STYRENE-bane for Vizagities (Vizag Gas Tragedy)

Team : B.Voc. (AGRICULTURE & HORTICULTURE)

A gas leak, reminiscent of the 1984 Bhopal tragedy, has claimed at least 11 lives and affected thousands of residents in five villages in Visakhapatnam in Andhra Pradesh. The source of the leak was a styrene plant owned by South Korean electronics giant LG, located at RRV Puram near Gopalapatnam, about 15 kms from the coast city.Initial reports indicate that several people from the surrounding villages — RR Venkatapuram, BC Colony, Padmapuram and Kamparapalem — fell unconscious on the roads. While 11 died due to prolonged exposure to the gas, while trying to escape from the leak.

What is styrene?

It is a flammable liquid that is used in the manufacturing of polystyrene plastics, fiberglass, rubber, and latex. Styrene is a chemical used to make latex, synthetic rubber, and polystyrene resins. These resins are used to make plastic packaging, disposable cups and containers, insulation, and other products. Styrene is also produced naturally in some plants.According to Tox Town, a website run by the US National Library of Medicine, styrene is also found in vehicle exhaust, cigarette smoke, and in natural foods like fruits and vegetables.

Styrene monomer

Styrene is used in polyester resins as a solvent until cross-linking takes place, when it becomes an integral part of the thermoset. Unused styrene remaining in the resin is encapsulated or released into the atmosphere in gaseous state. Emissions of styrene produce a noticeable odour and at certain levels can produce a narcotic effect. Unsaturated polyester resins typically contain 35–50% styrene monomer as a cross-linking agent, and it is unavoidable that some of this will escape as vapour during open moulding and other processes that expose large surface areas of uncured resin during fabrication. At the least, styrene monomer vapour is an irritant and every effort must be made to minimize it at the workplace. The effect of various concentrations can be roughly classified as follows (measured in parts per million in the atmosphere):

  • 100 ppm: maximum allowable concentration (MAC)

  • 400 ppm: moderate irritation to eyes and lungs

  • 1200 ppm: extreme irritation to eyes and lungs

  • 10 000 ppm: may be fatal

There is considerable research by resin manufacturers to offer resins and processes that minimize emissions of styrene, to conform to increasingly tight legislation at the workplace. Styrene is not known to present any hazard to the general public, during the use of moulded products.

Preparation

Styrene is prepared commercially by the reaction of benzene and ethylene to make ethylbenzene, its dehydrogenation to styrene, and a final finishing stage. Styrene monomer is a basic building block of the plastics industry. The conventional method of producing styrene involves the alkylation of benzene with ethylene to produce ethylbenzene, followed by dehydrogenation of ethylbenzene to styrene. Styrene undergoes polymerization by all the common methods used in plastics technology to produce a wide variety of polymers and copolymers. Styrene is readily polymerized and copolymerized by both batch and continuous mass polymerization, emulsion, suspension and solution processes.

How It's Transported

Styrene is shipped in oceangoing vessels, from Jubail Chevron Phillips Petrochemical Plant (a joint venture facility).Styrene Polymers are the 150th most traded product and the 243rd most complex product according to the Product Complexity Index (PCI).The top exporters of Styrene Polymers are South Korea ($4.03B), Other Asia ($3.89B), Belgium-Luxembourg ($1.74B), Germany ($1.52B) and the United States ($1.34B). The top importers are China($5.38B), Germany ($1.51B), Hong Kong ($1.37B), the United States ($1.32B) and Italy ($911M).Styrene Polymers are also known as styrofoam, cases, containers, clamshells, lids, bottles, trays, tumblers, disposable, cutlery.

What It's Used For

The most important products are solid polystyrene (PS), expandable polystyrene (EPS), styrene butadiene latex (SBL), acrylonitrile-butadiene-styrene/terpolymer (ABS), unsaturated polyester resins (UPR), and styrene-butadiene rubber (SBR). An approximate breakdown of styrene’s markets are: