Polymer Overview: How to Pump Polymers
Polymers form through the bonding of numerous small molecules called monomers, which can occur either naturally or synthetically, resulting in a compound composed of multiple (poly) molecules—polymers. Alternatively, one can liken polymers to a completed recipe comprising various components, akin to monomers. 
Examples of naturally occurring polymers are cellulose, proteins, silk and DNA. Synthetic polymers are obtained from petroleum bases and include rayon, nylon, polyester, Teflon and Polyethylene.
Natural and artificial polymers are bonded with a variety of chemicals to form new products which can be more durable through chemical reactions or vulcanization. Such processes typically require low shear, constant pressure without pulsations to feed mechanical equipment
During some processes, certain molecules such as lignin in wood cellulose are removed and starch in food processing.
Pump Selection Considerations for Pumping Polymers
Selecting a pump for pumping polymers in industrial applications requires careful consideration of several factors to ensure efficient and reliable operation. Polymers present unique challenges due to their flow behaviour, viscosity variability, and sensitivity to shear forces. Here are key factors to consider:
Viscosity and Shear Sensitivity: Polymers often exhibit unique flow behaviour, meaning their viscosity changes with shear rate. It is crucial to choose a pump capable of handling the varying viscosity of polymer solutions without causing excessive shear, which could degrade the polymer chains and alter its properties. Positive displacement pumps, such as progressive cavity pumps or peristaltic pumps, are commonly used for pumping polymers due to their gentle handling and ability to maintain consistent flow rates.
Material Compatibility: Polymers come in various forms, including aqueous solutions, suspensions, or melts, each with different chemical compositions. The pump materials must be compatible with the specific polymer being pumped to prevent chemical reactions, contamination, or degradation. Stainless steel, polypropylene, or other corrosion-resistant materials are often used for pump construction to ensure compatibility with a wide range of polymers.
Abrasion Resistance: Some polymers, particularly filled or reinforced polymers, can be abrasive and cause wear on pump components. Selecting a pump with abrasion-resistant materials, such as hardened steel, Stainless Steel, Hastelloy or ceramics, can extend the pump's lifespan and reduce maintenance requirements in abrasive polymer pumping applications.
Temperature Control: Polymers may be sensitive to temperature changes, which can affect their viscosity and flow properties. Consideration should be given to the temperature control requirements of the polymer solution and whether the pump needs heating or cooling capabilities to maintain optimal viscosity and flow characteristics.
Flow Rate and Pressure Requirements: Determine the required flow rate and pressure for the polymer pumping application to select a pump with the appropriate capacity and performance capabilities. Positive displacement pumps offer precise control over flow rates and are often preferred for polymer pumping applications requiring accurate dosing or metering.
Maintenance and Reliability: Evaluate the ease of maintenance and reliability of the pump, considering factors such as accessibility of components, seal integrity, and the pump's history of performance in similar polymer pumping applications. Regular maintenance, including cleaning and inspection of pump internals, is essential for preventing downtime and ensuring continued reliability.
By carefully considering viscosity and shear sensitivity, material compatibility, abrasion resistance, temperature control, flow rate and pressure requirements, and maintenance needs, industrial operators can select the most suitable pump for pumping polymers in their specific applications, ensuring efficient and reliable polymer handling.
To discuss your polymer pumping requirements with a process specialist – get in touch.
