Polypropylene

its all about poly propylene

1. POLYPROPYLENE PRESENTED BY : ASHFAK KAGZI

2. WHAT IS A POLYPROPYLENE ? Polypropylene (PP) is a linear hydrocarbon polymer. expressed as CnH2n. 

3. PP, like polyethylene and polybutene (PB), is a polyolefin or saturated polymer. Polypropylene is one of those most versatile polymers available with applications, both as a plastic and as a fibre, in virtually all of the plastics end-use markets.

4. Contents… Development Properties Chemical structure Manufacture Application

5. DEVELOPMENT Following work by zieglar in Germany, the process for producing “ stereo regular ” polymers was perfected by professor gulio natta in Italy. Natta produce the first poly propylene resin in spain in 1954. Natta utilised catalysts developed for the polyethylene industry and applied the technology to propylene gas.

6. These new polymers with their ability to crystallise soon became popular and polypropylene is now a very successful product in many areas. Type Product Moulding Automotive component s, sailing dinghies Etc. Fibres Carpet , balling twine , clothing, etc. Tape Replace d jute Film biaxially oriented film Foam Structural foam, and low density packaging

7. PROPERTIES The properties of polypropylene include.. Semi rigid Translucent Good chemical resistance Tough Good fatigue resistance Integral hinge property Good heat resistance

8. PP does not present stress cracking problems and offers excellent electrical and chemical resistance at higher temperatures.

9. CHEMICAL PROPERTIES Polypropylene at room temperature is resistant to fats and almost all organic  solvents apart from strong oxidants.   Non oxidizing agent  and  bases  can be stored in containers  made of PP . Most commercial polypropylene is  isotactic  and has an intermediate level of  crystallinty  between that of Low density Polyethylene  (LDPE) and  High density Polyethylene (HDPE ).

10. Isotactic & atactic polypropylene is soluble in P-xylene at 140 °C. Isotactic precipitates when the solution is cooled to 25 °C and atactic portion remains soluble in P-xylene . There are three general types of polypropylene :. 1) Homo polymer 2) Random Copolymer 3) Block copolymer

11. The  comonomer  is typically used with ethylene .   Ethylene-propylene rubber or  EPDM added to polypropylene homopolymer increases its low temperature impact strength . Randomly polymerized ethylene monomer added to polypropylene homopolymer decreases the polymer crystallinity, lowers the melting point and makes the polymer more transparent.

12. Tacticity : The term  Tacticity  describes for polypropylene how the methyl group is oriented in the polymer chain . Tacticity is differentiate in three group : 1) isotactic 2) syndiotactic 3) Actic

13. Isotactic : Syndiotactic :

14. Atactic

15. Manufacture Polypropylene is produced by the  chain-growth polymerization   of   propene

16. The industrial production processes can be grouped into gas phase polymerization   Bulk polymerization     slurry polymerization All state-of-the-art processes use either gas-phase or bulk reactor systems . In gas-phase and slurry-reactors, the polymer is formed around heterogeneous catalyst particles.

17. The gas-phase polymerization is carried out in a fluidized bed reactor , propene is passed over a bed containing the heterogeneous (solid) catalyst and the formed polymer is separated as a fine powder and than converted into pellets . Unreacted gas is recycled and fed back into the reactor.

18. in bulk polymerization, liquid propene acts as a solvent to prevent the precipitation of the polymer. The polymerization proceeds at 60 to 80 °C and 30-40 atm are applied to keep the propene in the liquid state. For the bulk polymerization, typically loop reactors are applied. The bulk polymerization is limited to a maximum of 5 % ethen as comonomer due to a limited solubility of the polymer in the liquid propene.

19. In the slurry polymerization, typically C4 - C6 alkanes ( butane ,   pentaneor   hexane ) are utilized as inert diluent to  suspend the growing polymer particles. Propene is introduced into the mixture as a gas.

20. Application

21. Advantage Low cost Excellent flexural strength Good impact strength Low coefficient of friction Excellent electrical insulation Good fatigue resistance Excellent moisture resistance Very good chemical resistance

22. Disadvantage It has a high thermal expansion coefficient which limits its high temperature applications. It is susceptible to UV degradation. It is known to be difficult to paint as it has poor bonding properties. It has a high flammability. It is susceptible to oxidation.