Structural film adhesives resist moisture in the bond line and are extremely resistant to severe environmental exposure. F are now available. All are compatible with reinforcing fibers. G lass ceramics , polycrystalline solids produced by the controlled crystallization of glass, have highly desirable properties for service as matrix materials. Dimensional stability, thermal stability, heat resistance, corrosion resistance, and the ability to maintain strength at high temperatures make these materials attractive despite their inherent brittleness.
Failure occurs when the matrix viscosity becomes too low to transfer the load to the reinforcement.
Thermal compatibility between the matrix and fibers must be good. If the coefficients of thermal expansion are not similar, the brittle matrix will not comply with any differences. Also, the need for high forming temperatures to bring about matrix flow among the reinforcing fibers requires thermochemical compatibility between the fibers and matrix material to prevent reactions at the fiber-matrix interface that produce unwanted interphases that degrade the fibers and reduce their strength. A coupling agent , also known as a bonding agent or binder, provides a flexible layer at the interface between fiber and matrix that will improve their adhesion and reduce the number of voids trapped in the material. Voids , air pockets in the matrix, are harmful because the fiber passing through the void is not supported by the matrix.