When it comes to the performance of fiber-reinforced plastics, ensuring a good compatibility between the sizing and the polymer matrix is a crucial factor. In every sizing formulation, one of the key components is the film former. Our waterborne polyurethane dispersions are used as film formers for sizing to enhance the properties of both thermoplastic and thermoset applications.
- Waterborne PU dispersions as film former for superior fiber sizing
To fully exploit their ability to reinforce plastics, fibers are coated with sizing directly after production. Sizing has two important functions. First, it protects fibers and prevents damage to individual filaments during production and post-production operations such as handling, weaving or molding. Second, sizing ensures a compatible interface between the fiber and the resin matrix in composite parts. Sizing therefore has a significant effect on the mechanical properties of composites. Optimizations to sizing chemistry can have a vast influence on properties such as tensile strength, impact resistance, fatigue, thermal or hydrolytic stability. Fiber sizing formulations contain several chemical components; one of their main elements is the film former. Designed to protect and lubricate fibers, the film former holds fibers together before the composite is manufactured but it also enables their separation during impregnation with the polymer matrix.
To ensure an optimal fiber sizing composition, a film former should offer very good film-forming properties, dilutability and good shear stability. Characteristics such as polarity and compatibility with common sizing additives should also be considered for maximal formulating flexibility. For these needs as well as the specific requirements of composite technologies, we engineered our line of Baybond® waterborne polyurethane dispersions (PUDs). Our film formers include both polyester and polyether polyurethanes based on aliphatic isocyanates. Due to their unique structure, Baybond® film formers and crosslinkers offer a wide range of solutions tailored to individual customer requirements.