BLOG 4: What is the elasticity of a bandage? What are the differences between extensibility and elongation?

BLOG 4: What is the elasticity of a bandage? What are the differences between extensibility and elongation?

In previous posts we have discussed the different characteristics of a bandage, among which is elasticity. Speaking generally, elasticity is: “the ability of a material or substance to return to its original shape, size and condition after it has been stretched.”

 

How is the elasticity of a bandage calculated?

 

Elasticity is the property of a bandage to stretch and return to its original position after the force that stretched it has ceased to act. The elasticity of a bandage gives it the ability to deform to form a bandage in an area that is uneven in shape, such as the elbow or knee. In this way, a bandage, thanks to its elasticity, can modify its length at different points of the area where it is being applied.

 

If a bandage were made of an inelastic fabric, there are regions where there would be folds, since in areas of complex shapes it would not adapt itself correctly. In contrast, an elastic fabric can change its length and adapt itself depending on the needs of the shape.

Figura 4.1 Elaboración propia: Posición inicial; tracción larga estirada; tracción corta estirada

Figure 4.1 Prepared by Carlos Izquierda S.L.: Initial position; stretched long-stretch; stretched short-stretch

The way to calculate the elasticity of a bandage in Europe is given by EN 14704-1:2005 which is calculated by the following formula:

Figura 4.2 British Standard BS EN 14704-1-2005 Determination of the elasticity of fabrics (BSi)

Figura 4.2 British Standard BS EN 14704-1-2005 Determination of the elasticity of fabrics (BSi)

S (%): Elasticity of the bandage in %.
E (mm): Maximum length in mm after stretching it to its maximum extension 5 times
L (mm): Initial length of bandage in mm without being stretched

From here we see that the elasticity is measured in percentage (%).  For example, using a bandage of 5 meters initially and without stretching, if after the five cycles of maximum stretching it has a length of 10 meters, the elasticity of the bandage would be 100%.

 

What is elongation?

 

When we talk about the elongation of a bandage, it is exactly the same as elasticity. Analyzing the European standard DIN 53504, this is confirmed. In fact the formula for the calculation of elongation is the same as for elasticity.

So when we talk about the elongation of a bandage or the elasticity of a bandage, we are referring to the same thing.

 

Extensibility of a bandage

 

Technically speaking, the extensibility is the property of the bandage to stretch to the point of rupture, hence its extensibility will be given by the point before that rupture occurs. But we must be careful since there is a clear difference between this and elasticity. While elasticity means the stretching and the return of the bandage to its usual position if there are no forces that stretch it, extensibility is not the same thing and only involves the maximum stretching capacity.

 

This is due to the fact that from the point of maximum elasticity to the point of maximum extensibility the bandage deforms and does not return to its original position even if there are no forces applied to it. If the maximum elasticity is exceeded by 10%, this is not recovered and the bandage without forces applied will have 10% more length. In other words, once the maximum point of elasticity is exceeded, extensibility begins, and it does not recover its original shape. The extensibility is measured until the fibers break.

 

In any case, these are technical and theoretical definitions; in everyday life, it is common to refer to elasticity, elongation and extensibility as synonyms.

 

No mention has been made of how to classify bandages according to their elasticity. As a simplification, since there is no consensus on the matter, a possible classification would be as follows:

 

  • Inelastic bandages: elasticity < 10%
  • Elastic bandages: elasticity >10%. Within this category we would also have:
    • Short-stretch bandages: elasticity between 10% and 100%
    • Long-stretch bandages: elasticity greater than 100%

 

However, as we have just mentioned, this is only an approximation based on the categorization made in the European standard DIN 61632 “Verbandmittel” (1985).

Figura 4.3: DIN 61632 Verbandmittel. Idealbinden

Figura 4.3: DIN 61632 Verbandmittel. Idealbinden

To conclude, it is worth mentioning that no reference has been made at any time to the compression of the bandage. This is because the elasticity of the bandage and the compression it exerts depend on other factors, as we will see in future posts on compression.

 

Prepared by the technical department of Calvo Izquierdo S.L.

with the collaboration of Carmen Alba Moratilla

Bibliography:

 

  • https://www.collinsdictionary.com/dictionary/english/elasticity
  • British Standard BS EN 14704-1-2005 Determination of the elasticity of fabrics (BSi)
  • http://oa.upm.es/38763/1/Manual_%20textiles2021.pdf
  • https://www.sciencedirect.com/topics/engineering/stretch-bandage
  • EN 29073-3 look for this standard. It is the test methods for textiles and you will find useful information.
  • DIN 61632 Verbandmittel. Idealbinden. Berlin, Wien, Zu ̈ rich: Beuth Verlag; 19
  • Partsch H, Clark M, Mosti G, Steinlechner E, Schuren J, Abel M, et al. Classification of compression bandages: practical aspects. Dermatologic Surgery 2008;34(5):600-9. [PUBMED: 18261106]
WE EXPAND THE PRODUCTION CAPACITY AT CALVO IZQUIERDO, SL

WE EXPAND THE PRODUCTION CAPACITY AT CALVO IZQUIERDO, SL

CALVO IZQUIERDO SL has been expanding its production capacity for months. This allows us to provide a better service to all our customers around the world.

Our objective has always been the same, to provide our clients with a high quality product at a competitive price.
For this expansion in the CALVO IZQUIERDO, S.L. through the line “Aid for investments to improve the competitiveness and sustainability of industrial SMEs in the sectors of the Comunitat Valenciana, within the third phase of implementation of the Strategic Plan of the Valencian industry for the year 2020″, convened by the CONSELLERIA DE CONOMINA SOSTENIBLE, SECTORS PRODUCTS, TRADE AND LABOUR” has received a grant of 40. 40,952.73 for the execution of the project “Expansion of the production capacity of the company Calvo Izquierdo, S.L.”.

BLOG 2: What types of yarns are used in bandages?

BLOG 2: What types of yarns are used in bandages?

As we mentioned in the previous post, bandages are made up of yarn, either a single type of yarn or several types of yarn. All of them are normally interwoven transversely and longitudinally to form the bandage fabric.

Yarns are usually divided into two main families. Thus we find natural yarns, those that come from plants or nature, and synthetic yarns, which are manufactured artificially and come from petroleum.

Natural yarns

Regarding natural yarns, the most commonly used in bandages are cotton and viscose. Cotton is a natural fiber and does not generate allergies. Some of its main characteristics are that it is biodegradable, its absorption capacity is low and it gives body to the bandage fabric. To achieve a higher absorption capacity, cotton must undergo a hydrophilization process.

Cotton is found in a wide range of bandages, among which are crepe bandages, cohesive bandages or compressive bandages. Its main disadvantage is that it has a higher price than synthetic or viscose yarns.

Viscose is noted for its ability to absorb liquids—superior to that of cotton—and it does not generate allergies. It is mainly used to retain those liquids and keep the covered area dry. It has elastic and resistant properties very similar to cotton but at a lower cost.

In recent years, other natural yarns are being experimented with such as bamboo yarn, which is antibacterial. Calvo Izquierdo has already developed a research project on this material and is looking into how to introduce it in bandages and socks.

Continuing with natural yarns, we have another group where the yarn itself has compressive properties due to its elasticity.  The most commonly used material is natural rubber. This yarn comes from latex and is very elastic. It is widely used in the manufacture of highly elastic bandages, although it has two disadvantages. The first is that it is a very thick yarn; the other is that it contains latex, which can cause allergies when in contact with the skin. For this reason it is a yarn that is no longer used in the healthcare sector.

Synthetic yarns

Synthetic yarns are usually derived from petroleum and there are different yarns for different uses.

Polyester is inelastic and is heavily used in common fabrics such as shirts, sheets, table linen, etc. due to its low cost. It is a continuous fiber that when extracted from petroleum is a very fine yarn, so it is not worked alone but grouped in a set of filaments (28 filaments or 120 filaments for example).

In addition, we have yarns that only provide elasticity to the bandage, such as polyamide and polybutylene terephthalate (known in the industry as PBT).

Polyamide is a synthetic yarn derived from petroleum, which is elastic and consists of many long and very fine fibers. It has a high elastic capacity and is present in many bandages such as support or cohesive bandages. An example of a synthetic polyamide is Nylon.

 

Prepared by Calvo Izquierdo S.L.

PBT is a variation of polyester that also provides elasticity to bandages but without endowing them with compressive properties on their own. PBT is now becoming popular because it has very similar properties to polyamide but is less expensive.

Elastane is used as a substitute for elastic or natural rubber yarn. In 1958, elastane yarn, developed by the DUPONT company, was introduced under the brand name Lycra. Elastane is known in the US as Spandex. This yarn, being a petroleum derivative, does not contain latex but has properties very similar to natural rubber, making it a very suitable substitute to avoid latex allergies. As a result, elastane is increasingly being marketed and used in sanitary bandages. This is what is commercially called technical yarn.

Yarn-free fabrics

Finally, and so as not to leave out any type of fabric used in the most common bandages, we have the nonwoven fabric bandages. These bandages consist of a mixture of synthetic materials (such as polyester and polyamide) and in some cases natural yarns. Yarn-free fabrics also have the property that they are thermoweldable, that is, at a certain temperature the synthetic fibers fuse and remain joined with each other. Natural fibers are not welded. The welding is done by taking fibers of between 1 and 3 cm long and other microscopic fibers that are sprinkled on the larger fibers. Once the two have been put together, pressure and heat are used to create a product that is known as nonwoven (NWF).

As we have been able to observe, there are a number of yarns with completely different properties, which serve to obtain a different final product based on the needs of the market. The following table shows a small summary of the yarns mentioned:

 

Natural yarnsCottonNatural rubber
ViscoseBamboo
Synthetic yarnsPolyesterPBT
PolyamideElastane

 

 

 

 

 

 

 

 

In future posts, when we talk about the properties of the different bandages, we will relate them to these materials since the composition of the bandage is closely related to its final properties and purpose.

Prepared by the technical department of Calvo Izquierdo S.L.

with the collaboration of Carmen Alba Moratilla

Bibliography

Calvo Izquierdo develop the project VENDAGEN 2.0.

Calvo Izquierdo develop the project VENDAGEN 2.0.

The Valencian company Calvo Izquierdo SL. Carried out the project VENDAGEN 2.0. (2013-2015) “Research and development of a new generation of bandages for medical and sports applications”.

 

The project is supported and funded by the Center for the Development of Industrial Technology (CDTI).

VENDAGEN 2.0 is carried out by a multidisciplinary team integrated by personnel from Calvo Izquierdo SL, and also from the Textile Technological Institute (AITEX).

AITEX is a N061 notified body with 17050 accredited laboratory with complementary competences and capabilities and with great experience in different fields such as medical and hospital textiles, biomedicine, chemistry, physics, biomechanics, engineering, design, materials science, computer science, etc.

This project encompasses two very important lines of research for the company, such as obtaining a 100% textile cohesive bandage and obtaining sports bandages with a cold/heat effect.

Cold/ heat effect

 

Through this project, a new generation of bandages was researched and developed with compounds containing a selection of natural active ingredients such as:

-Cayenne pepper.

-Camphor.

-Arnica.

-Menthol.

-Eucalyptus.

-Etc…

 

Objectives:

Evaluation of 6 types of bandages impregnated with active ingredients designed to provide coolness and warmth to athletes during their use.

To analyze the effects on skin temperature of the impregnated bandages compared to the control bandages in an objective way, by means of infrared thermography and infrared gun.

  1. To study if the impregnated bandages have noticeable effects after soccer training on the comfort perceived by the participants and to see which aspects were perceived as more or less comfortable.
  2. To evaluate the participants’ overall assessment of the new product in terms of satisfaction and sensations when using it.
Calvo Izquierdo participates in the INNPACTO Project

Calvo Izquierdo participates in the INNPACTO Project

 

The Valencian company Calvo Izquierdo, S.L., actively participates in the INNPACTO project “Personalized healthy children’s footwear for obese children and children with allergic dermatitis” (2014).

Through this project, the aim is to design footwear suitable for the characteristics of the feet of these children and thus improve the quality of life of those affected by overweight and obesity and/or allergic contact dermatitis.

The project is carried out by a multidisciplinary team composed of 4 SMEs, 1 business grouping and 1 private research center, with complementary competences and capabilities and with great experience in different fields such as biomedicine, chemistry, physics, biomechanics, engineering, design, materials science, computer science, etc.

The development of customized consumer goods according to the needs and expectations of certain groups, represents a high added value for this type of products and an element of differentiation with respect to articles manufactured by third countries, thus improving the competitiveness of Spanish companies.

Therefore, this project is related to the research and development of customized healthy materials and products, aimed at improving the welfare of children affected by overweight and obesity and/or allergic contact dermatitis and other related diseases, products that are currently difficult to find in the market.

 

To achieve this general objective, the following scientific-technical aspects related to materials will be addressed during the development of the project:

– Establishment of the needs and expectations of children affected by obesity, which will make it possible to establish the technical requirements to be met by the materials, designs and products to be developed.

– Selection and/or adaptation of safe and healthy materials for the manufacture of specific products that help to improve the quality of life of each group:

 

  1. Establishment of mechanical requirements.
  2. Selection and/or development of alternative hypoallergenic materials for healthy, safe and sustainable children’s footwear.
  3. Selection and/or development of active materials for preventive and palliative care of the foot and skin conditions.
  4. Development and/or selection of materials for the preventive care of feet of children with obesity: development of materials for the control of the management of excess sweating and proliferation of microorganisms, in cases of dermatitis, diabetes, etc., related to obesity.

 

Technologies used for the project:

– Digitization of the foot: obtaining an accurate digital image of the foot in three dimensions, for comparison with the corresponding shoe last or the manufacture of a specific last.

– Plantar pressure map: Distribution of the individual’s plantar pressures in order to know “how he/she is walking” and, if necessary, to adapt the most appropriate insole.

– 3D shoe design on the last.

Follow the link below for more information: http://calzadoinfantil.inescop.es/