Jordan University of Sciences & TechnologyEngineering Faculty

Chemical Engineering Department

A report on the

POLYMERS:

High Density POLYETYLENE PRODUCTION

Chemical Industries (CHE 521) course

Submitted By:

Abdulrahman Abdulkareem Ali 20072022009

Ibrahim Mousa Mahmoud Shana’ah 20090022062

Ahmad Fahmi Abdallah Jawabreh 20090022017

Osama Abd Al-Hafeez Hazaimeh 20070022112

TABLE OF CONTENTS

TABLE OF CONTENTS………………………………………………......II

List of figures …………………………………………………………… III

Summary ............................................................................1

Chapter One: Introduction Of polymer & polyethylene.......................2

Chapter two: High Density Polyethylene Industry………………..... 6

Chapter three: Process Technology: ……………………………….7

Chapter four: Production lines, Main reaction and a Flow sheet ………10

Chapter five: Safety Hazards of High density Polyethylene ……......... …13

Chapter six: Application of HDPE & Marketing …………………………….14

Recommendations: ………………………………………………15.

Conclusion………………………………………….. …………. 15

References……………………………………………………….16

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List of figures:

Figure (1): Pipes Made from Polyethylene .

Figure (2): Vessel reactor (Polymerization) .

Figure (3): Filtration plate

Figure (4): Drying air for polymerization process.

Figure (5): Ziegler-Natta polyethylene process.

Figure (6): Philips catalyst process.

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Summary:The main objective of this project is to discuss a polyethylene industry, from a raw

material through a process technology to a main reaction and the flow chart.

Finally a the safety Hazards have been discussed.

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Chapter1: Introduction:

1.1 : Definition of Polymer :

A polymer is a chemical compound or mixture of compounds consisting of repeating

structural units created from a monomer molecule that has a small molecular weight

through a process called polymerization .

Monomers is a molecule with small molecular weight that may bind chemically to

other molecule to form a polymer compound that has a high molecular weight. Such

as ethylene (C2H4) is a monomer with small molecular weight to form polymer called

polyethylene (C2H4)n H2 with high molecular weight .

A monomer molecule is classified into two main categories:

1-Homopolymer: is a polymer which is formed from only one type of monomer such

as ethylene to form a polymer Polyethylene.

2-Copolymer: is polymer contains at least two monomers such copolymers of ethylene and an alpha-olefin monomer such as 1-hexene, 1-butene or 1-octene.

Polymers are found in the world either natural such as wood, natural rubber, starch,

and cotton or synthetic like plastic and artificial rubber. Polymer are formed from its

monomer by two main reaction:

1-Addition polymer: An addition polymer is a polymer which is formed by an

addition reaction, where many monomers bond together via rearrangement of bonds

without the loss of any atom or molecules as shown below:

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2-Condensation Polymerization: are any kind of polymers formed through a condensation

reaction, where molecules join together losing small molecules as by-products such as water

or methanol.

.

Polymer product from their monomers and its usage are shown below in table

1:Table1.1: Polymer production from their monomers and its usage:

Name(s)FormulaMonomerPropertiesUsage

Polyethylenelow density (LDPE)

–(CH2-CH2)n–ethyleneCH2=CH2

soft, waxy solidfilm wrap, plastic bags

Polyethylenehigh density (HDPE)

–(CH2-CH2)n–ethyleneCH2=CH2

rigid, translucent solidelectrical insulationbottles, toys

Polypropylene(PP) different grades

–[CH2-CH(CH3)]n–propyleneCH2=CHCH3

atactic: soft, elastic solidisotactic: hard, strong solid

similar to LDPEcarpet, upholstery

Poly(vinyl chloride)(PVC)

–(CH2-CHCl)n–vinyl chlorideCH2=CHCl

strong rigid solidpipes, siding, flooring

Poly(vinylidene chloride)(Saran A)

–(CH2-CCl2)n–vinylidene chlorideCH2=CCl2

dense, high-melting solidseat covers, films

Polystyrene(PS)

–[CH2-CH(C6H5)]n–

styreneCH2=CHC6H5

hard, rigid, clear solidsoluble in organic solvents

toys, cabinetspackaging (foamed)

Polyacrylonitrile(PAN, Orlon, Acrilan)

–(CH2-CHCN)n–acrylonitrileCH2=CHCN

high-melting solidsoluble in organic solvents

rugs, blanketsclothing

Poly tetrafluoro ethylene(PTFE, Teflon)

–(CF2-CF2)n–tetrafluoroethyleneCF2=CF2

resistant, smooth solidnon-stick surfaceselectrical insulation

Poly(methyl methacrylate)(PMMA, Lucite, Plexiglas)

–[CH2-C(CH3)CO2CH3]n–

methyl methacrylateCH2=C(CH3)CO2CH3

hard, transparent solidlighting covers, signsskylights

Poly(vinyl acetate)(PVAc)

–(CH2-CHOCOCH3)n–

vinyl acetateCH2=CHOCOCH3

soft, sticky solidlatex paints, adhesives

1.2 : Definition of Polyethylene (C 2H4)n H2:

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It’s a common plastic manufacturing synthetically from an ethylene monomer

C2H4(gaseous hydrocarbons that comes from a petroleum or natural gas after a steam

cracking process)by a process called addition polymerization.

Polyethylene is a thermoplastic polymer (it’s a type of polymer that become pliable

and moldable at high temperature and return to a solid phase upon cooling).

Consisting of long hydrocarbon chains. Depending on the crystallinity and molecular

weight.

Figure1: Pipes Made from Polyethylene .

1.3: Classification of Polyethylene :

Polyethylene is classified into several different categories based mostly on its density

and branching:

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1-High Density Polyethylene(HDPE) :

Defined by a density of greater or equal to 0.941 g/cm3 . It has a low degree of

branching and thus low intermolecular forces and tensile strength. HDPE is used in

products and packaging such as milk jugs, detergent bottles, butter tubs, garbage

containers and water pipes. In 2007 the global HDPE consumption reached a volume

of more than 30 million tons.

2-Medium Density Polyethylene(LDPE):

It's defined by a density range of 0.926–0.940 g/cm3 . MDPE has good shock and drop

resistance properties. MDPE is typically used in gas pipes and fittings, sacks, shrink

film, packaging film .

3-Low Density Polyethylene (LDPE):

LDPE is defined by a density range of 0.910–0.940 g/cm3. It has a high degree of

short and long chain branching, which means that it chains do not pack into the crystal

structure as well and therefore less strong intermolecular forces and tensile strength.

LDPE is used for both rigid containers and plastic film applications such as plastic

bags. In 2009 the global LDPE market had a volume of circa US$22.2 billion (€15.9

billion.There are many other types of polyethylene but the previous types are more

common in industrial.

Chapter 2: High Density Polyethylene Industry:

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The first production of polyethylene was discovered in 1933 by ICI chemist,

Michael Perrin upon applying an extremely high pressure (several hundred

atmospheres) to a mixture of ethylene in a vessel reactor , this high-pressure

polymerization created polyethylene that called low density polyethylene(LDPE) with

many branches; these branches are created due to intermolecular and intramolecular

chain transfer during polymerization, because of high capital cost(equipment needed

to withstand high pressure) and operating cost(Power needed to increase a pressure up

to required pressure), a Ziegler(German scientist) was trying to create polyethylene at

atmospheric pressure and had made the greatest contribution to producing high-

density polyethylene. The production of high density polyethylene is very important

today because its use in packaging such as milk jugs , One third of all toys are

manufactured from HDPE and also it has a high resistance to the both strong acid and

base.

Chapter 3: Process Technology:

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3.1 :Main Raw materials:

High density polyethylene produced by a different process and the two most methods

are Ziegler-Natta Catalyst process and Philips process. The two previous methods are

different in type of the catalyst that used.

The basic raw material for two methods is ethylene (C2H4) monomer that comes from

cracking or burning a petroleum or natural gas. In Ziegler-Natta Catalyst process the

types of catalyst used are metals, one is called organometallic compound (titanium

tetrachloride(TiCl4) and the other is metal alkyl (aluminum triethyl). Beside a

hydrocarbons solvent(mainly CH4 ) , and also alcohol are used to deactivate a

catalyst.

In Philips process the type of catalyst is different and is used chromium oxide on a

high surface area on silica, and dry air in a drying process .

3.2 :Equipment used in Production of (HDPE):

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3.2.1-:Vessel reactor:

A vessel reactor was designed to contain chemical reactions, especially in this process

a vessel reactor has been used to achieve an active site that necessarily for

polymerization to occur by mixing an aluminum triethyl(methyl alkyl) with titanium

tetrachoride.

Figure(2): Vessel reactor (Polymerization)

3.2.2 :Decativation Catalyst vessel:

This type of reactor has been used to deactivate a polymer& especially in our process

to deactivate a polyethylene to be grown by using an alcohol solution

3.2.3 :Filtration: commonly the mechanical or physical operation which is used for the

separation of solids from fluids (liquids or gases) by interposing a medium through

which only the fluid can pass. Epically in this process a polyethylene is separated

from a slurry solution(Hydrocarbons solvent :CH4 plus metallic catalyst).

Figure( 3 ): Filtration plate

3.2.4:Drying:

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is a mass transfer process consisting of the removal of water or another solvent by

evaporation from a solid, semi-solid or liquid. This process is often used as a final

production step before selling or packaging products. A polymer is not dry it contains

a significant amount of methane solvent that required to be removed from it by

adding a dry air.

Figure ( 4): Drying air for polymerization process.

Chapter 4: Production lines , Main reaction and a Flow sheet

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The production of high density polyethylene from a Zigler process is shown below:

Figure( 5 ): Ziegler-Natta polyethylene process .

A brief description of the Ziegler process will be explained in the following

paragraph. First, the organometallic compound (i.e. titanium tetrachloride) is reacted

in a reaction vessel with a metal alkyl at a temperature between 100-130 degrees

Celsius in the presence of a solvent. The pressure of the reaction vessel is between

atmospheric and 20 atm. Ethylene is introduced into the reactor vessel in the gas

phase. The boiling point of ethylene is approximately –100 degrees Celsius. The

ethylene reacts with the active site of the catalyst to produce polyethylene. The

solvent is used to dissipate heat. The solvent must not vaporize or react with any of

the compounds in the reactor (inert solvent). The melting point of high-density

polyethylene is approximately 130 degrees Celsius. Therefore, the polyethylene

formed is in the solid phase. This type of polymerization is called slurry

polymerization or suspension polymerization. The slurry solution is passed to a

catalyst decomposition bed where the catalyst is deactivated to prevent a chain growth

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of polyethylene. Catalyst is not completely used in the polymerization process. So its

decomposition is achieved with the addition of an alcohol. Polyethylene is then

recovered from a slurry solution by filtration process, hydrocarbons (CH4 ) is recycled

to a polymerization process. Polyethylene is then entering a dryer column to remove

any moisture conent, finally it be processed and manufactured. The polyethylene

created by the Ziegler process has a molecular weight 20,000 and 1.5 million. The

molecular weight is controlled in a number of different ways: pressure of the reactor

vessel (higher pressure, less branches), temperature in preparation of catalyst (too

high of temperature deactivates catalyst), chain transfer reagents.

The other process for manufacturing of polyethylene is a Phillips process. The only

different between a Philips process and Zigler-Natta process is a type of catalyst has

been used. Phillips Petroleum utilizes a highly active catalyst, chromium oxide on

high-surface area silica, to produce high-density polyethylene. The active site for

polymerization, Cr-C bond, is achieved by reacting the catalyst with an olefin. The

olefin reduces the valence state of the transition-metal atoms, thus, making it more

reactive. The reaction mechanism is similar to the mechanism explained for the

Zeigler process. The mechanism is classified as anionic polymerization or "living"

polymerization. An alcohol was added to deactivate the catalyst. Many of the polymer

processes had in front of the main reactor a special reactor in which the catalyst

preparation took place and the viscosity, morphology, control was a very important

step. The use of a silica base eliminates this problem. The catalyst is very active and it

no longer needs to be removed because all of the catalyst is reacted with the monomer

ethylene. The active sites on the monomer are equally accessible to the monomer

throughout the particle. Therefore, the polymer chains grow not only outwards but

also inwards, causing the granule to expand progressively. The polymer particle will

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be a replica of the catalyst particle if the mechanical strength of the particle is high

enough. Because of the complexity and importance of the silica base catalyst, the

catalyst is often prepared in a separate production plant. The Phillips process is shown

below:

Figure(6 ): Philips process for production of HDPE

The Phillips process creates HDPE with fewer branches than the HDPE created by the Ziegler

process. The use of a silica based catalysts greatly reduces recovery and deactivation time.

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Chapter 5: Safety Hazards of High density Polyethylene

(HDPE) :

In general a release of chemicals associated with plastic products may occur in all phases of the life cycle during production, will affect the exposure for humans andthe environment. The physical chemical properties of these substances, e.g. boiling point, vapor pressure, water solubility, and octanol-water partition coefficient, can be used to predict the environmental fate. Especially in polyethylene (HDPE): Eye and skin contact :contact with HDPE or dust may cause irritation or corneal injury due to mechanical action (scratching). Vapor from the heated resin may cause mild discomfort and redness of the eyes. Prolonged skin contact is essentially nonirritating. These materials are often processed as molten polymers at elevated temperatures and skin contact with the heated material may cause burns.Inhalation – No adverse effects are anticipated from a single exposure to dust. Vapors or fumes released during thermal processing may cause respiratory irritation.Ingestion – These materials have very low toxicity if swallowed. However, the granules may represent a choking hazard. Finally the important thing in high density polyethylene is an environmentally conscious material in that it can be recycled, according to Waste Age. It will not compost or biodegrade, however, making it an environmental hazard if not recycled.

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Chapter 6: Application of HDPE&Marketing:

HDPE is Food and Drug Administration approved for use with all food products, reports Dynalab Corp. Common examples of food use include milk jugs, reusable water bottles and cutting boards.

major outlet for HDPE is in blow-moulding applications such as bottles for milk and other non-carbonated drinks, drums, fuel tanks for automobiles, toys and household goods. Because HDPE has good chemical resistance, it is used for packaging many household and industrial chemicals such as detergents, bleach and acids.

Also HDPE can be injection moulded into articles including crates, pallets, packaging containers and caps, household goods and toys. It can be extruded into pipes for water, natural gas and irrigation, corrugated pipe for drains and sewers, and conduit for electrical and telecommunication cables.

For Marketing:Global HDPE markets had been growing steadily at around 5%/year. Eastern and

Central Europe, South America, Asia Pacific, the Middle East and Africa have growth

rates higher than the global average with Asia Pacific having the highest growth in

terms of volume. However, this growth was abruptly halted by an unprecedented

demand crash in the second half of 2008 as a result of the credit crisis and its impact

on economic activity. With declining polymer prices exacerbated by falling feedstock

prices, purchasers withdrew from the market and inventories along the value chain

reduced significantly. This resulted in a fall in demand being far beyond that

anticipated by the economic downturn.

In 2009, global HDPE demand saw a weak recovery with demand growing by 1.1%

compared to 2008. Much of the recovery was driven by strong growth in China as a

result of the economic stimulus package. HDPE will recover growth in the next few

years as the industry restocks the inventory chain and the economic outlook improves.

Growth in the 2009-2015 period is 5.5%/year. Bimodal HDPE will continue to be the

focus for much of this growth based on an expanding product performance envelope

and the potential for single gas phase reactor production which would have lower

capital and production costs. While demand growth is expected to be heavily focussed

in China, Western Europe and North America will also see growth, which although

low in terms of growth rates, it will still be sizeable in terms of absolute demand

increment.

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Conclusion &Recommendation:

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References:

Websites:

WWW.WikiPedia.com

WWW.icis.com

WWW.Msdssearch.dow.com

Books:

Chemicals industrials process.

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