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
Inventors
Reghu, Aravind • LIN, Jui Ming • Russell, James • Hammond, Jeremy
Assignees
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Publication Number
US-12352774-B2
Publication Date
2025-07-08
Expiration Date
Abstract
A method for determining the density of particles includes passing a carrier fluid and particles through a fractionation cell at a predetermined rate, where the carrier fluid has a predetermined density, the fractionation cell has a housing including a first axial end and a second axial end and the fractionation cell defines an interior carrier fluid flow-through channel, and an upper fluid outlet and a lower fluid outlet positioned below the upper fluid outlet, passing the carrier fluid and the particles through the upper fluid outlet and the lower fluid outlet, measuring a first concentration of particles passing through the upper fluid outlet, measuring a second concentration of particles passing through the lower fluid outlet, and determining a density of the particles based at least in part on the first concentration and the second concentration of particles.
Core Innovation
The disclosed invention provides a method for determining the density of particles by passing carrier fluid and particles suspended within the carrier fluid axially through a fractionation cell. The carrier fluid has a predetermined density and flows through an interior carrier fluid flow-through channel extending between a first axial end and a second axial end of a housing, and the fractionation cell defines at least an upper fluid outlet and a lower fluid outlet positioned below the upper fluid outlet in a vertical direction at the second axial end, with both outlets in fluid communication with the channel.
The method includes 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 and 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. The disclosed approach is described as a modified split flow thin (SPLITT) fractionation method for quality control of polymer particles in suspension by determining particle density.
Particle distribution between the upper and lower outlets is assessed by measuring first and second particle concentrations or flow rates from the two outlets, and particle density is inferred based on whether the concentrations or flow rates are unequal or about equal, corresponding to density differences relative to neutral buoyancy. Experiments using PMMA beads at different bead sizes are described as yielding particle densities closely matching manufacturer values under near-equal outlet particle concentration conditions.
Claims Coverage
The document includes one independent claim directed to a density-determination method using a fractionation cell with vertically spaced upper and lower outlets and measuring particle flow rates through both outlets. The dependent claims refine the density inference with comparative or about-equal flow-rate relationships and add structural and measurement specifics, including a separator wall and a concentration-based measurement variant.
Density determination by comparing particle flow rates at vertically spaced outlets
Passing carrier fluid and particles suspended within the carrier fluid axially through a fractionation cell at a predetermined rate, the carrier fluid having a predetermined density, passing the carrier fluid and the particles through an upper fluid outlet and a lower fluid outlet, measuring a first flow rate of particles through the upper fluid outlet and a second flow rate of particles 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.
Fractionation cell defining an axial flow-through channel and vertically positioned upper and lower outlets
Using a fractionation cell having a housing including a first axial end and a second axial end opposite the first axial end, the fractionation cell defining 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, with 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.
Separator wall between upper and lower outlets
The fractionation cell includes a separator wall that extends axially into the channel between the upper fluid outlet and the lower fluid outlet.
Mapping flow-rate inequality to particle density relative to carrier-fluid density
Determining whether the first particle flow rate is greater than the second particle flow rate and, in response, determining that the particle density is less than the density of the carrier fluid.
Mapping flow-rate inequality to particle density relative to carrier-fluid density
Determining whether the first particle flow rate is less than the second particle flow rate and, in response, determining that the density of the particles is greater than a density of the carrier fluid.
Neutral buoyancy mapping via about-equal outlet flow rates
Determining that the first and second flow rates are about the same and, in response, determining that the particle density is the same as the density of the carrier fluid.
Upper-outlet particle flow rate measured based on particle concentration
Measuring the flow rate of particles passing through the upper fluid outlet by measuring the particle concentration passing through that upper outlet.
Overall, the independent claim establishes particle density determination by measuring particle flow rates at an upper and a lower outlet of a SPLITT fractionation cell with a predetermined carrier-fluid density. The dependent claims refine the density determination using specific comparative or about-equal relationships between the two outlet flow rates and add optional structural and measurement limitations.
Stated Advantages
Fast
Accurate
Cost-effective
Higher-throughput than SdFFF
Closely matching manufacturer values for particle density under near-equal outlet particle concentration conditions
Documented Applications
Quality control of polymer particles in suspension by determining particle density using a modified split flow thin (SPLITT) fractionation approach.
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