Download
1 / 24
E N D
Everything around us is plastic • Toothbrush, clothing, food containers, cooking spatulas, pans, bottled water, automobile parts, bicycle parts, eye glasses, iPod, calculator, mouse, computer parts, printer, stapler, head phones, TV, clock, flash memory housing, usb connector, keyboard, shoes, backpack parts, cell phone, credit cards.. The list is almost endless
Could we go for a day without plastic? The short answer was no.
Polymers are macromolecules built up by the linking together of large numbers of small molecules (monomer). Polymers contain repeating units
Historical background When we say that polymers are everywhere, we mean it. Money doesn’t grow on trees, but polymers do. Natural fibers. Ages ago- Building block of cellulose (C6H10O5)n Cotton In fact, polymers have existed in natural form since life. Ex. DNA The monomer units of DNA are nucleotides, and the polymer is known as a ‘polynucleotide’.
1839- Charles Goodyear Goodyear's discovery of the Vulcanization process for natural rubber (NR) 1843- Nelson The first thermosetting material to be involved in a chemical modification of natural material (NR:Sulfur = 100:30-32) Ebonite bracelet from 1880
Phenol-formaldehyde ‘Bakelite’ 1905- Dr. Leo Baekeland The first truly synthetic plastic A network polymer Replacing rubber for insulation in electrical apparatus donotbecomesoftonheating donotchangetheirshapeonheating
1920s- Hermann Staudinger Introducing the word‘ macromolecules’ to describe polymer Polymers were composed of very large molecules containing long sequences of simple chemical units linked together by covalent bonds The 1953 Nobel Prize in Chemistry Development of commercial polymers
Classification of Polymers Polymers Polyethylene Polymethyl methacrylate Melamine formaldehyde Natural rubber
Thermoplastics, often referred to just as Plastics, can be linear or branched polymers Repeating H units H H H H H C C C C C C H H H Polyethylene (PE) H H H Linear polymers branched polymers Strong covalent bonds
o Polymer chains can slide past each other upon the application of heat.
semi-crystalline thermoplastic Translucentvs Transparent
Polypropylene o The crystal is large enough to scatter light
CODE SYSTEM FOR PLASTIC MATERIALS These codes allow consumers to separate plastics for recycling. polyethylene terephthalate PETE 1 soft drink bottles high-density polyethylene milk and beverage containers, products in squeeze bottles HDPE 2 polyvinyl chloride bottles with cleaning agents in them, some shampoo bottles 3 V low-density polyethylene thin plastic bags, plastic wrap LDPE 4
PLASTIC MATERIALS CODE SYSTEM (cont) 5 PP heavy-duty, microwavable containers used in the kitchen polypropylene foam beverage cups, envelope windows PS 6 polystyrene 7 Other All other resins, multilayered materials, containers made of other materials ketchup bottles, snack containers, mixtures where the top differs from the bottom The codes are frequently stamped on the bottom of containers.
