Multifunctional Polymer Composites Produced by Melt-Blown Technique to Use in Filtering Respiratory Protective Devices

Abstract

In this work, a multifunctional polymer composite is made using melt-blowing technology from polypropylene (88 wt.%) and poly (ethylene terephthalate) (12 wt.%) with the addition of functional modifiers, that is, 3 g of a superabsorbent polymer and 5 g of a biocidal agent (Biohaloysite). The use of modifiers is aimed at obtaining adequate comfort when using the target respiratory protection equipment (RPE) in terms of microclimate in the breathing zone and protection against harmful aerosols including bioaerosols. The developed production method is innovative in that the two powdered modifiers are simultaneously applied in the stream of elementary polymeric fibers by two independent injection systems. Aerosols of the modifiers are supplied via a specially designed channel in the central segment of the die assembly, reducing the amount of materials used in the production process and saving energy. The results show that the proposed method of incorporating additives into the fiber structure did not adversely affect the protective and functional properties of the resulting filtration nonwovens. The produced nonwoven composites are characterized by SEM, FTIR, and differential scanning calorimetry (DSC). Given their high filtration efficiency at 5%, satisfactory airflow resistance (~200 Pa), very good antimicrobial activity, and excellent water absorption capacity, the obtained multifunctional nonwoven composites may be successfully used in filtering respiratory protective devices.

Keywords: biocide; filtering nonwoven; melt-blowing technique; polymer composites; superabsorbent polymer.

Figure 1

Diagram of the melt-blowing setup for the fabrication of multifunctional polymeric composites. 1—polymer extruder, 2—fiber-forming head, 3—fiber-attracting nozzle, 4—fiber-embedding mesh, 5—carriage shifting the mesh perpendicular to the extruder axis, 6—trolley enabling the device to exit from under the fiber-forming head (for cutting off the sheet), 7—vacuum installation, 8—enclosure walls, 9—air filter with modifiers, 10—air heater, 11—perforated pipe for dust extraction, 12—electrostatic activator, 13—autotransformer supplying the lower head heater, 14—autotransformer supplying the upper head heater, 15—voltmeter, 16—polymer melt temperature indicator, 17—set of devices for introducing modifiers, 18—autotransformer supplying air heaters, 19—extruder control cabinet.

Figure 2

The process of applying two modifiers to the stream of elementary fibers in melt-blown technology. 1—fiber-forming head, 2—injector, 3—modifier dispenser plate, 4—tube transporting the modifiers to the fiber-forming zone, 5—mixed modifiers, 6—nonwoven layer, 7—modifier tank, 8—stirrer drive, 9—polymeric monofilaments, 10—compressed air inlet, 11—modifier intake suction nozzle.

Figure 3

SEM images of Biohaloysite. (a) Polymeric superabsorbent (SAP), (b) unmodificated nonwoven WSB₀, (c) nonwoven with functional additives WSB₁, and (d) at a magnification of 1600×.

Figure 4

Particle size of (a) Biohaloysite and (b) SAP.

Figure 5

Particle size histogram of fibers in nonwoven WSB₁.

Figure 6

FTIR spectrum for modifiers: SAP (1—Black line) and Biohaloysite (2—Red line).

Figure 7

FTIR spectrum of nonwoven based on polypropylene WP₀ (1—black line) and nonwoven WSB₀ (2—red line).

Figure 8

Thermograph of nonwoven with functional additives WSB₁.