Thermosetting plastics melt processing

Keywords Additives, Compounding, Deformation of melts, Extrusion foaming. Flow properties, Influences of processing on properties. Injection molding. Plastic melts, Processing of elastomers and thermosets. Processing of fiber composites. Processing of thermoplastics... 

The first five of these techniques involve deformation and this has to be followed by some setting operation which stabilises the new shape. In the case of polymer melt deformation this can be affected by cooling of thermoplastics and cross-linking of thermosetting plastics and similtir comments can apply to deformation in the rubbery state. Solution-cast film and fibre requires solvent evaporation (with also perhaps some chemical coagulation process). Latex suspensions can simply be dried as with emulsion paints or subjected to some... 

The so-called solvent-based binder systems contain polymers which solvate or swell in a solvent (e.g. water, alcohol). Typical polymers used in extrusion are PEG, PVA, agar agar and cellulose. Thermoplastic materials are polymers which when heated, soften, melt or become more pliable, and harden during cooling in a reversible physical process. Materials in this class which are used quite often for ceramic processing are PE, PP, EVA, POM and PMMA. Thermosetting materials are polymers which can be melted only once and which, after melting, harden as more heat is added. Thermoset plastics which are used in the ceramic industry are phenolic resins and different silicon resins like polysiloxane. 

Plastics are materials that can be formed into various shapes, usually by the application of heat and pressure. Thermoplastic materials can be reshaped. For example, plastic milk containers are made from the polymer polyethylene. These containers can be melted down and the polymer recycled for some other use. In contrast, a thermosetting plastic is shaped through irreversible chemical processes and, therefore, cannot be reshaped readily. An elastomer is a material that exhibits rubbery or elastic behavior. When subjected to stretching or bending, an elastomer regains its original shape upon removal of the distorting force, if it has not been distorted beyond some elastic limit. Rubber is the most familiar example of an elastomer. 

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