LDPE (Low density polyethylene), chemical and apllication

             Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. Its manufacture employs the same method today. The EPA estimates 5.7% of LDPE (recycling number 4) is recycled. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In 2009 the worldwide LDPE market reached a volume of US$22.2 billion (15.9 billion Euro).

              LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles, tubing, plastic bags for computer components, and various molded laboratory equipment. Its most common use is in plastic bags. Other products made from it include:

• Trays and general purpose containers
• Corrosion-resistant work surfaces
• Parts that need to be weldable and machinable
• Parts that require flexibility, for which it serves very well
• Very soft and pliable parts such as snap-on lids
• Six pack rings
• Juice and milk cartons are made of liquid packaging board, a laminate of paperboard and LDPE (as the water-proof inner and outer layer), and often with of a layer of aluminum foil (thus becoming aseptic packaging).
• Parts of computer hardware, such as hard disk drives, screen cards, and optical disc drives
• Playground slides
• Plastic wraps

             

Chemical resistance

• Excellent resistance (no attack) to dilute and concentrated acids, alcohols, bases and esters
• Good resistance (minor attack) to aldehydes, ketones and vegetable oils
• Limited resistance (moderate attack suitable for short-term use only) to aliphatic and aromatic hydrocarbons, mineral oils, and oxidizing agents
• Poor resistance, and not recommended for use with Halogenated hydrocarbons.

This picture is ID code of LDPE (Low density polyethylene)

THE ZOO

                       One day, the zoo was crouded. Because at the day is sunday and the zoo has events. Many family goes to the zoo. When people come to the zoo, the old lion was sleeping.

                        "Lions ought not to behave like that!" the young lion said to himself, so he roared at all the visitors and tried to break the bars of the den.

                          At three o'clock a man brought a big piece of meat and put it in the old lion's den. Then, he put a bag of nuts and two bananas in the young lion's den.

                          The young lion was very surprised. "I don't understand this." he said to the old lion. "I behave like a real lion, while you lie there and do nothing and look what happens!"


                           "Okay, I'll behave like a real lion" said the old lion, and the old lion was roared to all visitors. Many people came closer to their cage. So their visitor was very happy and many visitor buy some meat for it. And the lion was happy.

HDPE (High Density Polyethylene) and application

                        High-density polyethylene (HDPE)  is a polyethylene thermoplastic made from petroleum. HDPE (High-density polyethylene) is commonly used in the production of plastic bottles, corrosion-resistant piping, geomembranes, and plastic lumber.It takes the equivalent of 1.75 kilograms of petroleum (in energy and raw materials) to make one kilogram of HDPE. HDPE is commonly recycled, and has the number "2" as its recycling symbol.In 2007, the global HDPE market reached a volume of more than 30 million tons.


                         HDPE is known for its large strength to density ratio.The mass density of high-density polyethylene can range from 0.93 to 0.97 g/cm3. Although the density of HDPE is only marginally higher than that of low-density polyethylene (LDPE), HDPE has little branching, giving it stronger intermolecular forces and tensile strength than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength.It is also harder and more opaque and can withstand higher temperatures (120 °C/ 248 °F for short periods, 110 °C /230 °F continuously). High-density polyethylene (HDPE) unlike polypropylene, which cannot withstand normally required autoclaving conditions. The lack of branching is ensured by an appropriate choice of catalyst (e.g., Ziegler-Natta catalysts) and reaction conditions. HDPE contains the chemical elements carbon and hydrogen.


                         HDPE  has a wide variety of applications because it is resistant with many different solvent for example:

• Arena Board (puck board)
• Backpacking frames
• Ballistic plates
• Bottle caps
• Chemical resistant piping systems
• Coax cable inner insulator
• Food storage containers
• Fuel tanks for vehicles
• Corrosion protection for steel pipelines
• Electrical and plumbing boxes
• Far-IR lenses
• Folding chairs and tables
• Geomembrane for hydraulic applications (such as canals and bank reinforcements) and chemical containment
• Geothermal heat transfer piping systems
• Heat-resistant fireworks mortars
• Hard hats
• Hula hoops
• Natural gas distribution pipe systems
• Plastic bags
• Plastic bottles suitable both for recycling (such as milk jugs) or re-use
• Plastic lumber
• Plastic surgery (skeletal and facial reconstruction)
• Root barrier
• Snowboard rails and boxes
• Storage sheds
• Telecom ducts
• Tyvek
• Water pipes for domestic water supply and agricultural processes
• Wood plastic composites (utilizing recycled polymers)

HDPE Plastic Code 

Polyethylene terephthalate (PETE) and uses

                           Polyethylene terephthalate commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber. The term polyethylene terephthalate is a source of confusion because this substance, PET, does not contain polyethylene. Thus, the alternate form, poly(ethylene terephthalate), is often used in scholarly journals for the sake of accuracy and clarity.

                          Depending on its processing and thermal history, polyethylene terephthalate probably as an amorphous (transparent) and as a semi-crystalline polymer.Semicrystalline material might appear transparent (particle size < 500 nm) or opaque and white (particle size up to a few microns) depending on its crystal structure and particle size. Its monomer (bis-β-hydroxyterephthalate) can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct, or by transesterification reaction between ethylene glycol and dimethyl terephthalate with methanol as a byproduct. Polymerization is through a polycondensation reaction of the monomers (done immediately after esterification/transesterification) with water as the byproduct.

                          The majority of the world's PET production is for synthetic fibers (more than 60%), with bottle production accounting for around 30% of global demand. In the context of textile applications, PET is referred to by its common name, "polyester," whereas the acronym "PET" is generally used in relation to packaging. Polyester makes up about 18% of world polymer production and is the third-most-produced polymer; polyethylene (PE) and polypropylene (PP) are first and second, respectively.

                           PET is an excellent barrier material, plastic bottles made from PET are widely used for soft drinks. For certain specialty bottles, PET sandwiches an additional polyvinyl alcohol layer to reduce its oxygen permeability.Biaxially oriented PET film it can be aluminized by evaporating a thin film of metal onto it to reduce its permeability, and to make it reflective and opaque (MPET). These properties are useful in many applications, including flexible food packaging and thermal insulation such as "space blankets". Because of its high mechanical strength, PET film is often used in tape applications, such as the carrier for magnetic tape or backing for pressure sensitive adhesive tapes.

                           Non-oriented PET sheet can be thermoformed to make packaging trays and blisters. If crystallizable PET is used, the trays can be used for frozen dinners, since they withstand both freezing and oven baking temperatures.When filled with glass particles or fibers, it becomes significantly stiffer and more durable.PET is also used as substrate in thin film and solar cell.

 
                                   Picture of  PETE product

Production of plastics, Incineration of plastics, Pyrolytic disposal

                   Plastic production of crude oil requires 62-108 MJ of energy per kilogram.While Producing silicon and semiconductors for modern electronic equipment is even more energy consuming: 230 to 235 MJ per 1 kilogram of silicon, and about 3,000 MJ per kilogram of semiconductors. This is much higher, compared to many other materials, e.g. production of iron from iron ore requires 20-25 MJ of energy, glass (from sand, etc.) - 18-35 MJ, steel (from iron) - 20-50 MJ, paper (from timber) - 25-50 MJ per kilogram.                  

                Controlled high-temperature incineration, above 850C for two seconds, performed with selective additional heating, breaks down toxic dioxins and furans from burning plastic, and is widely used in municipal solid waste incineration. Municipal solid waste incinerators also normally include flue gas treatments to reduce pollutants further. This is needed because uncontrolled incineration of plastics produce carcinogenic polychlorinated dibenzo-p-dioxins, a cancer causing chemical. The problem occurs as the heat content of the waste stream varies. Open-air burning of plastic occurs at lower temperatures, and normally releases such toxic fumes.

                  Plastics can be pyrolyzed into hydrocarbon fuels, since plastics have hydrogen and carbon. One kilogram of waste plastic produces roughly a liter of hydrocarbon.

                    This picture is place of incineration 



                          This picture is process of incineration

Nylon

                Nylon was the first purely synthetic fiber, introduced by DuPont Corporation at the 1939 World's Fair in New York City. In 1927, DuPont Corporation had begun a secret development project name Fiber66. Wallace Carothers the Harvard Chemist and  Elmer Keiser Bolton is the department chemist as director. Carothers was hired to perform pure research, he worked to understand the new materials molecular structure and physical characters.

                 And he was found synthetic nylon fiber, which was very strong and also very flexible. The first application was for bristles toothbrushes. However, Du Pont's real target was silk, particularly silk stockings. It took DuPont twelve years and US$27 million to refine nylon, to synthesize and develop the industrial processes for bulk manufacture. With a major investment, it wasn't surprise that Du Pont spared little expense to promote nylon after its introduction, creating a public sensation, or "nylon mania".

                   Nylon was stop at the end 1941 because of America had World War II. After 1946 DuPont Corporation was promote Nylon again to public .Nylons still important plastics, and not just for use in fabrics. In its bulk form it is very wear resistant, particularly if oil-impregnated, and it used to build gears, plain bearings, valve seats, seals and because of good heat-resistance, increasingly for under-the-hood applications in cars, and other mechanical parts.

                               Picture of Wallace Carothers

                               Picture of Elmer Keiser Bolton

Polyvinyl chloride

         Polyvinyl chloride, commonly abbreviated PVC, is the third-most widely produced plastic, after polyethylene and polypropylene. PVC or Polyvinyl chloride has a stiff resistance properties, strong, heat and weather, the nature of the recommended use for pipes, ditches, walls, enclosures for computers and other electronic equipment. PVC can also be softened through a chemical process, and at the present time can be used in the form of shrink-wrap, food packaging, and rain gear (raincoats).
form Pure polyvinyl chloride is a white, brittle solid. this things insoluble in alcohol, but slightly soluble in tetrahydrofuran.

          In 1835 PVC was found by French chemist Henri Victor Regnault and then in 1872 by German chemist Eugen Baumann. 

 Eugen Baumann German Chemist

Henri Victor Regnault France Chemist

                The relatively low cost PVC been tested either through biological and chemical processes that lead to PVC pipes are used for disposal of waste, door frames, wire insulators, etc.

Pipe

                 Pipes, which are lightweight, low maintenance costs can be accounted for 66% in the American market are usually planted in the ground and used as a waste dump, the distribution of clean water.

Electric Cables

                   

                 PVC uses the electrical wiring is a good barrier to prevent sparks that shorted can be minimized.

Sign
 

                  Polyvinyl chloride is formed from a flat sheet with a variety of shapes and colors. usually in the form of lines of the car body.

                  

Clothing and furniture 

                  PVC has been used as well as clothes to replace materials such as leather, rubber, and latex. Besides pvc also waterproof so can be used for coats, ski equipment, jackets, aprons, and bags.

 Medical Equipment

                One-third of the medical equipment is made ​​of PVC for example scissors, knives, cutter, clamp, blood bags, etc.     

  

Flooring

               PVC can be used as flooring because besides cheap, shiny and easy maintenance suitable for homes, hospitals, offices, schools, etc.

Other Apllications

                PVC can be used on kids toys, interior clauding, custom truck troppers, green house, kids play ground, etc.