Chemistry of Plastics, Resins, Rubber
Plastics are made up of polymers, but some polymers like biopolymers are not plastics. Plastic materials are being used in day to day life like computers, pen, mobile phones, compact discs, pendrive, and toothbrushes etc.
Plastic is defined as any synthetic or semi-synthetic organic material that can be shaped or molded into any form. Chemical composition of plastics includes chains of carbon, oxygen, sulfur or nitrogen.
History of plastics
In 1284 naturally made plastic compounds from horn and tortoiseshell were identified
1820 plastic timeline
In 1823, Scottish chemist Charles Macintosh discovered rubber.
In 1845, Henry Bewley produced natural rubber from plant gutta percha
In 1850, first submarine telegraph cable in gutta percha laid between Dover and Calais
In 1862, Londoner Alexander Parkes unveiled first man-made Parkesine plastic compound
In 1869, John W. Hyatt invented Celluloid [colorless flammable material]
In 1872, Hyatt brothers patented first plastics injection moulding machine
In 1880 cellulose nitrate replacing horn as the preferred material for combs
In 1885, George Eastman Kodak patents machine for producing continuous photographic film based on cellulose nitrate.
1900 plastic timeline
In 1908, Jacques E. Brandenberger invented Cellophane [transparent cellulose material]
In 1909, Casein plastics, derived from milk, developed by Erinoid.
In 1909, H. Baekeland created first fully synthetic plastic product called Bakelite
In 1916, Rolls Royce begins to use phenol formaldehyde in its car interiors.
In 1920, Polyvinyl chloride or PVC was created.
In 1925, Plastic term was coined.
In 1930, in this year scotch tape was invented by 3M company
In 1933, Fawcett and Gibson discovered polyethylene material
In 1938, first toothbrush with nylons tufts manufactured.
In 1939, in this year nylon created.
In 1942, Dr Harry Coover discovered Super Glue (methyl cyanoacrylate).
In 1948, Acrylonitrile-butadiene-styrene (ABS) produced.
In 1949, Tupperware material made from low density polyethylene.
In 1949, DuPont invented Lycra product which is based on polyurethane.
In 1953, Lexan plastic material was invented by Daniel Fox.
In 1959 Barbie Doll unveiled at American International Toy Fair.
In 1965 DuPont released products with the trade name of Kevlar.
In 1973, Polyethylene terephthalate beverage bottles introduced.
In 1988, triangular recycling symbols relating to plastics were introduced.
2000 to 2022 plastic timeline
In 2003 Recovinyl [it is a European PVC recycling system] was established
2005 in this year NASA explores the advantages of a polyethylene based material RFX1 [RFX1 used for spaceship construction]
In 2011, vinylplus — sustainability programme established
In 2012 PVC fabric used in the construction of London Olympic venues
2020 PVC products production will reaches to 800,000 tones per year
2022 in this year the FIFA world cup qatar showcase stadium is planning to use super reflective, triangulated PVC fabric to create a zero carbon.
Manufacturing process of plastics
Preparation of raw materials
Preparation of monomer
Conversion of polymer resins to plastic products
In the process of converting polymer resins to plastic product following steps are involved
- Injection molding
- Blow molding
- Rotational molding
Applications of plastics
Plastics are widely used in following industrial sectors for various purposes
Textile industry – polyester used for making of some cloths
Packaging industry — Polyethylene terephthalate chemical used in carbonated drinks bottles, peanut butter jars, plastic film, microwavable packaging
Plastic also used in
- Supermarket bags
- Window frames, outdoor furniture
- Toothbrush bristles
- Traffic lights
- Cushioning foams
- Thermal insulation foams
- Surface coatings
Rubber is considered as elastic substance, which is obtained from the exudations of certain tropical plants (natural rubber) or derived from petroleum and natural gas. Rubber also termed as elastomer, a type of polymer. In 1770 Joseph Priestley coined the term rubber.
Rubber is divided into two groups based on its origin
Natural rubber – used in racing car tires, bus tires, truck tires
Synthetic rubber – examples butadiene rubber, styrene butadiene rubber, neoprene
Physical & Chemical properties of rubber
Did your ever wonder how rubber will stretch?
Before you want to know the reason one should know the physical and chemicals properties of rubber
In relaxed state, rubber is in the form of long, coiled-up chains. By stretching of rubber the all chains will come very close as result, kinetic energy exerted in the form of heat. In chain elongation process entropy and temperatures required during this process are increases. When chain in relaxed state both entropy and temperatures decreases.
Relaxation of a stretched rubber band is thus driven by a decrease in entropy and temperature, and the force experienced is a result of the cooling of the material being converted to potential energy. The material undergoes adiabatic cooling during contraction.
Vulcanization of rubber creates disulfide bonds between chains. The result is that the chains tighten more quickly for a given strain, thereby increasing the elastic force constant and making rubber harder and less extensible.
Like plastic, rubber is also a type of polymer, made of subunits called monomers. In rubber, the monomer is isoprene. As the latex dries, the isoprene molecules mass together and one isoprene molecule attacks a carbon-carbon double bond of a neighboring molecule. One of the double bonds breaks and the electrons repositioned to form a bond between the two isoprene molecules.
The process continues until long strands of many isoprene molecules linked like a chain. This long chain of strands is called as polyisoprene polymer. As the drying continues, the polyisoprene strands stick together by forming electrostatic bonds. The attraction between these strands holds the rubber fibers together and allows them to stretch and to recover.
Synthetic rubber production
Emulsion polymerization is the widely used method to produce synthetic rubber.
Emulsion polymerization is a type of radical polymerization process that usually starts with an emulsion incorporating water, monomer, and surfactant. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer (the oil) are emulsified (with surfactants) in a continuous phase of water.
In emulsion polymerization, the monomers are emulsified in water with a suitable soap and a water-soluble free-radical catalyst is added to induce polymerization. After polymerization has reached the desired level, the reaction is stopped by adding a radical inhibitor. About 10 per cent of synthetic elastomer produced through emulsion technique. The rest is coagulated with acidified brine, washed, dried, and pressed into 35-kg bales.
Resin is a natural or synthetic hydrocarbon secreted many plants, particularly coniferous trees. Its applications ranging from art to polymer production and many consumers interact with products that contain it on a daily basis.
The resin produced by most plants is a viscous liquid, composed mainly of volatile fluid terpenes, with lesser components of dissolved non-volatile solids which make resin thick and sticky. The most common terpenes in resin are the bicyclic terpenes alpha-pinene, beta-pinene, delta-3 carene and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene and delta-cadinene. Some resins also contain a high proportion of resin acids.
Types of resins
Oleoresins are naturally occurring mixtures of oil and a resin. Oleoresins contain benzoic acid or cinnamic acid.
Formaldehyde resin is a synthetic resin product made with formaldehyde. This product is used in a wide variety of settings and industries, and is one of the oldest synthetic resins around.Plastic resins are made by heating hydrocarbons. Plastic resins are used to make many different kinds of products.
Epoxy resins are created by transforming liquid polyethers into infusible solids through a special curing process. Epoxy resins fiber optics, optoelectronics, and dentistry.
Silicone resins are a type of silicone material which is formed by branched, cage-like oligosiloxanes with the general formula of RnSiXmOy.
Applications of resins
Resins is used in following sectors
- Therapeutic purposes
- Musical instruments
- In making sculptures
- Integrated circuits
- Hybrid circuits
- Printed circuit boards
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Originally published at www.worldofchemicals.com.