Curing methods

If infra-red heating or any other radiation curing method is employed, areas which are shaded from the rays or are outside the area of greatest flux density, cannot dry as hard as the fully irradiated surfaces, and may form weak spots susceptible to mechanical damage and consequent corrosion. 

Such chemical cure methods have been used for many years but, due to the inherent hazards of flammability and toxicity of the system, are not accepted in several countries. Also, if all the exposed working surfaces have not been properly treated, unvulcanised areas may occur which would rapidly deteriorate when the lining is put into service. 

This paper describes an irradiation curing method which improves the mechanical, chemical, and thermal properties of multilayered flexible materials, increases the bond strength among the adhesively bonded layers, and provides flexible packages that can withstand the thermo-... 

EB irradiation (like the other ionizing radiation techniques) can bring about the vulcanization of saturated chemically inert polymers which cannot be achieved in the conventional thermochemical curing methods [44]. 

It is possible to cross-link polyisobutylene and poly(isobutylene-isoprene) and chlorobutyl rubber by means of certain additives however, the physical properties of the vulcanizates prepared by conventional curing methods cannot be attained. The most promising results were obtained with chlorobutyl compounds containing thioether polythiols as prorads. ... 

There are numerous methods of applying liquid systems to different surfaces, and the following sections will discuss some of them. Many of these techniques are used in both UV and EB curing processes. Some are very specific to UV technology, and these will be dealt with separately in connection with that curing method. 

Normally, the last UV unit should ensure an adequately thorough cure. This may be a problem for thick layers, particularly if they are pigmented. In such cases electron beam irradiation would be the preferred curing method. ... 

Comparison of Heating and Curing Methods for Thermosetting and UV Curable Powders... 

This system involves the use of some form of heating by air or steam in a chamber in a manner such that the vulcanization occurs immediately after the rubber is formed in an extruder or calender. This is a suitable process for extruded profiles and calendered sheets and conveyor belts. Liquid curing method (LCM) is also a continuous process which involves the use of suitable hot liquid baths in which extruded profiles can be passed through and vulcanized continuously. Items can be cured rapidly at temperatures from 200°C to 300°C however the compounds must be suitably designed to prevent porosity as this is a common problem with any extrudate. Suitable materials for curing medium includes bismuth-tin alloys, an eutectic mixture of potassium nitrate and... 

Vulcanization by the traditional curing methods utilized in the rubber industry is based on sulfur or sulphur-containing compounds and is also the most widely applied technique for curing liquid rubbers containing macromolecules with double bonds. Chinons, peroxides, phenol formaldehyde resins, and other compounds are often used for curing liquid rubbers as an alternative sulfur vulcanization. 

The cationic photoinitiators are sensitive to moisture, and the acid species formed can promote corrosion. Frequently the formulation for these curing methods contains solvent, which evaporates during curing, so that an important environmental advantage is lost. For these reasons cationic uv cure is usually preferred over free radical cure only when the higher-performance properties are justifiable. 

The traditional thermal curing methods mainly depend on a high rate of energy transfer. The rate of heat transfer and the efficiency of the process are demonstrated in the following three modes ... 

Although speed may be the most important factor in considering induction curing, this curing method is also characterized by a uniform heat distribution within a sharply defined boundary and by unique, precisely controlled temperature. Thus, the quality of the joint can be better and more consistent with induction curing than with other heating methods. 

Epoxy adhesives have achieved their commercial success due in no small way to their processing capabilities. Epoxy chemistry is compatible with (1) a variety of formulating techniques and processes accessible to the adhesive manufacturer and (2) a variety of application and curing methods accessible to the end user. 

A variety of forms and curing methods to optimize the assembly process... 

The properties of fiber cement-based composites are largely controlled by the manufacturing process. During manufacturing, different parameters, such as fiber content, the properties of the matrix (i.e., water-to-cement ratio, sand-to-cement ratio), the molding pressure, and the curing method, can be varied to achieve the desired properties in the composite. 

Curing conditions play an important role in the composite behavior, which has been attributed primarily to the influence of curing on the matrix properties. Two curing methods that are generally used in fiber cement composites are air/moist curing (normal pressure and temperature) and autoclave curing (high pressure and temperature). 

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