Polymer quality criteria
PET or polyethylene terephthalate

Because of the diversity of applications, the properties sought and the control tests implemented differ from one product to another. Depending on the application, polymer properties may be assessed on finished or semi-finished products (wire, film or standardized test specimen). Nevertheless, a number of criteria are common to most products. Some of these are actually specifications.

• The polymer's viscosity index is measured in solution, usually in a 50/50 volume phenol/dichlorobenzene mixture (ISO 1628/5). Other solvents are used in practice, such as orthochlorophenol, or dichloroacetic acid, which is suitable for filled or post-condensed polymers.

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