain cutting edges makes the residual depth of cut increased. But, the increase of effective cutting edges makes the finished surface roughness improved. (3) Residual depth of cut caused by the height distribution and displacement of the grain cutting edges is almost generated at the start of grinding. (4) It was found that there is an optimum rubber hardness of contact wheel.

Ply and Rubber Stresses and Contact Forces for a Loaded Radial Tire

Abstract A P215/75R15, steel-belted radial tire subjected to inflation pressure and footprint loading is modeled using laminated, geometrically nonlinear finite elements. The resulting stresses in both the rubber and the plies are presented. Assumptions made include fixed boundary conditions at the bead-flange interface, linear material property representation, and symmetry with respect to the meridional and tread centerline planes. The footprint loading is simulated by enforcing vertical displacements at selected nodes of the model to yield a contact patch force distribution. In-plane patch forces are not included. Experimental results are given showing comparisons with analytical predictions. Advantages of this approach over models presented earlier are the capability to extract information from each layer and to apply displacements directly to the contact patch rather than using a Fourier approach. The model is exercised using the MSC/NASTRAN program. The straightforward restart capability along with the ability to include or exclude nodal points in the contact patch set during the iteration process make the MSC/NASTRAN program convenient to use for this class of problems.

Disulfiram Hypersensitivity and Rubber Contact Dermatitis

DISULFIRAM is a valuable adjunct in the outpatient therapy of ethanol abuse. Persons taking maintenance doses of disulfiram avoid alcohol, as ingestion causes unpleasant symptoms such as flushing, dyspnea, headache, and vomiting. The danger of a severe reaction with tachycardia and hypotension has received much publicity and is minimized by lower disulfiram doses, abandonment of intentional challenge with ethanol, and careful screening of candidates for cardiopulmonary disability. It is little recognized that screening should also seek a history of rubber contact sensitivity. No such precaution is noted in the disulfiram prescribing information. This case illustrates the dangers of administering disulfiram to a patient with this history. Report of a Case A 32-year-old white male bartender requested disulfiram therapy as an aid to resist the temptation to drink at his job. He was otherwise well, with no history of major illnesses, and had abstained from alcohol for one week. A screening

Disulfiram hypersensitivity and rubber contact dermatitis

Disulfiram hypersensitivity and rubber contact dermatitis

Clinical Investigations of Hydrophilic Silicone Rubber Contact Lens ‘Hisilic’: Summarized Report, presented at the International Contact Lens Congress, Fiji, July 1978.

Two types of contact lens are presently used in the ophthalmological field, (1) hard contact lenses made mainly from PMMA and (2) soft contact lenses made mainly from 2–HEMA. Hard contact lenses have good optical performance, are harmless to the human body, relatively easy to sterilize and store, and can be precisely prescribed. However, they exert strongly stimulating effects on the cornea due to their hard nature and less than perfect prescription and over wearing of a hard contact lens tend to cause corneal thickening, edema, spectacle blue, and the over wear syndrome.

The properties and special characteristics of the silicone rubber contact lens “Silflex” from the practitioner's point of view

The possibility of making contact lenses from silicone rubber material was first reported in the 1960s, but so far little has been heard about its use in routine practice. In Apri l 1977, following four years of research, W t h l k Contact Lenses developed a silicone lens which has been fitted to patients at the Wth lk Fitting Institute in Kiel. This report is a summary of experience gained from the first 500 fittings made during the past six months of the silicone contact lens . A short description of the physical and chemical propert ies of the material, the method of production and the lens geometry shou ldcome first. Silicone consists of silicium, hydrogen, carbon and oxygen. These constituents are chemically joined to chains. In this process silicium combines with two methyl groups. This viscous compound is mixed with a filling material, silicic acid, and reaches its final state through cross linking (vulcanisation). Vulcanisation takes place between quartz moulds which determine the shape of the finished lens. This first stage of production is very similar to the production of the parabolar /parabolet t hard lens. A completely-new technology had to be developed for working the edges of the lens, but this need not be discussed at this stage. This method of production results in a lens with a two-curve inner surface and a lenticular outer surface with an optical zone of 8.0mm diameter. The aim of this lens shape is to achieve a particularly thin edge (0.03mm) and a comfortable lens which remains mobile on the eye all day. Silicone is however a hydrophobic material and an essential part of production is, therefore, a process (developed by chemists and physicists from Wacker Chemic and Agfa-Gavaert) which renders the surface of the silicone lens hydrophilic. To achieve this result the finished SILFLEX contact lens is bombarded with electrons and oxygen ions whereby the filling material (silicic acid), which has hydrophilic properties, is exposed and the silicone melted. The result is a hydrophilic surface with a thickness of 4 5 u.

Studies of lubricated rubber friction: Part 2: Optical techniques applied to practical problems

The development of optical interferometry for examining lubricated rubber contacts was described in Part 1 of this article. Part 2 focuses attention on the application of optical techniques to some commonly encountered rubber devices such as fluid seals, wiper blades and road tyres.

Luminescence of Tyre Marks and Other Rubber Contact Traces

Transfer of luminescent or potentially luminescent contact traces from tyres and from rubber articles generally is a widespread phenomenon that can be exploited evidentially. The circumstances under which transfers occur and the factors governing detection and application of such evidence are discussed and illustrated.

Lubricant behaviour in loaded rubber contacts

In some work on the lubrication of soft contacts using optical interferometry a number of effects have been brought to light which are complementary to work of Gaman, Higginson and Harman [1]. In the present work the normal approach of a rubber specimen to a flat glass plate is taken to the point where the lubricant completely disappears. A simple theoretical model shows that the disappearance of the fluid is due to absorption of the fluid into the rubber and not a squeezing out through the very thin residual film existing around the trapped bubble.

Characterisation of rubbers, rubber contact traces and tyre prints by fluorescence spectroscopy

Fluorescent contact traces are transferred from many rubber articles, and may be characterised, after extraction, by synchronously excited fluorescence emission spectroscopy. The fluorescence is due mainly to extender and process oils, to antioxidants, and to polynuclear aromatic hydrocarbons. Variation in these components in tyre treads, caused by variation in manufacture and wear, enables tread rubbers, and their prints, to be efficiently distinguished from one another. Fluorescent tyre print formation is controlled by the nature of the surface, and by contact time and pressure. Some of the fluorescent material solvent-extracted from such prints is present initially as non-fluorescent particles of rubber. Tyre sidewall rubbers are distinguished from tread rubbers by differences in the extraneous polynuclear aromatic hydrocarbon emissions and, in the case of radial tyres, principally by differences in extender oil emissions. The techniques described are also applied to traces left by footwear and by erasers, to the detection of mineral oil in failed brake seals, and can be generally applied in the comparative examination of rubbers.

平面ベルト研削における角だれ深さと取りしろの適正配分

In belt grinding rubber contact wheels are usually used, by which many kinds of works are come to be possible in better grinding. But on the other hand, the use of the rubber contact wheel makes one of causes of decline of form accuracy on ground works. Therefor, in this paper, analysis of the corner slope of the work is tried on the base of the elastic deformation of the contact wheel. And a formula that expresses the relation between the depth of corner slope at the edge and the setting depth of cut is obtained through the analysis, and the depth of corner slope at the edge may be calculated by substituting into the formula the values of grinding condition before the grinding. Then, with the results of the analysis of the depth of cut at the edge of entrance side, the optimum distribution of the depth of cut on each of head of the surface belt grinder with multi-heads was decided. Its results are shown following:(1) The depth of cut should be increased at the first step of the two grinding heads with decreasing the table speed and increasing the hardness of the contact wheel if the grinding conditions are same on each grinding head without the grinding allowance.(2) When more heads than two are used, the ratio of the depth of cut on two heads next to each other should be set the same value as when two heads.

Surface energy and the contact of elastic solids

This paper discusses the influence of surface energy on the contact between elastic solids. Equations are derived for its effect upon the contact size and the force of adhesion between two lightly loaded spherical solid surfaces. The theory is supported by experiments carried out on the contact of rubber and gelatine spheres.

Lens extraction with the hyelophake. A preliminary report.

The delivery of the crystalline lens by the use of suction, termed phako erisis by Barraquer, 1 has enjoyed a period of popularity over the past 50 years. His original description in 1916 incorporated a motor driven pump connected to an erisophake by a rubber tube. This was modified by Dimitry 2 in 1939 who advocated the use of a simplified sucking-disc instrument. It used less suction and, therefore, limited the hazard of extreme suction on the vitreous and iris, as well as on the lens capsule itself. In 1948, Bell 3 devised a surgical instrument which consisted of a small rubber contact glass sucker and a Dimitri tip. In 1951, Harrington 4 further modified Bell's erisophake by using a solid handle rigidly fastened to the needle holding the suction cup. This eliminated the chance of pressure on the rubber ball and the loss of suction on the lens