Polypropylene 1

Polypropylene

Polypropylene

Identifiers

CAS number 9003-07-0 [1] 

Properties

Molecular formula (C3H6)n

Density 0.855 g/cm3, amorphous0.946 g/cm3, crystalline

Melting point 130–171 °C (266–340 °F)

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)

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Infobox references

Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applicationsincluding packaging and labeling, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts andreusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymerbanknotes. An addition polymer made from the monomer propylene, it is rugged and unusually resistant to manychemical solvents, bases and acids.In 2008, the global market for polypropylene had a volume of 45.1 million metric tons, which led to a turnover ofabout $65 billion (~ €47.4 billion).

Chemical and physical properties

Micrograph of polypropylene

Most commercial polypropylene is isotactic and has an intermediatelevel of crystallinity between that of low-density polyethylene (LDPE)and high-density polyethylene (HDPE). Polypropylene is normallytough and flexible, especially when copolymerized with ethylene. Thisallows polypropylene to be used as an engineering plastic, competingwith materials such as ABS. Polypropylene is reasonably economical,and can be made translucent when uncolored but is not as readily madetransparent as polystyrene, acrylic, or certain other plastics. It is oftenopaque or colored using pigments. Polypropylene has good resistanceto fatigue. The melting point of polypropylene occurs at a range, so amelting point is determined by finding the highest temperature of adifferential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercialisotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on atactic material and

crystallinity. Syndiotactic PP with a crystallinity of 30% has a melting point of 130 °C (266 °F). The melt flow rate (MFR) or melt flow index (MFI) is a measure of molecular weight of polypropylene. The measure helps to

Polypropylene 2

determine how easily the molten raw material will flow during processing. Polypropylene with higher MFR will fillthe plastic mold more easily during the injection or blow-molding production process. As the melt flow increases,however, some physical properties, like impact strength, will decrease. There are three general types ofpolypropylene: homopolymer, random copolymer, and block copolymer. The comonomer is typically used withethylene. Ethylene-propylene rubber or EPDM added to polypropylene homopolymer increases its low temperatureimpact strength. Randomly polymerized ethylene monomer added to polypropylene homopolymer decreases thepolymer crystallinity and makes the polymer more transparent.

DegradationPolypropylene is liable to chain degradation from exposure to heat and UV radiation such as that present in sunlight.Oxidation usually occurs at the tertiary carbon atom present in every repeat unit. A free radical is formed here, andthen reacts further with oxygen, followed by chain scission to yield aldehydes and carboxylic acids. In externalapplications, it shows up as a network of fine cracks and crazes that become deeper and more severe with time ofexposure. For external applications, UV-absorbing additives must be used. Carbon black also provides someprotection from UV attack. The polymer can also be oxidized at high temperatures, a common problem duringmolding operations. Anti-oxidants are normally added to prevent polymer degradation. Microbial communitiesisolated from soil samples mixed with starch have been shown to be capable of degrading polypropylene.

HistoryPropylene was first polymerized to a crystalline isotactic polymer by Giulio Natta as well as by the German chemistKarl Rehn in March 1954. This pioneering discovery led to large-scale commercial production of isotacticpolypropylene by the Italian firm Montecatini from 1957 onwards.[3] Syndiotactic polypropylene was also firstsynthesized by Natta and his coworkers.Polypropylene is the second most important plastic with revenues expected to exceed US$145 billion by 2019. Thedemand for this material was growing at a rate of 4.4% per year between 2004 and 2012.[4]

Synthesis

Short segments of polypropylene, showing examples of isotactic (above) and syndiotactic(below) tacticity.

An important concept in understandingthe link between the structure ofpolypropylene and its properties istacticity. The relative orientation ofeach methyl group (CH3 in the figure) relative to the methylgroups in neighboring monomer unitshas a strong effect on the polymer'sability to form crystals.

A Ziegler-Natta catalyst is able to restrict linking of monomer molecules to a specific regular orientation, eitherisotactic, when all methyl groups are positioned at the same side with respect to the backbone of the polymer chain,or syndiotactic, when the positions of the methyl groups alternate. Commercially available isotactic polypropylene ismade with two types of Ziegler-Natta catalysts. The first group of the catalysts encompasses solid (mostly supported)catalysts and certain types of soluble metallocene catalysts. Such isotactic macromolecules coil into a helical shape;these helices then line up next to one another to form the crystals that give commercial isotactic polypropylene manyof its desirable properties.

Polypropylene 3

A ball-and-stick model of syndiotacticpolypropylene.

Another type of metallocene catalysts produce syndiotacticpolypropylene. These macromolecules also coil into helices (of adifferent type) and form crystalline materials.

When the methyl groups in a polypropylene chain exhibit no preferredorientation, the polymers are called atactic. Atactic polypropylene is anamorphous rubbery material. It can be produced commercially eitherwith a special type of supported Ziegler-Natta catalyst or with somemetallocene catalysts.Modern supported Ziegler-Natta catalysts developed for thepolymerization of propylene and other 1-alkenes to isotactic polymersusually use TiCl4 as an active ingredient and MgCl2 as a support.[5] The catalysts also contain organic modifiers, eitheraromatic acid esters and diesters or ethers. These catalysts are activatedwith special cocatalysts containing an organoaluminum compound such as Al(C2H5)3 and the second type of amodifier. The catalysts are differentiated depending on the procedure used for fashioning catalyst particles fromMgCl2 and depending on the type of organic modifiers employed during catalyst preparation and use inpolymerization reactions. Two most important technological characteristics of all the supported catalysts are highproductivity and a high fraction of the crystalline isotactic polymer they produce at 70–80 °C under standardpolymerization conditions. Commercial synthesis of isotactic polypropylene is usually carried out either in themedium of liquid propylene or in gas-phase reactors.

Commercial synthesis of syndiotactic polypropylene is carried out with the use of a special class of metallocenecatalysts. They employ bridged bis-metallocene complexes of the type bridge-(Cp1)(Cp2)ZrCl2 where the first Cpligand is the cyclopentadienyl group, the second Cp ligand is the fluorenyl group, and the bridge between the two Cpligands is -CH2-CH2-, >SiMe2, or >SiPh2.[6] These complexes are converted to polymerization catalysts byactivating them with a special organoaluminum cocatalyst, methylaluminoxane (MAO).[7]

Industrial processesTraditionally, three manufacturing process are the most representative ways to produce polypropylene.Hydrocarbon slurry or suspension: Uses a liquid inert hydrocarbon diluent in the reactor to facilitate transfer ofpropylene to the catalyst, the removal of heat from the system, the deactivation/removal of the catalyst as well asdissolving the atactic polymer. The range of grades that could be produced was very limited. (The technology hasfallen into disuse).Bulk (or bulk slurry): Uses liquid propylene instead of liquid inert hydrocarbon diluent. The polymer does notdissolve into a diluent, but rather rides on the liquid propylene. The formed polymer is withdrawn and any unreactedmonomer is flashed off.Gas phase: Uses gaseous propylene in contact with the solid catalyst, resulting in a fluidized-bed medium.

Polypropylene 4

ManufacturingMelt processing of polypropylene can be achieved via extrusion and molding. Common extrusion methods includeproduction of melt-blown and spun-bond fibers to form long rolls for future conversion into a wide range of usefulproducts, such as face masks, filters, diapers and wipes.The most common shaping technique is injection molding, which is used for parts such as cups, cutlery, vials, caps,containers, housewares, and automotive parts such as batteries. The related techniques of blow molding andinjection-stretch blow molding are also used, which involve both extrusion and molding.The large number of end-use applications for polypropylene are often possible because of the ability to tailor gradeswith specific molecular properties and additives during its manufacture. For example, antistatic additives can beadded to help polypropylene surfaces resist dust and dirt. Many physical finishing techniques can also be used onpolypropylene, such as machining. Surface treatments can be applied to polypropylene parts in order to promoteadhesion of printing ink and paints.

Biaxially oriented polypropylene (BOPP)When polypropylene film is extruded and stretched in both the machine direction and across machine direction it iscalled biaxially oriented polypropylene. Biaxial orientation increases strength and clarity.[8] BOPP is widely used asa packaging material for packaging products such as snack foods, fresh produce and confectionery. It is easy to coat,print and laminate to give the required appearance and properties for use as a packaging material. This process isnormally called converting. It is normally produced in large rolls which are slit on slitting machines into smaller rollsfor use on packaging machines.

Development trendsWith the increase in the level of performance required for polypropylene quality in recent years, a variety of ideasand contrivances have been integrated into the production process for polypropylene.[9]

There are roughly two directions for the specific methods. One is improvement of uniformity of the polymerparticles produced using a circulation type reactor, and the other is improvement in the uniformity among polymerparticles produced by using a reactor with a narrow retention time distribution.

Polypropylene 5

Applications

Polypropylene lid of a Tic Tacs box, with a livinghinge and the resin identification code under its

flap

As polypropylene is resistant to fatigue, most plastic living hinges,such as those on flip-top bottles, are made from this material.However, it is important to ensure that chain molecules are orientedacross the hinge to maximise strength.

Very thin sheets of polypropylene are used as a dielectric withincertain high-performance pulse and low-loss RF capacitors.

Polypropylene is used in the manufacturing piping systems; both onesconcerned with high-purity and ones designed for strength and rigidity(e.g. those intended for use in potable plumbing, hydronic heating andcooling, and reclaimed water).[10] This material is often chosen for itsresistance to corrosion and chemical leaching, its resilience againstmost forms of physical damage, including impact and freezing, itsenvironmental benefits, and its ability to be joined by heat fusion ratherthan gluing.[11][12][13]

A polypropylene chair

Many plastic items for medical or laboratory use can be made frompolypropylene because it can withstand the heat in an autoclave. Its heatresistance also enables it to be used as the manufacturing material ofconsumer-grade kettles[citation needed]. Food containers made from it will not meltin the dishwasher, and do not melt during industrial hot filling processes. For thisreason, most plastic tubs for dairy products are polypropylene sealed withaluminum foil (both heat-resistant materials). After the product has cooled, thetubs are often given lids made of a less heat-resistant material, such as LDPE orpolystyrene. Such containers provide a good hands-on example of the differencein modulus, since the rubbery (softer, more flexible) feeling of LDPE withrespect to polypropylene of the same thickness is readily apparent. Rugged,translucent, reusable plastic containers made in a wide variety of shapes andsizes for consumers from various companies such as Rubbermaid and Steriliteare commonly made of polypropylene, although the lids are often made ofsomewhat more flexible LDPE so they can snap on to the container to close it.

Polypropylene can also be made into disposable bottles to contain liquid, powdered, or similar consumer products,although HDPE and polyethylene terephthalate are commonly also used to make bottles. Plastic pails, car batteries,wastebaskets, pharmacy prescription bottles, cooler containers, dishes and pitchers are often made of polypropyleneor HDPE, both of which commonly have rather similar appearance, feel, and properties at ambient temperature.

A common application for polypropylene is as biaxially oriented polypropylene (BOPP). These BOPP sheets areused to make a wide variety of materials including clear bags. When polypropylene is biaxially oriented, it becomescrystal clear and serves as an excellent packaging material for artistic and retail products.Polypropylene, highly colorfast, is widely used in manufacturing carpets, rugs and mats to be used at home.[14]

Polypropylene is widely used in ropes, distinctive because they are light enough to float in water.[15] For equal mass and construction, polypropylene rope is similar in strength to polyester rope. Polypropylene costs less than most

Polypropylene 6

other synthetic fibers.Polypropylene is also used as an alternative to polyvinyl chloride (PVC) as insulation for electrical cables for LSZHcable in low-ventilation environments, primarily tunnels. This is because it emits less smoke and no toxic halogens,which may lead to production of acid in high-temperature conditions.Polypropylene is also used in particular roofing membranes as the waterproofing top layer of single-ply systems asopposed to modified-bit systems.Polypropylene is most commonly used for plastic moldings, wherein it is injected into a mold while molten, formingcomplex shapes at relatively low cost and high volume; examples include bottle tops, bottles, and fittings.It can also be produced in sheet form, widely used for the production of stationery folders, packaging, and storageboxes. The wide color range, durability, low cost, and resistance to dirt make it ideal as a protective cover for papersand other materials. It is used in Rubik's Cube stickers because of these characteristics.The availability of sheet polypropylene has provided an opportunity for the use of the material by designers. Thelight-weight, durable, and colorful plastic makes an ideal medium for the creation of light shades, and a number ofdesigns have been developed using interlocking sections to create elaborate designs.Polypropylene sheets are a popular choice for trading card collectors; these come with pockets (nine forstandard-size cards) for the cards to be inserted and are used to protect their condition and are meant to be stored in abinder.Expanded polypropylene (EPP) is a foam form of polypropylene. EPP has very good impact characteristics due to itslow stiffness; this allows EPP to resume its shape after impacts. EPP is extensively used in model aircraft and otherradio controlled vehicles by hobbyists. This is mainly due to its ability to absorb impacts, making this an idealmaterial for RC aircraft for beginners and amateurs.Polypropylene is used in the manufacture of loudspeaker drive units. Its use was pioneered by engineers at the BBCand the patent rights subsequently purchased by Mission Electronics for use in their Mission Freedom Loudspeakerand Mission 737 Renaissance loudspeaker.Polypropylene fibres are used as a concrete additive to increase strength and reduce cracking and spalling.Polypropylene is used in polypropylene drums.

ClothingPolypropylene is a major polymer used in nonwovens, with over 50% used[citation needed] for diapers or sanitaryproducts where it is treated to absorb water (hydrophilic) rather than naturally repelling water (hydrophobic). Otherinteresting non-woven uses include filters for air, gas, and liquids in which the fibers can be formed into sheets orwebs that can be pleated to form cartridges or layers that filter in various efficiencies in the 0.5 to 30 micrometrerange. Such applications could be seen in the house as water filters or air-conditioning-type filters. The high surfacearea and naturally oleophilic polypropylene nonwovens are ideal absorbers of oil spills with the familiar floatingbarriers near oil spills on rivers.Polypropylene, or 'polypro', has been used for the fabrication of cold-weather base layers, such as long-sleeve shirtsor long underwear. Polypropylene is also used in warm-weather clothing, which transports sweat away from the skin.More recently, polyester has replaced polypropylene in these applications in the U.S. military, such as in theECWCS.[16] Although polypropylene clothes are not easily flammable, they can melt, which may result in severeburns if the service member is involved in an explosion or fire of any kind.[17] Polypropylene undergarments areknown for retaining body odors which are then difficult to remove. The current generation of polyester does not havethis disadvantage.[18]

Thanks to its specific weight, polypropylene yarn is the lightest fibre of all synthetic and natural fibers. Producersgain economic and ecological advantages when producing fabrics and clothes out of polypropylene yarn. Final usersgain more comfort because the garments are lighter. This enables them to give better performance during their

Polypropylene 7

activities and gives them the freedom of movement. For example, If they hike, they have less weight to carry.Polypropylene yarn has very good insulation properties. Its water absorption is almost nil. Fabric made ofpolypropylene yarn transports humidity to the outside or to another absorbent layer from where it graduallyevaporates.The material has recently been introduced into the fashion industry through the work of designers such as AnoushWaddington, who have developed specialized techniques to create jewelry and wearable items from polypropylene.

MedicalIts most common medical use is in the synthetic, nonabsorbable suture Prolene, manufactured by Ethicon Inc.Polypropylene has been used in hernia and pelvic organ prolapse repair operations to protect the body from newhernias in the same location. A small patch of the material is placed over the spot of the hernia, below the skin, andis painless and rarely, if ever, rejected by the body. However, a polypropylene mesh will erode over the uncertainperiod from days to years. Therefore, the FDA has issued several warnings on the use of polypropylene meshmedical kits for certain applications in pelvic organ prolapse, specifically when introduced in close proximity to thevaginal wall due to a continued increase in number of mesh erosions reported by patients over the past few years.[19]

Most recently, on 3 January 2012, the FDA ordered 35 manufacturers of these mesh products to study the sideeffects of these devices.

EPP toy aircraftSince 2001, expanded polypropylene (EPP) foams have been gaining in popularity and in application as a structuralmaterial in hobbyist radio control model aircraft. Unlike expanded polystyrene foam (EPS) which is friable andbreaks easily on impact, EPP foam is able to absorb kinetic impacts very well without breaking, retains its originalshape, and exhibits memory form characteristics which allow it to return to its original shape in a short amount oftime. In consequence, a radio-control model whose wings and fuselage are constructed from EPP foam is extremelyresilient, and able to absorb impacts that would result in complete destruction of models made from lightertraditional materials, such as balsa or even EPS foams. EPP models, when covered with inexpensive fibreglassimpregnated self-adhesive tapes, often exhibit much increased mechanical strength, in conjunction with a lightnessand surface finish that rival those of models of the aforementioned types. EPP is also chemically highly inert,permitting the use of a wide variety of different adhesives. EPP can be heat molded, and surfaces can be easilyfinished with the use of cutting tools and abrasive papers. The principal areas of model making in which EPP hasfound great acceptance are the fields of:•• Wind-driven slope soarers•• Indoor electric powered profile electric models•• Hand launched gliders for small childrenIn the field of slope soaring, EPP has found greatest favour and use, as it permits the construction of radio-controlledmodel gliders of great strength and maneuverability. In consequence, the disciplines of slope combat (the activeprocess of friendly competitors attempting to knock each other's planes out of the air by direct contact) and slopepylon racing have become commonplace, in direct consequence of the strength characteristics of the material EPP.

Polypropylene 8

Recycling

Polypropylene is recyclable and has the number "5" as its resin identification code:[20]

RepairingMany objects are made with polypropylene precisely because it is resilient and resistant to most solvents and glues.Also, there are very few glues available specifically for gluing PP. However, solid PP objects not subject to undueflexing can be satisfactorily joined with a two part epoxy glue or using hot-glue guns. Preparation is important and itis often helpful to roughen the surface with a file, emery paper or other abrasive material to provide better anchoragefor the glue. Also it is recommended to clean with mineral spirits or similar alcohol prior to gluing to remove anyoils or other contamination. Some experimentation may be required. There are also some industrial glues availablefor PP, but these can be difficult to find, especially in a retail store.[citation needed]

PP can be melted using a speed welding technique. With speed welding, the plastic welder, similar to a solderingiron in appearance and wattage, is fitted with a feed tube for the plastic weld rod. The speed tip heats the rod and thesubstrate, while at the same time it presses the molten weld rod into position. A bead of softened plastic is laid intothe joint, and the parts and weld rod fuse. With polypropylene, the melted welding rod must be "mixed" with thesemi-melted base material being fabricated or repaired. A speed tip "gun" is essentially a soldering iron with a broad,flat tip that can be used to melt the weld joint and filler material to create a bond.

Health concernsIn 2008, researchers in Canada asserted that quaternary ammonium biocides and oleamide were leaking out ofcertain polypropylene labware, affecting experimental results.[21] As polypropylene is used in a wide number of foodcontainers such as those for yogurt, Health Canada media spokesman Paul Duchesne, said the department will bereviewing the findings to determine whether steps are needed to protect consumers.[22]

The Environmental Working Group classifies PP as of low to moderate hazard.[23] PP is dope-dyed, no water is usedof its dyeing in comparison for example with cotton.[24]

References[1] http:/ / www. commonchemistry. org/ ChemicalDetail. aspx?ref=9003-07-0[2] http:/ / en. wikipedia. org/ w/ index. php?title=Special:ComparePages& rev1=477171874& page2=Polypropylene[3] This week 50 years ago (http:/ / www. newscientist. com/ article/ mg19426014. 900-this-week-50-years-ago. html) in New Scientist 28 April

2007, p. 15[4] Market Study: Polypropylene – 2nd edition (UC-4205) (http:/ / www. ceresana. com/ en/ market-studies/ plastics/ polypropylene). Ceresana

Research.[5] Moore, E. P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers:

New York, ISBN 1569902089[6] Benedikt, G. M. and Goodall, B. L. (eds.) (1998) Metallocene Catalyzed Polymers, ChemTech Publishing: Toronto. ISBN

978-1-884207-59-4.[7] Sinn, H.; Kaminsky, W. and Höker, H. (eds.) (1995) Alumoxanes, Macromol. Symp. 97, Huttig & Wepf: Heidelberg.[8] Biaxially Oriented Polypropylene Films (http:/ / www. granwell. com/ bopp/ ). Granwell. Retrieved: 2012-05-31.[9] Sato, Hideki and Ogawa, Hiroyuki (2009) Review on Development of Polypropylene Manufacturing Process (http:/ / www. sumitomo-chem.

co. jp/ english/ rd/ report/ theses/ docs/ 20090201_6jw. pdf), Sumitomo Kagaku.[10][10] ASTM Standard F2389, 2007, "Standard Specification for Pressure-rated Polypropylene (PP) Piping Systems", ASTM International, West

Conshohocken, PA, 2007, , www.astm.org.[11] Green pipe helps miners remove the black (http:/ / contractormag. com/ news/ green-pipe-mine-2345) Contractor Magazine, 10 January

2010[12] Contractor Retrofits His Business (http:/ / www. achrnews. com/ Articles/ Feature_Article/

BNP_GUID_9-5-2006_A_10000000000000690490). the News/ 2 November 2009.

Polypropylene 9

[13] What to do when the piping replacement needs a replacement? (http:/ / www. esmagazine. com/ Articles/ Case_In_Point/BNP_GUID_9-5-2006_A_10000000000000691766) Engineered Systems. 1 November 2009.

[14] Rug fibers (http:/ / www. fibersource. com/ f-tutor/ olefin. htm). Fibersource.com. Retrieved on 2012-05-31.[15] Braided Polypropylene Rope is Inexpensive and it Floats (http:/ / www. contractorsrope. com/ braided-polypropylene-rope. html).

contractorrope.com. Retrieved on 2013-02-28.[16] Generation III Extended Cold Weather Clothing System (ECWCS) (http:/ / web. archive. org/ web/ 20081217143906/ http:/ / peosoldier.

army. mil/ factsheets/ SEQ_CIE_ECWCS. pdf). PM Soldier Equipment. October 2008[17] USAF Flying Magazine. Safety. Nov. 2002 (http:/ / permanent. access. gpo. gov/ lps11992/ 2002/ fsmnov02. pdf). access.gpo.gov[18] Ellis, David. Get Real: The true story of performance next to skin fabrics (http:/ / web. archive. org/ web/ 20100602092559/ http:/ / www.

outdoorsnz. org. nz/ cms_show_download. php?id=168). outdoorsnz.org.nz[19] FDA Public Health Notification: Serious Complications Associated with Transvaginal Placement of Surgical Mesh in Repair of Pelvic

Organ Prolapse and Stress Urinary Incontinence (http:/ / www. fda. gov/ MedicalDevices/ Safety/ AlertsandNotices/PublicHealthNotifications/ ucm061976. htm), FDA, 20 October 2008

[20] Plastics recycling information sheet (http:/ / www. wasteonline. org. uk/ resources/ InformationSheets/ Plastics. htm), Waste Online[21] Plastic additives leach into medical experiments, research shows (http:/ / www. physorg. com/ news145545554. html), Physorg.com, 10

November 2008[22] Scientific tests skewed by leaching plastics (http:/ / www. canada. com/ chilliwacktimes/ story.

html?id=be27d48b-ef01-4e78-b2bf-c108801884c2), November 6, 2008.[23] POLYPROPYLENE || Skin Deep® Cosmetics Database | Environmental Working Group (http:/ / www. cosmeticdatabase. com/ ingredient.

php?ingred06=705094). Cosmeticdatabase.com. Retrieved on 2012-05-31.[24] Chapagain, A.K. et al. (September 2005) The water footprint of cotton consumption (http:/ / www. waterfootprint. org/ Reports/ Report18.

pdf). UNESCO-IHE Delft. Value of Water Research Report Series No. 18. waterfootprint.org

External links• Chain structure of Polypropylene (http:/ / www. pslc. ws/ mactest/ pp. htm)• Polypropylene on Plastipedia (http:/ / www. bpf. co. uk/ plastipedia/ polymers/ pp. aspx)

Article Sources and Contributors 10

Article Sources and ContributorsPolypropylene  Source: http://en.wikipedia.org/w/index.php?oldid=605590738  Contributors: 4n5 6n6, 7e7, 7infinity, 97198, AKGhetto, AThing, Aboalbiss, Abraaoemelquisedeque,AgentPeppermint, Ahoerstemeier, Ajraddatz, Akawhite, Alan Liefting, Albmont, Alex Rio Brazil, Alex.muller, Alphamuchi, Alynna Kasmira, AmolKoldhekar, Ank329, Ankerman101,Antandrus, Appeltree1, Astronautics, AxelBoldt, Bartledan, Bass747, Beetstra, BenFrantzDale, Bentogoa, Bert Hickman, Bert63, Best name, Bigfoamcow, Biiillyboy, Biopresto, Bishop610,Blackboxxx, Bluemere2, Bmk, Boing! said Zebedee, Bonbonbub6, Borgx, Bpeps, BrentN, Brianhe, Brijeshhsejirb, Brzydalski, Btball, CLW, Capnned, Casty, Cbritland, CensoredScribe, CharlesBrooking, ChaseAm, Chasingsol, Chem-awb, ChemGardener, ChemNerd, Chimpex, Chris Bainbridge, Chris the speller, ChrisGualtieri, Christian75, Clarince63, ClockworkSoul, Cmgoogin,CoolMike, Cornerstp, Courcelles, CrazyChemGuy, Cwcltd, DMacks, DVD R W, DanMatan, Dana boomer, DanielBeaver, Daniele Pugliesi, Dave3457, David Gale, Deepshark5, DennyColt,DerHexer, Dforest, Doctorfluffy, Dougher, Dr guywalker, Drphilharmonic, Dudecon, Duk, Dynalab, EchoBravo, Edgar181, Eldudus, Electron9, Elemented9, Elkman, Enquire, Enviroboy, EricKvaalen, Excirial, Exhilaration157, Fehrgo, Fezmeistr, Fibonacci, Finlay McWalter, Flat Out, Flewis, Foobar, Fraggle81, Frpcad, Fæ, Gene Nygaard, Giftlite, Giraffedata, Glenn, GoShow,Gobeirne, Gregh, Grunt, Gwizi, Gökhan, Götz, H Padleckas, Hadal, HappyCamper, Hgilbert, Hgrosser, Hignatz, Hopkapi, Horkana, Hroðulf, I80and, IP9191, Ilmari Karonen, Imoen, Infrangible,Ionutzmovie, Ixfd64, J.delanoy, Jabbsworth, Jamieswihart, Jauerback, Jawaharcompany, Jcw69, Jerryscuba, Jesterbard, Jjordahl, Jmh649, JohnOwens, JohnSRoberts99, JonRichfield, JorisvS,Jpt262, Jrcla2, Jsaxin, Jyngyr, Karol Langner, Kate, KeawBeer, Keith Edkins, Keobeer5, Kuru, Lamro, LarryMorseDCOhio, Leedeth, Lemonus', Leyo, Libstooge 01, LittleDan, LittleOldMe old,Lordmwa, Luna Santin, M.Ebner, M1ss1ontomars2k4, MC10, MER-C, Mankarse, Marshalldunn, Master Jay, Master of Puppets, Materialscientist, Matrix61312, Matthew Kornya, Maximus Rex,Maxis ftw, McDutchie, Mdann52, Mendaliv, Mermaid from the Baltic Sea, Merope, Mesoderm, Michi zh, Mike Rosoft, Minimac, Mintleaf, Mipadi, MissMJ, Mogism, Mojoworker, Mrlennart,Mubashar88, Murry1975, Naerii, Neparis, Nicolar71, Nlu, Nposs, Nuggetboy, Number 8, Nutriveg, Nv8200p, Ofem, Olsonist, PJueckstock, PMLawrence, Paul August, Pbznyyankeez, Peak,Peterlewis, Pevernagie, Philip Trueman, Playa Shark, Podzemnik, Polyparadigm, Pontificalibus, PrincessofLlyr, Prolen, Prolog, Prometheanized, Rafael.japiassu, Raghith, Range,Raremetalmining, RazorICE, RexNL, Rhetth, RicHard-59, Rich Farmbrough, Richard Taytor, Rifleman 82, Rjensen, Rjwilmsi, Rlsheehan, Rob Hooft, Ronz, Roux, RyanCross, Samw,Sander123, Securiger, Shaddack, Shadowjams, Shootbamboo, Shyran, SirThomasGriffin, Slakr, Songriter en, Sowff, Srleffler, Stephenb, StradivariusTV, Subhadeep1908, THEN WHO WASPHONE?, Tassedethe, Telecomboy, Templew, Tentinator, Tgrudo, The chemistds, TheCardinal, TheKMan, Thelvyn, Thomas Linton, Tickettofly, TigerShark, Tobin Richard, Tolly4bolly,Tyhgbnswderf, Tyrael123, Unara, Unbound, User7984, V8rik, VX, Vina, Wameya, WatchAndObserve, Wavelength, West London Dweller, Wikfr, Wikieditor06, William919191, Wizard191,Wkltan, Wmahan, Wrdc, WriterHound, Writeswift, Yamamoto Ichiro, Ykissin, Zephyric, Ziounclesi, Zro, Zzuuzz, 529 ,יורם שורק anonymous edits

Image Sources, Licenses and ContributorsFile:Polypropylen.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Polypropylen.svg  License: Public Domain  Contributors: NEUROtikerFile:Yes check.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Yes_check.svg  License: Public Domain  Contributors: AnomieFile:X mark.svg  Source: http://en.wikipedia.org/w/index.php?title=File:X_mark.svg  License: Public Domain  Contributors: User:GmaxwellImage:Polypropene migrograph.png  Source: http://en.wikipedia.org/w/index.php?title=File:Polypropene_migrograph.png  License: Public domain  Contributors: UnboundImage:Polypropylene tacticity.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Polypropylene_tacticity.svg  License: Creative Commons Attribution-Sharealike 3.0  Contributors:User:RicHard-59Image:Syndiotactic polypropene.png  Source: http://en.wikipedia.org/w/index.php?title=File:Syndiotactic_polypropene.png  License: Public Domain  Contributors: User:Ilmari KaronenImage:Mint box polypropylene lid.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Mint_box_polypropylene_lid.JPG  License: Public domain  Contributors: Andy Dingley, FrankC. Müller, Ingolfson, Polyparadigm, Vanischenu, Waldir, ZureksImage:Red Polypropylene Chair with Stainless Steel Structure.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Red_Polypropylene_Chair_with_Stainless_Steel_Structure.JPG License: Creative Commons Attribution-Sharealike 3.0  Contributors: Alex Rio BrazilImage:Resin-identification-code-5-PP.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Resin-identification-code-5-PP.svg  License: Public Domain  Contributors: TotoBaggins (talk)(Uploads)

LicenseCreative Commons Attribution-Share Alike 3.0//creativecommons.org/licenses/by-sa/3.0/