Autoclave vulcanization

Un-vulcanized butyl rubber/PVC lining for autoclave vulcanization or hot-air vulcanization. 

Un-vulcanized Butyl Rubber/PVC Lining for Autoclave Vulcanization or Hot-air Vulcanization... 

Extrusion. Extmsion techniques are used in the preparation of tubing, hose, O-ring cord, preforms and shaped gaskets. Typical extmsion conditions are 70 to 85°C for the barrel temperature and 95 to 110°C for the head temperature. The extmded forms are normally cured in a steam autoclave at 150 to 165°C. Some special grades of peroxide curable fluorocarbon elastomers can be hot air vulcanized. 

The oldest technology involved in the elastomer blending and vulcanization process is essentially a temperature controlled two roll mill as well as internal mixers followed by an optimum degree of crosslinking in autoclave molds (compression, injection, etc.) in a batch process or in a continuous process such as continuously heated tube or radiated tubes. A few examples of laboratory scale preparation of special purpose elastomeric blends is cited here. 

A thin layer of a mix of natural rubber, sulfur, precipitated silica, water, and some additives, such as carbon black and vulcanizing agents, is extruded on a paper support belt, calendered, and vulcanized as a roll in an autoclave under elevated pressure and temperature ( 180 °C). A modi-... 

Rubber lining is the skilled application of unvulcanized rubber sheets to prepared metal surfaces. The lined equipment is then vulcanized in a steam autoclave, fully bonding the rubber to the metal surface creating a durable and resilient protective rubber coating. 

Polychloroprene material that may be vulcanized in the shop with hot air or steam in an autoclave or can self-vulcanize on-site within 2-3 months at ambient temperature of 25°C. 

Un-vulcanized bromobutyl material, to be vulcanized in an autoclave applied with a two-layer adhesive system. 

Un-vulcanized CSM/PVC material (chloro sulphonated polyethylene/polyvinyl chloride blend) for autoclave or hot-air vulcanization applied with the two-layer adhesive system. 

Un-vulcanized NR material that can be vulcanized in the workshop with pressurized steam (autoclave). Applied with the two-layer adhesive system. 

The welds should not be porous or should not have any cracks. As the lining is usually subjected to vulcanization in autoclave at a temperature of 130 to 150 deg C, the entrapped air inside the weld could expand and blow out the lining, necessitating repair work on the lined vessel. 

If the tank is intended to be lined and vulcanized in the autoclave, the overall dimensions of the tank or its sections and branch pipes should suit the size of the autoclave. 

Autoclave curing Open steam curing Hot water curing Self-vulcanizing Cold bond lining and... 

Apart from the above three types there are custom built rubber products such as expansion joints, flexible cell covers and large size rubber foils for the caustic soda industry, and many inflatables, fabric reinforced products and thick moulded sheets for specialty applications in certain process plants. These are all hand formed in aluminium or cast iron moulds or forms by laying up process and then cured in autoclave. Here the flow of the un-vulcanized rubber during cure is not very important as the shape is already formed rather the green strength and the stiffness of rubber stock with a low scorch time are the important requisites. A rubber expansion joint made by a hand layup method and cured in autoclave is shown in the following figure 14.1. 

Autoclave - A pressure vessel used for the curing or vulcanization of rubber parts by means of steam under pressure. 

The finished dry rubber and latex based rubber products can be vulcanized by several techniques depending on the type of rubber compound (dry rubber compound/latex compound), size of the finished product, and its shape and structure. Moulded rubber products are vulcanized by press curing using compression, transfer, or injection moulding presses. The vulcanization techniques other than moulding may be grouped into batch and continuous methods. The batch methods include the use of autoclaves, hot air/gas oven, and hot liquid/ water bath. Rubber products may be vulcanized at room temperature by cold curing either by immersion of rubber products in a carbon disulphide solution of sulphur chloride (SjCy, or by exposure to its vapour. 

This decay rate is nearly equivalent to that exhibited by one g of radium in equilibrium with its disintegration products. A miUicurie (mCi) is 0.001 curie, curie point See magnetized curie point, curing See autoclave nitrogen atmosphere cure extruder wire and cable process, dry cure inhibitor prepreg volatile content reinforced plastic resin transfer molding test, Barcol hardness test, scorch Mooney thermoset plastic vulcanization welding, induction. 

Being more highly cross-linked, ebonite linings are even more resistant to swelling and permeation than soft rubber linings. However, they have to be vulcanized in woikshop autoclaves their use is generally restricted to relatively small items whose volume does not exceed about 100 m. ... 

Vulcanization is the process to chemically convert a polymer compound (rubber) to an elastic and final end-use product (i.e., in its final shape). The process is dependent on time, temperature and the processing method. Typical equipment used include a press, autoclave, oven, fluid beds, microwave, combinations of techniques. 

Either hot or cooled finished mix is fed into the extruder (as a hot strip or crumb fed to a hot-feed extruder, or a cooled strip or pellets into a cold-feed extruder). The extruder can form extruded profiles suitable as components of built-up products, such as side walls or treads of tires. The extruder can also form profiles that are vulcanized on the run by passing the endless extrudates through a heated salt bath or hot oven, either of which is long enough for vulcanization to sufficiently occur before the profile exits the oven or hot bath. Profiles of unvulcanized products, such as hoses, can be vulcanized after extrusion in a steam autoclave or hot oven. 

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