PolypropyleneSYED FIAZ HUSSAIN

Introduction, History, Production Process, Properties and Uses.

Definition Polypropylene is a100% synthetic fiber

which is transformed from 85% propylene. The monomer of polypropylene is propylene. Polypropylene is a by-product of petroleum.

History Phillips Petroleum chemists J. Paul Hogan and

Robert L. Banks first polymerized propylene in 1951.

Propylene was firstpolymerized to a crystallineisotactic polymer by Giulio Natta as well as by the Germanchemist Karl Rehn in March 1954.

This pioneering discovery led to large-scale commercial production of isotactic polypropylene by the Italian firm Montecatini from 1957 onwards.

History Syndiotactic polypropylene was also first

synthesized by Natta and his coworkers. Polypropylene is the second most

important plastic with revenues expected to exceed US$145 billion by 2019. The sales of this material are forecast to grow at a rate of 5.8% per year until 2021.

Structure Polypropylene (PP) is a thermoplastic. 

It is a linear structure based on the monomer CnH2n. It is manufactured from propylene gas in presence of a catalyst such as titanium chloride. Beside PP is a by-product of oil refining processes. 

Structure Most polypropylene used is highly

crystalline and geometrically regular (i.e. isotactic) opposite to amorphous thermoplastics, such as polystyrene, PVC, polyamide, etc., which radicals are placed randomly (i.e. atactic). 

Structure It is said that PP has an

intermediate level of crystallinity between lowdensity polyethylene (LDPE) and high densitypolyethylene (HDPE); Onthe other hand PP has higher working temperatures and tensile strength than polyethylene

Cross Section

Raw Material Poly (propene) is produced from propene.

Propene is produced in large quantities from gas oil, naphtha, ethane and propane.

Ziegler-Natta catalysts are used in the polymerization process. These are produced by interaction of titanium (IV) chloride and an aluminium alkyl, such as triethyl aluminium.

Making Of Polymer There are two methods to make the

polymer for the production of Polypropylene fiber:

› Gas Phase Process

› Liquid Phase Process

Making Of Polymer Gas Phase Process:

› Unipol®:PP A fluidized-bed process with one or two reactors for the production of PPnhomopolymers, random polymers and impact polymers.

Making Of Polymer

Making Of Polymer Gas Phase Process:

› Novolen®:A gas-phase stirred-bed process with two reactors in series for the production of PP.

Making Of Polymer Gas Phase Process:

› A mixture of propene and hydrogen is passed over a bed containing the Ziegler-Natta catalyst at temperatures of 320-360 K and a pressure of 8-35 atm.

› The polymer is separated from the gaseous propene and hydrogen using cyclones and the unreacted gas is recycled.

Making Of Polymer› Both processes can be operated

continuously and use 'stereo specific' Ziegler-Natta catalysts to effect the polymerization. The catalyst remains in the product and needs to be destroyed using water or alcohols, before the polymer is converted into pellets.

› Gas phase processes has virtually eliminated gaseous and aqueous effluents by the use of high activity catalysts, resulting in low residues in the final polymer.

Making Of Polymer Liquid Phase Process:

› Borstar®:PP A supercritical slurry process, which combines a loop reactor with gas phase reactor.

Making Of Polymer

Making Of Polymer Liquid Phase Process:

› Spheripol®:A slurry process for the production of PP homopolymer plus random copolymers.

Making Of Polymer Liquid Phase Process:

› In liquid-phase processes catalyst and polymer particles are suspended in an inert solvent, typically a light or heavy hydrocarbon.

› Super-critical slurry polymerization processes use supercritical propane as diluent.

Making Of Polymer Liquid Phase Process:

› Slurry processes run in loop reactors with the solvent circulating, stirred tank reactors with a high boiling solvent or a “liquid pool“ in which polymerization takes place in a boiling light solvent.

› A variety of catalysts can be used in these processes.

Making Of Polymer Liquid Phase Process:

› Processes in solution require, as their last step, the stripping of the solvent. Supercritical polymerization in the slurry loop provides advantages (e.g. higher productivity, improved product properties) over subcritical polymerization.

Making Of Polymer Liquid Phase Process:

› Advanced processes combine a loop reactor with one or two gas-phase reactors, placed in series, where the second stage of the reaction takes place in the gas-phase reactors. For bimodal polymers, lower molecular weights are formed in the loop reactor, while high molecular weights are formed in the gas-phase reactor.

MANUFACTURING PROCESS OF POLYPROPYLENE FIBER/FILAMENT

Processing

Processing› Polypropylene chips can be converted to

fiber/filament by traditional melt spinning. As an example, the staple fiber production is shown in the above figure.

› One or more spinning gear pumps receives the molten polymer and sends it through the spinning pack to homogenize the product, feed the spinning pack at a constant rate, and prevent fluctuation due to screw extruder.

Processing› Polymer formed is passing through the

filtering media to remove the impurities and other residues from it.

› Melt polymer is extruded through the jets of spinneret (a metal nozzle device having a number of holes in it for extrusion of polymer) and air is provided through oench duct and filament is formed which passes through the certain rollers, steaming bath for stretching or drawing. Filament fiber or yarn is also given crimps in the crimpers.

Processing› Filament fibers can be cut into 20 to 120

mm length depending on whether they are intended for cotton or woolen system.

› Spinning: the spinning pack consists of three parts-filters, distributor (which distributes the molten polymer over to die surface) and the die.

› Quenching: newly extruded filaments are cooled in a good “box" which will distribute 3 m3/min of cool air without damaging the filaments.

Processing› Finishing: to improve antistatic and

reduce abrasion.› Hot Stretching: to enhance the physico-

mechanical properties.› Crimping: to improve the bulk.› Thermosetting: it is a treatment in hot

air or steam that removes the internal stresses and relaxes fibers. The resultant fibers are heat-set with increased denier.

Processing

Polypropylene fibers are composed of crystalline and non-crystalline regions. The spherulites developed from a nucleus can range in size from fractions of a micrometer to centimeters in diameter. The a-axis of the crystal unit cell is aligned radially and the chain axis is homogeneously distributed in planes perpendicular to this radial direction.

FIBER STRUCTURE

FIBER STRUCTURE Each crystal is surrounded by non-crystalline

material. Fiber spinning and drawing may cause the orientation of both crystalline and amorphous regions. If the extension is less than 0.5%, the spherulite deformation is elastic and no disruption of the structure occurs, otherwise spherulites are highly oriented in the direction of the force and finally are converted to micro fibrils. These highly anisotropic microfibrillar structures lead to anisotropic fiber properties.

PHYSICAL PROPERTIES OF POLYPROPYLENE FIBER

  Tensile strength (g/den) 3.5 to 5.5

Elongation (%) 40 to 100

Abrasion resistance Good

Moisture absorption (%) 0 to 0.05

Softening point (ºC) 140

Melting point (ºC) 165

Chemical resistance Generally excellent

Relative density 0.91 g/cm3

Thermal conductivity 6.0 (with air as 1.0)

Electric insulation Excellent

Resistance to mildew, moth Excellent

Chemical Properties Effect of Acids

Excellent resistance to most acids except chlorosulphonic and concentrated sulfuric acid.

 Effect of AlkalisExcellent resistance with the exception of some oxidizing agents.

Effect of Bleaches and SolventsExcellent resistance. However, chlorinated hydrocarbons cause swelling at room temperature and dissolve polypropylene at 71 °C. and higher.

Organic SolventOrganic solvent does not cause harm during action.

Protection ability against lightIt looses energy in sunlight.

Protection ability against mild dewGood.

Protection ability against insects It does not get affected by insects.

DyesDifficult to dye polypropylene because its moisture regain is 0% . But pigment dye is possible .

Uses Polypropylene is a major polymer used

in nonwovens, with over 50% used for diapers or sanitary products

Other uses include filters for air, gas, and liquids. Such applications could be seen in the house as water filters or air-conditioning-type filters.

Pipe Connections

Filters Non Wovens

Uses The high surface area and

naturally oleophilicpolypropylene nonwovens are ideal absorbers of oil spills withthe familiar floating barriers near oil spills on rivers

Polypropylene is also used inwarm-weather clothing, whichtransports sweat away from the skin

Oil Absorber

Clothing

Uses Polypropylene has been used

in hernia and pelvic organ prolapse repair operations to protect the body from new hernias in the same location.

PP Chairs, sheets, bags are very important

Uses In the formation of colored ropes,

plastic products, gloves, clothing and non wovens.

Uses

Applications area of PP