How to Optimize Mixing Polymers

Polymers are large molecules that are made of many repeating units called monomers. They can be natural, like cellulose, or human-made, like plastics. A mixture of two or more different polymers is called a blend. Mixing Polymers with EvenMix can help manufacturers achieve the performance they need to meet their production goals. In addition to cost savings, blending can provide better processing performance, mechanical properties, thermal behavior, and other physical properties than either of the individual polymers alone.

In order to optimize the performance of a blend, it is important to understand the chemistry of the materials and how they interact. To do this, researchers must perform a variety of tests to determine how the different polymers work together.

These tests can include mechanical testing, viscosity measurements, and thermal analysis. These data can be used to develop mixing rules that describe the relationship between the desired material properties and composition. The rules can be synergetic, meaning that the property increases with the volume fraction of the minor component, or non-synergetic, meaning that the property deteriorates.

Heterogeneous blending can be more challenging than homologous blending. Heterogeneous blending involves a miscible phase and an immiscible phase. The miscible phase is a crystalline or amorphous polymer; the immiscible phase is either a continuous polymer or a dispersed polymer. Heterogeneous blending is not well-suited to the use of mixing rules developed for homologous blends. This is because the Tg of a heterogeneous blend is a strong function of composition and can be asymmetric or broader than the Tg of the pure components.

The rheological characteristics of immiscible blends are also affected by the composition. This is because the morphology of a blended immiscible is that of spheres of the minor polymer dispersed in a matrix of the major polymer. This can cause the immiscible blend to have a higher viscosity than a sample of the major polymer. It can also result in a higher frequency response with respect to the major polymer, making the blend a more complex viscoelastic material.

A good way to improve the rheological properties of an immiscible blend is to add a compatibilizer. These are molecules that have hydrophobic and hydrophilic regions that can help to decrease the interfacial tension between the phases. Compatibilizers can also change the morphology of the mixture, helping to create a more disperse phase.

In terms of the mechanical properties of an immiscible blend, the spheres of the minor polymer in the matrix of the major polymer will tend to be bigger, because they are trying to minimize contact with the other spheres. The larger spheres can absorb more stress and energy, which can lead to improved mechanical properties.

For both homologous and heterogeneous blending, the mixing process can be improved by adjusting the composition to make the blend more compatible. This can be done by adding a co-solvent or by changing the chemistry of the materials themselves. Regardless of the chemistry, it is important to ensure that the mixing equipment is properly adjusted to the specific needs of the blend. This will help to prevent issues such as stringers and fisheyes from occurring during the manufacturing process.