ABSTRACT
Polymer toughness has attracted a great deal of creative and resourceful attention from researchers for some time. The bulk of that attention has been directed at composites and bulk materials, and very little has been directed at coatings. The various combinations of flexibility and hardness that one typically associates with toughness are commonly expressed by the terms formability or postformability, fab-ricability, processability, impact resistance, and chip resistance. The chapter aims to review some of the relationships between structure and coating toughness of ther-moset polymers and to show how toughness is revealed in thermomechanical measurements. The conventional method of determining the ultimate elongation of coatings is by application of the Instron tensile test to free films of the coatings. The link between coating flexibility (Tg) and coating formability is more complex. The Tg or flexibility of a thermoset is sensitive to variations in molecular structure of both the polymer and cross-linker components of the cured system and to crosslinking.
