Hettich Exzenter-Verbinder VB 35 19 mm vernickelt

Plastics differ from polymers due to the addition of additives. Typical additives include plasticisers, stabilisers, colourants, fillers and reinforcing agents. Plastics can be classified according to various criteria, e.g. molecular synthesis, molecular structure, chemical origin or, based on their mechanical and thermal behaviour, into the three main groups: thermoplastics, thermosets and elastomers.

Nickel coatings are produced either by electroplating in accordance with DIN EN ISO 4526 or by chemical processes in accordance with DIN EN ISO 4527. In the case of electroplating, there is a risk of hydrogen embrittlement in fasteners with a hardness exceeding 390 HV. This necessitates specific measures (such as annealing), although these do not provide a 100 per cent guarantee against embrittlement.