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