Chemistry

From monomer to material - polystyrene

From monomer to material - polystyrene



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Do you have problems understanding the learning unit From Monomer to Material - Polystyrene? Then you may be missing the following basics:

From Monomer to Material - Introduction to Macromolecular Chemistry30 min.

ChemistryMacromolecular Chemistryintroduction

Based on examples of natural and artificial macromolecules, important basic terms of macromolecular chemistry are explained.

From monomer to material - terms and definitions30 min.

ChemistryMacromolecular Chemistryintroduction

Terms such as monomer, polymer and oligomer are explained. The names of the reactions for the formation of macromolecules are defined.

From monomer to material - styrene, the chameleon among monomers20 min.

ChemistryMacromolecular Chemistryintroduction

The properties of styrene that characterize it as a monomer for polymerizations are presented here.


Polytetrafluoroethylene

Polytetrafluoroethylene (Abbreviation PTFE, occasionally too Polytetrafluoroethylene) is an unbranched, linearly structured, partially crystalline polymer made of fluorine and carbon. Colloquially, this plastic is often referred to as the trade name Teflon of the DuPont company. Other frequently used trade names from other manufacturers of PTFE are Dyneon PTFE (formerly Hostaflon) and Gore-Tex for PTFE membranes.

PTFE belongs to the class of polyhalogenolefins, which also includes PCTFE (polychlorotrifluoroethylene). It belongs to the thermoplastics, although it also has properties that require processing that is more typical for thermoset plastics.


Areas of application

A large number of transparent and non-transparent components are made from polymethyl methacrylate.

PMMA is indispensable in dentistry, where it is used for prostheses. For this purpose, the plastic is colored with metal salts so that the typical pink color is created. In a transparent form, it is used for bandage splints. The plastic is freely mixed and hardens under heat and pressure. Activators can also be added.

Important areas of application are:

  • Automotive technology: Indicator and taillight lenses, reflectors, light guides, door / pillar trim in the exterior area (A / B / C pillar trim)
  • Aviation: Windows, hoods, headlight covers
  • Lighting technology: Floodlight signs and "acrylic light design", lamp covers, illuminated advertising
  • Optics: Sight glasses, lenses, spectacle glasses, Fresnel lenses, optical fibers
  • Jewellery: So-called plugs and other jewelry for e.g. & # 160B. widened piercings
  • Household: Bowls, casings, salad spoons, salt and pepper mills
  • Construction: Polymer concrete, industrial flooring, glazing (e.g. & # 160B. Double wall sheets), sealing and coating of balconies and terraces, detail sealing in flat roofs, industrial door glazing (Plustherm system glazing), sanitary components (e.g. & # 160B. Bathtub), furniture, room dividers, door panels , Lampshades
  • Musical instruments: Drums, key pads on the piano
  • Orthopedics: Bone cement (e.g. & # 160B. For anchoring hip endoprostheses)
  • Dentistry: Full and partial dentures, temporaries, occlusal splints
  • Medicine: Hard intraocular lenses, PMMA balls enriched with gentamicin, drawn up as chains for continuous antibiotic treatment
  • Hearing aid acoustics: Earmold (earmold)
  • Textile industry: Part of polyacrylic fibers, see polyacrylonitrile
  • Semiconductor industry: Use as a resist (photoresist) or a component thereof in photo and electron beam lithography
  • Horticulture: Roofing material, greenhouses
  • Pyrotechnics: Part of delay rates
  • Submarine pressure hull: see Deep Rover DR1002
  • Visual arts: as material and image carrier
  • Model and prototype construction: as a mineral glass replacement for single pieces and small series
  • Machine protection: Protective hoods and protective doors
  • Watch industry: watch glass
  • Adhesives:Methyl methacrylate adhesive

EPS - material for packaging and insulation

EPS & # 8211 Expanded polystyrene has become an indispensable part of modern material production as a packaging and insulating material. The film explains the chemical properties of the raw material polystyrene, a hydrocarbon, and the physical properties of Styrofoam, which consists of 98% air and is therefore particularly used in the packaging and insulation industry. Modern production technology and the most important areas of application of the material are presented clearly and in individual steps. The possibilities of reuse in multi-stage recycling processes are also dealt with intensively.

  • Vocational training o Structural engineering - & gt Building materials o Chemistry, physics, biology - & gt Production engineering
  • Chemistry - & gt Angewandte Chemie - & gt Chemistry in everyday life and the environment

Materials Plastics Construction technology Packaging Recycling Styrofoam Plastics technology Process engineering Isolation Reuse

Recognize that EPS is a foamed polystyrene. Gain insight into the production of EPS. You can name applications for EPS. Get to know the advantages of EPS as a packaging material. Find out about the insulating effect and recycling of EPS

Recommended addressees: Grammar school (7-13) Vocational school


Description From rubber to car tires

Hello and welcome! The historic wheels and the first cars still had wooden wheels. Today it doesn't rumble anymore, because you ride on rubber. The rubber tree (Hevea tree) provides the raw material for this. But before a tire can drive, the rubber is given various additives. They give the rubber strength and elasticity. If the tires are old, they must be disposed of. You can still make various valuable things from old tires. Have fun watching!

Transcript From rubber to car tires

Hello and welcome! This video is called “From rubber to car tires”. Have you ever seen a picture of the first bicycles, it was still the balance bikes. Or maybe a photo of the first cars? Take a look at their bikes. So? What do you notice? Right! The bikes of that time did not have rubber tires. So it wasn't fun to drive these vehicles. Because the roads back then were much worse than the roads today. You can believe me.

Today rubber is a matter of course. I want to correct a pencil drawing - no problem. You use an eraser for this. And so that the bicycles and cars drive smoothly, they do not move on metal-clad wooden wheels but on rubber.

The raw material for rubber has been known for a long time. It's the rubber. It is obtained as latex from the Hevea tree (rubber tree). Please do not confuse it with the rubber tree, the Ficus elastica. Because that is the fig tree. Rubber was already known to the Maya. In modern times, elastic rubber is made from rubber. Here is just a small selection of rubber objects: the rubber duck, the rubber mallet, the eraser and the cyber duck. Balloons, the toy car, rubber tires and hair ties. The rubber boat and the rubber boots. And finally, condoms and part of the stethoscope.

In order to give natural rubber suitable properties and to protect it from aging, it has to be processed before use. An important measure for this is vulcanization, here a vulcanization press. The individual rubber parts are permanently bonded to the other components under pressure and heat. Plastic rubber becomes elastic rubber. The Americans discovered the vulcanization of Goodyear as early as 1839, when sulfur is added to the rubber. This prevents premature aging and increases the strength of the material. The more sulfur is added, the harder the rubber becomes.

Rubber is a polymer that consists of many isoprene molecules. Its degree of polymerization is between 8,000 and 30,000. In contrast to other plastics, it contains double bonds. Now it becomes clear why the rubber has to vulcanize.

During the manufacture of the car tire, the natural rubber is vulcanized with sulfur. There is a crosslinking of the polymer and an increase in hardness. In addition, various substances are added. The rubber for the tire has the following composition: rubber: 45% carbon black, silicane: 30% sulfur: 10% oil: 15%

A different compound is required for the tread of the tire. Summer and winter tires have different compositions. Likewise the tires of cars and trucks.

Since natural rubber is not enough, rubber is also produced synthetically. In Germany this started before the First World War. Even the best tire has to be disposed of one day. When old rubber is recycled, the tires are first shredded. Then they are processed further. You win rubber mats or sports field coverings. Sometimes the rubber is burned to generate energy. These are needed for the production of cement.

That was it again. I wish you all the best and good luck! Bye your André


Raw materials / starting materials

Main ingredients

The table below shows the composition by elements of polystyrene.

Hydrogen, H
Content in% by weight

Carbon, C
Content in% by weight

The numerical values ​​refer to the pure polymers, without taking additives, plasticizers and fillers into account. Pure PS, like polypropylene and polyethylene, consists only of carbon and hydrogen. Plasticizers and UV stabilizers are necessary for technical products, the residual monomer content (styrene) can lead to pollution.

The main raw material sources are crude oil and, in some cases, coal. Benzene and ethylene are obtained from these non-renewable resources, from which polystyrene is produced via the intermediate stages of ethylbenzene and styrene. At the time of this writing, an Ecoprofile for Polystyrene from PlasticsEurope is not available. The data can therefore only be given for expandable PS and ABS. For comparison with expandable PS, the values ​​for rigid polyurethane foam are given. ABS can be compared to HDPE.

The high consumption of fossil raw materials for the production of polystyrene is due to the composition of carbon and hydrogen. Both elements come from fossil raw materials. Compared to polyethylene, the production of polystyrene requires large amounts of cooling water.

Raw material requirement per kg of plastic

Polystyrene (raw material)

Expandable PS

High density polyethylene (HDPE)

renewable raw materials [kg]

mineral raw materials [kg]

Water consumption without cooling [l]

Water consumption with cooling [l]

The data come from the PlasticsEurope eco-profiles (see sources). The numerical values ​​refer to the requirement for the production of 1 kg of the specified material including all additives and modifiers. The processing steps from the granulate to the finished product as well as any additives and modifiers that are only added during the final processing are not included. The information for expandable PS does not include the step of foaming into EPS insulation materials.

Environmental and health relevance

Extraction of the primary raw materials

The ecological consequences of the extraction of fossil raw materials are described in the corresponding lexicon term.

Availability

With the gradual depletion of petroleum reserves, the potential for the production of polypropylene and other plastics also diminishes in a few decades. However, the raw materials for the production of polystyrene could also be made from coal, which would, however, involve a greater expenditure of energy.

Use of recycling materials / production waste

As a thermoplastic, polystyrene production waste can basically be reused in production by melting it.

Radioactivity

Polystyrene is not radioactive.

Land Use (Landuse)

Polystyrene production is associated with low land consumption for oil production and refinery sites, but the areas of natural spaces destroyed by tanker accidents can be considerable.

Sources

I. Bousted: Eco-profiles of the European Plastics Industry, Acrylonitrile-Butadiene-Styrene Copolymer (ABS), PlasticsEurope, Brussels, 2005

I. Bousted: Eco-profiles of the European Plastics Industry, Polystyrene (Expandable) (EPS), Brussels, 2006

I. Bousted: Eco-profiles of the European Plastics Industry, High Density Polyethylene (HDPE), PlasticsEurope, Brussels, 2005


Phenoplasts are among the first industrially produced plastics. The first phenoplast to be produced on a large scale is the phenol-formaldehyde condensation resin invented by Leo Hendrik Baekeland in 1907, which was marketed under the Bakelite trademark and used in many areas for decades. Because of their temperature resistance, surface hardness and their low price, phenoplasts are still the most important thermosets today [1] and are used, among other things, to manufacture brake linings.

Phenoplasts consist of cured phenolic resins that are obtained by synthesizing phenols with aldehydes. [2] In addition to phenol, compounds such as 3-cresol, 3,5-xylenol and resorcinol are also used. [3]

By electrophilic substitution of phenol, acid-catalyzed precursors are formed which, depending on the amount of formaldehyde used, have one to three hydroxymethyl groups (–CH2–OH). As acidic catalysts, inter alia. Hydrochloric acid or oxalic acid are used. [4] The substitution takes place only in ortho- or para-Position of the phenol:

It forms O-Hydroxymethylphenol (1) and p-Hydroxymethylphenol (2). With an excess of formaldehyde and under basic conditions, compounds with up to three hydroxymethyl groups can form. The resins are formed by catalyzed polycondensation of these phenol derivatives. Depending on the desired result, the precondensates are then mixed with acidic or basic condensation agents.

Novolaks: In acidic Environment are formed from the phenyl alcohols by condensation via a methylene group (–CH2-) linked oligomers, the so-called novolaks. Formaldehyde and phenols are converted in a ratio of 4: 5 or less formaldehyde:

Novolaks are semi-liquid or still meltable. They are stable in storage, so they are not self-curing. Together with formaldehyde donors such as hexamethylenetetramine, novolaks harden at temperatures above 120 ° C to form infusible, thermosetting compounds.

Resole: With basic Condensation agents, on the other hand, form fusible resins that are soluble in many solvents Resole. As a result of the larger amounts of formaldehyde usually used (up to 2.5: 1), ether groups are formed in addition to methylene groups.

General structure of resol

Resoles tend to self-harden through further condensation and form the intermediate stage Resitol. If the precondensates are heated, with further elimination of water, crosslinked polymers, the infusible and insoluble final stage, are obtained Resit.

After a resin has cured, closely-meshed, crosslinked polymers are formed, since the phenol groups are linked to one another by up to three methylene groups.


From monomer to material - polystyrene - chemistry and physics

Introduction: plastics as macromolecular materials

Experiments: Proof of the organic nature by charring or heating a plastic powder with copper (II) oxide and proof of the carbon dioxide with lime water.

Reference to the macromolecular character: viscosity of a plastic solution

Staudinger postulated the existence of macromolecules in 1920 (Nobel Prize only 1953)

Natural rubber only became of technical importance after the discovery of vulcanization (Goodyear 1839)

(Artificial horn) made of casein precipitated with rennet - crosslinked with methanal

Nitrocellulose - celluloid

Fire hazard! Production by nitriding cellulose (experiment)

Phenol-formaldehyde synthetic resin (originally as an ivory substitute)

- Demonstration material - crude oil as a raw material

Plastics in competition with natural substances?

Naturally occurring macromolecules can serve as models for how one can artificially produce macromolecules: cellulose, starch, chitin

Low molecular building blocks (Monomers) the at least two reactive groups contain (or at least one reactive double bond) can through multiple reactions to macromolecules (Polymers) can be linked.

Petrochemical products as raw materials

Fractional distillation

Separation of the constituents of the petroleum in a distillation column according to different boiling points delivers

The quantitative distribution of the products does not correspond to the need = & gt conversion necessary.

Crack process

Long-chain hydrocarbons are broken down into shorter ones.

Thermal cracking of gasoline supplies the important chemical raw materials ethene and propene

Other processes: catalytic cracking and hydrocracking

Reform

Isomerization to form branched-chain alkanes and cycloalkanes as well

Dehydrogenation (splitting off of hydrogen) with formation of aromatics:

Ethene as a starting material for organic syntheses:

Synthesis through polyreactions (polymerisation, polycondensation, polyaddition)

In the Polymerization unsaturated compounds assemble to form macromolecules with the establishment of the double bond.

Example: styrene (monomer) - & gt polystyrene

Experiment: Depolymerization of polymethyl methacrylate (= Plexiglas) and detection of the double bond

- Brown coloration of alkaline permanganate solution

Free radical mechanism of polymerization

Experiment: Polymerization of styrene

The polymerization of the monomers can be triggered by radicals. The radical combines with an unsaturated molecule, e.g. styrene, which then becomes a radical itself.

(Comparison of the principle of the free hand with dancing couples)

1. Start reaction: radical formation

e.g. organic peroxides as starters Example: dibenzoyl peroxide

2. Growth reaction: The new radical reacts with another styrene molecule, etc. A carbon chain is created that is held together by atomic bonds:

3. Termination reactions: union of two radicals (recombination) or formation of alkane and alkene through the transition of a hydrogen atom:

Technically important polymers

Monomers Polymers
Ethene Polyethene PE
Propene Polypropene PP
Styrene Polystyrene PS
Vinyl chloride Polyvinyl chloride PVC
Acrylonitrile Polyacrylonitrile PAN
Methacrylic acid ester Polymethacrylic acid ester PMMA
Tetrafluoroethylene Polytetrafluoroethylene PTFE

Polycondensation

In the Polycondensation monomers with at least two functional groups are combined to form macromolecules with the escape of a small molecule, usually water

Examples of link options:

Amide bond and ester bond:

Amine carboxylic acid amide (peptide)

Carboxylic acid alcohol ester

Experiment: Production of nylon 6,6 by interfacial condensation of hexanedicarboxylic acid dichloride with 1,6-diamino-hexane:

Technical synthesis of nylon 66 from AH salt: adipic acid + hexamethylenediamine

Perlon (= nylon 6) from H2N- (CH2)5-COOH over caprolactam

Experiment: Production of a polyester from glycerine and benzene-1,2-dicarboxylic acid (= phthalic acid)

Procedure: 3 g of phthalic anhydride and 3 ml of propanetriol are added to a rg. The glass is not attached completely perpendicular to the tripod and heated over a small flame for about 20 minutes. Result: The originally thin mass becomes thick. It solidifies as it cools down.

from glycol and benzene-1,4-dicarboxylic acid (= terephthalic acid)

unsaturated polyester (e.g. for glass fiber reinforced materials) e.g. from maleic acid + two-w. Alcohol - & gt unsaturated linear polyester - crosslinking with styrene

Phenoplasts and aminoplasts

Experiment: Synthesis of a phenolic resin

Add half the amount of methanol solution to resorcinol, add 10 drops of diluted sodium hydroxide solution, mix, wait, possibly warm up slightly (caution!). A solid, red-brown mass is created

Explanation: Methanal attacks the phenol in the o- and p-position electrophilically with the formation of a trifunctional hydroxymethylene compound - linking of the phenol building blocks with elimination of water with the formation of methylene bridges - three-dimensional crosslinking - & gt duroplast

Experiment: Synthesis of a urea resin

Cover 3 cm high urea with 35% methanol solution (= formalin), heat until the urea dissolves - 3 drops of conc. Add hydrochloric acid (caution!). After a short time, urea resin separates out as a solid white mass.

Polycarbonate (e.g. CD) made from phosgene and a diol (e.g. bisphenol A)

The hydrolysis of dimethyldichlorosilane (and methyltrichlorosilane) forms the corresponding silanol, which forms silicone through elimination of water (polycondensation):

Polyaddition

Polyaddition: Formation of macromolecules by linking multifunctional monomers without leakage of water, but migration of a proton with each reaction step.

Alcohol isocyanate urethane

Addition of multifunctional alcohols (e.g. glycol) with multifunctional isocyanates:

Experiment: Production of a polyurethane foam mushroom

Foam is created by adding water to the alcohol component. Water reacts with isocyanate, developing CO2, this gas inflates the plastic that is being formed:

Another example: polyoxymethylene by polyaddition of methanal

Structure and properties (Pr): thermoplastic, duroplastic, elastomer

Experiments: Behavior of thermoplastics and thermosets when heated

Thermoplastics : become plastic when heated and can be deformed

Only minor forces act between the molecular threads. The intermingled but not interconnected molecular threads can break free from each other due to thermal vibrations. They can therefore be deformed when heated.

Elastic: The shape returns to its original state after stretching, even at high temperatures.

Examples: natural and synthetic rubbers

Explanation: The molecular chains are covalently linked in some places, so they cannot completely separate from each other, but the ball always tries to return to its original state, even if it has been stretched a lot.

/ * Natural and synthetic rubber

Vulcanization turns rubber with predominantly plastic properties into a rubber with predominantly elastic properties. This is achieved by cross-linking: heating with 3 - 5% sulfur - & gt formation of bridges (with a higher sulfur content hard rubber is formed!):

Manufactured from dimethylsiloxane. Advantages: Temperature resistant up to 200 ° C, aging resistance. Disadvantage: slightly less elasticity

Thermosets: Hard, rigid plastics that neither become plastic nor liquid when heated.

Explanation: The elasticity is lost as a result of close-knit networking via numerous cross-connections. Thermal oscillations are largely blocked. The plastic can no longer be deformed after it has fully hardened.

Structure of thermoplastics

Polyethylene PE: partially crystalline

Amorphous sections (partially crystalline order) lie between crystalline areas. The crystalline areas have high strength, the disordered elasticity. PE therefore combines strength with resilient elasticity. The plastic appears milky, as crystalline and amorphous areas differ in density and refractive index.

Polystyrene PS: bulky side chains

- & gt large phenyl group strongly hinders the mobility of the molecular threads - therefore hardly crystallizes - PS is hard and brittle and crystal clear - because of its low softening temperature it is suitable for foams

Polyvinyl chloride PVC: dipole forces

- & gt additional cohesion - higher softening temperature - melt with rubber-like toughness, because the chains are intrinsically mobile, but the dipoles are not ineffective.

Behavior to solvents: resistant to non-polar (hydrocarbons) and strongly polar solvents, on the other hand swelling in solvents with a medium dipole character. Principle: A substance can be separated by the same forces that make it cohesive.

Plasticizers : PVC becomes rubber-like elastic through the incorporation of plasticizer molecules. Plasticizers are, for example, low-volatility esters of polybasic acids (phthalic acid) with long-chain alcohols (decanol).

During this softening process, the rigid dipole-dipole assemblies are separated and linked again by movable plasticizer dipoles (shielding and hinge effect).

Plasticizers can easily be extracted, so soft PVC is sensitive to solvents.

Experiment: Removing the plasticizer from soft PVC

Procedure: A strip of soft PVC is shaken in hot methanol that has been changed several times, then dried between filter paper.

Result: The soft PVC treated with methanol is significantly more brittle than an untreated comparison piece.

/ * Manufacture of synthetic fibers:

Melt spinning process: The polymer is melted and pressed through spinnerets under high pressure. It solidifies into thin threads when it cools down

Wet spinning process: The solvent is dissolved in the water

Experiment: Representation of threads made of polyacrylonitrile

Procedure: An approximately 8% strength spinning solution is prepared by dissolving 0.5 g of polyacrylonitrile in 5 ml of dimethylformamide in an Rg. This solution is pressed into a water-filled container with the help of an injection syringe, the needle of which must not be too narrow.

Result: The solution solidifies into a thread when it leaves the cannula, which is grasped and carefully pulled off. Since the test conditions differ significantly from the specifications of the technical process, the thread has insufficient strength. He cannot be stretched either.

Dry spinning process: The solution is pressed into a hot gas space

Experiment: Stretching a PE film: The previously tangled, jumbled molecular threads are arranged in parallel.

Texturing: The previously smooth fiber is curled fluffy

Heat setting: Forming at high temperature, remains permanently when it cools, e.g. wrinkles

Ion exchanger contain exchangeable groups bound to solid supports (= Anchor groups). The counterions B take the place of the counterions A.

By type of Counterions a distinction is made Cations- and Anion exchanger

strongly acidic: sulfonic acid group -SO3H

slightly acidic: phenolic OH group

weakly basic: amino group -NH2

strongly basic: trialkylamine group -NR3 +

Complete desalination of the water by connecting a cation and an anion exchanger in series - & gt cations are exchanged for protons, anions for hydroxide ions, both combine to form water.

If the polyelectrolyte framework in a cation exchanger is loaded with oxonium ions, the oxonium ions can be exchanged for cations in the solution flowing past in the event of a neutral reaction.

If all counterions A have been replaced by counterions B, the exchange capacity of the ion exchanger is exhausted and it must be regenerated.

Regeneration of the exhausted cation exchanger with acids, an exhausted anion exchanger with alkali.

Peat moss Sphagnum as an ion exchanger - raised bog

Tasks on the chemistry of plastics

* What is a plastic?

** What structural requirements must monomers have so that spatially networked macromolecules can arise?

*** When polymerizing a CH-type monomer2= CH-X, branched polymer chains also occur. Think about a possible mechanism of origin.

*** CH-type monomers2= CH-X can also be polymerized by adding acids (proton donors). Represent the start and growth reaction with structural formulas.

** The following structural formulas show sections of plastic molecules. Give structural formulas and names of the monomers and state the type of polyreaction.

Polystyrene is produced from styrene through polymerization

a) Establish the reaction mechanism with structural formulas for this reaction.

b) Dibenzoyl peroxide is used as the initiator for the polymerization. Why is the often used expression "dibenzoyl peroxide acts as a catalyst" incorrect?

c) Why doesn't polystyrene melt at a certain temperature?

d) Styrene polymerizes after a long time in the storage bottle, even without adding a starter. Think about how this is possible.

e) What influence does the addition of p-divinylbenzene CH have on the structure and properties of the polystyrene?2= CH-C6H4-CH = CH2 to styrene before polymerization?

f) What influence does an increase in the starter concentration have on the structure and properties of the polystyrene?


Areas of application

A large number of transparent and non-transparent components are made from polymethyl methacrylate.

PMMA is indispensable in dentistry, where it is used for prostheses. For this purpose, the plastic is colored with metal salts so that the typical pink color is created. In a transparent form, it is used for bandage splints. The plastic is freely mixed and hardens under heat and pressure. Activators can also be added.

Important areas of application are:

  • Automotive technology: Indicator and taillight lenses, reflectors, light guides, door / pillar trim in the exterior area (A / B / C pillar trim)
  • Aviation: Windows, hoods, headlight covers
  • Lighting technology: Floodlight signs and "acrylic light design", lamp covers, illuminated advertising
  • Optics: Sight glasses, lenses, spectacle glasses, Fresnel lenses, optical fibers
  • Jewellery: So-called plugs and other jewelry for e.g. & # 160B. widened piercings
  • Household: Bowls, casings, salad spoons, salt and pepper mills
  • Construction: Polymer concrete, industrial floors, glazing (e.g. & # 160B. Double wall sheets), sealing and coating of balconies and terraces, detail sealing in flat roofs, industrial door glazing (Plustherm system glazing), sanitary components (e.g. & # 160B. Bathtub), furniture, room dividers, door panels , Lampshades
  • Musical instruments: Drums, key pads on the piano
  • Orthopedics: Bone cement (e.g. & # 160B. For anchoring hip prostheses)
  • Dentistry: Full and partial dentures, temporaries, occlusal splints
  • Medicine: Hard intraocular lenses, PMMA balls enriched with gentamicin, drawn up as chains for continuous antibiotic treatment
  • Hearing aid acoustics: Earmold (earmold)
  • Textile industry: Part of polyacrylic fibers, see polyacrylonitrile
  • Semiconductor industry: Use as a resist (photoresist) or a component thereof in photo and electron beam lithography
  • Horticulture: Roofing material, greenhouses
  • Pyrotechnics: Part of delay rates
  • Submarine pressure hull: see Deep Rover DR1002
  • Visual arts: as material and image carrier
  • Model and prototype construction: as a mineral glass replacement for single pieces and small series
  • Machine protection: Protective hoods and protective doors
  • Watch industry: watch glass
  • Adhesives:Methyl methacrylate adhesive

Manufacturing

PTFE is made from chloroform CHCl3 by partial fluoridation produced, initially with chlorodifluoromethane CHClF2 and tetrafluoroethylene C2F.4 be generated. Antimony (V) chloride fluoride (SbCl) acts as a catalyst4F).

Tetrafluoroethylene is then subjected to radical polymerization under pressure. Depending on the conditions, there are different molecule and particle sizes:

Since this reaction is strongly exothermic and the monomer units decompose explosively at high temperatures, the polymerization is carried out in suspension. In addition, the instability of the monomer means that the polymer and monomer production facilities are in close proximity, since the monomer can only be transported to a very limited extent due to the risk of explosion.


Table of contents

As early as 1839, the pharmacist Eduard Simon observed in Berlin that styrene thickened over several months into a gelatinous, viscous mass, which he assumed to oxidize Styrene oxide called. [7] Six years later, John Buddle Blyth and August Wilhelm von Hofmann reported that the conversion took place without giving up or giving up any element and only through the molecular change of the styrene, and named the styrene oxide Metastyrene around. [8] The designation Polystyrene was used for the first time by Abraham Kronstein, who understood it to be a gel-like intermediate product, which then becomes glass-like with styrene Metastyrene should form. [9] [10]

In 1931, the technical production of polystyrene began at the I.G. Farben plant in Ludwigshafen am Rhein. The use as foam plastic (Styrofoam) was developed in 1949 by Fritz Stastny and his boss Rudolf Gäth at BASF, patented in 1950 [11] and presented in 1952 at the plastics trade fair in Düsseldorf. In the USA it was developed as Styrofoam by Ray McIntire at Dow Chemical Company (patent 1944).

The following table gives an overview of polystyrene homopolymers.

Abbreviations [12] Other abbreviations
Standard polystyrene, normal polystyrene Standard PS, Normal PS, GPPS
Polystyrene syndiotactic PS-S, PS- (M) sPS
Polystyrene foam and expandable polystyrene PS-E EPS

GPPS is derived from the English name General Purpose Polystyrene from, EPS from Expanded polystyrene.

This table gives an overview of the most important polystyrene copolymers:

Styrene-butadiene graft copolymers SB
Styrene-butadiene block copolymers SBS
Styrene-acrylonitrile copolymers SAN
Acrylonitrile-butadiene-styrene copolymers SECTION
cross-linked polystyrene PS-X

In polystyrene, tacticity describes the extent to which the phenyl group in the polymer chain is aligned (arranged) uniformly. The tacticity has a strong impact on the properties of the plastic. Standard polystyrene is atactic.

Polystyrene is obtained by polymerizing styrene. A large number of polymers are made by chain polymerization, including: four of the five most important plastics in terms of quantity, namely polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and also polystyrene (PS). Styrene has exceptional polymerisation properties; it can be polymerised by free radicals, cationic, anionic or using Ziegler-Natta catalysts.

There are currently two processes of industrial importance for the production of styrene, the dehydrogenation of ethylbenzene and the SM / PO process. In 2012, the annual world production of styrene was about 20 million tons.

The finished plastic is sold as granulate in order to be processed as extrudable polystyrene (XPS) into plastic parts or containers (e.g. food packaging with aluminum heat-sealed lids). Expandable polystyrene (EPS) acquires gas inclusions during the polymerization to form solid spheres. The beads are transported to the processor. If the spheres are heated there under steam a little over 100 ° C, the gas expands and the thermoplastic material puffs up. The edges of the bubbles merge. The result is a shaped solid, depending on the shape, everything from simple plates to geometrically complex molded parts is possible.

Edit physical properties

Unmodified polystyrene has a low melting point, is hard and brittle, and relatively permeable to oxygen and water vapor. [6]

The density of compact polystyrene is between 1040 and 1090 kg / m³. Foamed polystyrene (EPS or PS-E) has a density between 15 (insulation in construction) and 90 kg / m³ (ski helmet).

When expanded, polystyrene has a very low thermal conductivity. For gray insulation boards to which graphite is added (e.g. Neopor), it is slightly lower at ≈0.032 W / (mK) than for white insulation boards (e.g. Styrofoam) with 0.035 ... 0.040 W / ( m · K).

Mechanical properties edit

Solid amorphous polystyrene is crystal clear, hard and sensitive to impact. It produces a brittle, clattering, almost glass-like sound when knocked (butter dishes). When it is bent or broken, it smells clearly of styrene. Polystyrene can be colored in all colors. Solid polystyrene tends to form stress cracks. It is not very heat-resistant, aging accelerates from 55 ° C, which is why it can only be used up to 70 ° C. The glass transition temperature is approx. 100 ° C, depending on the processing conditions, the melting temperature is 240 ° C for isotactic polystyrene and 270 ° C for syndiotactic polystyrene. Atactic polystyrene is an amorphous solid and has no melting temperature. [13] Atactic polystyrene is an inexpensive plastic with a large market share, syndiotactic PS has so far only been used for special applications, isotactic PS is of no industrial interest because of its low crystallization rate.

Foamed polystyrene is white and opaque. Compared to solid polystyrene, it has lower mechanical strength, but higher elasticity.

Chemical properties edit

Polystyrene has good resistance to aqueous alkalis and mineral acids, but not to non-polar solvents such as gasoline and longer-chain ketones and aldehydes. It is sensitive to UV.

Polystyrene can e.g. B. be dissolved with dichloromethane and welded almost seamlessly.

Even small amounts of solvents such as acetone, ethyl acetate or toluene are enough to "eat away" a relatively large volume of polystyrene foam by attacking the relatively low-mass foam structure and at the same time releasing the high-volume propellant gas enclosed in the foam.

Syndiotactic polystyrene crystallizes sufficiently quickly; it is used as a construction material in typical injection molding processes, especially because of its extreme resistance to chemicals, hot water and coolants. This makes it an alternative to established engineering plastics. It is made using metallocene catalysts.

Fire behavior edit

Polystyrene burns with a bright yellow, heavily sooting flame. The styrene released has a flowery-sweet odor in practice, however, the vapors often have a pungent odor due to additives.

The fire behavior of expanded polystyrene is dominated by the fact that it softens at temperatures a little above 100 ° C and then drips off, whereby the drops (also due to their low mass and the associated poor heat dissipation) can catch fire and then drip off burning. Above about 300 ° C, the material decomposes into styrene, among other things (flash point of about 31 ° C). If necessary, residues of the propellant pentane (flash point approx. −50 ° C) are released. This can lead to the polystyrene burning and dripping off by itself. [14] Burning dripping polystyrene can lead to fire spreading by igniting materials underneath.

Suitable flame retardants can reduce the flammability of (expanded or extruded) polystyrene. In the past, polybrominated diphenyl ethers or hexabromocyclododecane were often used as additives, the use of which is no longer permitted in the raw material, but can still be introduced into the end products through recyclate. Today a brominated styrene-butadiene copolymer is mostly used. These flame retardants split off bromine-containing gases during combustion, thereby breaking off the radical chain reactions that occur during combustion by scavenging the oxygen and thus inhibiting combustion, which can result in polybrominated dibenzodioxins and dibenzofurans.

The fire behavior of flame-retardant polystyrene rigid foam for construction applications is classified according to EN 13501-1 and classified in the European class for fire behavior E. When installed, the fire behavior depends on the specific structure of the insulation system. For information on the fire behavior of thermal insulation composite systems and controversies following media reports on facade fires, see thermal insulation composite system # Fire behavior.

Weather resistance edit

Polystyrene is resistant to the effects of water, but rots when it is exposed to UV radiation. Polystyrene embrittles relatively quickly when exposed to light and then tends to form stress cracks. Photooxidation of polystyrene occurs at wavelengths of λ < displaystyle lambda> = 253.7 nm, with the chromophoric groups absorbing and numerous decomposition products (hydroperoxides, hydroxyl and carbonyl compounds, aliphatic and aromatic ketones, peroxy esters, volatile compounds such as benzaldehyde and Acetophenone), radiation λ < displaystyle lambda> greater than 300 nm is not absorbed. [15]

Effects on Organisms and the Environment Edit

Polystyrene is physiologically harmless and unrestrictedly approved for food packaging.

However, as shown below, brominated flame retardant additives in packaging [16] [17] and their migration into food cannot be ruled out. [18] There are also indications that cell cultures can be negatively influenced by a softening of the material under culture conditions. [19]

In countries with inadequate waste disposal, polystyrene can end up in the sea. There it accumulates in the debris of floating garbage in the oceans, where it breaks down into small crumbs through photolysis and the impact of the waves, which are ingested by animals (for more on this see garbage vortex).

The flame retardant hexabromocyclododecane (HBCD), which was previously added to polystyrene for insulation boards and rigid foam boards, is classified as "very toxic to aquatic organisms with long-term effects" according to the CLP regulation. [20] [21] It is only relatively difficult to degrade (persistent) and toxic to aquatic organisms with a very high bioaccumulation and biomagnification potential. [22] [23] Migration into the environment from undamaged expanded polystyrene is small in terms of quantity, [24] emissions can occur in the event of fire, photolysis and recycling.

In 2015, researchers at Stanford University discovered that mealworms are able to consume polystyrene and convert into CO2 and decompose rotting feces. One hundred larvae consumed 34–39 mg daily. After the month-long experiment, no difference was found between the health status of mealworms that ate polystyrene and those that ate conventional food. The digestive process has not yet been researched in detail. [25]

Edit material pests

Woodpeckers and the brown garden ant usually nest in rotten trees. However, polystyrene insulation panels are used by both as alternative living spaces. Woodpeckers destroy z. B. the plaster layer of a thermal insulation composite system (woodpecker damage) [26] to create a breeding cave in it. The workers of the brown garden ant create paths and nests in polystyrene insulation panels [27] in which they raise their brood. With their pincers, they break up the individual polystyrene balls into tiny, transportable parts [27] and transport them to other cavities or to the outside, which also makes the pest infestation visible.

As a material, polystyrene homopolymer has an excellent profile of properties when transparency, surface quality and rigidity are required. Its range of applications is also significantly expanded by copolymers and other modifications (blends e.g. with PC and syndiotactic polystyrene). [28]: 102–104 The brittleness of common polystyrene is overcome by elastomer-modified styrene-butadiene copolymers. The copolymer made from styrene and acrylonitrile (SAN) is more resistant to thermal stress, heat and chemicals than the homopolymer and is also transparent. ABS has similar properties, can be used at low temperatures, but is opaque.

Styrene-Butadiene Copolymers Edit

Styrene-butadiene copolymers can be made with a low proportion of butene. Either PS-I or SBC (see below) can be produced, both copolymers are impact-resistant. PS-I is made by graft copolymerization, SBC by anionic block copolymerization, which allows it to be transparent. [29]

If styrene-butadiene copolymer has a high proportion of butene, styrene-butadiene rubber (SBR) is formed.

The impact strength of the styrene-butadiene copolymers results from phase separation; polystyrene and polybutadiene are not soluble in one another (see Flory-Huggins theory). A boundary layer is created by copolymerization without complete mixing. The butadiene components (the "rubber phase") accumulate to form particles that are embedded in a matrix made of polystyrene. The decisive factor for the improved impact strength of the styrene-butadiene copolymers is the higher capacity for deformation work. Without applied force, the rubber phase initially behaves like a filler. When subjected to tensile stress, crazes (micro-cracks) form, which spread to the rubber particles. The energy of the spreading crack is then transferred to the rubber particles lying on its way. Due to a large number of cracks, the originally rigid material contains a lamellar structure. The formation of each individual lamella contributes to the consumption of energy and thus to an increase in the elongation at break. PS homopolymers deform until they break when a force is applied. At this point, the styrene-butadiene copolymer does not break, but begins to flow, solidifies until it is tear-resistant and only breaks at a much higher degree of elongation. [30]: 426

If there is a high proportion of polybutadiene, the effect of the two phases is reversed. Styrene-butadiene rubber behaves like an elastomer, but can be processed like a thermoplastic.

PS-I edit

PS-I (from English impact resistant polystyrene) consists of a coherent polystyrene matrix and a rubber phase dispersed in it. It is made by polymerizing styrene in the presence of polybutadiene dissolved (in styrene). The polymerization proceeds in two ways simultaneously: [31]

    : The growing polystyrene chain reacts with a double bond of the polybutadiene. As a result, several polystyrene chains are attached to a polybutadiene molecule.
  • Homopolymerization: styrene polymerizes to polystyrene and does not react with the polybutadiene present.

The polybutadiene particles (rubber particles) in PS-I usually have a diameter of 0.5 - 9 μm. As a result, they scatter visible light, which makes PS-I opaque. [32]: 476 The material is stable (no further segregation takes place) because polybutadiene and polystyrene are chemically linked. [33] Historically, PS-I was initially created by simply mixing polybutadiene and polystyrene (the result is a polymer blend, not a copolymer). However, this material has significantly poorer properties. [32]: 476

Styrene-Butadiene Block Copolymers Edit

SBS (S.tyreneB.utadienS.tyrol block copolymer) is produced by anionic block copolymerization and consists of three blocks: [34]

SSSSSSSSSSSSSSSSSSSS BBBBBBBBBBBBBBBBBBBB SSSSSSSSSSSSSSSSSSSS

S stands for the styrene repeat unit, B for the butadiene repeat unit. Often, however, the middle block does not consist of such a butadiene homopolymer, but of a styrene-butadiene copolymer:

SSSSSSSSSSSSSSSSSSS BB S BB S B S BBBB S B SS BBB S B SSSSSSSSSSSSSSSSSSS S

By using a random copolymer at this point, the plastic becomes less susceptible to crosslinking and flows better in the melt.

In anionic copolymerization, styrene is first homopolymerized, and an organometallic compound such as butyllithium serves as the catalyst. Only then is butadiene added, after which styrene is added again. The catalyst remains active all the time (for which the chemicals used must be of high purity). The molecular weight distribution of the polymers is very low (polydispersity in the range of 1.05, so the individual chains have very similar lengths). The length of the individual blocks can be specifically adjusted through the ratio of catalyst to monomer. The size of the rubber particles in turn depends on the block length. Very small particles (smaller than the wavelength of the light) ensure transparency. In contrast to PS-I, however, the block copolymer does not form particles, but has a lamellar structure.

Styrene-butadiene rubber edit

Styrene-butadiene rubber (SBR from English Styrene Butadiene Rubber), like PS-I, is produced by graft copolymerization, but with a lower styrene content. As a result, SBR consists of a rubber matrix with a polystyrene phase dispersed in it. [33] Unlike PS-I and SBC, it is not a thermoplastic, but an elastomer.

The polystyrene phase aggregates to form domains within the rubber phase. As a result, it creates a physical network at the microscopic level. When the material is heated above the glass transition point, the domains disintegrate, the crosslinking is temporarily removed and the material can be processed like a thermoplastic. [35]

Polystyrene is one of the standard plastics and takes fourth place in terms of production volume after polyethylene, polypropylene and polyvinyl chloride. In Germany, around 12.06 million tonnes of plastics (excluding adhesives, varnishes, resins, fibers) were processed in 2015, of which 655,000 tonnes (5.4 percent) were polystyrene and expanded polystyrene PS / PS-E. [36]

Films and sheets are produced by extrusion.

The low tendency of polystyrene to shrink or shrink during production enables components that are very near-net-shape (see lost foam process). Furthermore, very fine contours, edges and straight surfaces can also be produced for plastics. This property enables the production of components that are relatively precisely fitting. So z. B. tape cassettes and CD cases made of transparent polystyrene.

Polystyrene is permitted as food packaging, for example as a yoghurt cup or foam tray, if certain requirements are met [37].

Injection molded parts made of non-foamed polystyrene are used in plastic model making.

Polystyrene is used in electrical engineering because of its good insulating properties. It is used to manufacture switches, bobbins and housings (High Impact Polystyrene, HIPS) for electrical appliances. Polystyrene is used for mass-produced items (e.g. classic CD packaging, video cassettes), in precision engineering and for inspection glasses.

Polystyrene is the main component of Napalm-B, which is used in incendiary bombs.

Edit polystyrene sheet

Transparent polystyrene film is used, among other things, for packaging purposes.

Stretched polystyrene foil (trade names: Styroflex for the copolymer with butadiene, Trolitul) is used together with aluminum or tin foil for the production of low-loss and tightly tolerated capacitors. [38]

In infrared spectroscopy, polystyrene film is used as the wavelength standard. A card with a foil that fits into the specimen holder is enclosed with the device by the device manufacturer. [39]

Processing of expanded polystyrene

Propellants such as cyclopentane or carbon dioxide are added to the raw material, which cause the material, which is liquid under the action of heat, to foam. [40]

There Expanded polystyrene can be cut very well with a thermal saw and is at the same time very inexpensive, it has established itself as a building material in model and scenery construction. The foamed material is used in model aircraft construction. Model builders as well as city and landscape planners use it for landscape elements because it can be edited very well.

Loose, free-flowing polystyrene foam balls typically around 2–6 mm in diameter are used as filling for beanbags, vacuum mattresses in rescue services, in road construction, to loosen heavy soils in gardening and landscaping and sometimes as a means of buoyancy when lifting shipwrecks. [41]

Polystyrene foam is also used in nuclear weapons, where it is used to maintain the cavity of the subcritical masses and for compression in fusion bombs.

Expanded polystyrene (EPS) machining

Styrofoam [42] is generally known as a light, white packaging and insulating material. This is a rather coarse-pored one EPS rigid foam (E.expanded P.olystyrol). For production, granules are filled into a mold and foamed in hot steam. The particles of the granulate stick together, but usually do not completely fuse with one another. The spherical, foamed granules are often recognizable in the end product and can sometimes be separated individually. Depending on the manufacturing process, expanded polystyrene rigid foam is more or less permeable to air and water vapor.

EPS rigid foam panels can be cut from a block in almost any thickness.

Foamed polystyrene is widely used as packaging material and for protective helmets, solid life jackets and surfboards.

Styrofoam is originally a brand name of BASF. The IVH (Industrieverband Hartschaum e.V.) has been exercising the rights to the name Styropor since the 1990s. Only manufacturers of EPSwho submit to the special quality requirements of the IVH are allowed to use their material Styrofoam to name.

Other well-known trade names for EPS are Austrotherm, Steinopor, Sagex, Swisspor, Hungarocell (Hungary), Telgopor (Spanish speaking countries) and Frigolite (Sweden).

The common brand name was established in 2014 under the direction of the European Association of EPS Processors (European Manufacturers of Expanded Polystyrene, EUMEPS) airpop introduced with the aim of minimizing the large variety of names for EPS in Europe. In Germany, the IK Industrievereinigung Kunststoffverpackungen e.V. is responsible for the implementation of the European strategy in the field of EPS packaging. [43]

Extruded Polystyrene (XPS) Edit

Another method of making polystyrene foam is extrusion. The starting material made of polystyrene granulate and blowing agent is foamed by heat and at the same time continuously pushed out through a defined opening and cooled. This creates a more homogeneous, finer-pored XPS rigid foam (E.xtruded P.olystyrol), which usually has a closed surface and a closed-cell structure. It is classified as impervious to air, water and water vapor and only absorbs a small amount of water.

Trade names are e.g. B. Austrotherm XPS (Color pink), Floormate, Jackodur (JACKON Insulation, color purple), Roofmate, Styrodur (BASF, color green), Styrofoam (Dow Chemical, color blue) and URSA XPS (URSA Deutschland GmbH, color yellow).

In the construction area edit

Foamed polystyrene is used as an insulating material for the thermal insulation of buildings. The construction industry is the largest consumer of EPS: in 2012 it accounted for more than 60% of global EPS sales, which are expected to increase to US $ 15 billion by 2020. [44]

Due to its high compressive strength and low water absorption (closed porosity), XPS is used, for example, to insulate buildings from the ground (perimeter insulation). This material is used for shower elements at ground level and flush with the floor [45] because of its high compressive strength.

As of the end of 2014, buildings in Switzerland contained almost 500,000 tonnes of EPS and 200,000 tonnes of XPS as insulation. [46] Rigid foam panels for the construction sector are specially equipped to meet the various requirements:

  • Panels for impact sound insulation should absorb and damp vibrations elastically.
  • Panels that are used for thermal insulation usually have to be flame-retardant. The lighter and finer-pored the panels are, the higher their insulation value. Plates offset with graphite (gray EPS) are offered under the trade name Neopor, among others.
  • Platten für die Perimeterdämmung und für Umkehrdächer dürfen nur geringe Mengen Wasser aufnehmen, damit der vorgesehene Dämmwert auch in feuchter Umgebung erhalten bleibt.

Für EPS-Dämmstoffe gelten die Anforderungen der EN 13163, für XPS-Dämmstoffe jene der EN 13164. In Deutschland müssen zusätzlich Fassaden-Dämmplatten aus EPS-Hartschaum der allgemeinen bauaufsichtlichen Zulassung Z-33.4-… bzw. Z-33.40-… des Herstellers entsprechen Qualitäts-Richtlinien und Prüfbestimmungen der Bundesfachabteilung Qualitätssicherung EPS-Hartschaum (BFA QS EPS) sind zu erfüllen. [47]

In Deutschland sind 2016 etwa 5 Millionen Tonnen Kunststoffabfälle angefallen, davon 110.200 Tonnen oder 2,2 % EPS- und XPS-Abfälle. Diese wurden zu 33 % recycelt, zu 65 % einer energetischen Verwertung zugeführt und zu 2 % deponiert. [48]

Recycling Bearbeiten

Zur Zeit stehen folgende werkstoffliche Recyclingverfahren zur Verfügung:

  • Extrusion: Die Polystyrol-Abfälle werden nach Zerkleinerung und Extrusion für die Gewinnung von Polystyrol-Regranulat verwendet.
  • Mechanisches Recycling: Die EPS-Abfälle werden in einer Mühle gemahlen und das daraus entstandene Mahlgut entstaubt. Das EPS-Granulat wird z. B. für gebundene EPS-Schüttungen, EPS-Recyclingplatten, als Leichtzuschlag für Beton oder zur Porosierung von Mauerziegeln verwendet. [49]

Die größten Probleme des EPS-Recyclings sind: [50]

  • Abfälle von EPS verursachen aufgrund der sehr geringen Schüttdichte von ca. 6,5 kg/m³ enorm hohe spezifische Transportkosten.
  • EPS wird wegen Verschmutzungen und Vermischungen kaum recycelt. EPS-Recyclat kann deshalb in Deutschland nur in geringen Mengen zu Polystyrol-Granulat und in der Folge für hochwertige Spritzgussanwendungen verarbeitet werden. Ein Teil des EPS-Abfalls wird thermisch verwertet.
  • Derzeit werden flammschutzmittelhaltige Schaumstoff-Recyclate zu anderen Produkten weiterverarbeitet. Dadurch sind signifikante Restgehalte an bromierten Flammschutzadditiven auch in sensiblen Anwendungen (Verpackung, Blumentrays etc.) nicht auszuschließen.

Einen Ausweg bietet ein Sammel- und Recyclingverfahren, das das Freising­er Fraunhofer-Institut IVV mitentwickelt hat. [51] [52] Dabei werden Abfälle von Polystyrol bereits während der Sammlung in einem Lösungsmittel selektiv gelöst (und im Volumen auf 1/50 verringert). Aus der Lösung kann Polystyrol hochrein wiedergewonnen werden. In Montreal (Kanada) ist 2018 die weltweit erste lösemittelbasierte EPS-Recyclinganlage mit einer Jahresleistung von 600 Tonnen in Betrieb gegangen. [53] In Terneuzen (Niederlande) soll durch die Genossenschaft PolyStyreneLoop eine auf dem CreaSolv® Prozess basierende EPS- und XPS-Recyclinganlage mit einer Jahresleistung von 3.000 Tonnen errichtet werden. [54]

Energetische Verwertung Bearbeiten

Falls kein Recycling erfolgt, werden Polystyrol-Abfälle durch Verbrennung zur Energieerzeugung genutzt. [49]

Die Stadt Würzburg hat die Mitverbrennung von HBCD-haltigen Polystyrol-Schaumstoffabfällen gemeinsam mit kommunalem und gewerblichem Restmüll untersucht. Dabei hat sich gezeigt, dass die sichere Zerstörung des Flammschutzmittels HBCD gewährleistet ist. [55] [56]

In Deutschland mussten HBCD-haltige Polystyrol-Dämmstoffe nach einer Änderung der Abfallverzeichnis-Verordnung ab 1. Oktober 2016 als gefährlicher Abfall entsorgt werden. Aufgrund dieser Einstufung kam es zu Entsorgungsengpässen, da viele Müllverbrennungsanlagen nicht über die entsprechende Genehmigung verfügten. [57] Um weiterhin die Entsorgung in diesen Müllverbrennungsanlagen zu ermöglichen, regelten einige Bundesländer über Erlasse, dass HBCD-haltige Polystyrol-Dämmstoffe bis zu einem bestimmten Anteil im Baumischabfall zulässig sind. [58] Nach einer weiteren Änderung der Abfallverzeichnis-Verordnung gelten HBCD-haltige Polystyrol-Dämmstoffe ab 28. Dezember 2016 als nicht gefährlicher Abfall und können in Müllverbrennungsanlagen entsorgt werden. [59] Am 17. Juli 2017 wurden die POP-Abfall-Überwachungs-Verordnung und eine Änderung zur Abfallverzeichnis-Verordnung erlassen (BGBl. I S. 2644 ). HBCD-haltige Polystyrol-Dämmstoffe können damit auch weiterhin in Müllverbrennungsanlagen entsorgt werden, allerdings gelten für sie ein Getrenntsammlungsgebot, ein Vermischungsverbot sowie Nachweis- und Registerpflichten. [60] In Österreich werden HBCD-haltige EPS-Dämmstoffe als nicht gefährlicher Abfall (Abfallschlüsselnummer 57108 „Polystyrol, Polystyrolschaum“) eingestuft. Sie dürfen in Verbrennungsanlagen für nicht gefährliche Abfälle (Müllverbrennungsanlagen) mitverbrannt werden. [61]

Deponierung Bearbeiten

2006 wurden in den USA 870.000 Tonnen Polystyrol-Teller und -Tassen sowie 590.000 Tonnen aus anderen Produkten auf Deponien abgelagert. [62] Da Polystyrol unter Lichtausschluss biologisch nicht abgebaut wird, [63] bleibt es in Deponien erhalten.


Video: 2 Polymerization of Styrene (August 2022).