What is cellulose?

Cellulose is an organic compound with the formula (C6H10O5)n. It is a polysaccharide. Cellulose plays an important role in the structural component of the primary cell wall of green plants. There are many forms of algae and the oomycetes.
Cellulose is the most abundant organic polymer on Earth.
It is mainly used to produce paperboard and paper. Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton.
Some animals, like ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts, such as Trichonympha. In humans, cellulose acts as a hydrophilic bulking agent for feces and is often referred to as a "dietary fiber".
Structure and properties of cellulose
Cellulose has no taste, is odorless, is hydrophilic with the contact angle of 20–30, is insoluble in water and most organic solvents,and is biodegradable. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature.
Cellulose is derived from D-glucose units, which condense through β(1→4)-glycosidic bonds. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch, glycogen, and other carbohydrates. Cellulose is a straight chain polymer. The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbor chain, holding the chains firmly together and forming microfibrils with high tensile strength.
Cellulose is a crystalline compound. It requires a temperature of approximately 320 °C and a pressure of 25 MPa to become amorphous in water.
Several different crystalline structures of cellulose are known, corresponding to the location of hydrogen bonds between strands. Natural cellulose is cellulose I, with structures Iα and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV.
Cellulose consists of crystalline and amorphous regions. By treating it with strong acid, the amorphous parts can be broken up, ended up producing nanocrystalline cellulose.

What is Polycarbonates???

Polycarbonates are a particular group of thermoplastics. These plastics are widely used in modern industries manufacturing as they are easily worked, molded, and thermoformed. The reason why they are called polycarbonates are because they are polymers having functional groups linked together by carbonate groups (-O_(C=O)-O-) in a long molecular chain. Besides carbon monoxide was used as a C1-synthon on an industrial scale to produce diphenyl carbonate, being later trans-esterificated with a diphenolic derivative affording polyaromatic carbonates. The C1-synthon can be divided into polyaromatic carbonates and polyaliphatic carbonates. The polyaliphatic carbonates are a product of the reaction of carbon dioxide with epoxides, what owing to the thermodynamical stability of carbon dioxide requires the use of catalyst. The working systems are based on porphyrins, alkoxides, carboxylates, salens and beta-diiminates as rganic, chelating ligands and aluminium, zinc, cobalt and chromium as the metal centres. Polyaliphatic carbonates display promising characteristics of having a better biodegradability than the aromatic ones and could be employed to develop other speciality polymers.

Advantages
-Durable material
-Can be laminated to make bullet-proof ‘glass’
-Bullet-resistance
-Stronger but more expensive
-Highly transparent to visible light
-Good light transmission

Uses
-Making eyeglasses lenses as it has high optical and mechanical properties
-Uses in making compact disks as it is tough and durable
-Making polycarbonate lenses that blocks ultra-violet (UV) rays
-Used in electronics industries

What is PVC???

Polyvinyl chloride or PVC in short, is a plastic which has a chemical formula of CH2=CHCI .It is a thermoplastic that contains high levels of chlorine which can reach up as high as 57% and the other 43% of it is made of carbon which is derived from oil and gas involved in the PVC fabrication. PVC is produced by polymerization of the monomer vinyl chlorine (VCM). The high level of chlorine is obtained and manufactured by the electrolysis of sodium chloride which is a salt. The chlorine is then being combined with ethylene that has been produced from the oil. The result of the both element produces ethylene dichloride, which is converted at a very high temperatures to vinyl chloride monomer. These monomer molecules are then polymerized to form polyvinyl chloride resin. Moreover, PVC which is a thermoplastic material is useful in the industries as they have the characteristics that it can be melted again and again. These materials can be heated to a certain temperature and will harden again as they cold down. This odourless and solid plastic that is white, brittle can be found on the market in the form of pellets or white powder. It is also highly resistance to oxidation and degradation makes it possible to store material for long period of time.

Uses of PVC
-Predominant in the construction industry due to low cost, ease to mold and light in term of weight
-Used as a replacement for metal where corrosion can be compromise functionality and maintenance cost can be escalate
-Used to make pipe fitting and pipe conduits as it is installation flexible where they can be connected with the use of joints, solvent cements and special glues
-PVC is also present in electrical components such as electrical insulation and cable coating
-In the health care industry it is used to make feeding tubes, blood bags, intravenous (IV) bags, parts of dialysis devices and many more items
-In daily use, it is used to make raincoats, plastic bags, toys, credit cards, doors, hoses and many more

Advantages
-Light in weight
-Biocompatible
-Clarity and transparency
-Resistance to chemical stress cracking
-Low thermal conductivity
-Little to no maintenance
-Can be recycled and converted into a newer product
-Chemical stability

What is polyethylene??

Polyethylene is the most common form of plastic that is used in our world. It is normally used in plastic bags ,plastic bottles, plastic films and many more. Most of them have the chemical formula of (C₂H₄)_nH_2.  The IUPAC name for polyethylene is polyethene or polymethylene. 

Physical properties.

Polyethylene is a thermoplastic polymer. They consist of a long hydrocarbon chain. The temperature at which these occur varies strongly with the type of polyethylene. For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (221 to 239 °F).

Chemical properties.

Polyethylene have a strong chemical resistance. Strong acids and strong bases can hardly affect them.

They can usually be dissolved at elevated temperature in aromatic hydrocarbons or chlorinated solvents.

There are 2 types of process in this polyethylene.

One of them is monomer.

The ingredient of monomer is ethylene . It is a gaseous hydrocarbon with the formula C₂H₄. The ethylene has a high purity because it is highly reactive. The  specifications for this to happen are <5 ppm for water, oxygen, as well as other alkenes. Ethylene is usually produced from petrochemical sources, but also is generated by dehydration of ethanol.

Polymerization

Ethylene is a more stable molecule compared to other molecules . It  polymerizes only upon contact with catalysts. This conversion is highly exothermic. So we can say this conversion gives out a high amount of heat. Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. The most common catalysts consist of titanium(III)chloride, the so-called Ziegler Natta catalyst. Another common catalyst is the Phillips catalyst, prepared by depositing Chromium(VI)oxide on silica. Ethylene can be produced through radical polymerization, but this route has only limited utility and typically requires high pressure apparatus.

Classification

Polyethylene can classed into different several groups depending on its density and its branching. Its mechanical properties mainly depends on its branching like molecular weight and crystal structure. The most important polyethylene grades are HDPE, LLDPE and LDPE

High-density polyethylene (HDPE)

-Has density of greater or equal to 0.941 g/cm³. 

-has a low degree of branching so have a low intermolecular forces and tensile strength. 

-can be produced by chromium/silica catalysts, Ziegler Natta catalyst or metallocene catalysts. 

-used in products and packaging such as milk jugs, detergent bottles, butter tubs, garbage containers and water pipes. 

-One third of all toys are manufactured from HDPE. In 2007 the global HDPE consumption reached a volume of more than 30 million tons.

Linear low-density polyethylene (LLDPE)

-has a density range of 0.915–0.925 g/cm³. 

-has higher tensile strength than LDPE. 

-has better environmental stress cracking resistance but is not as easy to process. 

-is used in packaging, particularly film for bags and sheets. Lower thickness may be used compared to LDPE. Cable covering, toys, lids, buckets, containers and pipe.

-In 2009 the world LLDPE market reached a volume of almost US$24 billion (€17 billion)

Low-density polyethylene (LDPE)

-has a density range of 0.910–0.940 g/cm³.

 -has a high degree of short and long chain branching, which means that the chains do not pack into the crystal structure as well. Therefore it has less strong intermolecular forces .  

-is created by free radical polymerization. 

-the high degree of branching with long chains gives molten LDPE unique and desirable flow properties. 

-is used for both rigid containers and plastic film applications such as plastic bags and film wrap. 

-In 2009 the global LDPE market had a volume of about US$22.2 billion (€15.9 billion).

Acrylic

There are a few chemical compounds that acryloyl group derived from acrylic acid. 

Example:

             1. Acrylic fiber

             2. Acrylic paint

             3. Acrylic glass

             4. Acrylic resin

             5. Acrylate polymer

      From the examples above, I would like to discuss some of the chemical compounds that derived from acrylic acid. 

      Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile). To be called acrylic in the U.S, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. DuPont created the first acrylic fibers in 1941 and trademarked them under the name Orlon or acrilan fabric. It was first developed in the mid-1940s but was not produced in large quantities until the 1950s. Strong and warm, acrylic fiber is often used for sweaters and tracksuits and as linings for boots and gloves, as well as in furnishing fabrics and carpets. It is manufactured as a filament, then cut into short staple lengths similar to wool hairs, and spun into yarn. In an additional, modacrylic is a modified acrylic fiber that contains at least 35% and at most 85% acrylonitrile monomer. The comonomers vinyl chloride, vinylidene chloride or vinyl bromide used in modacrylic give the fiber flame retardant properties. End-uses of modacrylic include faux fur, wigs, hair extensions and protective clothing.

      These are some of the characteristics of acrylic fiber. It is outstanding wickability and quick drying to move moisture from body surface. Acrylic fiber can be easily washed and retains its shape. Besides that, it also resistant to moths, oil and chemical. It is a superior resistance to sunlight degradation too.

      Below are the photos of acrylic fiber and how is the acrylic fiber structure looks like.

       Next, I would like to talk about the acrylic paint. Acrylic paint is a fast-drying paint containing pigment suspension in acrylic polymer emulsion. Acrylic paints are water soluble, but become water-resistant when dry. Depending on how much the paint is diluted with water or modified with acrylic gels, media, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting, or have its own unique characteristics not attainable with other media.

      As early as 1934 the first usable acrylic resin dispersion was developed by German chemical company BASF, which was patented by Rohm and Haas. The synthetic paint was first used in 1940s, combining some of the properties of oil and watercolor. Between 1946 and 1949, Leonard Bocour and Sam Golden invented a solution acrylic paint under the brand Magna paint. These were mineral spirit-based paints. Acrylics were made commercially available in the 1950s. A waterborne acrylic paint called "Aquatec" would soon follow. Otto Rohm invented acrylic resin, which quickly transformed into acrylic paint. In 1953, the year that Rohm and Haas developed the first acrylic emulsions, Jose L. Gutierrez produced Politec Acrylic Artists' Colors in Mexico, and Permanent Pigments Co. of Cincinnati, Ohio, produced Liquitex colors. These two product lines were the very first acrylic emulsion artists' paints.

      Some of us will always think that acrylic paint and oil paint are the same things or product. Now, I will discuss about the difference between acrylic paint and oil paint. 

              Acrylic paint: - "water-based" (or sometimes "water-borne")

                                   - fast evaporation of water but "water-based" can be slowed with                                                       the use of acrylic retarders.

                                   - Not all pigments in oil are available in acrylic. Acrylic paints, unlike                                                  oil, may also be fluorescent.

                                   - more flexible nature and more consistent drying time between                                                          colors

                                   - acrylic paint is very elastic, which prevents cracking from occur

              Oil paint: - "oil-based"

                             - allow for more time to blend colors and apply even glazes over                                                         underpaintings

                             - require the use of solvents such as mineral spirits or turpentine to thin                                               the paint and clean up; these generally have some level of toxicity                                                 and are often found objectionable

                             - higher pigment load

      These are some of the photos of acrylic paint and some of the art work which uses acrylic paint.

      At last, I would like to discuss about acrylate polymer. Acrylate polymers belong to a group of polymers which could be referred to generally as plastics. They are noted for their transparency, resistance to breakage, and elasticity. They are also commonly known as acrylics or polyacrylates. 

      Monomers, acrylic monomers are used to form acrylic polymers. They are based on the structure of acrylic acid, which consists of a vinyl group and acarboxylic acid terminus. Other typical acrylate monomers are derivatives of acrylic acid, such as methyl methacrylate in which one vinyl hydrogen and the carboxylic acid hydrogen are both replaced by methyl groups, and acrylonitrile in which the carboxylic acid group is replaced by the related nitrile group. 

There are others examples of acrylic monomers:

                     Methacrylates                               Methyl acrylate
                     Ethyl acrylate                                2-Chloroethyl vinyl ether
                     2-Ethylhexyl acrylate                    Hydroxyethyl methacrylate
                     Butyl acrylate                               Butyl methacrylate

      Let discuss about the properties of acrylic polymers. Acrylic offers light transmittance of 92%--theoretically the maximum obtainable--with particular clarity at lower wavelengths of 270 to 350 nm. Acrylic polymers have good mechanical strength and dimensional stability, along with high tensile and flexural strength. Acrylic also provides good surface hardness for scratch resistance, an important quality in medical applications. Because acrylic is a rigid material, standard grades do not provide high impact resistance. Acrylic does perform well in electrical applications, due to its insulating nature; an increase in absorbed moisture makes it more conductive. As temperatures increase, acrylic becomes more flexible and exhibits less flexural strength. Under sustained loading, strain on the material can induce excessive molecular movement that increases with time under load and higher temperatures and results in the phenomenon known as creep that is common to all thermoplastics.

      Before I end this article, I would like to show some of the photos of acrylic polymers.

All above show that there are different types of acrylic compounds that can be derived from the acrylic acid. Through this article, we can understand more about acrylic compounds with different properties and different structure.

Disadvantages of polymer!

Disadvantages of polymers are: 

1. All types of polymer are non bio-degradable. When it is disposed, it takes up a long time to decay. It may takes up to hundred years to decay and break down totallly. 
2. Polymer are easily breakable item. polymer are more fragile compared to some natural item.
3. When polymers incorporated with additives are burnt they emit a lot of poisonous gases into the atmosphere. This gasses is bad to human health and may also cause greenhouse effect to happen and lead to more serious problem.  
4. Improper disposal of polymer made product leads to environmental pollution. 
5. Polymer undergo oxidation and ozonation easily.

Benefits of polymer

The invention of polymer brings a lot of convenient and advantages to human kind.  Below are something that polymer are able to do to us...

• Polymers can be very resistant to chemicals. Consider all the cleaning fluids in your home that are packaged in plastic. Reading the warning labels that describe what happens when the chemical comes in contact with skin or eyes or is ingested will emphasize the need for chemical resistance in the plastic packaging. While solvents easily dissolve some plastics, other plastics provide safe, non-breakable packages for aggressive solvents.

• Polymers can be both thermal and electrical insulators. A walk through your house will reinforce this concept, as you consider all the appliances, cords, electrical outlets and wiring that are made or covered with polymeric materials. Thermal resistance is evident in the kitchen with pot and pan handles made of polymers, the coffee pot handles, the foam core of refrigerators and freezers, insulated cups, coolers, and microwave cookware. The thermal underwear that many skiers wear is made of polypropylene and the fiberfill in winter jackets is acrylic and polyester.

• Generally, polymers are very light in weight with significant degrees of strength. Consider the range of applications, from toys to the frame structure of space stations, or from delicate nylon fiber in pantyhose to Kevlar, which is used in bulletproof vests. Some polymers float in water while others sink.  But, compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials

• Polymers can be processed in various ways. Extrusion produces thin fibers or heavy pipes or films or food bottles. Injection molding can produce very intricate parts or large car body panels. Plastics can be molded into drums or be mixed with solvents to become adhesives or paints. Elastomers and some plastics stretch and are very flexible. Some plastics are stretched in processing to hold their shape, such as soft drink bottles. Other polymers can be foamed like polystyrene (Styrofoam™), polyurethane and polyethylene.

• Polymers are materials with a seemingly limitless range of characteristics and colors. Polymers have many inherent properties that can be further enhanced by a wide range of additives to broaden their uses and applications. Polymers can be made to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers can also make possible products that do not readily come from the natural world, such as clear sheets and flexible films.

• Polymers are usually made of petroleum, but not always. Many polymers are made of repeat units derived from natural gas or coal or crude oil.  But building block repeat units can sometimes be made from renewable materials such as polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been made from renewable materials such as cellulose acetate used for screwdriver handles and gift ribbon.  When the building blocks can be made more economically from renewable materials than from fossil fuels, either old plastics find new raw materials or new plastics are introduced.

• Polymers can be used to make items that have no alternatives from other materials.  Polymers can be made into clear, waterproof films. PVC is used to make medical tubing and blood bags that extend the shelf life of blood and blood products. PVC safely delivers flammable oxygen in non-burning flexible tubing.  And anti-thrombogenic material, such as heparin, can be incorporated into flexible PVC catheters for open heart surgery, dialysis, and blood collection. Many medical devices rely on polymers to permit effective functioning.

What is polymer?

Polymers are made up of many many molecules all strung together to form really long chains (and sometimes more complicated structures, too). This is a polymer. What makes polymers so fun is that how they act depends on what kinds of molecules they're made up of and how they're put together. The properties of anything made out of polymers really reflect what's going on at the molecular level. So, things that are made of polymers look, feel, and act depending on how their atoms and molecules are connected, as well as which ones we use to begin with! Some are rubbery, like a bouncy ball, some are sticky and gooey, and some are hard and tough, like a skateboard.

Poly- means "many" and -mer means "part" or "segment". Mono means "one". So, monomers are molecules that can join together to make a long polymer chain. 

This is a simple diagram of a chain of monomers.

Sometimes polymers are called "macromolecules". "Macro" means "large" and by now you've figured out that polymers must be very large molecules!

Most of the polymers we'll talk about here are linear polymers. A linear polymer is made up of one molecule after another, hooked together in a long chain. 

Now, linear polymers don't have to be in a straight, rigid line. Those single bonds between atoms in the backbone can swivel around a bit.

To the rest of the world, "linear" means "straight and not curved" but for polymers, linear means "straight and not branched".

          This is a linear polymer!              

                                                            This is a branched polymer!

Polymers Are Like TV: Both Have Lots and Lots of Repeats

The atoms that make up the backbone of a polymer chain come in a regular order, and this order repeats itself all along the length of the polymer chain. (Boy, that makes sense, doesn't it - given that polymers are made by hooking up one molecule after another after another after another.....)

For example, look at polypropylene (sounds like polly-pro-pill-een):

Its backbone chain is made up of just two carbon atoms repeated over and over again. One carbon atom has two hydrogen atoms attached to it, and the other carbon atom has one hydrogen atom and one pendant methyl group (CH₃). 

To make things simple, we usually only draw one unit of the repeat structure, like this:

The repeat unit is put inside brackets, and the subscript n just stands for the number of repeat units in the polymer chain.

Another example: styrene monomers join together to make polystyrene:

 

There are a lot of example of polymer. Example include nylon, acrylic, PVC, polycarbonate , cellulose, and polyethylene!

Nylon

Nylon is a generic designation for a family of synthetic polymers known generically as aliphatic polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station. Nylon is one of the most common polymers used as a fiber. Nylon is used to make clothing all the time, but also in other places, in the form of a thermoplastic. Nylon's first real success came with it's use in women's stockings, in about 1940. They were a big hit, but they became hard to get, because the next year the United States entered World War II, and nylon was needed to make war materials, like parachutes and ropes. But before stockings or parachutes, the very first nylon product was a toothbrush with nylon bristles.  

        Nylons are also called polyamides, because of the characteristic amide groups in the backbone chain. Proteins, such as the silk nylon was made to replace, are also polyamides. These amide groups are very polar, and hydrogen can bond with each other. Because of this, and because the nylon backbone is so regular and symmetrical, nylons are often crystalline, and produce very good fibers. Nylons are condensation copolymers formed by reacting equal parts of a diamine and a dicarboxylic acid, so that amides are formed at both ends of each monomer in a process analogous to polypeptide biopolymers. Chemical elements included are carbon, hydrogen, nitrogen, and oxygen. The numerical suffix specifies the numbers of carbons donated by the monomers; the diamine first and the diacid second. The most common variant is nylon 6-6 which refers to the fact that the diamine (hexamethylene diamine, IUPAC name: hexane-1,6-diamine) and the diacid (adipic acid, IUPAC name: hexanedioic acid) each donate 6 carbons to the polymer chain. As the "repeating unit" consists of one of each monomer, copolymers alternate in the chain. Since each monomer in this copolymer has the same reactive group on both ends, the direction of the amide bond reverses between each monomer, unlike natural polyamide proteins which have overall directionality: C terminal → N terminal.

      In the laboratory, nylon 6-6 can also be made using adipoyl chloride instead of adipic acid. It is difficult to get the proportions exactly correct, and deviations can lead to chain termination at molecular weights less than a desirable 10,000 daltons (u). To overcome this problem, a crystalline, solid "nylon salt" can be formed at room temperature, using an exact 1:1 ratio of the acid and the base to neutralize each other. Heated to 285 °C (545 °F), the salt reacts to form nylon polymer. Above 20,000 daltons, it is impossible to spin the chains into yarn, so to combat this, some acetic acid is added to react with a free amine end group during polymer elongation to limit the molecular weight. In practice, and especially for 6,6, the monomers are often combined in a water solution. The water used to make the solution is evaporated under controlled conditions, and the increasing concentration of "salt" is polymerized to the final molecular weight.

      There are some characteristics for nylon. Nylon has the ability to be very lustrous, semilustrous or dull. Nylon's high tenacity fibers are used for seatbelts, tire cords, ballistic cloth and other uses. Besides that, nylon is high elongation and excellent in abrasion resistance. It is highly resilient. Paved the way for easy-care garments. High resistance to insects, fungi, animals, as well as molds, mildew, rot and many chemicals are the characteristics of nylons too. It is used in carpets, nylon stockings and in many military applications. Nylon has good specific strength and is transparent to infrared light (−12dB).

      These are some of the photo of nylon structure and nylon product:

All the above are the products that made by nylon.

     

      Above are the chemical structure of nylon.