Rubber toughening and damage competition theory. In material selection it is important to look at the interaction between the matrix and the secondary phase. For example, crosslinking within the rubber phase will promote high strength fibril formation that will toughen the rubber, preventing particle fracture. Carboxyl-terminated butadiene-acrylotnitrile (CTBN) is often used to toughen epoxies, but using CTBN alone increases the toughness at the cost of stiffness and heat resistance. Amine-terminated butadiene acrylonitrile (ATBN) is also used. Using ultra-fine full-vulcanized powdered rubber (UFPR) researchers have been able to improve all three, toughness, stiffness, and heat resistance simultaneously, resetting the stage for rubber toughening
Rubber toughening viable option for practical applications in architecture and car manufacturing as a substitute for glass when high transparency is necessary. Incorporating a rubber filler phase increases the toughness. Such fillers need to form strong interfacial bonds with the PMMA matrix. In applications where optical transparency is important, measures must be taken to limit light scattering. It is common in toughening PMMA, and in other composites, to synthesize core-shell particles via atom-transfer radical-polymerization that have an outer polymer layer that has properties similar to those of the primary phase that increases the particle’s adhesion to the matrix. Developing PMMA compatible core-shell