What type of polymerization produces polystyrene?
Radical polymerization
Radical polymerization is used to produce poly(phenylethene) (polystyrene). The process is an example of addition polymerization. The predominant polymerization technique is continual thermal mass polymerization which is initiated by heat alone.
What materials are affected by UV degradation?
This damage, called UV degradation, affects many natural and synthetic polymers including some rubbers, neoprene and polyvinyl chloride (PVC). With too much exposure, these materials can: Fade color.
Can UV light break down plastic?
Like human skin, plastics are susceptible to degradation due to ultraviolet (UV) light from the sun. With enough exposure, UV light can cause a chemical reaction in the plastic, which results in scission, or severing, of those big polymer molecules.
What causes styrene to polymerize?
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.
How can styrene polymerization be prevented?
Some compounds known to inhibit the polymerization of styrene are tert-butylcatechol (TBC), hydroquinone (HQ) and, the methyl ether of hydroquinone (MEHQ); elemental sulfur has also been employed.
How is XPS foam made?
Extruded polystyrene insulation or XPS Insulation is manufactured through an extrusion process. This manufacturing process involves melting together the plastic resin and other ingredients. The liquid formed is then continuously extruded through a die and expands during the cooling process.
Can UV pass through metal?
Metals are almost entirely unaffected by UV because of the availability of free electrons to absorb photon energy without undergoing energy transitions or bond dissociation.
How long does it take UV light to break down plastic?
Plastic is mostly decomposed by UV radiation, and it takes two years to more than 1 million years to decompose it.
Is LDPE UV resistant?
LDPE tubing: LDPE tubing is UV resistant and has good chemical resistance to acids, lyes, salts and organic solvents and has excellent bending properties.
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 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.
What are the commonly used extruded polystyrene foam materials?
Commonly extruded polystyrene foam materials include: 1 Styrofoam, also known as Blue Board, produced by Dow Chemical Company 2 Depron, a thin insulation sheet also used for model building More
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.