Thursday, 29 March 2018

Comfort, Appearance and Durability of Fabrics

Introduction: 
The term ‘Comfort‘ is being mentioned as “the absence of unpleasantness” or” a natural state compared to more active state of pleasure.” The most important factor affecting Comfort in clothing is the movement of heat and water vapour through a garment. There are two factors which keep the human being more comfortable.
Comfort wear
Comfort wear
Physical and Psychological Aspects 
Comfort is always depend on physiological effects of such climatic variables of temperature, relative humidity and air movement of a body situated in a particular condition and also clothing factors, particularly fabric geometry, pore volume and enclosed air content etc. 

Physical Aspects 
The physical factors determining the comfort performance of textiles. Particularly the heat transfer between man and his environment, together with movement of moisture for insensible heat transfer, constitutes a major comfort – Maintaining mechanism. Comfort involves a complex combination of properties. 

Both subjective andphysical. The movement of heat, moisture and air through a fabric are the major factors governing comfort: but some of the subjective factors such as size, fit and aesthetic behaviour (softness, handle and drape) obviously are very important. In addition, other factors such as the generation of static electricity and the control of noise are closely connected with apparel use. 

Thermal Properties and Comfort 
Body temperature is the most critical factor in deciding comfort. Heat is gained by the body from the solar energy, by internal metabolism by physical exercise or by involuntary contraction of skeletal muscles in shivering, Heat loss, by conduction. Convection or radiationdepends partly on the temperature gradient between the skin and environment, and this gradient is modified by varying the skin temperature. 

Blood flow near the body surface controls the skin temperature. Excessive heat may be dissipated rapidly by vaporisation of by body water, the body being used as a source of latent heat for the purpose; a clothing system that hinders free evaporation to any appreciable extent will thus be uncomfortable. On the other hand, undesirable heat loss can be prevented by increasing the thermal resistance and a low resistance will again result in discomfort for the wearer. 

In the nude human body, an envelope of warm air moves by convection in the upward direction around the body surface and facilitates heat exchange, by convection or evaporation with surrounding environment. The presence of clothing interferes with the freedom of this process and thus modifies the amount of rate of heat loss in a complex manner. The ambient air temperature is the dominant influence in determining the skin temperature. At a low temperature, clothing is essential for the regulatory process because the body does not have the ability to continue to compensate for heat loss under these conditions. 

Heat transfer 
The resistance that a fabric offers to the movement of heat through it is obviously of critical importance to its thermal comfort. The thermal resistance to transfer of heat from the body to the surrounding air is the sum of three parameters:
  1. Thermal resistance to transfer of heat from the surface of the material,
  2. Thermal resistance of the clothing material.
  3. Thermal resistance of the air interlayer.
The first two factors are taken into account for the movement of air through the material. The third factor controls the rate of filtration of air through the clothing assembly for a given wind speed. 

The heat transfer through a fabric is complex phenomenon affected by a number of factors. The three factors for the normal fabric appearance are:
  1. Thickness
  2. Enclosed still air and
  3. External air movement.
For a fixed weight thermal insulation increases with thickness (with increased enclosed air) whereas the property decreases with increase in weight (i.e., decrease inenclosed air) if the thickness is maintained constant. The entrapped air is the most significant factor in determining thermal insulation. 

Distinguished micro layers (those between contacting surfaces of the material) and macro layers (between non- contacting surfaces) of air enclosed within assembly shows that increase in either of these can increase thermal insulation. It appears that both thickness and entrapped air play a part in determining thermal insulation. 

One of the major functions of clothing is to project the wearer against extremer’s of environmental temperature, from the excessive ambient heat as well as cold. 

Moisture permeability 
The second important property of fabric, from a comfort point of view, is the way in which it allows water to pass through. This process can take place in both the liquid and vapour from of water, and the difference is an important one. If water evaporated at the skin and passes as vapour through the fabric (or to lesser extent, if it is transmitted to the surface by movement within fibres) the pores of the fabric remain free. 

This enables the movement of air through the fabric to continue and allows the heat insulation value of the air within these pores to be maintained. On the other hand, if skin moisture is transported to the surface in the liquid from by wicking action and only evaporates on reaching the layers at the fabric surface, comfort is reduced in two ways: The sensation of wetness is perceived by the nerve sensors on the skin, so the garment feels clammy and in addition the water filled fabric pores are no longer able to hold dead air pockets so that heat insulating ability is lost and the garment fells cold. 

In addition, if garment permits free accesses of liquid water it is uncomfortable inwet weather, where the reverse movement of exterior water towards the skin is experienced. The moisture vapours or lost at either the manufacturing or the finishing stages of the production process. 

Factors Affecting Permeability 
The movement of water vapour through a fabric depends considerably on the microspores, nature of the materials, and this movement can hence be modified by any operations that bring about a change in the structure. The effect of fabric properties and of finishing treatment on moisture vapour transport considers briefly the changes brought about by texturing, different yarn twist, blending, mechanical treatment, chemical finishing, fibre properties and garment design. 

Permeability and Comfort 
Although heat transmission may be critical to survival in cold weather, it is contestable that moisture- vapour transmission is crucial to comfort in both cold and hot weather. Free movement of water to the fabric surface is essential if discomfort due to perspiration causing fabric wetness and leading to freezing in water or clamminess in summer is to be prevented. 

Air Permeability 
The air permeability of fabric can influence its comfort behaviour in the following ways:
  • A material that is permeable to air is also in general likely to be permeable to water, in either vapour or liquid from. Thus the moisture – vapour permeability and the liquid moisture transmission are normally closely related to air permeability. 
  • The thermal resistance of a fabric is strongly dependent on the enclosed still air, and this factor is in turn influenced by the fabric structure, as also is the air permeability. A very open cloth can inflict serious wind –chill problem on the wearer in cold climates with a breeze blowing and may thus affect survival chance may be in extreme cases. A highly air- permeable fabric may be sheer or have a very open structure, so that aesthetic factors such as dimensional stability, drape, handle or even skin blotchiness in strong sunlight may result in discomfort of a psychological or physical nature to the wearer.
Size and Fit 
An important aspect of comfort, which is not strictly a textiles problem, but rather a clothing one, is size and fit. No matter how well a fabric is engineered to have optimum values of heat, heat water or air transmission, any garment made from it cannot be regarded as comfortable if it does not fit properly. 

Two distinct factors are clearly evident in determination of whether the fit of a garment is good. The first on is a subjective one, which depends on whether the wearer achieves psychological satisfaction from the garment. The other factor is physical one and is concerned with the conditions of contact between the fabric and the body. 

The body – fitting garments can restrict cardio –vascular flow causing skin abrasion, create unpleasant thermal or moisture conditions, induce irritation or cause any similar aggravations to the wearer in the form discomfort .There should be proper room for the movement of different parts body, particularlyarms , front and back of the shoulder joint. 

Aesthetic Comfort 

In examining the comfort behaviour of textiles, it is necessary to include some consideration of factors that are not measured by obvious physical tests and may be subjective in that two people may disagree about the level of comfortof the same fabric. These aesthetic factors include properties such as softness, handle, drape and similar properties and may also include properties such as colour, style, fashion compatibility and other similar characteristics. 

The most difficult among these terms, to define, is handling. The act of submitting a fabric to a tactile test between fingers and thumb is a result of stimulus from fabric acting on major sensory centres presumably present in the human hand. Measurement of softness may be regarded as one aspect of handle. 

Stiffness can be said to be most influential factor in governing softness. This factor is represented by the density, weave and softness of the fibre. The second of the aesthetic properties to be considered is drape. Weight and softness are the two important factors governing drape. 

Static Electricity 
A mild current of electricity is produced due to the friction between the garment and the skin of the wearer. This also is a cause of discomfort to the wearer. This is more so in case of garments made using synthetic fibres. 

To sum up, the capacity of a fabric to allow the transfer of heat and the flow of air and water are the most important factors which should be taken into consideration by the manufacturers of apparel fabrics to decide whether the fabric will be comfortable to the wearer or not. 

Conclusion: 
While customers buying the readymade garment, these three elements are considered to be the important namely, comfort, appearance and durability. Comfort can be defined as” the absence of unpleasantness”. The most important factor affecting comfort in the clothing is the movement of heat and water vapour through a garment, there are two factors which heap the modern man comfortable. 

Reference book: 
  1. Fashion Design Vol-1
  2. Fashion Concepts-Dr. Navneet Kaur
  3. Clothing Technology
  4. Fibre to Fabrics 

Future of Fire Retardant Fabrics

Brimming with smart devices and intelligent technologies, today’s world is no longer restricted to a single-tracked functionality in anything. Similarly, when it comes to clothing we no longer just think of covering our bodies, but we think “covering our bodies smartly”. Now that may sound tacky to start with, but it is not. With the new-age emerging technologies, where everything else is supposed to adapt itself to the environment and on-going changes, so are clothing.

Fire retardant fabric
Fig: Fire retardant fabric
So what is the concept behind smart clothing? – Quite simply your clothes are value-added textiles that are supposed to provide you a relaxed, comfortable, and stylish wear, at the same time, reciprocating to the changes in the environment. From the functionality point of view, smart fabricscan be categorized into aesthetics and performance enhancement textiles. Aesthetics refers to the ability of fabrics to gather energy from the environment and corresponding to the various inputs such as vibration, sound or heat. Whereas Performance Enhancement textiles are high-tech garments responding to the requirements of extreme sports and professions. These clothes help improve physical performance and control body temperatures by offering receptiveness to factors such as muscle vibration, the frequency of heartbeats, wind or heat resistant fabric etc. In addition to that, there are many characteristics that are being incorporated into clothing and will be the ‘new normal’ in future in clothing, such as anti-microbial properties, anti-static quality, oil and water repellence, soil and stain resistance, flexibility, and breath-ability. 

But a very major development is that textile industry is moving towards being environment friendly. So the concept of eco-friendly garments is emerging. This is not a new concept, but the innovative technologies of today are certainly changing the way this concept is perceived, putting it in a broader perspective. From a plant free production to low water consumption to low environmental impact, future of textiles is definitely to empower human-kind by improving people’s everyday life and general well-being as well as benefit the industry and the environment. The future of specialty fabrics like fire-resistant or flame-retardant textiles is no different. 

How does the Future look like for FR Fabrics? 
As the compliance requirements for different industries become more meticulous and the need for safety and employee’s general well-being continues to grow, fire resistant fabric manufacturers are determinedly looking for ways to continue to evolve with these requirements and design the best possible solution in proactive protective apparel for their clients. The future of fire retardent clothingspecifically holds a strong blend of both aesthetics and performance enhancement. Above and beyond their functional requirements to provide heat, fire or arc flash resistance, the future FR textiles are also expected to be responsive to their environment and climate changes. Their job is not just to protect the wearer’s body but to also improve performance at the workplace by offering qualities such as body temperature control, motion enhancement, comfort, breathability, evaporation, moisture control, flexibility, and anti-static property, all bundled into an attractive package. This is called ‘functional diversity’ or ‘multi-functional FR clothing’. 

But obviously different industries have varied requirements as do different climates and indeed workplace environment. This is precisely why flame-retardants fabric suppliers are focused on providing more customized clothing solutions in the future by designing and engineering adiverse range of versatile FR fabric blends to suit their client’s specific requirements. For instance, a client might need intense heat resistant properties in their FR wear mixed with the light weight of the fabric, breathability as well as moisture control in a very hot climate. Whereas, another client may require the same FR resistance in warmer clothing that also allows free bodily movement. So the future of FR garments is definitely headed for greater customization for individual clients. 

However, with earth’s environment under-going rapid changes and the call for manufacturing eco-friendly products, gaining momentum with every passing day, FR textile industry is also bent upon introducing innovative solutions that are toxins-free and environment friendly. So naturally, this means, treated FR fabrics that use more eco-friendly flame retardants or inherent FR fabrics using bio-degradable fiber blends that are easy on the environment. Until now and still, for the large part, FR textile industry relies on traditional brominated and halogen-based flame retardants. But because of growing opposition and resistance from environmental organizations, the push towards eco-friendly FR fabric production is more of an obligatory trend than a just a conscious choice. 

Future Trends and Latest Innovations: 
If we were,to sum up, the future developments for fire or flame retardant clothing, we can summarize those under three major trends: proactive, multi-functional garments; client-specific customized FR solutions; and eco-friendly FR textiles. To this end, there are many innovations that have taken place within the FR industry to accommodate for environment friendly flame retardants. 

Before moving forward though, let us see what is so wrong with the traditional brominated flame retardants. The brominated flame retardants contain toxic chemicals that give off highly contaminated gases upon ignition that are detrimental to both people and environment. These toxic substances are found to be vastly persistent in the environment having accumulated over time and thus become a part of food chain ultimately making way forour bodies. In addition, these chemicals are also associated with various health issues upon exposure such as skin allergies, respiratory problems, liver problems, neurobehavioral problems etc. 

So the quest for alternative human and eco-friendly flame retardants remains fast in pursuit. To this end, many innovations have come forth and continue to evolve as more discoveries are met along the way. The initial research into phosphorous based chemicals for flame retardants expanded into nano materials, resulting in the advent of halogen-free flame retardants. By nature, these substances have a very low toxicity profile and they are bio-degradable which means they eventually mineralize in nature and do not have a harmful effect on the food chain. 

Phosphorus-based flame retardants are composed of various organic and inorganic compounds that can either be reactive products, chemically bound into the polymer material; or additive products, incorporated into the material – initially being used in the production of polyurethane foams for FR textile industry. Nano-clay flame retardants are developed with clay – being a completely natural fire resistant material, the environmental concerns are minimal with these flame retardants. 

However, the discovery of Nano-Intumescent technology for flame retardants is a feat in itself. These flame retardants expand upon exposure to flame to form tiny bubbles on the surface of the fabric creating a ‘multi-cellular char layer’ – aninsulating and protective barrier that prevents the fabric material from igniting rather than just controlling the spread of fire. Being miniscule in form, the water-based polymers have the tendency to soak in to each and every fiber of an FR material such as cotton and provide a highly specialized garment which is truly a ‘fire-proof’ fabric - low on toxicity profile but with a huge impact on the personal safety aspect. 

Decidedly, FR fabric and chemical industry have new records to set in future and with the innovative technologies at hand, we are hopefully not very far from the day the fire-retardant textile industry will be churning out highly customized, multi-functional, eco-friendly smart FR fabrics completely free of brominated chemicals. 

You may also like:

  1. Textiles For Safety | Flame Resistant Protective Clothing | Safety Textiles in Space
  2. Applications of Smart and Interactive Textiles
  3. An Overview of Smart Textile

Garment Fitting