"Plastic"
┗▶ Definition ::
★ A plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable.
★ Plastics are typically organic polymers of high molecular mass, but they often contain other substances.
★ They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.
┗▶ Classification ::
★ Plastics are usually classified by their chemical structure of the polymer's backbone and side chains.
★ Often a polymer is defined by its monomers.
★ Some important groups in these classifications are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics.
★ Plastics can also be classified by the chemical process used in their synthesis, such as condensation, polyaddition, and cross-linking Thermoplastics and thermosetting polymers.
┗▶ Types of Plastics ::
★ There are two types of plastics: thermoplastics and thermosetting polymers.
1 - Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be moulded again and again.
★ Examples include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polytetrafluoroethylene (PTFE).
★ Common thermoplastics range from 20,000 to 500,000 amu, while thermosets are assumed to have infinite molecular weight.
★ These chains are made up of many repeating molecular units, known as repeat units, derived from monomers; each polymer chain will have several thousand repeating units.
2 - Thermosets can melt and take shape once; after they have solidified, they stay solid.
★ In the thermosetting process, a chemical reaction occurs that is irreversible.
★ The vulcanization of rubber is a thermosetting process.
★ Before heating with sulfur, the polyisoprene is a tacky, slighly runny material, but after vulcanization the product is rigid and non-tacky.
┗▶ Common plastics and uses ::
★ Polyester (PES) – Fibers, textiles.
★ Polyethylene terephthalate (PET) – Carbonated drinks bottles, peanut butter jars, plastic film, microwavable packaging.
★ Polyethylene (PE) – Wide range of inexpensive uses including supermarket bags, plastic bottles.
★ High-density polyethylene (HDPE) – Detergent bottles and milk jugs.
★ Polyvinyl chloride (PVC) – Plumbing pipes and guttering, shower curtains, window frames, flooring.
★ Polyvinylidene chloride (PVDC) (Saran) – Food packaging.
★ Low-density polyethylene (LDPE) – Outdoor furniture, siding, floor tiles, shower curtains, clamshell packaging.
★ Polypropylene (PP) – Bottle caps, drinking straws, yogurt containers, appliances, car fenders (bumpers), plastic pressure pipe systems.
★ Polystyrene (PS) – Packaging foam/"peanuts", food containers, plastic tableware, disposable cups, plates, cutlery, CD and cassette boxes.
★ High impact polystyrene (HIPS) -: Refrigerator liners, food packaging, vending cups.
★ Polyamides (PA) (Nylons) – Fibers, toothbrush bristles, fishing line, under-the-hood car engine moldings.
★ Acrylonitrile butadiene styrene (ABS) – Electronic equipment cases (e.g., computer monitors, printers, keyboards), drainage pipe.
★ Polycarbonate (PC) – Compact discs, eyeglasses, riot shields, security windows, traffic lights, lenses.
★ Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS) – A blend of PC and ABS that creates a stronger plastic. Used in car interior and exterior parts, and mobile phone bodies.
★ Polyurethanes (PU) – Cushioning foams, thermal insulation foams, surface coatings, printing rollers (Currently 6th or 7th most commonly used plastic material, for instance the most commonly used plastic found in cars).
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