Properties and applications of best liquids in textile and Polymer industries

 

Liquids:

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, and plasma), and is the only state with a definite volume but no fixed shape.

General Properties of best Liquid:

1.      Liquids are almost incompressible. In liquids molecules are pretty close to each other. The molecules do not have lot of space between them. The molecules cannot have squeezed closer to one another.

2.    Liquids have fixed volume but no fixed shape. They have fixed volume but they do not have fixed or definite shape. If you take 100 ml of water, pour water in a cup, it will take the shape of the cup. Now pour the liquid from cup to a bottle, the liquid has changed its shape and now it has taken the shape of bottle.

3.      Liquids flow from higher to lower level.

4.    Liquids have their boiling points above room temperature, under normal conditions. The liquids on heating slowly changes to vapor or gaseous phase. This process is called boiling.

5.    Viscosity, density, and surface tension, are three measurable properties of liquids. As we all know, a liquid is a state of matter in which atoms move around freely. Two properties that can be measured are density and viscosity.

6.      Density is the mass of a liquid per unit volume. For example, liquid mercury has a greater density than water does.

7.      Viscosity is a liquid's resistance to flowing. For example, water flows very easily but slime doesn't. Slime has a high viscosity.

8.      Surface tension is another property that can be measured. It is the result of the inward pull among the molecules of a liquid that brings the molecules on the surface closer together.

9.      Evaporation is another property of liquid when the particles of a liquid are in constant motion, they will collide with one another, and with the sides of the container. Such collisions transfer energy from one particle to another. When enough energy is transferred to a particle at the surface of the liquid, it will eventually overcome the surface tension holding it to the rest of the liquid. Evaporation occurs when surface particles gain enough kinetic energy to escape the system. As the faster particles escape, the remaining particles have lower average kinetic energy, and the temperature of the liquid cools. This phenomenon is known as evaporative cooling.

10.  Volatility can be thought of as how likely a substance will be to vaporize at normal temperatures. Volatility is more often a property of liquids, but some highly volatile solids may sublime at normal room temperature. Sublimation happens when a substance passes directly from solid to gas without passing through the liquid state. 

  General Applications of best liquids:

1.    In tribology, liquids are studied for their properties as lubricants. Lubricants such as oil are chosen for viscosity and flow characteristics that are suitable throughout the operating temperature range of the component. Oils are often used in engines, gear boxes, metalworking, and hydraulic systems for their good lubrication properties.

2.      Many liquids are used as solvents, to dissolve other liquids or solids. Solutions are found in a wide variety of applications, including paints, sealants, and adhesives. 

3.      Naphtha and acetone are used frequently in industry to clean oil, grease, and tar from parts and machinery. Body fluids are water based solutions.

4.      Surfactants are commonly found in soaps and detergents. Solvents like alcohol are often used as antimicrobials. They are found in cosmetics, inks, and liquid dye lasers. They are used in the food industry, in processes such as the extraction of vegetable oil.

5.      Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components.

6.      The heat can be removed by channeling the liquid through a heat exchanger, such as a radiator, or the heat can be removed with the liquid during evaporation.

7.      Water or glycol coolants are used to keep engines from overheating. The coolants used in nuclear reactors include water or liquid metals, such as sodium or bismuth. 

8.      Liquid propellant films are used to cool the thrust chambers of rockets. 

9.      In machining, water and oils are used to remove the excess heat generated, which can quickly ruin both the work piece and the tooling. During perspiration, sweat removes heat from the human body by evaporating. In the heating, ventilation, and air-conditioning industry (HVAC), liquids such as water are used to transfer heat from one area to another.

10.  Liquids are often used in cooking for their better heat-transfer properties. In addition to better conductivity, because warmer fluids expand and rise while cooler areas contract and sink, liquids with low kinematic viscosity tend to transfer heat through convection at a fairly constant temperature, making a liquid suitable for blanching, boiling, or frying.

Properties and applications of best liquids in textile industries:

Moisture Management

Moisture management is a key performance characteristic in many fibrous products such as water-repellent fabrics, waterproof fabrics, stain-resistant fabrics and comfort products.

Moisture management is the controlled movement of liquid (perspiration) from the skin surface to the environment through the fabric. It is an important factor in optimizing comfort and maximizing performance. Transfer of perspiration from the skin to the atmosphere regulates the body temperature and maintains heat balance thus controlling the comfort level of environmental conditions and activity. Clothing plays an important role in eliminating extra heat produced to keep the body at a core temperature of 37°C. The role of moisture-management fabrics is to regulate heat and moisture to maintain the body temperature and keep the body cool as illustrated in Fig. Wetting and wicking take place before perspiration evaporates from the skin through the fabric into the atmosphere. Fibers preferred for moisture management include polyester for its low moisture absorption, polypropylene for its excellent moisture wicking, and polyamide for wicking and durability properties.

Fig. Moisture management in clothing.

Transferring moisture from the skin to the environment through clothing is influenced by fabric weight, fiber fineness, fabric construction, and garment design. Bedek evaluated cotton/polyamide/rayon, cotton, polyamide and viscose rib, and interlock fabrics for moisture management and suggested that fiber type, moisture regain, and fabric structure affect comfort-related properties. On the other hand, some countries evaluated moisture management for Coolmax/Cotton, Coolmax and Coolpus with different yarns and deniers, and found out that accumulative one-way transport capacity (OWTC) of fabrics depends on yarns, loop density, fabric structure, and fabric thickness. This suggests that moisture management depends on a number of fabric structural parameters. Therefore, fabric construction should be considered to improve moisture management.

Table: Moisture management indices

Index	Grade	1	2	3	4	5
Wetting time	Top	≥ 120 No wetting	20–119 Slow	5–19 Medium	3–5 Fast	< 3 Very fast
	Bottom	≥120 No wetting	20–119 Slow	5–19 Medium	3–5 Fast	<3 Very fast
Absorption rate	Top	0–10 Very slow	10–30 Slow	30–50 Medium	50–100 Fast	> 100 Very fast
	Bottom	0–10 Very slow	10–30 Slow	30–30 Medium	50–100 Fast	>100 Very fast
Maximum wetted radius	Top	0–7 No wetting	7–12 Slow	12–17 Medium	17–22 Large	> 22 Very large
	Bottom	0–7 No wetting	7–12 Slow	12–17 Medium	17–22 Large	>22 Very large
Spreading speed	Top	0–1 Very slow	1–2 Slow	2–3 Medium	3–4 Fast	> 4 Very fast
	Bottom	0–1 Very slow	1–2 Slow	2–3 Medium	3–4 Fast	>4 Very fast
One way transport capacity	<−50		− 50 to 100	100–200	200–400	> 400
	Poor		Fair	Good	Very good	Excellent
Overall moisture management	0–0.2		0.2–0.4	0.4–0.6	0.6–0.8	> 0.8
	Poor		Fair	Good	Very good	Excellent

water repellency, waterproof and hydrophilicity

The role of fabric finish is to enhance water repellency further. Chemical finishes used for this purpose are typically hydrophobic substances with a critical surface tension below that of the water because for a fabric to be water repellent, the critical surface tension of the fiber surface should be below 30 dynes cm⁻¹ (pure water typically has surface tension of about 72 dynes cm⁻¹). For oil repellency, lower fiber surface tensions will be required (below 13 dynes cm⁻¹). A common substance used for water repellent treatments is paraffin wax, which is the most economical treatment. This can be applied using solvent solutions, molten coatings or wax emulsions. This is not a permanent treatment as wax can be abraded by rubbing against other objects and dissolve in dry cleaning fluids. Pyridinium compounds are also used for water repellent treatments. These are long-chain fatty amides and wax resin mixture. Silicone water repellents are also used for a variety of fabrics because of their durability as they exhibit high resistance to abrasion and they are less soluble in dry-cleaning fluids or laundry detergents.

Fluoro-chemical repellents have the advantage of repelling both water and oil as a result of their low surface energy. These provide a very durable finish and their application is mainly based on the reduction of the critical surface energy tension of the finished fabric surface to levels below that of the wetting liquid (in this case water). This creates a chemical barrier, which prevents penetration of the liquid. Of all textile chemicals, only fluoropolymers show this unique property of reducing surface energy to such an extent that they repel both aqueous and oily substances (polar and non-polar liquids).

Properties and applications of best liquids in Polymer industries:

Composition of Polymer Clay:

Polymer clays contain a basis of PVC resin and a liquid plasticizer, making it a plastisol. Polymer clay plastisol is also categorized as a plastigel because of its rheological properties. It is a high yield thixotropic material: when a sufficient force is applied, the material yields, flowing like a viscous liquid until that force is removed, whereupon it returns to being a solid. This plasticity is what makes it useful as modeling clay as opposed to putty or paste. Plastigels retain their shape even when heat is applied, which is why polymer clay does not melt or droop when oven cured. Various gelling agents are added to give it this property, such as aminated bentonite, metallic soaps, or fumed silica.

The base resin can be modified in various ways. Mineral oil, lecithin, and odorless mineral spirits can be added to reduce its viscosity or alter its working properties. Small amounts of zinc oxide, kaolin, or other fillers are sometimes added to increase opacity, elastic modulus, or compression strength. Polymer clay is available in many colors, which can be mixed to create a wide range of colors or gradient blends. Special-effect colors and composites include translucent, fluorescent, phosphorescent, and faux "pearls", "metallics", and "stone."

Polyethylene:

Commonly used polyethylenes can be classified into low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE). Among them, HDPE has better thermal, electrical and mechanical properties, while LDPE and LLDPE have better flexibility, impact properties and film forming properties. LDPE and LLDPE are mainly used for plastic bags, plastic wraps, bottles, pipes and containers; HDPE is widely used in various fields such as film, pipelines and daily necessities because its resistance to many different solvents.

Polypropylene:

Polypropylene is widely used in various applications due to its good chemical resistance and weldability. It has lowest density among commodity plastics. It is commonly used in packaging applications, consumer goods, automatic applications and medical applications. Polypropylene sheets are widely used in industrial sector to produce acid and chemical tanks, sheets, pipes, Returnable Transport Packaging (RTP), etc. because of its properties like high tensile strength, resistance to high temperatures and corrosion resistance.

Lava Lamp:

A lava lamp contains two immiscible liquids (a molten wax and a watery solution) which add movement due to convection. In addition to the top surface, surfaces also form between the liquids, requiring a tension breaker to recombine the wax droplets at the bottom.