What is polymerization of styrene?
Polymerization of Styrene. Polystyrene (PS) is one of the largest volume vinyl polymers, used in countless products from food-packing and plastic cutlery to house insulation. The most common method is free radical polymerization, using benzoyl peroxide as initiator.
What is obtained by the polymerization of styrene monomer?
Styrene readily polymerizes to polystyrene by a relatively conventional free radical chain mechanism. Either heat or initiators will begin the polymerization. Styrene monomer will react with a variety of other monomers to form a number of copolymers. Polystyrene is an odorless, tasteless, rigid thermoplastic.
What is a polymerization reaction?
polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds.
Is polymerization of styrene exothermic?
First of all, the styrene polymerization reaction is relatively highly exothermic with a heat generation at around 71 kJ·mol–1. (10) At the same time, even without an initiator, two styrene molecules will undergo a Diels–Alder type of reaction and generate radicals to start self-polymerization upon heating.
Is polymerization an explosion?
Polymerization that is not sufficiently moderated and proceeds at a fast rate can be very hazardous. This phenomenon is known as hazardous polymerization and can cause fires and explosions.
How do you remove a styrene inhibitor?
Wash it with aqueous NaOH to remove inhibitors (e.g. tert-butanol), then with water, dry it for several hours with MgSO4 and distil it at 25o under reduced pressure in the presence of an inhibitor (such as 0.005% p-tert-butylcatechol). It can be stored at -78o.
Why is the polymerization of styrene so easy?
The relative ease of polymerization of styrene can be explained by resonance stabilization ofthe growing polystyrene in its transition state, that is the aromatic ring of the growth center delocalizes and stabilizes positive and negative charges as well as radicals as shown below.
How is polystyrene made from ethylbenzene?
Commercial polystyrene is mostly synthesized by bulk, suspension or solution polymerization of ethylbenzene (styrene). The most common method is free radical polymerization, using benzoyl peroxide as initiator. However, other initiators such as redox systems and azo compounds can be used as well to start the polymerization.
What is stystyrene monomer?
Styrene is one of the most versatile monomers. Besides (thermal or radiation induced) free radical polymerization, it can be polymerized by practically any other method of chain polymerization including cationic and anionic polymerization.
How to control the reaction exotherm during polymerization of styrene?
In the case of bulk or mass polymerization, the reaction exotherm is controlled by using a two-stage polymerization process. In the first stage, the styrene is polymerized in a stirred tank reactor, the so-called pre-polymerizer. Only a low conversion is achieved.
