Synthetic polymers are usually produced from hydrocarbon monomers through polymerization reactions, with the end product being a resin in powder, flakes or pellet form. A variety of additives are then added to the resin to modify or to obtain desirable properties. The compounded resin can then be processed - melted and shaped to a final product through molding, extrusion, or other conversion process.
In selecting a polymer for an end-product application, there is usually a balance between performance and its ability to be processed. To optimize the melt processing of polymers, a variety of chemical and engineering properties are usually determined, to ensure the processability criteria are met. The quality of a finished part is assessed based on its ability to perform end-use service functions, which could involve load-bearing, barrier properties, high temperature, or chemically aggressive environment.
It is therefore usually desirable for a polymer or compound to be characterized in a melt state, typically under conditions similar to when being processed– temperature, pressure, deformation rates, etc., and frequently in a solid state , in powder or pellet form, or as a representative sample from a solid processed part.
Material characterization tools from Malvern Instruments employ a range of technologies for meeting these analytical needs: Capillary and Rotational rheometers are used for melt rheological characterization and DMA testing of polymer in solid state. Laser Diffraction for particle size and distribution of resin powder, GPC for MW and MWD, and Imaging Systems for size and shape of resin powder or pellets.