POLYSTYRENE FOAMING

PREPARED BY:

WE’AM ALMASRI 20712061

AMJAD ALSHAER 20710232

MOHAMMAD QASRAWI 20711283

INSTRUCTOR:

DR. RA’ED MA’ALI1

STYRENE

Its the product of a two-fold reaction, Ethylene and

benzene, in the presence of a catalyst such as aluminum

chloride, form ethyl benzene, which is then

dehydrogenated to form styrene.

ETHYLENE BENZENE STYRENE

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POLYSTYRENE Initiators thermally decompose, thereby forming active free

radicals that are effective in starting the polymerization

process. Typically initiators used in the suspension process

include benzoyl peroxide and others. Potassium per sulfate is a

typical initiator used in emulsion polymerizations. In the

presence of inert materials, styrene monomer will react with

itself to form a homopolymer POLYStyrene.

STYRENE

MONOMER

STYRENE

MONOMERPOLYSTYRENE

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FOAMING:

BLOWING AGENTS:

Any gas can serve as a blowing agent, but not every gas can be

easily implemented in the foaming process.

The blowing agent’s quality, quantity, and nature are key

factors in the production of a foamed structure.

Foam develops by agglomeration of gas bubbles in a melt. The

individual gas bubbles are hindered from assuming the

energetically favorable round form which are governed by the

polymer matrix,

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The cellular structure and the gas composition a gaseous phase is being dispersed in a spherical form within a polymeric matrix, a composite structure is naturally formed, and the properties of this composite are determined by its constituents and their distributions.

Common foaming processes are the following:1. Air is whipped into a dispersion or solution of the plastic, which is then hardened by heat or

catalytic action or both.

2. A low-boiling liquid is incorporated in the plastic mix and volatilized by heat.

3. Carbon dioxide gas is produced within the plastic mass by chemical reaction.

4. A gas, such as nitrogen, is dissolved in the plastic melt under pressure and allowed to expand by reducing the pressure as the melt is extruded.

5. A gas, such as nitrogen, is generated within the plastic mass by thermal decomposition of a chemical blowing agent.

6. Microscopically small hollow beads of resin or even glass are embedded in a resin matrix.

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POLYSTYRENE FOAMS: Polystyrene is material that has properties such as light,

rigid, closed-cell plastic foams, having low thermal

conductivity and excellent water resistance, Therefore, the

polystyrene is widely used in the manufacturing of plastic

foams by two process injection and extrusion molding.

1. Extruded polystyrene foam.

2. Expandable polystyrene for molded foam.

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EXTRUDED POLYSTYRENE FOAM (XPS):

This material is made by extruding molten polystyrene

which is include a blowing agent , the process occurs

under elevated temperature and pressure into atmosphere

where the mass expands and solidifies into Desirable

form . the trade name Styrofoam . Which is Characterized

as lightweight material .

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THE EXTRUSION POLYSTYRENE FOAM PROCESS

By using two extruder to manufacture continuous length of foam. The first one melts and mix a dry blend of the polymer polystyrene and the additives

The process of (EXP) occurs in the following Sequence:

1. the process begins with polystyrene with solid polystyrene crystals .The crystals & ,special additives and a

blowing agent, are fed into an extruder.

2. Inside the extruder the mixture is blending and melting .Conditions of high temperature and pressure, into a

viscous plastic fluid. ”It is very important to get the suitable viscosity.

3. The hot, thick liquid is then forced in a continuous process through a die. As it emerges from the die it

expands to foam.

4. The thick liquid is shape, and it cools with suitable cooler systems. The last step in this process is to

finishing, and cutting the thick foam product.

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EXPANDED POLYSTYRENE FOAM (EPF) EPF is a linear polymer whose basic unit is styrene , Is a plastic material that Composed of individual cells

of low density polystyrene ,and has special properties due to its structure, EPF consists of a polymer chain with great molecular weight. A molecule's weight is equivalent to its mass.

PS quality-molded blocks are used for many applications, it must be cut to a desired dimension and, this type of foam is produced from beads containing a blowing agent . Thus, pellets taken from an ordinary melt extruder or beads produced by suspension polymerization are impregnated with a hydrocarbon such as pentane. The vapor pressure of the pentane dissolved in the polymer is low enough to permit storage of the expandable polystyrene in a closed container at ordinary temperature and pressure. The expandable polystyrene beads may be used in a tabular blow-extrusion process to produce polystyrene foam sheet.

Expandable polystyrene beads are often molded in two separate steps:

1. Preexpansion or prefoaming of the expandable beads by heat

2. Further expansion and fusion of the preexpanded beads by heat in the enclosed space of a shaping mold.

Tabular Blow-Extrusion to produce low density polystyrene foam sheet 9

EXPANDABLE POLYSTYRENE PROCESS CONSISTS of THE

FOLLOWING STEPS

PREPARING THE BEADS: The polymerization polystyrene consisting of beads made up of

polystyrene chains is cooled. These beads are then washed out and dried. Uniform bead size is achieved by

sorting the beads through meshes which filter out over- and undersized beads.

MAKING EXPANDED POLYSTYRENE FOAM: First, the beads of polystyrene must be

expanded to achieve the proper density. This process is known as pre-expansion, and involves heating the

polystyrene either with steam or hot air. During pre-expansion, a device is used to keep the beads from

fusing together. Since expanded beads are lighter than unexpanded beads, they are forced to the top of the

vessel's cavity and discharged. This process lowers the density of the beads to three percent of their original

value and yields a smooth-skinned, closed cell EPF that is excellent for detailed molding. Next, the pre-

expanded beads are usually "aged“ this allows air to diffuse into the beads, cooling them and making them

harder.

MOLDING: After aging, the beads are fed into a mold of the desired shape. Low-pressure steam is then

injected into and between the beads, expanding them once more and fusing them together. The mold is then

cooled, either by circulating water through it or by spraying water on the outside.

CUTTING, BONDING, AND COATING: EPF is usually cut with common wood-I working tools,

which must be kept very sharp at all times to cut smoothly. It can also be bonded with adhesives that do not

destroy it

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FIRE PERFORMANCE, SITE HANDLING

& STORAGE, AND ENVIRONMENT: FIRE:

1. Styrofoam extruded polystyrene products contain a flame retardant additive to inhibit accidental ignition

from a small fire source, if its exposed to an intense fire, may burn rapidly. Its products will melt when

brought into direct contact with high temperature heat sources.

HANDLING & STORAGE:

1. Styrofoam extruded polystyrene products should be stored on a clean, flat surface in an area free from

flammable or volatile materials.

2. When large quantities of the boards are stored indoors it is recommended that the building be ventilated to

allow a minimum of two air changes per hour.

3. To avoid surface degradation, the boards should be protected from direct sunlight when stored for long

periods in the open.

4. Light colored plastic sheeting is a suitable protective cover, but dark or transparent materials should be

avoided as they may cause excessively high temperatures to develop underneath.

5. Solvent attacks may occur if the blue extruded polystyrene products are used in direct contact with

materials containing volatile components.

6. Care should be taken to protect the boards from flames or other ignition sources during storage.

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APPLICATIONS:

1. Styrofoam extruded polystyrene was first used as a flotation material in life-rafts and life-

boats as it’s fully closed cell structure made it highly resistant to water absorption.

2. Styrofoam being regarded as the perfect thermal insulation material.

3. ROOFING: its excellent moisture resistance and thermal performance retention properties,

Styrofoam roofmate is the ideal insulation material for Upside-Down roofing.

4. WALLS: it’s considerably reduce energy loss through external walls of new and existing

buildings.

5. COLD STORES AND PANELS: Styrofoam is the ideal insulation for high-load-bearing floors

such as those found in cold stores, while its close tolerance, dust-free surface allows for

perfect bonding to a variety of sheet materials in high quality sandwich panels used in the

cold storage industry.

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ADVANTAGES AND DISADVANTAGES

of EXTRUDED POLYSTYRENE FOAM

ADVANTAGES DISADVANTAGES

1. The major advantage of Extruded polystyrene

foam surfboard blank is that it has a closed cell

structure. This makes is totally water repellent

2. Extruded polystyrene foam is exceptionally

strong, and isn’t damaged as easily as EPS foam

by compressions.

3. Extruded foam surfboard blanks will therefore

result in a faster and higher performance epoxy

surfboard.

4. The waterproofing layer is not exposed to UV

radiation, other kinds of solar radiation and other

atmospheric factors of aging. It’s perfectly

obvious and expected that its functional life will

be considerably longer.

1. In case of a leak, repair procedures are more

difficult.

2. There is only one choice for insulation

panels: extruded polystyrene.

3. Some quantities of water may be trapped

between insulation and waterproofing layer.

4. Slopes should be created with utmost care.

Allow for a slope of at least 2%. Preventively

increase calculated insulation thickness by 10%.

5. Ballast weight may not be acceptable for static

reasons

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ADVANTAGES AND DISADVANTAGES of

EXPANDED POLYSTYRENE FOAM

ADVANTAGES DISADVANTAGES

Has no impact on people´s health.

Expanded polystyrene insulation

installation is very easy.

Can be molded or any other way

shaped.

Waterproof and resistant against

all in water dissolvable stuff.

The foam polystyrene insulation is not resistant against organic solvents.

Cannot be used in combination with MPVC hydro-insulation foils.

Can cause irritation of the eyes, nose, and respiratory system; headache, fatigue, dizziness, confusion, drowsiness, weakness, unsteady gait; possible liver injury

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