synthetic polymers
DESCRIPTION
synthetic polymersTRANSCRIPT
SYNTHETIC POLYMERSHuman made polymers
Plastics are also called synthetic resins and are broadly classified into two categories: thermosetting resins and thermoplastic resins.
The thermosetting resins include phenolic resin and melamine resin, which are thermally hardened and never become soft again.
Thermoplastic resins include PVC, polyethylene (PE), polystyrene (PS) and polypropylene (PP), which can be re-softened by heating. Usually, thermoplastics are supplied in the form
of pelletised material (compounds) with additives (antioxidants, etc.) already blended in it.
Organic Polymers or (Common Polymers)
1. Polyethylene terephthalate (PETE)1. Low Density Polyethylene (LDPE)2. High Density Polyethylene (HDPE)
2. Polypropylene (PP)3. Polyvinyl Chloride (PVC)4. Polystyrene (PS)5. Nylon, nylon 6, nylon 6,66. Polytetrafluoroethylene Teflon7. Thermoplastic polyurethanes (TPU)8. Polycarbonate: Lexan9. Polymethyl methacrylate: Plexiglass
Polyethylene Terephthalate (PETE)
PETE is one of the most widely used polymers in industry today, it is used to make most plastic bottles and containers.
Low-density polyethylene (LDPE)
LDPE is a thermoplastic made from the monomer
ethylene. It was the first grade of polyethylene,
produce in 1933 by Imperial ChemicalIndustries(ICI)
Low-density polyethylene (LDPE)
LDPE is defined by a density range of 0.910–0.940 g/cm3. It is not reactive at room temperatures, except by strong oxidizing agents, and some solvent cause swelling. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. Made in translucent or opaque variations, it is quite flexible, and tough but breakable
HDPE is a polyethylene thermoplastic made from petroleum. 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, 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 somewhat higher temperatures (120 °C/ 248 °F for short periods, 110 °C /230 °F continuously).
High-density polyethylene (HDPE)
Polypropylene (PP) or Polypropene
PP is a thermoplastic polymer used in a wide variety of applications including packaging and labeling, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components.
Most commercial polypropylene has an intermediate level of crystallinity between that of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as an engineering plastic. Polypropylene is reasonably economical, and can be made translucent when uncolored but is not as readily made transparent as polystyrene, acrylic, or certain other plastics. It is often opaque or colored using pigments. Polypropylene has good resistance to fatigue.
Polypropylene (PP) or Polypropene
The melting point of polypropylene occurs at a range, so a melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F).
Polypropylene (PP) or Polypropene
Melt processing of polypropylene can be achieved via extrusion and molding. Common extrusion methods include production of melt-blown and spun-bond fibers to form long rolls for future conversion into a wide range of useful products, such as face masks, filters, diapers and wipes.
The most common shaping technique is injection molding.
Polypropylene (PP) or Polypropene
Polypropylene is used in the manufacturing piping systems; both ones concerned with high-purity and ones designed for strength and rigidity (e.g. those intended for use in potable plumbing, hydronic heating and cooling). This material is often chosen for its resistance to corrosion and chemical leaching, its resilience against most forms of physical damage, including impact and freezing, its environmental benefits, and its ability to be joined by heat fusion rather than gluing.
Polypropylene (PP) or Polypropene
Polypropylene (PP) or Polypropene
Polypropylene lid of a Tic-Tac box, with a
identification code under its flap
Polyvinyl chloride (PVC)
the third-most widely produced plastic, after polyethylene and polypropylene. PVC is used in construction because it is more effective than traditional materials such as copper, iron or wood. It can be made softer and more flexible by the addition of plasticizers. In this form, it is also used in clothing and upholstery, electrical cable insulation, inflatable products and many applications in which it replaces rubber.
Pure polyvinyl chloride is a white, brittle solid. It is insoluble in alcohol, but slightly soluble in tetrahydrofuran.
PVC's relatively low cost, biological and chemical resistance and workability have resulted in it being used for a wide variety of applications. It is used for sewerage pipes and other pipe applications where cost or vulnerability to corrosion limit the use of metal. With the addition of impact modifiers and stabilizers, it has become a popular material for window and door frames. By adding plasticizers, it can become flexible enough to be used in cabling applications as a wire insulator. It has been used in many other applications.
Polyvinyl chloride (PVC)
PVC pellets
PS is a synthetic aromatic polymer made from the monomer styrene, a liquid petrochemical. Polystyrene can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. It is a very inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants.
Polysterene (PS)
As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C on its glass transition temperature then becomes rigid again when cooled. This temperature behavior is exploited for extrusion, and also for molding and vacuum forming, since it can be cast into molds with fine detail.
Polysterene (PS)
It is very slow to biodegrade and therefore a focus of controversy, since it is often abundant as a form of litter in the outdoor environment, particularly along shores and waterways especially in its foam form.
Polysterene (PS)
Polysterene
Polysterene
Polysterene
Polysterene
Polysterene
CD case made from general purpose polystyrene (GPPS) and high impact polystyrene (HIPS) Disposable polystyrene razor
Polysterene
Expanded polystyrene packaging
The resin identification code symbol for polystyrene
Polysterene
Polystyrene foam is a major component of plastic debris in the ocean, where it becomes hazardous to marine life and "could lead to the transfer [of] toxic chemicals to the food chain “. Animals do not recognize this artificial material and may even mistake it for food.
Polystyrene foam blows in the wind and floats on water, and is abundant in the outdoor environment. It can be lethal to any bird or sea creature that swallows significant quantities.
Restricting the use of foamed polystyrene takeout food packaging is a priority of many solid waste environmental organizations. Efforts have been made to find alternatives to polystyrene, especially foam in restaurant settings. The original impetus was to eliminate chlorofluorocarbons (CFC), which was former component of foam.
Polysterene
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 commonly used polymers. Key representatives are nylon-6,6, nylon-6, nylon-6,9, nylon-6,12, nylon-11, nylon-12 and nylon-4,6.
Nylon is a thermoplastic, silky material, made of repeating units linked by amide bonds and is frequently referred to as polyamide (PA).
Nylon was the first commercially successful synthetic thermoplastic polymer. There are two common ways of making nylon for fiber applications. In one approach, molecules with an acid (-COOH) group on each end are reacted with molecules containing amine (-NH2) groups on each end. The resulting nylon is named on the basis of the number of carbon atoms separating the two acid groups and the two amines. These are formed into monomers of intermediate molecular weight, which are then reacted to form long polymer chains.
Nylon
Nylon was intended to be a synthetic replacement for silk and substituted for it in many different products after silk became scarce during World War II. It replaced silk in military applications such as parachutes and flak vests, and was used in many types of vehicle tires.
Nylon
Engineering-grade nylon is processed by extrusion, casting, and injection molding. Type Nylon 6,6 is the most common commercial grade of nylon, and Nylon 6 is the most common commercial grade of molded nylon.
Nylon
Nylon
Nylon
Nylon
Nylon
Nylon
Polytetrafluoroethylene (PTFE)
Is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The best known brand name of PTFE is Teflon by DuPont Co.
PTFE is a fluorocarbon solid, as it is a high-molecular-weight compound consisting of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE and possesses fairly high heat resistance, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction against any solid.
Polytetrafluoroethylene (PTFE)
PTFE is used as a non-stick coating for pans and other cookware. It is very non-reactive, partly because of the strength of carbon–fluorine bonds, and so it is often used in containers and pipework for reactive and corrosive chemicals. When used as a lubricant, PTFE reduces friction, wear, and energy consumption of machinery. It is also commonly used as a graft material in surgical interventions.
Polytetrafluoroethylene (PTFE)
PTFE is a thermoplastic polymer, which is a white solid at room temperature, with a density of about 2200 kg/m3. According to DuPont, its melting point is 600 K (327 °C; 620 °F). Its mechanical properties degrade gradually at temperatures above 194 K (−79 °C; −110 °F). PTFE gains its properties from the aggregate effect of carbon-fluorine bonds, as do all fluorocarbons. The only chemicals known to affect these carbon-fluorine bonds are certain alkali metals and most highly reactive fluorinating agents.
Polytetrafluoroethylene (PTFE)
In industrial applications, owing to its low friction, PTFE is used for applications where sliding action of parts is needed: plain bearings, gears, slide plates, etc. In these applications, it performs significantly better than nylon and acetal; it is comparable to ultra-high-molecular-weight polyethylene (UHMWPE), although UHMWPE is more resistant to wear than PTFE, for these applications, versions of PTFE with mineral oil or molybdenum disulfide embedded as additional lubricants in its matrix are being manufactured.
Polytetrafluoroethylene (PTFE)
PTFE is often used to coat non-stickfrying pans as it is hydrophobic and possesses fairly high heat resistance.
Polytetrafluoroethylene (PTFE)
Thermoplastic polyurethane (TPU)
(TPU) is any of a class of polyurethane plastics with many useful properties, including elasticity, transparency, and resistance to oil, grease and abrasion.
TPU are formed by the reaction of: (1) diisocyanates with short-chain diols (so-called chain extenders)(2) diisocyanates with long-chains. The practically unlimited amount of possible combinations producible
by varying the structure and/or molecular weight of the three reaction compounds allows for an
enormous variety of different TPU. This allows urethane chemists to fine-tune the polymer’s structure to the desired final properties of the material.
Polymethyl methacrylate or (plexiglass)
Poly(methyl methacrylate), which lazy scientists call PMMA, is a clear plastic, used as a shatterproof replacement for glass. i.e. The barrier at the ice rink which keeps hockey pucks
from flying in the faces of fans is made of PMMA. The chemical company Rohm and Haas makes
windows out of it and calls it Plexiglas. When it comes to making windows, PMMA has
another advantage over glass. PMMA is more transparent than glass. When glass windows are made too thick, they become
difficult to see through. But PMMA windows can be made as much as 13 inches (33 cm) thick, and they're still perfectly transparent.
This makes PMMA a wonderful material for making large aquariums, whose windows must be thick in order to contain the high pressure millions of gallons of water. In fact, the largest single window in the world, is at an observation window at California's Monterrey Bay Aquarium, made of one big piece of PMMA which is 54 feet long, 18 feet high, and 13 inches thick (16.6 m long, 5.5 m high, and 33 cm thick).
Polymethyl methacrylate or (plexiglass)
Polycarbonate
Lexan, also known as polycarbonate is approximately 250 times stronger than plate glass and 30 times stronger than acrylic of equal thickness. Polycarbonate sheet provides lasting protection against vandalism and burglary, as well as against natural occurrences, such as high winds, snow loads, and hailstorms. It is unlikely to break, shatter or chip when bombarded with thrown objects such as rocks, bricks, and bottles, nor is it likely that the material will break when hammered, twisted or bent.
THE EFFECT OF THE USES OF SYNTHESIS
POLYMERS TO OUR ENVIRONMENT Most polymers are not biodegradable. Polymers cannot be decomposed biologically
or naturally by bacteria or fungi as in the case of other garbage. Thus, the disposal of polymers has resulted in environmental pollution because they remain in the environment forever.
Discarded plastic items may cause blockage of drainage systems and rivers thus causing flash floods.
Plastic containers and bottles thrown around become good breeding places for mosquitoes which cause dengue fever, or malaria.
Small plastic items that are thrown into the rivers, lakes and seas are swallowed by aquatic animals. These animals may die from choking
burning of plastics gives rise to poisonous and acidic gases like carbon monoxide, hydrogen chloride and hydrogen cyanide. These are harmful to the environment as they cause acid rain.
Burning of plastics can also produce carbon dioxide, too much of this gas in the atmosphere leads to the `green house effect'.
The main source of raw materials for the making of synthetic polymers is petroleum. Petroleum is a non – renewable resource.