Sandviç kumaşların termal konfor özellikleri
Thermal comfort properties of spacer fabrics
Yazar: SENA TERLİKSİZ
Danışman: PROF. DR. FATMA KALAOĞLU ; YRD. DOÇ. DR. SELİN HANİFE ERYÜRÜK
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Tekstil Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2012
Konu: Tekstil ve Tekstil Mühendisliği = Textile and Textile Engineering

Özet:
Uyku kişi yaşamı için en temel etkinliklerden biridir ve fizyolojik bir ihtiyaçtır. Uyku sırasında beyin öğrenme, hafıza ve anlayış yaratma ile ilgili yolları oluşturur. Kişinin dinlenmişlik düzeyi sadece toplam uyku süresine değil aynı zamanda gecenin ne kadarını uykuda geçirdiğine ve uyku evrelerinin zamanlamasına bağlıdır. Uyku miktarı ve kalitesinin yetersiz olması ise uyku bozukluklarına yol açmaktadır. Uyku bozuklukları da fiziksel ve ruhsal olmak üzere pek çok hastalığın belirtisi olarak ortaya çıkmaktadır Fizyolojik bir ihtiyaç olarak uyku gereksinimi karşılanmadığı zaman kişinin yaşam kalitesi ve sağlığı bozulur. Çünkü uyku süreci organizmanın dinlenmesini sağlamak yanında insan vücudunun yenilenmesini sağlar.İyi bir gece uykusu sağlanması için çevre koşulları çok önemlidir. Parlak ışık ya da gürültü kaynakları, rahatsız yatak ve aşırı sıcak uyku ortamı uyku kalitesini bozarak kişinin yaşam kalitesini etkiler. Vücudun termal konforu günlük yaşamda olduğu gibi uyku sürecinde de çok önemlidir.Konfor ise memnuniyet ve rahatlık hissi veya fiziksel ya da ruhsal olarak iyi durumu ifade eden bir terimdir. Literatürde çok çeşitli konfor tanımları yapılmıştır. ?Acı ve konforsuzluktan bağımsız nötr durum?, ?İnsan ve çevre arasındaki fizyolojik uyum? bu tanımlardan en yaygınlarıdır. Termal konfor ise vücudun termal dengesi ve çevre ile giysiye olan dinamik etkileşimi ile ilgilidir. Isı ve nem termal konfor üzerinde büyük rol oynamaktadır.Bu çalışmada yatak zemininde kullanılan kumaşların termal konfor analizleri yapıla-rak, uyku süresince termal açıdan konforlu olunması için gerekli yatak kumaşı özel-likleri araştırılmıştır. Yatak yüzeyinde yaygın olarak kullanılan kumaşlar tanıtılmış, yatak ve yatak kumaşı üreticilerinin kullandıkları son teknolojiler incelenmiştir. Termal konfor koşullarının değerlendirilmesi amacıyla temin edilen kumaşların gramaj ölçümü, dikey ıslanma ve transfer ıslanma analizleri, buhar geçirgenliği, su buharlaşma hızı, ısıl iletkenlik, ısıl direnç, kalınlık ve hava geçirgenliği ölçümleri yapılmıştır. Ölçümlerden elde edilen sonuçların istatistiksel analizleri yapılarak sonuçlar değerlendirilmiştir. Değerlendirme sonucunda da kişinin yaşamının yaklaşık üçte birini kaplayan uyku süresince termal konfor durumunu etkileyen önemli bileşenlerden biri olan yatak yüzey kumaş özellikleri belirlenmeye çalışılmıştır.

Abstract:
Sleep is one of the basic activities for human life and is a physiological need. During sleep duation brain forms paths for learning, memory and perception creation. When physiological need of sleep is not satisfied human health and life quality are deteriorated. Because sleep duration relaxes and renews the human body. Inadequate sleep duration and quality cause sleep disorders. Insomnia or lack of sleep leads to serious health problems. Chronic insomnia increases the risk of obesity, diabetes, cardiovascular disease and infection.Environment conditions are very important for sleep quality. Bright light or noise sources, uncomfortable bed od extremely hot sleep environment disrupt sleep and affect person?s life quality.Sleep is mainly divided into two periods:1.NREM (Non rapid eye movement)2.REM (Rapid eye movement)NREM sleep is the relaxing and deeper sleep period. It refers to overall decrease in activity in physical and physiological sense. In REM period rapid eye movements are observed and human metabolism, heart and breath rate increase. Main factors influencing the sleep characteristics are the amount of the time it takes to fall asleep, total sleep duration and number of awakenings during the nightComfort is a term expressing a pleasant and comfortable state mentally and physically. In the literature there are various comfort definitions: ?Neutral state independent of pain and discomfort?, ?Physiological harmony between person and environment? are some common definitions. Thermal comfort is closely related to thermal balance of human body and dynamic interaction between human body and clothing material. It is defined as state of mind expressing satisfaction from the thermal environment. Heat and moisture play major role on thermal comfort.Overheating or overcooling the whole or a part of body leads to thermal discomfort. Factors determining the thermal comfort of people are divided into environmental and personal factors. Environmental factors are temperature, thermal radiation, moisture and air velocity. On the other hand personal factors are personal activity, physical condition and clothing.The term ?thermoregulation? refers to four mechanisms: sweating, shivering, vasodilatation and vasoconstriction. Sweating increases heat loss by the evaporation of perspiration from the body surface. Shivering leads to heat production by involuntary muscle action. Vasodilatation and vasoconstriction refer to variation in vessel diameters. These changes allow body temperature variation by changing bloodflow. Conductivity under body surface increase by changing bloodflow and internal body heat is transferred to body surface. Perspiration transferred to skin is transmitted to outer environment by evaporation and convection. In cold environments muscle straining and shivering accelerate heat production and body temperature. Combination of heat loss and heat intake control mechanisms protect internal body temperature interval.Skin is the first barrier between organism and its environment. It keeps uncontrolled water intake or loss in low level. Furthermore skin includes complex vascular systems and sweat glands which change skin conductivity due to the thermoragulation neeed of body. Four types of temperature sensitive nerve endings which can detect skin temperature are included in skin. Skin consists of two main layers called dermis and epidermis. Dermis is thicker than epidermis and its thickness changes according to the body part.Thermal environment is created by four main physical parameters: air temperature, mean radiant temperature, relative air velocity, vapor pressure in air. all of these four factors are controllable. Besides environmental factors activity level and clothing rhermal resistance influence thermal comfort.Internal temperature of resting person?s body is kept within a narrow range around 37oC. This temperature remains constant, even in case of major changes in ambient temperature. However internal body temperature varies in different body parts according to the local heat balance. Some organs are cooled and some organs are warmed by the blood flow. During physical activity internal body temperature increases according to the intensity of the activity. Increase in body temperature varies from person to person and depends on the maximum oxygen intake.When skin touches a surface hot or cold feeling due to transient heat conduction occurs. Lower surface temperature of fabric causes heat outflow from skin. Heat loss results in a decrease in body temperature. As the heat flux increases temperature reduction around thermoreceptors becomes more rapid. Structural characteristics of the fabric, especially the surface structure has an impact on the hot and cold sensation.In this study thermal comfort analysis of bed surface fabrics are made and fabric properties of thermally comfortable bed fabrics are investigated. Common bed surface fabrics are presented and latest technologies applied by manufacturers are surveyed. In order to evaluate the thermal comfort conditions of supplied fabrics fabric weight measurement, vertical wicking and transfer wicking analysis, water vapor permeability, water evaporation rate, thermal conductivity, thermal resistance, fabric thickness and air permeability measurements are made. Measurement results are statistically evaluated by IBM SPSS 20.In vertical wicking analysis fabric samples are immersed into distilled water for 10 minutes and water height is recorded. Vetical wicking is governed by capillary pressure. Fibers with small and smooth pores have high capillarity. Vertical wicking property of polyester fiber is good due to its high capillarity.In transfer wicking test liquid transfer between wet and dry fabric samples that are put in rubber discs is measured. Pressure applied by discs simulate the pressure applied to textile materials during use. In transfer wicking test liquid transfer characteristics of fabrics under pressure are analyzed.Water evaporation rate is a measure of drying rate of a fabric. The most important parameter for water evaporation rate is the fiber regain. Water vapour permeability is important for determination of fabric comfort features because perspiration is excreted from body in vapour form. Fabrics touching the skin should be water vapour permeable. In water vapour permeability the most important parameter is the pores between fibers.Thermal conductivity, thermal resistance and fabric thickness measurements are other tests performed for thermal comfort analysis of a fabric. Thermal conductivity and thermal resistance properties of fabrics used in bed surface are very important for thermal comfort and thermal insulation. Thickness is also critical for thermal comfort and insulation. Thickness has negative effect on thermal conductivity while it has negative effect on thermal resistance. Also weight has positive effect on thermal resistance.Air permeability is another important comfort property. Materials that are used in beds should be air permeable to provide comfortable sleep environment. In this study light fabrics are observed to have good air permeability.Comfort conditions in bed directly effect person?s sleep and life quality. As a result academic research about sleep environment and bed surface fabrics is of great importance. In this study it is tried to determine the role of textile materials used as bed surface material on thermal comfort of human body. The results obtained from performed analysis are evaluated and properties of ideal sleep surface material is tried to be determined.