Personal Protective Equipment (PPE), such as gowns, is a critical component of the hierarchy of controls used to protect people in medical environments (Reddy et al., 2019). Disposable isolation gowns are typically constructed of nonwoven materials or in combination with materials that offer increased protection from liquid penetration. They can be produced using a variety of nonwoven fibre-bonding technologies (thermal, chemical, or mechanical) to provide integrity and strength (Kilinc et al., 2015). The basic raw materials typically used for disposable isolation gowns are various forms of synthetic fibres such as polypropylene and polyethylene (Kilinc et al., 2015).
The most common materials in disposable isolation gowns are Polypropylene Spunbond and Polypropylene Spunbond-Meltblown-Spunbond (SMS), which are 3 layers of non-woven fabrics, are the most common materials in disposable isolation gowns. Non-woven materials are used more often than woven materials due to their lower propensity to produce lint or fluff which may become an infection source for patients.
Spunbond-meltblown-spunbond (SMS) materials are multi-layered fabrics, commonly used in medical gowns, face masks, drapes, and sterilization wraps. They are made of 100% Polypropylene.
The manufacturing processes for spunbond and meltblown non-wovens both start with a process called spun-melt, but then diverge to yield different types of fibres with different properties. Spun-melt creates nonwoven webs by heating thermoplastic polymers (e.g., polypropylene, polyester or nylon) and extruding them through a metal plate with a spinneret. This extrusion process is like a garlic press where the materials are pressed through a grate to create string-like fibres (Figure 1).
A. Spunbond Nonwoven Polypropylene
Spunbond fabrics are produced by extruding a melted polymer through a spinneret to form long thin filaments. These filaments (5 – 20 um diameter) are collected on a moving conveyor belt, where they form a fibrous web. The web of nonwoven fibres is then passed between two heated rollers, which thermally bond the web together to give it better strength and durability. (Figure 2). Table (x) shows other properties that spunbond fabrics exhibit from this process.
|· Soft, Lightweight, Breathable
· Good tensile Strength and Elongation.
· Excellent Resistance to moisture, temperature, and chemicals.
· Does not mould or deteriorate in the presence of bacteria or fungi.
· Extraordinary flexibility and drapeability
|· Lower melting point
· Poor filtration
B. Meltblown Non-woven Spunbond Polypropylene
Meltblown nonwovens start off with a spun-melt process like that of spunbond fibres. However, the process after filaments are extruded from the spinneret is different. , the extruded fibres are immediately subjected to high-velocity hot air streams coming from both sides of the spinneret. These rapidly moving streams of hot air hit the molten polymer at the edge of the spinneret and blow it into very fine filaments (~1 -5 μm diameter) (Songer et al., 2020). The rapidly moving air causes these fibres to break into shorter, discontinuous filaments, which are then randomly dispersed and collected into a web on the roll below (Songer et al., 2020).
Although made from the same raw stock as spunbond Non-woven Spunbond Polypropylene (), the structure of the meltblown material, and the size of the fibres are different. Meltblown fabrics have many ultrafine fibres for a given weight and create fabrics with large surface areas, which yields excellent filtration properties as well as good insulating properties. However, meltblown NWPP tears easily is harder to sterilize and may pose an inhalation risk. Table (x) details other properties that meltblown fabrics display.
|· a filter to fluids and bacteria
· efficient barrier against bacteria
· exceptional microbial barrier
|· tears easily
· harder to sterilize
· may pose an inhalation risk.
PrimeOn gowns in AAMI level 2, 3 and 4 are made of SMS material. Additionally, AAMI level 4 has been tested and met the test results of ASTM F671 (viral penetration) and ASTM F6170 (synthetic blood test).
Is SMMMMMS better than SMS?
Some products in the market are described as having multiple layers of melt-blown layers between the spunbond materials. Though this sounds good, it is not possible to differentiate between the different meltblown layers in the finished product as they end up combining together.
What is more important to consider is the thickness of the meltblown layers. A gown with 5 layers of 0.2 grams of meltblown will have the same effectiveness when compared with another gown with a single 1 gram meltblown layer. It is therefore best to judge the gown’s integrity and quality by the weight of its fabric.
Polyethylene is a very useful plastic and is used as a fibre to make such items as medical gowns Polyethylene is a lightweight, durable thermoplastic with a variable crystalline structure (Omnexus, 2021). and is made from the polymerization of ethylene (or ethene) monomer. Low-Density Polyethylene (LDPE) is a very flexible material with unique flow properties that makes it particularly suitable for gowns and other plastic film applications. LDPE has high ductility but low tensile strength, which is evident in the real world by its propensity to stretch when strained.
Polyethylene, like every other polymer, has advantages and disadvantages that make it more suitable for certain uses than others. These are listed in the table below.
|– Fluid Resistant
– High Resistance to corrosion*
|– Not breathable
– High flammability
– Susceptible to UV degradation
Our PrimeOn thumb-hook gowns are made of a polyethylene-film, has been tested and meets AATCC 42 (penetration of water) and AATCC 127 (penetration of water under hydrostatic pressure) and meets the AAMI PB70 standard.
Kilinc F. S. (2015). A Review of Isolation Gowns in Healthcare: Fabric and Gown Properties. Journal of engineered fibers and fabrics, 10(3), 180–190.
Mask Fabrics: Introduction to Fibers and Fabrics – MakerMask. (2021). Retrieved 12 March 2021, from https://makermask.org/mask-fabrics-101-introduction-to-fibers-and-fabrics/
Omnexus, (2021) Polyethylene (PE) Plastic: Properties, Uses & Application. Retrieved 5 April 2021, from https://omnexus.specialchem.com/selection-guide/polyethylene-plastic#:~:text=Polyethylene%20is%20a%20lightweight%2C%20durable,are%20produced%20worldwide%20each%20year).&text=Polyethylene%20is%20made%20from%20the,ethylene%20(or%20ethene)%20monomer.
Reddy, S., Valderrama, A., & Kuhar, D. (2019). Improving the Use of Personal Protective Equipment: Applying Lessons Learned. Clinical Infectious Diseases, 69(Supplement_3), S165-S170. doi: 10.1093/cid/ciz619
Songer, J., & Rizvi, S. (2020). Mask Fabrics: Introduction to Fibers and Fabrics. Retrieved 8 March 2021, from https://makermask.org/mask-fabrics-101-introduction-to-fibers-and-fabrics/