formation and uses of pvc and nylon

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1. Synthetic Polymers (PVC and Nylon) 22.5.2. Describe the formation and uses of PVC and nylon EHTISHAM UL HAQ

2. Formation of PVC The basic raw materials for PVC are derived from salt and oil.  Chlorine is manufactured by the electrolysis of sodium chloride, salt.  This is why the first PVC manufacturing plants were located close to natural sources of salt. The electrolysis of salt water produces chlorine. The chlorine is then combined with ethylene that has been obtained from oil .

3. Formation of PVC The resulting element is ethylene dichloride, which is converted at very high temperatures to vinyl chloride monomer .(VCM) These monomer molecules are polymerized forming polyvinyl chloride resin . For example rigid PVC like the one which is used in windows frames is normally PVCU (" unplasticized "). On the other hand flexible PVC is achieved by adding plasticizers such as phthalates . Furthermore, pure poly- chloroethene is unstable when exposed to visible light or UV. In order to modify this disadvantage and make it suitable for different applications antioxidants are added.

4. Formation of PVC First, the raw material VCM is pressurised and liquefied, and then fed into the polymerisation reactor, which contains water and suspending agents in advance. Through high-speed agitation within the reactor, small droplets of VCM are obtained. Next , the initiator for polymerisation is fed into the reactor, and PVC is produced by reaction under a few bar at 40 - 60°C. PVC obtained through suspension polymerisation is suspended in water as particles of 50~200 μm diameter (in slurry form).

5. Formation of PVC Thereafter the slurry discharged from the polymerization reactor is stripped of residual monomer, dehydrated, dried and the particle size controlled by screening to yield PVC in the form of a white powder. The un-reacted VCM is entirely recovered through the stripping process, and after purification, recycled as raw material for reuse in this process. PVC resin produced via this ‘suspension’ process is referred to within the industry using the abbreviation S-PVC.

6. Formation of PVC Emulsion polymerization and bulk polymerization are alternative, much less extensively employed, technologies to manufacture PVC. Emulsion polymerization produces finer resin grades having much smaller particles, which are required by certain applications. This type of resin is sometimes called ‘paste’ PVC and referred to within the industry using the abbreviation P-PVC to distinguish it from S-PVC.

7. Formation of PVC

8. Uses of PVC It is used: For sewerage pipes and other pipe applications where cost or vulnerability to corrosion limit the use of metal . For making window  and door frames.  In cabling applications as a wire insulator . To make vinyl records. More recent examples include wallcovering , greenhouses, home playgrounds, foam and other toys, custom truck toppers (tarpaulins), ceiling tiles and other kinds of interior cladding . Due to PVC piping being cheaper than metals used in musical instrument making, it is a common alternative when making instruments, often for leisure or for rarer instruments such as the contrabass flute.

9. Formation of Nylon Nylon 6,6: It is prepared by the condensation polymerization of hexamethylenediamine with adipic acid under high pressure and at high temperature.

10. Formation of Nylon Nylon 6: It is obtained by heating caprolactum with water at a high temperature.

11. Uses of Nylon Nylon 6,6 is used in: M aking sheets B ristles for brushes T extile industry. Nylon 6 is used for the manufacture of: Tyre cords F abrics R opes.