A battery is a chemical device that stores electrical energy in the form of chemicals and uses an electrochemical reaction to convert stored chemical energy into direct current (DC) electrical energy. The 1st battery was invented by Italian physicist Alessandro Volta in 1800. The electrochemical reaction in a battery involves the transfer of electrons from one material to another (called electrodes) by electrical current.

Functions:

Even if the term battery is used frequently, the basic electrochemical unit that is responsible for storing energy is called a cell. A cell, as just mentioned, is the basic electrochemical unit that is the source of electrical energy produced by the conversion of chemical energy. In its basic form, a cell typically contains three main components: two electrodes and an electrolyte, and it also consists of connectors, a separator, and a container. Speaking of electrodes, there are two types of electrodes called anode and cathode. 

The anode is the negative electrode (also called the fuel electrode or reduction electrode). It loses electrons to the external circuit and is oxidized in the electrochemical reaction. The cathode, on the other hand, is the positive electrode (also called the oxidation electrode). It takes electrons from the eternal cycle and is reduced during the electrochemical reaction. Therefore, the conversion of energy in a battery is due to an electrochemical oxidation-reduction reaction.

The third component of a cell is the electrolyte. An electrolyte serves as the medium for the transfer of charge in the form of ions between the two electrodes. Therefore, the electrolyte is sometimes called an ion conductor. Here it is important that the electrolyte is not electrically conductive, but only ionically conductive. A battery often consists of one or more "cells" that are electrically connected in series or parallel to provide the necessary voltages and currents.

Main types:

Basically, all electrochemical cells and batteries are divided into two types: 

1) Primary (non-rechargeable) 

2) Secondary (rechargeable) 

Although there are several other classifications within these two types of batteries, these two are the basic types. Simply put, primary batteries are non-rechargeable batteries, that is, they cannot be charged electrically, while secondary batteries are rechargeable batteries, that is, they can be charged electrically.

Primary battery:

A primary battery is one of the simple and convenient power sources for various portable electronic and electrical devices such as lamps, cameras, watches, toys, radios, etc. Since they cannot be electrically charged, they are useful and when discharged they are discarded.

primary batteries are usually inexpensive, lightweight, small, and very convenient to use with relatively little or less maintenance. Most primary batteries used in Household applications are single-cell batteries and generally have a cylindrical configuration (although they are very easy to manufacture in various shapes and sizes).

Types:

Zinc anode batteries were the predominant primary battery types until the 1970s. In the 1940s, World War II, and after the war, zinc-carbon batteries have an average capacity of 50 Wh / kg. The most important development in battery technology took place between 1970 and 1990. 

During this time the famous zinc/alkaline manganese dioxide batteries were developed, which slowly replaced the older types of zinc-carbon as the main primary battery. Zinc-mercury oxide and cadmium-mercury oxide batteries were also used during this period, but due to environmental concerns related to the use of mercury, these types of batteries were gradually phased out.

During this time, the development of batteries with lithium as the active anode material began and is considered a great achievement due to the high specific energy and longer service life of lithium batteries compared to conventional zinc batteries. Lithium batteries are manufactured as button and button cell batteries for a specific application (such as watches, memory backup, etc.), while larger cylinder batteries are also available.

The following table shows different types of primary batteries with their properties and applications. 

 1) Zinc - carbon - Common, inexpensive, various sizes - Radios, toys, instruments 

 2) Magnesium (Mg / MnO2) - High capacity, long service life - Military, and aircraft radios 

 3) Mercury (Zn / HgO) - Very high capacity, long service life - Medicine (hearing aids, pacemakers) 

 4) Alkaline (Zn / Alkaline / MnO2) - Very popular, moderate costs, high performance - Most popular primary batteries 

 5) Silver/zinc (Zn / Ag2O) - Higher capacity, expensive, shallow discharge - Hearing aids, photography, Pager 

 6) Lithium / soluble cathode -  High energy density, good performance, wide temperature range - Wide range of applications with capacities between 1 - 10,000 Ah 

 7) Lithium / solid cathode - High density of energy, low-temperature performance, long service life -  Replacement for button and cylindrical batteries 

 8) Lithium / solid electrolyte - Low power consumption, extremely long life, -  memory circuits, medical electronics

Secondary battery:

A secondary battery is also called a rechargeable battery because it can be electrically charged after it has been discharged. The chemical state of electrochemical cells can be "charged" to its original state by passing a current through the cells against their discharge direction.

Types:

In principle, secondary batteries can be used in two ways, In the first category of application, secondary batteries are primarily used as energy storage devices, where they are electrically connected to and are also charged by the main power source and, if necessary, they also supply energy. Examples of such applications are Hybrid Electric Vehicles (HEV), Uninterruptible Power Supplies (UPS), etc. 

The second category of secondary battery applications is those where the battery is used as the primary battery and is discharged. If it is completely discharged (or almost completely discharged), the battery is not disposed of but is recharged using a suitable charging mechanism. Examples of such applications are all modern portable electronic devices like cell phones, laptops, electric vehicles, etc.

The energy density of secondary batteries is relatively lower than that of primary batteries, but it has other good properties such as high power density, flat discharge curves, high discharge rate, and low-temperature performance. There are several other types of secondary batteries, but the four main types are:

There are several other types of secondary batteries, but the four main types are: 

a) lead-acid batteries 

b) nickel-cadmium batteries 

c) nickel-metal hydride batteries 

d) lithium-ion batteries

Lead-acid batteries:

Lead-acid batteries are by far the most popular and widely used rechargeable batteries. lead-acid batteries that were developed in the late 1850s. They have been a successful product for more than a century. Lead-acid batteries are available in a variety of configurations, from small sealed cells with a capacity of 1 Ah to large cells with a capacity of 12,000 Ah. 

One of the main uses of lead-acid batteries is in the automotive industry since they are used mainly as SLI (Start, Lighting, and Ignition) batteries. The first and most widely used rechargeable batteries are called lead-acid batteries. They are based on the electrochemical pair lead-lead dioxide (Pb - PbO2). The electrolyte used in these types of batteries is very common sulfuric acid.

Other applications for lead-acid batteries are energy storage, emergency power, electric vehicles (including hybrid vehicles), communication systems, emergency lighting systems, etc. The wide range of applications for lead-acid batteries results from their wide voltage ranges, different shapes and sizes, low costs, and relatively easy maintenance. Compared to other secondary battery technologies, lead-acid batteries are the most cost-effective option for any application and offer very good performance. 

The electrical efficiency of lead batteries is between 75 and 80%. Due to this efficiency, they are suitable for energy storage (uninterruptible power supplies - UPS) and electric vehicles.

Nickel-cadmium batteries:

Nickel-cadmium batteries or simply NiCd batteries are one of the oldest types of batteries available today, along with lead-acid batteries. Which were developed at the beginning of the 20th century. Nickel-cadmium batteries. 

They have a very long service life and are very reliable and robust. The second type of battery is called nickel-cadmium battery. They are based on nickel oxide hydroxide (nickel oxide) as a positive electrode and a cadmium metal base as a negative electrode. An alkaline solution of potassium hydroxide is used as the electrolyte.

One of the main advantages of NiCd batteries is that they can be exposed to high discharge rates and operate in a wide range of temperatures. Also, the lifespan of NiCd batteries is very long. The basic cost per watt-hour of these batteries is higher than that of lead-acid batteries but lower than that of other types of alkaline batteries. 

As mentioned above, NiCd batteries use nickel oxyhydroxide (NiOOH) as the cathode and metallic cadmium (Cd) as the anode. Typical consumer batteries have a line voltage of 1.2 V. In industrial applications, NiCd is second only to lead-acid batteries due to its low-temperature properties, flat discharge voltage, long service life, low maintenance requirements, and excellent reliability.

Unfortunately, there is an important property of NiCd batteries, the "memory effect", which is their only drawback. When NiCd batteries are partially discharged and then recharged, they gradually lose, ie, H. Cycle by cycle, their capacity. "Conditioning" is the process by which the lost capacity of batteries can be restored. Cells are fully discharged to zero volts and then fully charged again.

Nickel-metal hydride batteries:

These are relatively new battery types, an expanded version of the nickel-hydrogen electrode batteries that were used exclusively in aerospace (satellite) applications. The positive electrode is nickel oxyhydroxide (NiOOH), while the negative electrode of the cell is a metal alloy in which hydrogen is reversibly stored. After the technology was invented in 1967, work on NiMH batteries began at the BattelleGeneva Research Center. In 1989, the first NiMH consumer cells were launched.

During charging, the metal alloy absorbs hydrogen to form a metal hydride, and during discharge, the metal hydride loses hydrogen. One of the main advantages of nickel-metal hydride batteries over NiCd batteries is their higher specific energy and energy density. Nickel metal hydride sealed batteries are commercially available as small cylindrical cells and are used in portable electronic devices.

Lithium-ion batteries:

The lithium-ion battery turned out to be innovative and with its high specific energy, it became commercially superior. The advent of lithium-ion batteries in recent decades has been phenomenal. More than 50% of the consumer market has adopted the use of lithium-ion batteries. In particular, laptops, cell phones, cameras, etc. are the most important uses for lithium-ion batteries.

Akira Yoshino developed a prototype Li-ion battery in 1985, based on previous research by John Goodenough, M. Stanley Whittingham, Rachid Yazami, and Koichi Mizushima in the 1970s to 1980s, and then a commercial Li-ion battery was manufactured by a company. the battery developed by Sony. and the Asahi Kasei team under the leadership of Yoshio Nishi in 1991.

lithium-ion batteries have a significantly high energy density, high specific energy, and longer service life. Other main advantages of lithium-ion batteries are their slow self-discharge and the wide operating temperature range.

Reference:

1) https://www.britannica.com/technology/battery-electronics

2) https://www.science.org.au/curious/technology-future/batteries

3) https://en.wikipedia.org/wiki/List_of_battery_types

4) https://depts.washington.edu/matseed/batteries/MSE/classification.html

5) https://en.wikipedia.org/wiki/Rechargeable_battery

6) https://byjus.com/physics/uses-of-battery/

The sunglasses provide protection against ultraviolet rays in sunlight. Ultraviolet (UV) light damages the cornea and retina. Good sunglasses can completely eliminate UV rays. Sunglasses offer protection against strong light. When the eye receives too much light, the iris closes naturally. Once you have closed the iris as much as possible, the next step is to squint. If there is too much light left, as can happen when sunlight reflects off snow, this causes damage to the retina. Good sunglasses can block 97% of the light from entering the eyes to prevent damage.

Components:

1) Lens

2) Mirror coating

3) Scratch-resistant coating

4) Polarizing film

5) Anti-reflective coating

6) Photochromatic coating

Sunglasses offer protection against glare. Certain surfaces, such as water, can reflect a lot of light, and bright spots can distract or hide objects. Good sunglasses can completely eliminate this type of polarization glare. Sunglasses eliminate certain frequencies of light. Certain frequencies of light can blur vision and others can enhance contrast. Choosing the right color for your sunglasses can make them work better in certain situations.

1) Lens:

The lens is made up of both Crown glass and plastic glasses. Crown glass is a type of optical glass that is used in lenses and other optical components. It has a relatively low refractive index (≈ 1.52) and low dispersion (with Abbe numbers around 60). Crown glass is made from alkali-calcareous silicates with approximately 10% potassium oxide and is one of the first low dispersion glass.

Polycarbonate lens:

Transparency, excellent toughness, thermal stability, and very good dimensional stability make polycarbonate (PC) one of the most widely used engineering thermoplastics. CDs, protective screens, vandal-proof glazing, baby bottles, electrical components, protective helmets, and headlight goggles are typical applications for PCs. Polycarbonate is most commonly formed by reacting bisphenol A (produced by condensing phenol with acetone under acidic conditions) with carbonyl chloride in an interfacial process. PC belongs to the family of polyester plastics. 

Polycarbonate, the main material, is produced by the reaction of bisphenol A (BPA) and phosgene COCl2. In the first synthetic step, bisphenol A is treated with sodium hydroxide, whereby the hydroxyl groups of bisphenol A are deprotonated. Diphenoxide (Na2 (OC6H4) 2CMe2) reacts with phosgene to form a chloroformate, which is then attacked by another phenoxide. About 1 billion kg of polycarbonate is produced each year.

CR-39 lens:

CR39 or polyallyl diglycol carbonate (PADC) is a plastic monomer that, along with the other material PMMA (polymethylmethacrylate), is often used in the manufacture of spectacle lenses. 

 The abbreviation stands for "Columbia Resin # 39", the 39th formula for a thermoset plastic, which was developed by the Columbia Resins project in 1940 during World War II to reduce weight and increase the range of the bomber. After the war, the Armorlite Lens Company of California is credited with manufacturing the first CR39 lenses in 1947. CR39 plastic has a refractive index of 1,498 and an Abbe number of 58. CR39 is now a branded product from PPG Industries 

CR39 is manufactured by polymerizing diethylene glycol bis allyl carbonate (ADC) in the presence of a diisopropyl peroxydicarbonate (IPP) initiator. The presence of the allyl groups allows the polymer to form crosslinks; therefore, it is a thermosetting resin. The ADC monomer polymerization program using IPP is generally 20 hours with a maximum temperature of 95 ° C. Elevated temperatures can be achieved with a water bath or convection oven. To be delivered.

2) Mirror coating:

Sunglasses with a reflective optical coating (called a mirror coating or flash coating) on ​​the outside of the lenses to make them look like small mirrors. Contact lenses typically impart a brown or gray tint to the wearer's vision. The mirror coating reduces the amount of light that penetrates through the tinted glass by an additional 10–60%, making it especially suitable for sand, water, snow, and high altitudes. 

Mirrored sunglasses are unidirectional mirrors The simplest version of a mirror coating is a single layer of a deposited thin film of a suitable metal, usually made by ion beam deposition, sputter deposition, or vapor deposition. . However, this type of coating is very susceptible to scratches and deterioration, especially in a corrosive environment such as saltwater.

Newer reflective coatings generally consist of several alternating layers of certain thicknesses made of dielectric materials and sometimes metals. The metal layer can consist of titanium, nickel or chromium, or an alloy such as nichrome or Inconel and has a thickness in the range of 0.5 to 9 nanometers. The dielectric layer comprises a suitable oxide such as chromium oxide, silicon dioxide, or titanium dioxide; its thickness determines the reflective properties of the resulting dielectric mirror.

3) Scratch-resistant coating:

As an anti-scratch coating for polycarbonate (PC) or poly (methyl methacrylate) (PMMA), they do not impair the optical properties of these materials. Under normal circumstances, the thickness of this coating is very small, around 130 nm, which does not affect the optical properties of the polymers.

Aluminum oxide nanoparticles as an anti-scratch coating have 37% non-volatile substances with 30% nanoparticle content, which is essentially surface-modified polysiloxane. These are efficient and effective scratch-resistant coatings. They are suitable for rugged and demanding scratch-resistant coating applications such as military ballistic panels, window glazing. 

Silica Nanoparticles as scratch-resistant coating are surface-modified silicas with 50% non-volatile substances and 50% nanoparticle content. In the organic group, silica tends to increase the crosslinking density of all reactive groups. It is a popular anti-scratch coating for plastics that combines ease of processing and flexibility.

4) Polarizing film:

Polarizers are made in many ways. One of the most common polarizers is known as a Polaroid and it is made up of iodine crystals embedded in a polymer. To create the polarizer, the polymer film is stretched, causing the polymers to line up.

The film is then dipped in an iodine solution and the iodine molecules adhere to the polymer. The ordered structure of the Polaroid allows light to be absorbed parallel to the polymer chains and light to pass perpendicular to the chains. Researchers are trying to create even better polarizers by using aligned nanowires instead of iodine-coated polymer chains.

5) Anti-reflective coating:

Anti-reflective coating, or AR coating, is a special technology that removes unwanted reflections from the front and back of your lenses so you can see with crystal clarity. When you wear glasses with an anti-reflective coating, there is more room for light to pass through your lenses and this allows you to see smoothly. This special coating is ideal not only for glasses but also for sunglasses. Even when in the sun, its AR coated bezel prevents glare from sunlight from reflecting off your eyes so you can see better.

The closest materials with good physical properties to a coating are magnesium fluoride, MgF2 (with an index of 1.38), and fluoropolymers, which can have indexes up to 1.30 but are more difficult to use. MgF2 on a corona glass surface gives a reflectance of approximately 1% compared to 4% for bare glass. MgF2 coatings work much better on higher refractive index glasses, especially those with a refractive index close to 1.9. MgF2 coatings are widely used because they are cheap and durable. If the coatings are designed for a wavelength in the middle of the visible band, they will give reasonably good antireflection properties throughout the band.

6) Photochromatic coating:

Photochromic lenses were developed in the 1960s by William H. Armistead and Stanley Donald Stookey at Corning Glass Works Inc. The glass version of these lenses achieves their photochromic properties by embedding microcrystalline silver halides (usually silver chloride) in a glass substrate. Photochromic plastic cups use organic photochromic naphthopyrans to achieve the reversible darkening effect.

These lenses darken when exposed to UV light at the intensity of sunlight, but not when exposed to artificial light. In the presence of UVA light (wavelengths 320 to 400 nm), the electrons in the glass combine with the colorless silver cations to form elemental silver. Since elemental silver is visible, the lenses appear darker. Back in the shadows, this reaction is reversed. The silver returns to its original ionic state and the lenses become transparent.

Because the photochromic material is dispersed on the glass substrate, the degree of darkening depends on the thickness of the lens, which is problematic for lenses with varying thickness in prescription glasses. In the case of plastic lenses, the material is typically embedded in the surface layer of the plastic with a uniform thickness of up to 150 µm. 

Metal oxide coatings reduce the amount of UV radiation transmitted through sunglasses and therefore protect your eyes. Organic dyes can stain plastic lenses. The exact chemicals used are kept under lock and key. Silver atoms form groups that absorb ultraviolet and visible light. The Cu + ions in the glass reduce the Cl atoms and prevent them from escaping. 

Photochromic glass lenses can use copper-doped silver halide salts, which generate elemental silver in ultraviolet light and darken. Plastic cups are based on organic compounds that reversibly isomerize in ultraviolet light to produce dark tints.

Reference:

1) https://www.piedmont.org/living-better/what-are-sunglasses-really-doing-for-your-eyes

2) https://en.wikipedia.org/wiki/Crown_glass_(optics)

3) https://en.wikipedia.org/wiki/Polycarbonate

4) https://en.wikipedia.org/wiki/CR-39

5) https://en.wikipedia.org/wiki/Photochromic_lens

6) https://en.wikipedia.org/wiki/Anti-reflective_coating

7) https://www.fivepointseyecare.com/eyeglasses/polarized-lenses-and-anti-reflection-coating/

Kevlar was invented by American chemist Stephanie Kwolek while working for DuPont in anticipation of a gasoline shortage. In 1964, her group began looking for a new lightweight and strong fiber for light but strong tires. 

Kevlar is not like cotton: not everyone can make it with the right raw materials. It is a proprietary material manufactured solely by the DuPont chemical company and comes in two main grades called Kevlar 29 and Kevlar 49 (other grades are made for special uses)

Kevlar was introduced in 1971 after it was discovered in the early 1960s by American chemist Stephanie Kwolek (1923-2014) who, along with Paul Morgan, received US Patent 3,287,323 for her invention in 1966. Originally developed as a lightweight replacement for steel reinforcements, vehicle tires, probably best known today for use in things like bulletproof vests; By the time Kwolek died in 2014, she had sold a million Kevlar vests and countless lives had been saved.

Properties:

The tensile strength and modulus of aramid fiber are significantly higher than previous organic fibers and the elongation of the fiber is lower. Aramid fibers are easier to weave on looms than brittle fibers such as glass, carbon, or ceramic. They also have an inherent resistance to organic solvents, fuels, lubricants, and exposure to flames.

It is strong but relatively light. The specific tensile strength (tensile strength or tensile strength) of both Kevlar 29 and Kevlar 49 is more than eight times that of steel wire. Unlike most plastics, it does not melt - it can withstand temperatures to some degree and only breaks down at around 450 ° C (850 ° F).

Very low temperatures have no effect on Kevlar: DuPont found no "embrittlement or decomposition" down to -196 ° C (-320 ° F). As with other plastics, prolonged exposure to ultraviolet light (such as sunlight) causes discoloration and some degradation of Kevlar fibers. Kevlar can resist attack by many different chemicals, although prolonged exposure to strong acids or bases will degrade it over time.

Production:

Kevlar is synthesized in a solution from the monomers 1,4-phenylenediamine (paraphenylenediamine) and terephthaloyl chloride in a condensation reaction, producing hydrochloric acid as a by-product. The result shows a liquid-crystalline behavior and the polymer chains are oriented in the direction of the fibers by mechanical traction. 

You probably know that natural materials like wool and cotton need to be spun into fibers before they can be made into useful textiles, just like man-made fibers like nylon, kevlar, and Nomex.

The basic aramid is turned into fibers by a process called wet spinning, which involves forcing a hot, concentrated, and very viscous solution of poly-para-phenylene terephthalamide through a spinneret (a metal former a bit like a sieve) to make long, thin, strong, and stiff fibers that are wound onto drums. The fibers are then cut to length and woven into a tough mat to make the super-strong, super-stiff finished material we know as Kevlar.

Types: 

Kevlar fibers and filaments are available in a variety of types, each with its own unique properties and performance characteristics for different protection needs.

 1) Kevlar K29 -    in industrial applications such as cables, asbestos substitutes, brake pads, and body/vehicle armor. 

 2) Kevlar K49    -     High modulus for cable and rope products. 

 3) Kevlar K100  -     Colored version of Kevlar 

 4) Kevlar K119  -     Higher elongation, more flexible, and more resistant to fatigue. 

 5) Kevlar K129  -     Higher toughness for ballistic applications. 

 6) Kevlar AP      -     Has 15% higher tensile strength than K29. 

 7) Kevlar XP      -     Lighter resin and KM2 plus fiber combination. 

 8) Kevlar KM2   -    Increased ballistic resistance for armor applications.

Applications: 

Kevlar is a type of aramid fiber. It is woven in textile materials and is extremely strong and lightweight, resistant to corrosion and heat. It is used in extensive applications such as aerospace engineering (such as the body of the airplane), bulletproof vests, car, and boat brakes.

Automotives:

Kevlar cellulose brake pads are better equipped for friction abrasion with their increased thermal stability and inherent resistance to abrasion; Kevlar-reinforced brake pads are designed for long life and safe, quiet braking. 

Kevlar is also effective in clutches subject to high friction. Tests have shown that Kevlar clutch linings do not need to be repaired or replaced as often as standard clutch linings.

Formula 1 racing cars are known to crash at high speeds and catch fire. This was mainly due to the gas tank being punctured and the fuel caught on fire / exploded. Some drivers were seriously injured and died. Modern Formula 1 cars have Kevlar reinforced fuel tanks. These types of tanks are very difficult to pierce and are flexible enough that such a tank will fit into a narrow space of unusual shape. Safety has been improved due to the level of protection provided by Kevlar. 

 Kevlar fibers help improve the safety, performance, and durability of automotive components for a wide variety of vehicles, from cars and trucks to professional racing cars. Kevlar auxiliaries provide internal and external strength to automotive components. 

DuPont Kevlar fiber helps improve the safety, performance, and durability of automotive components such as automotive hoses and belts for a wide variety of vehicles, from cars and trucks to professional race cars

Armors:

The armor systems made of Kevlar-Aramid fiber are designed to protect human life and vital equipment against ballistic threats, the ballistic resistance of Kevlar-Aramid is due to its excellent thermal properties, its high crystallinity, its highly oriented fine structure, and its high strength properties. . The high glass transition temperature and thermal stability of Kevlar fiber ensure the integrity of the ballistic structure at a relatively high temperature in a ballistic event. 

Kevlar fiber is a very important component of military assets. By incorporating its inherent protection technology into military helmets, it has helped save thousands of lives.

Kevlar is an excellent anti-ballistic material (resistant to bullets and knives) because it takes a lot of energy to get through a knife or bullet. Tightly entangled fibers of highly oriented (aligned) polymer molecules are extremely difficult to separate - it takes energy to separate them. Energy is "stolen" from a bullet (or a knife hit hard by an attacker) as it tries to breakthrough. If it manages to penetrate the material, it will slow down considerably and cause much less damage. 

Kevlar provides a lightweight and effective armor solution that helps protect against ballistic attacks and allows cars and trucks to retain most of their original drivability while stopped for multiple laps. Law enforcement agencies, cash security companies, and people who live or work in harsh environments rely on Kevlar armor to increase safety in vehicles where weight is a critical factor.

Cables:

Kevlar ropes and cables help deliver performance and value to customers in the fine rope industry by providing excellent strength, fatigue resistance, shrinkage, and durability. Find out how branded Kevlar fibers strengthen ropes and cables to withstand extreme temperatures and harsh environments. Due to its chemical and thermal stability, Kevlar reinforcement helps make seals strong and durable.

Kevlar is used as a reinforcement in fiber optics. Kevlar, which is normally placed on the edge of the cable, provides the necessary protection. Kevlar also offers additional functionality that meets the dielectric, weight, diameter, flexibility and handling requirements of a fiber optic cable.

Sports:

It is used as the inner lining of some bicycle tires to avoid punctures. In table tennis, Kevlar layers are added to custom layer blades or paddles to increase bounce and reduce weight. It is used for motorcycle safety clothing, especially in padded areas such as the shoulders and elbows.

In kyudo or Japanese archery, it can be used as an alternative to more expensive hemp for bowstrings. It is one of the most important materials for paragliding suspension lines. In fencing, it is used in protective jackets, breeches, plastrons, and the front of the masks. Tennis rackets are usually covered with Kevlar. It is even used in sails for high-performance racing boats.

Space:

Kevlar is a material widely used in the design and manufacture of the shields that protect the manned elements of the International Space Station (ISS) from the threat of meteorites and space debris that are increasingly polluting the Earth's orbits. Kevlar was also selected for extensive use in the fabrication of innovative flexible structures that are under development for future manned exploration missions.

Kevlar was originally chosen for its excellent ballistic properties to protect debris, but its compatibility with the space environment had to be carefully evaluated. In parallel with the high-speed impact tests, a significant amount of analysis, testing, and simulations were carried out to quantify its capabilities in reducing the lethality of space debris to understand and characterize the behavior of Kevlar under space conditions. 

Kevlar's ability to protect human crews from the powerful mixture of high-energy charged particles destined for long-term missions has been studied.

Reference:

1) https://en.wikipedia.org/wiki/Kevlar

2) https://materials-today.com/kevlar-uses-properties-and-processing/

3) https://sites.google.com/site/sailclothscience/sailcloths/composite/kevlar/synthesis

4) https://www.dupont.com/products/dupont-kevlar-fiber.html

5) https://kevlarweb.wordpress.com/applications/

6) https://textilelearner.net/kevlar-fiber-types-properties-manufacturing/

Graphene is a single layer of graphite, the carbon-based material found in pencil leads. Graphite has been known for centuries, but it wasn't until 2003 that graphene was isolated by cutting layers of graphite with tape. It is a layer of carbon atoms one atom thick arranged in a flat hexagonal lattice structure. 

It is originally seen on electron microscopes in 1962, but only examined while in use on metal surfaces. The material was later rediscovered, isolated, and examined in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester, who received the Nobel Prize in Physics in 2010 for their "pioneering experiments on the two-dimensional material graphene." The high-quality graphic turned out to be surprisingly easy to isolate.

Properties: 

Graphene is an allotrope of carbon made up of a single layer of atoms arranged in a two-dimensional honeycomb nanostructure. The name is derived from "graphite" and the suffix En, which reflects the fact that allotropic graphite of carbon contains numerous double bonds. Each atom in a graphene sheet is linked to its three closest neighbors by a σ bond and contributes an electron to a conduction band that runs the length of the sheet. 

Graphene's reputation as a "wonderful material" is based on its excellent properties. Its strong carbon-carbon bonds make it a million times thinner than a sheet of paper, but stronger than diamond and 200 times stronger than steel. It is also a flexible material and conducts heat and electricity better than copper. Since it is only one atom thick, almost 98% of visible light passes through graphene, making it transparent.

Production: 

Graphene is an extremely diverse material and can be combined with other elements (including gases and metals) to produce various materials with various superior properties. Researchers around the world are constantly studying and patenting graphene for its various properties and uses.

The only method of making large-area graphene was a very expensive and complex process (chemical vapor deposition, CVD) that used toxic chemicals to grow graphene as a monolayer by exposing platinum, nickel, or titanium carbide to ethylene or benzene at high temperatures.

There were no alternatives to using crystalline epitaxy on anything other than a metallic substrate. These production problems initially made graphene unavailable for development research and commercial purposes. Furthermore, the use of CVD graphene in electronics has been hampered by the difficulty of removing the graphene layers from the metal substrate without damaging the graphene.

Applications: 

Graphene has been a hot topic in materials and chemical research since its discovery in 2003. It has been associated with biomedical, electronic, and water purification applications. But how close are we really to using graphics in our daily lives? Here are some applications of the wonder material.

Display: 

Thanks to its transparency and conductivity, graphene can be used in screens and touch screens. However, these are currently more expensive to produce than the currently used material, indium tin oxide. 

James Tour, a professor of chemistry at Rice University who worked on ways to make graphene by dissolving pieces of graphite. The team has already created a flexible touch screen using polymer-supported graphene to create the screen's transparent electrodes. The indium tin oxide material currently used to make transparent electronic components is expensive and brittle. Making graphene into flexural polyester sheets is the first step in making transparent electronics stronger, cheaper, and more flexible. "In theory, you could roll up your iPhone and stick it behind your ear like a pencil," says Tour.

Water filters:

The graphene filter lets water through, but not other liquids and gases, so it can be used for water purification. Researchers are working on a device that could filter salt from seawater. 

In this latest research, Yang, Yang, and their colleagues devised a method to create centimeter-sized layers of porous graphene that do not suffer from the effects of defects. To do this, a mesh-like network of single-walled carbon nanotubes was applied to a graphene sheet, which essentially strengthens the material and blocks the propagation of cracks and tears. The pores are then etched into the material to create a desalination membrane. 

In the test, the equipment's membranes were able to remove 8597% of the salt from seawater. While this is impressive for membranes of this size, it should be increased to over 99% for use in commercial desalination systems. Scaling the membrane to meter sizes shouldn't be a problem, the team says.

Electronics:

Graphene was touted as the successor to silicon and was used to make very fast transistors. However, its conductivity cannot be "switched off" like silicon. Other 2D materials look more promising.

Researchers at the University of Manchester have already created the world's smallest graphene transistor. The smaller the transistors, the better they work in circuits. The fundamental challenge of the electronics industry in the next 20 years is the further miniaturization of technology.

Medical:

Several biomedical applications are being explored for graphene, including drug delivery, cancer therapy, and uses as a sensor. However, the toxicity profile must be assessed before each clinical application. 

Recent research has shown that graphene has multiple uses in the medical field, as researchers have discovered that graphene can be used to enhance cancer-fighting treatments. The main objective of the treatment of this type of disease is to destroy the diseased cells and affect the healthy cells as little as possible.

Several studies have found that combining charts with different medications and treatments can improve results. The load of the drug that reaches the cancer cells increases, increasing the chances of successful treatment. However, the use of this material is not limited to this, it is also estimated that there is a high probability that graphene-based muscle and bone implants will be produced. It has numerous properties that make it very useful for medical applications.

Energy storage:

Graphics-based energy storage is possible. It can also replace graphite in normal batteries and improve efficiency. Also, materials can be added to make them stronger and lighter.

The high conductivity of interconnected graphic networks also increases their interest in energy storage applications. Other factors such as its porous microstructure, its electrochemical stability, and its good mechanical stability are some of the advantages of graphene when used as an energy store. Some of these devices include their application in fuel cells, solar cells, batteries, and supercapacitors.

Reference:

1) https://en.wikipedia.org/wiki/Graphene

2) https://www.atriainnovation.com/en/graphene-characteristics-and-applications/

3) https://iopscience.iop.org/article/10.1149/2162-8777/abbb6f

4) https://www.graphene.manchester.ac.uk/learn/applications/electronics/

5) https://nanografi.com/blog/applications-of-graphene-in-medicine/

6) https://www.thegraphenecouncil.org/page/EnergyStorage15JUL

The twin pen and ink tools have been used since around 2500 BC. C. Used when Chinese and Egyptian societies independently developed writing ink. Today, as then, ink for pens is made according to a similar recipe: a strongly colored substance is suspended with stabilizers in a liquid that a pen can slide over the paper. Since then, innovations in chemistry have varied the chemical composition of the ink.

Fountain pens that preceded ballpoint pens used fine water-based ink and hung from gravity to draw the ink to the tip of the pencil. They had to be held at certain angles and used with caution; otherwise, the mechanisms will break or the ink will stain.

The development of the rough ball in the early 1940s by the Hungarian brothers Lasdislas and Georg Biro (whose names are still on some Bic pens) solved the problem of gravity in combination with thick oil-based newspaper ink. . It wasn't until 1949 that Fran Seech developed the modern formula for pen ink that made Paper Mate pens so popular. It took more than paint and solvent.

Colorants:

The color of ink comes from a dye that can be dissolved in water or from a pigment that is insoluble in water. The Eosin Y dye gives red ink its color and is made by adding the element bromine to a fluorescent compound. Inks that use pigments include white ink (which contains titanium oxide) and metallic gold ink (which, surprisingly, uses a copper-zinc alloy). Soot, a pigment made from carbon and oil, is an integral part of black pen ink.

The ink in a normal pen consists of dye or pigment particles: Carbon for black pens, eosin for red or a suspected cocktail of Prussian blue, crystal violet, and phthalocyanine blue for the classic blue pen.

Solvents:

The earliest forms of writing ink consisted of stabilizers that contained fuel residues, perhaps the most abundant liquid solvent on the planet: water. Centuries later, manufacturers began to use chemicals other than solvents. Petrochemicals, which are mainly made up of carbon and hydrogen, continue to be used in ballpoint inks.

Markers use ink made with alcohol as the solvent. However, recent restrictions on the use of carbon-based compounds in the industry have led manufacturers to revert to the idea of ​​water-based inks.

Colorant suspended in an oil or water solvent. The most common oils are benzyl alcohol or phenoxyethanol, which are mixed with pigments or dyes to create a smooth, vibrant ink that dries quickly. However, ink is more than its two main components. The pen works with pigment and solvent only but might need some improvement.

Stabilizers:

Inks can coagulate when their dye or pigment particles clump together. Stabilizers prevent clotting by sticking to molecules and moving them over each other, giving the ink a smoother flow. Polymers, large molecules made up of chains of repeating units, are excellent stabilizers. 

In the past, plant resin and egg albumin served as sources of stabilizing polymers. Laboratory creations such as polyvinyl chloride and polyvinyl acetate fulfilled this role in the late 20th century.

Research has also suggested other additives that can improve the basic properties of the ink. Glycerides, which contain fatty acids and glycerin alcohol, can be extracted from plants and added to facilitate the glide of the ink on the paper. Chemicals that regulate the pH of the ink, such as triethanolamine, prevent the ink from becoming acidic or corrosive enough to damage the pens.

Election ink:

The silver nitrate is used in election ink. Ink dries in less than 40 seconds and leaves a dark stain. However, the strength of the stain depends on the amount of silver nitrate used. According to the manufacturers, the concentration of silver nitrate is between 7% and 25%, but the exact composition cannot be revealed due to property problems.

The ink stays on the skin for at least 72 hours. Silver nitrate is preferred because it is soluble in water and gives an ink-black solution. When applied to the skin, silver nitrate reacts with salt to form silver chloride. Silver chloride is not soluble in water and adheres to the skin. It cannot be washed with soap and water. It can't even be washed with hot water, alcohol, nail polish remover, or bleach. The ink will disappear as the old skin cells die.

Mysore Paints and Varnish Limited is a company based in the city of Mysore, India. It is the only company in India authorized to manufacture indelible ink that is used in elections to prevent people from voting multiple times. 

To remove the stain pour excess household ammonia on the stained areas of ​​the skin. Rub the area firmly with a cloth to remove the silver chloride stain. Silver chloride reacts with ammonium hydroxide and is poorly soluble in ammonia, but according to Le Chatelier's principle, it dissolves in an excess of concentrated ammonia solution. If it did not vanish then use concentrated acids like nitric acid, sulfuric acid, and hydrochloric acid. 

Reference:

1) https://en.wikipedia.org/wiki/Ink

2) https://www.pcimag.com/articles/85040-pigments-in-ink

3) https://www.chemistryworld.com/news/ink-chemistry/3002158.article

4) https://en.wikipedia.org/wiki/Election_ink

5) https://youtu.be/Fypi6dAJB8E