Mixing Polymers With a Tote

Mixing Polymers with EvenMix is the process of combining two or more different types of polymer materials in order to achieve desired physical properties. Combining polymer materials can create a material that is stronger or more flexible than either of the individual components alone. Mixing can also increase the flowability of a material or make it easier to process. There are a number of ways to combine polymers, such as dissolving them in the same solvent, extruding them together through an injection molding machine, or melting them and pouring them into a mold. Polymer blending is one of the most important processes in the plastics industry because it allows manufacturers to develop new materials that offer better performance than existing ones without investing in the cost and time to develop new equipment.

Blending can improve the performance of many different materials and help meet market demands for improved strength, flexibility or other properties. There are a number of challenges to successful blending, however, including the difficulty of bringing immiscible mixtures back to uniformity after settling or stratifying. These issues can be overcome with the use of portable mixers, specifically designed for tote applications.

A common technique for combining polymers is solution blending. This is the most common method for producing commercially useful materials because it is relatively simple and cost effective. Solutions can be made from almost any combination of soluble polymers. The most commonly used solutions are polyethylene terephthalate (PET) and polyvinyl alcohol (PVA), although other combinations are used as well.

Immiscible polymer blends are difficult to prepare and control, not only because of their high viscosity, but also because of thermodynamic reasons. The entropy of mixing that so easily drives the mixing of small molecules becomes much smaller for high molecular weight materials. In addition, the interfacial tension tends to regulate one phase’s dispersion into another, so that a given spatial arrangement is stable under certain conditions but changes dramatically when these conditions change.

In a typical immiscible blend, the PVA particles tend to be deposited in small spheres on top of the PET. When the mix is processed under flow, the spheres become rods that extend away from the center of the mixture and act like the fibers of a composite material. These rods make the mixture stronger in the direction that the flow is going, but weaker in the opposite direction.

To make a strong immiscible blend, the ratio of the two polymers must be very closely controlled. If the ratio is too large, the result will be a tough and brittle blend with poor processing properties; if the proportion is too small, the resulting mixture will have no mechanical strength. A good way to estimate the optimum ratio is to study the frequency response of the mixture with rheology equipment, such as a parallel plate or steady-state rheometer, and then compare the results to the predicted values. This is possible because the rheological properties of blends can be modeled with lattice theory.