Glossary of Fabrication and Plastics Terms

Initial or early stage in the reaction of some thermosetting resins in which the material is still soluble in certain liquids and fusible referred to as resol. 

Chemical that acts as a stabilizer by chemically combining with an acid that may be present initially in trace quantities in a plastic also may be formed via decomposition of the resin. 

Group of plastics based on resins generated from the polymerization of acrylic monomers (e.g., ethyl acrylate and methyl methacrylate). 

A component or body held to another body by an adhesive. 

Condition in which two surfaces are bonded together by interfacial forces caused by valence forces or interlocking forces or both (see mechanical adhesion and specific adhesion). 

Fluorinated rubbers, copolymers of hexafluoropropylene and vinylidene-fluorides, have excellent resistance to oils, fuels and lubricants at temperatures up to 200°C. They have better resistance to aliphatic, aromatic and chlorinated hydrocarbons and most mineral acids than other rubbers, but their high cost restricts their engineering applications. Cheremisinoff et al. [54] provide extensive physical and mechanical properties data on engineering plastics. A glossary of terms concerned with fabrication and properties of plastics is given in the last section of this chapter. 

Organic coatings are applied mainly to mild steel structures and equipment. They are also used on aluminum, zinc-sprayed and galvanized steel, but to a lesser extent. The applications for organic coatings can be divided into three areas corrosion by atmospheric pollution, protection from splash by process liquors, and linings for immersion in process liquors [70-74]. 

Application of protective paints consists of surface preparation of steel, priming coat and finishing coats. Wherever possible, steel should be blast-cleaned before painting. Primers thoroughly wet the metal to promote adhesion of finishing paints and carry inhibitive pigments. For example, red lead oxide will minimize the spread of rust on metal surfaces. The total thickness of fmishing coats must be at least 0.125 mm for adequate protection and life. Four coats of paint usually are necessary to achieve this. 

Paints based on phenolic resins are oil modified to permit drying at ambient temperatures. They are very suitable for most industrial atmospheres. Paints with a higher standard of chemical resistance are required for equipment that is splashed by corrosive process liquors. 

Chlorinated rubber paints and vinyl paints have excellent resistance to high concentrations of acids and alkalis at temperatures up to 80°C. High-build chlorinated rubber paints, which give a thickness of 0.12 mm per coat are commonly used for process plant equipment. 

---