thermosettingadj.

1929 Brit. Plastics & Moulded Products Trader June 24/2 Thermoplastic mouldings..comprise substances which go through a process of thermo-setting on the application of heat and pressure.]

1931 British Plastics Yearbk. 74 Thermo-setting plastics, those compositions that though thermo-plastic in the first instance, harden off rapidly under the influence of heat.

1937 Jrnl. Royal Aeronaut. Soc. 41 525 Some kinds of synthetic resins and to a limited extent one natural resin (shellac) have the valuable characteristic of being ‘thermosetting’, i.e., when once moulded they set to permanently infusible products. Most resins are ‘thermoplastic’, i.e., they become soft whenever the temperature exceeds a certain value.

1951 Archit. Rev. 109 166/2 Hardness and resistance to scratching and heat..is one of the main advantages of the thermo-setting plastics.

1973 J. M. G. Cowie Polymers i. 19 The thermoset plastics generally have superior abrasion and dimensional stability characteristics compared with the thermoplastics which have better flexural and impact properties. In contrast to the thermoplastics, thermosetting polymers..are changed irreversibly from fusible, soluble products into highly intractable crosslinked resins which cannot be moulded by flow.

1982 M. Duke Flashpoint xviii. 134 The thermosetting polyurethane plastic floor.

1983 Daily Tel. 12 Dec. 19/3 The inclusion of fillers, particularly metallic ones, in thermosetting plastics is a known and recognised practice for reducing and dissipating exotherm.