Methods for determining the density of polymer particles for quality control materials using split flow thin (splitt) cell fractionation principle and fractionation cell for carrying out the methods

A method for determining the density of particles, the method comprising

• (a) passing a carrier fluid and particles suspended within the carrier fluid axially through a fractionation cell at a predetermined rate, wherein:
• the carrier fluid has a predetermined density;
• the fractionation cell has a housing including a first axial end and a second axial end opposite the first axial end and the fractionation cell defines:
• an interior carrier fluid flow-through channel extending between the first axial end and the second axial end;
• and
• at least an upper fluid outlet and a lower fluid outlet positioned below the upper fluid outlet in a vertical direction and the upper fluid outlet and the lower fluid outlet in fluid communication with the channel and positioned at the second axial end of the housing;
• (b) passing the carrier fluid and the particles through the upper fluid outlet and the lower fluid outlet;
• (c) measuring a first concentration of particles passing through the upper fluid outlet;
• (d) measuring a second concentration of particles passing through the lower fluid outlet;
• (e) determining whether the first concentration is greater than or less than the second concentration;
• and
• (f) in response to determining the first concentration is greater than or less than the second concentration, changing a predetermined density of the carrier fluid, and repeating steps (a)-(e).

A method for determining the density of particles, the method comprising

• passing carrier fluid and particles suspended within the carrier fluid axially through a fractionation cell at a predetermined rate, wherein:
• the carrier fluid has a predetermined density;
• the fractionation cell has a housing including a first axial end and a second axial end opposite the first axial end and the fractionation cell defines:
• an interior carrier fluid flow-through channel extending between the first axial end and the second axial end;
• and
• at least an upper fluid outlet and a lower fluid outlet positioned below the upper fluid outlet in a vertical direction and the upper fluid outlet and the lower fluid outlet in fluid communication with the channel and positioned at the second axial end of the housing;
• passing the carrier fluid and the particles through the upper fluid outlet and the lower fluid outlet;
• measuring a first flow rate of particles passing through the upper fluid outlet;
• measuring a second flow rate of particles passing through the lower fluid outlet;
• and
• determining a density of the particles based at least in part on the first flow rate and the second flow rate of particles.