Aayushee Ghorpade

Veermata Jijabai Technological Institute,Mumbai


Compression garments (such as bandages and compression sleeves) are extensively used in varied sports(improved blood flow, better muscle oxygenation, reduced fatigue, faster recovery, reduced muscle oscillation and reduced muscle injury) and medical applications, involving the treatment and prevention of deep vein thrombosis, leg ulceration, varicose veins, burns (scar management) and lymphedema. They are required to exert a required amount of compression when applied at a constant tension.

Lymphatic system is a subsystem of the circulatory system that comprises a complex network of vessels, tissues, and organs. This system helps maintain fluid balance in the body by collecting excess fluid and particulate matter from tissues and depositing them in the bloodstream and also helps defend the body against infection by supplying disease-fighting cells (white blood cells) called lymphocytes.

Lymphedema is the condition caused by a blockage in the lymphatic system, part of the immune or circulatory systems and also by lymph node removal or damage due to cancer radiation.

The main symptom is swelling in an arm or leg that may be accompanied by pain or discomfort.

An intelligent and evolved technology is the compression treatment which puts even pressure on the area of swelling but needs to be firm on the tissues in the area, reducing the swelling. The pressure helps the trapped lymph fluid to flow through the lymph vessels.

The parameters involved in the selection of yarns are :

  • Elastic recovery or Resilience
  • A low density (for producing light weight fabric)
  • High extensibility
  • High tensile strength or tenacity or low modulus(dry tenacity as well as wet tenacity)
  • Good abrasion and wear resistance
  • Finer yarn count (for small pore size in the fabric)
  • Moderate Moisture absorbency (for sweat to percolate)
  • Resistant to alkali,bases and bleaching agents(must not degrade during washing) and microbial attacks.
  • Can be dyed in most dyestuffs (for aesthetic advancement).
  • Good light and washing fastness (must not degrade when exposed UV radiation and washing).
  • High Dimensional Stability(moderate stiffness)
  • Cost of the fibre and low cost manufacturing of the yarn.
  • Mostly multifilament or multicomponent yarns( eg-Spandex and cotton) are preferred,instead of spun yarns(to avoid hairiness and pilling tendency).

Fibres used for the fabrication of compression garments are :

Polyamides (Nylon), elastomeric yarns and cotton.

Why Polyamides?

Polyamides are basically Nylon i.e. Nylon 6,Nylon 6,6 and recently developed Nylon 7,Nylon 11,Nylon 12.

The properties that they inherit are :

  • Finer Tex(3.3Tex onwards)
  • Low Density(1.15 g/cc)
  • High dry tenacity(6-9 g/d)
  • High Elastic recovery(100%)
  • Stiffness(29-48 g/d)
  • Good impact and wear resistance
  • Moisture absorbency( at 65%rh 8%)
  • Excellent resistance to biological attacks,alkalis and bases(pH 4-14) and UV radiation
  • Can be dyed in all dyestuffs.
  • Manufacturing of nylon yarn : Nylon yarns are extruded and extracted by solution or melt spinning.

Why elastomers?

Elastomeric fibres involve Polyurethanes under the name of Spandex(85% polyurethane), Lycra,Vyrne, Prelon U.

Some recent developments include Anidex.

The properties that they inherit are :

  • Finer yarn count(2.2 Tex-7.8 Tex)
  • Elongation at break (greater than 200% i.e. 400% to 800%)
  • High Elastic recovery (99% at 200% extension)
  • Moderate tenacity(0.5-1.2 g/d)
  • High Toughness index(2.4-2.8 g/d)
  • Low density(1-1.05 g/cc)
  • Moderate Moisture absorbency (1.3%)
  • Resistant to peroxide bleaches and alkalis
  • Resistant to UV radiation, but photo stabilizers are added for enhancement in protection from UV radiation, along with providing color stability.
  • Can be dyed in all dyestuffs.

Manufacturing of elastomeric yarn :

Elastomeric yarns can be manufactured by melt spinning, dry spinning, wet spinning or chemical reaction spinning for extrusion of finer filament yarns.

The manner in which the clothing material interacts with the human body and the degree of clothing pressure depends on the following parameters :

  • The size and shape of the body part to which it is applied
  • Physical features of the materials (Fibres and yarn)
  • Garment construction (Knitted is more preferred than woven)
  • The type of activity involved .
  • The garment pressure,depending on the way it stretches and compresses with regard to the fabric structure thereby incorporating different design structures to custom-make a compression garment with a specific pressure.
  • High breaking elongation
  • High Fabric elasticity
  • High Bursting strength(optimum pressure bearing capacity)
  • High Shear Strength
  • Appropriate Bending Modulus (For fabric dimensional stability)
  • High Durability(best till 6 months if used on daily basis)
  • Porosity of the fabric (pore size can be adjusted)
  • Small pore size for Air permeability(breathability) and water repellency(size of the pore is small enough so that no water percolates).
  • Finishes used for applied on the Fabric for water repellency.
  • Resistant to abrasion
  • Thermal insulation in cold climates[normal filament(25%-65%) and high tenacity filament(15%-28%).
  • No. of layers (double-layered construction provides a larger range of target pressure at a particular strain than single layered fabrics)

Why have knitted fabric replaced woven ones?

Knitted Fabrics by Flat Knitting or Circular Knitting(for tubular structures) made from Nylon/Spandex are open structure exhibiting dimensional stability(Spandex only being present in the wale direction for dimensional stability) are more preferred as compared to woven fabrics as loops in the knitted garments have extensibility(upto 200%),high elastic recovery(more than 95%),high breaking load (above 200 N),high bursting strength and enhanced durability(upto 2 years), thereby assisting adequate fit and uniform pressure application along the circumference of the human body part.

Knitted fabrics assist in better comfort properties comprising superior  heat–moisture comfort, tactile comfort, pressure comfort providing water vapor and air permeability and thermal insulation.

Pressure application by compression garments :

Human skin can be extensible from 20 to 200 % due to physical movement.

An appropriate compression garment affects the energy level, work efficiency and health of the wearer. Insufficient pressure will limit the efficiency, and perhaps reduce the aesthetic appeal of the garment, while too much pressure will result in reducing heart and lung functions, and perhaps cause serious damage to health.

The pressure application is tested by the PicoPress® pressure sensor (for single point) and FlexiForce pneumatic pressure sensor (for all points).

The garment pressure is divided into static pressure and dynamic pressure.

Static pressure is defined as the pressure exerted on a special area of the human body when the compression garments have no additional deformation, while dynamic pressure is defined as the pressure exerted during the multi-dimensional deformation of compression garments.

The Laplace formula computing the pressure exerted by compression garments covering a cylindrical body part(circular cross section), is given by the ratio of the tensile force to circumference for a given fabric.

However, knit compression garments having variable curvature radii exert required unit pressure along the individual body part with higher curvature radii(due to swelling).

Pressure in mmHg : [Tension in KgF x No. of layers x 4620]

                                    / [circumference in cm x Compression garment width in cm]

However, majority of the fabrics lose a considerable amount of their initial tension overtime owing to fabric fatigue that leads to decrease in applied pressure after repeated wear and laundering.

Stitch length also affects the interfacial pressure resulting in an eventual decrease of pressure application over a prolonged period.

High stretch fabrics due to a high percentage of elastic yarns have increased wale-wise elasticity but also undergo serious stress relaxation problems under constant deformation, resulting in pressure degradation.

Also, decrease in elasticity in course wise direction is due to missing yarn

But, the elasticity in either direction decreases due to overlapping of yarn.     

Types of compression techniques :

A compression sleeve may be enough for mild lymphedema, but for more advanced cases bandaging is needed before a compression sleeve can be used.

Compression Sleeves :

Sleeves apply a resting pressure which is higher when the arm is at rest. When you move your arm, the elastic fabric moves right along with it, which actually reduces the amount of pressure.Compression sleeves require high extensibility and high stretchability. 

Compression bandages and its synthesis :

Bandaging is a mainstay of treatment for stage 2 and stage 3 lymphedema (moderate to severe lymphedema).Bandages work differently than compression sleeves, which support the flow of lymph in the right direction but don’t decongest (move fluid out of) the limb.

Bandaging can be single layered(for moderate) or multi-layered[MLLB] (for severe) depending on the severity of lymphedema.

Bandaging involves creating a soft padding enclosed by a dense foam layer made of polyester, cotton, or foam on the arm or upper body,followed by wrapping with multiple overlapping layers of short-stretch bandage in all sizes.,that are comprised of nylon,cotton and spandex as the basic component(yarns) and flat knitted to get the desired length,thickness and design.Generally, there would be more layers further down on the limb and fewer layers higher up, creating graded pressure that helps fluid move up and out of the arm.

Cotton is usually used for soft padding as it has a high moisture regain(8.5%),high tenacity(9-13 g/d) and is resistant to microbial attacks.

Market Share :

The size of the global compression garments and stockings market is valued at USD 2916.8 Million in 2020 and is estimated to grow at a CAGR of 5.35 % and will reach USD 3785.7 Million by 2025.

References :


Post a Comment