CHEMISTRY OF PLASTICS & POLYMER


plastic production life cycle

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.

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Chemistry of Resins


 

Natural Resin

Natural Resin

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.

 

Resins

Resins

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.

Resin

Resin

Applications of resins

Resins is used in following sectors

  • Varnishes
  • Adhesives
  • Therapeutic purposes
  • Musical instruments
  • In making sculptures
  • Motors
  • Generators
  • Transformers
  • Switchgear
  • Bushings
  • Insulators
  • Integrated circuits
  • Transistors
  • Hybrid circuits
  • Printed circuit boards

Chemistry of Rubber Production, Structure


 

rubber plant

Natural rubber plant

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

synthetic- 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.

Chemical properties

Rubber Structure

Rubber Structure

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

Synthetic rubber production

Synthetic rubber production

Emulsion polymerization is the widely used method to produce synthetic rubber.

 Emulsion polymerization

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.

 

Caffeine, aerogel technology, new catalyst, solid material as liquid


Caffeine mixed with gold may kill cancer cells, finds new study

A new research reports that caffeine mixed with gold can selectively stop cancer cells from growing without hurting other cells. The scientists found that, at certain concentrations, one of the compounds of the series selectively killed human ovarian cancer cells without harming healthy cells… Read more

Aerogel technology to clean up oil spills efficiently

A research group at University of Wisconsin–Madison is examining alternative materials that can be modified to absorb oil and chemicals. If further developed, the technology may offer a cheaper and “greener” method to absorb oil and heavy metals from water and other surfaces… Read more

New cost-effective catalyst to convert carbon dioxide to methanol

An international research team has discovered a potentially clean, low-cost way to convert carbon dioxide into methanol, a key ingredient in the production of plastics, adhesives and solvents, and a promising fuel for transportation… Read more

Newly discovered solid material behaves like liquid!

Scientists have discovered a new type of microscopic particle cluster that is found in solid materials but strangely behaves like a liquid. They called it the ‘dropleton.’ The new entity, infinitely small is a quasiparticle – a combination of other, fundamental particles with unusual properties that exist in solids, with a life span of just a blink of the eye… Read more