Melt blowing is a conventional fabrication method of micro- and nanofibers where a polymer melt is extruded through small nozzles surrounded by high speed blowing gas. The randomly deposited fibers form a nonwoven sheet product applicable for filtration, sorbents, apparels and drug delivery systems. The substantial benefits of melt blowing are simplicity, high specific productivity and solvent-free operation. Choosing an appropriate combination of polymers with optimized rheological and surface properties, scientists have been able to produce melt-blown fibers with an average diameter as small as 36 nm.

History

During volcanic activity a fibrous material may be drawn by vigorous wind from molten basaltic magma called Pele's hair. The same phenomenon applies for melt blowing of polymers. The first research on melt blowing was a naval attempt in the US to produce fine filtration materials for radiation measurements on drone aircraft in the 1950s. Later on, Exxon Corporation developed the first industrial process based on the melt blowing principle with high throughput levels. China produces 40% of the non-woven fabric in the world with the majority produced in

Hebei Hebei is a Provinces of China, province in North China. It is China's List of Chinese administrative divisions by population, sixth-most populous province, with a population of over 75 million people. Shijiazhuang is the capital city. It bor ...

province (2018).

Polymers

Polymers with thermoplastic behavior are applicable for melt blowing. The main polymer types commonly processed with melt blowing: *

Polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene. Polypropylene belongs to the group of polyolefin ...

Polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...

Polyesters Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...

Polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...

Polyamides A polyamide is a polymer with repeating units linked by amide bonds. Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made throug ...

(

nylon Nylon is a family of synthetic polymers characterised by amide linkages, typically connecting aliphatic or Polyamide#Classification, semi-aromatic groups. Nylons are generally brownish in color and can possess a soft texture, with some varieti ...

s) *

Polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

Polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...

Process

Melt blowing is a manufacturing process used to create

nonwoven fabrics Nonwoven fabric or non-woven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing ind ...

and materials. It is particularly known for its ability to produce fine fibers, which can be used in various applications. Here's an overview of how melt blowing works: * Melt Extrusion: The process begins with a polymer resin being melted and extruded through a spinneret, which is a device with tiny holes. * High-Speed Airflow: Simultaneously, high-speed hot air or gas is blown onto the extruded polymer streams. * Fiber Formation: The force of the air stretches and elongates the molten polymer into very fine fibers, which are then collected on a moving conveyor belt or drum.

Uses

The main uses of melt-blown nonwovens and other innovative approaches are as follows.

Filtration

Nonwoven melt-blown fabrics are porous. As a result, they can filter liquids and gases. Their applications include water treatment, masks, and air-conditioning filters. During the COVID-19 pandemic, the price of meltblown spiked from few thousand USD per ton to approximately 100 thousand USD per ton.

Sorbents

Nonwoven materials can retain liquids several times their own weight. Thus, those made from polypropylene are ideal for collecting oil contamination.

Hygiene products

The high absorption of melt-blown fabrics is exploited in disposable diapers and feminine hygiene products.

Apparels

Melt-blown fabrics have three qualities that help make them useful for clothing, especially in harsh environments:

thermal insulation Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...

, relative moisture resistance and breathability.

Drug delivery

Melt blowing can produce drug-loaded fibers for controlled

drug delivery Drug delivery involves various methods and technologies designed to transport pharmaceutical compounds to their target sites helping therapeutic effect. It involves principles related to drug preparation, route of administration, site-specif ...

. The high drug throughput rate (extrusion feeding), solvent-free operation and increased surface area of the product make melt blowing a promising new formulation technique.

References

{{reflist

External links

What is Melt-Blown Extrusion and How is it Used for Making Masks?
Polymer physics Nanomaterials