In most cases, melt mixing two polymers results in blends that are characterized as weak and brittle. Incorporation of a dispersed phase into a matrix mostly leads to an evolution of stress concentrations and weak interfaces, which are directly linked to poor mechanical coupling between phases. Impact resistance and elongation to break tend to suffer dramatically, and overall mechanical performance is less than the individual components. Likewise, in coextrusion the adhesion between two polymers hinges on the level of compatibility between them.
Compatibilizers are the answer. These are additives designed to act at the interface between two incompatible polymers. In the case of blends, the result is smaller dispersed domain size that in turn, brings about large improvements in mechanical properties.
In recent years, compatibilization of blends has become even more important due to a surge in recycling where blends are the rule because it is impractical to completely separate the plastic waste stream. Furthermore, compatibilization has facilitated a rash of commercial blends that play a vital role in the polymer industry. In co-extrusion compatibilzers can replace tie-layers and prevent delamination through enhanced adhesion.
A small amount of the correct compatibilizer can elevate the performance of a formulation to a new level. However, the design of these additives is not trivial. Their chemistry must be tuned such that they interact well with both polymer phases and molecular weight must be selected to encourage diffusion to the interface. This requires exact molecular control and expertise. That is where Cray Valley comes in. With decades of experience and a powerful chemical toolkit, we can provide drop-in or custom solutions to maximize the performance of your products.
Cray Valley has experience in commercially viable blends such as PA-ABS and PA-PPE. In both cases, the appropriate selection of chemistry enhanced the mechanical properties of the blend. Anhydride containing product lines, Ricon®, provide solutions to incompatibility and can by a drop-in differentiating solution.