Abstract: The invention relates to a polyamide-imide containing recurring units according to the formula ##STR1## where Y is an arylene group, andR and R' are alkylene groups, in which at least 50 mole % of R and/or R' is a butylene group.The polyamide-imides are semi-crystalline.They are suitable for injection moulding applications, structural moulded parts, films, coatings and fibres. They can preferably be used in fields of application where temperatures above 200.degree. C. occur.

Abstract: The invention relates to a polyimide substantially built up from monomeric units of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and monomeric units of a primary aliphatic diamine. The polyimide according to the invention is characterized in that the primary aliphatic diamine is substantially 1,4-diaminobutane. The thermal stability of the polyimide according to the invention has surprisingly been found to be very good. Owing to this very good thermal stability, the polyimides according to the invention can very well be processed at--relatively--high processing temperatures without any appreciable thermal degradation of the polyimide. As a result, the polyimides processing potential has increased considerably. Also, articles made of the polyimides according to the invention can be used at significantly higher temperatures. Said articles have very good mechanical properties. Articles containing a polyimide are suited for being used in the most diverse applications.