Polymer Rheology for Meltblown Processing
topic
Meltblown polymer rheology requires low-viscosity melt flow index resins of 400 to 1500 grams per 10 minutes for polypropylene compared to 35 grams per 10 minutes for spunbond grades, achieved through controlled molecular weight degradation by peroxide addition or selection of specifically polymerised meltblown grade resins, with the low viscosity enabling the high attenuation ratios needed to produce micron-diameter fibres from 0.3 millimetre die orifices.
Role
Governs the achievable fibre diameter and production throughput of meltblown systems through polymer melt viscosity that must be sufficiently low for the air jet to attenuate the extruded melt to micron-diameter fibres without fibre breakage and shot formation that would create web defects, with polymer grade selection and melt temperature management being the primary rheological process parameters for achieving fine fibre production at target throughput rates.