Structure and properties of segmented polyamides

Abstract

Segmented polyamides composed of polyether and polyamide structural units are industrially very interesting thermoplastic materials of construction, having a broad spectrum of properties. The principal reason for this broad spectrum is the polyphase structure of the materials and the possibility of influencing this structure by choice of the ratio of oligoether to oligomaide as well as choice of the mean block lengths.

In general, three phases can be detected:

• 1. an amorphous phase, generally forming the matrix, of oligolactan sequences and oligoether sequences. The oligoether component produces internal plasticisation (a marked lowering of the glass transition temperature),

• 2. a discontinuous amorphous phase which essentially consists of oligoether structural units and acts as an internal toughener (glass transition far below room temperature), and

• 3. a crystalline phase of sufficiently well ordered lactam sequences. Its melting range is drastically shifted towards lower temperatures with increasing oligoether content of the total material.

In addition, at relatively high oligoether contents, a crystalline oligoether phase is at times encountered to a minor degree.

In part given as a lecture at the Makromoleulares Kolloquium, Freiburg/Br. 28.02.–02.03.1985.