engineering plastics 1

8/8/2019 Engineering Plastics 1

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Engineering Plastics

(Contd)


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Polyurethanes (Perlon U)

n O=C=N-(CH 2)6-N=C=O + n HO-(CH 2)4-OH1,6 hexamethylene 1,4 butane diol

di-isocyanate

O O- C-NH-(CH 2)6-NH-C-O-(CH 2)4-O -

Polyurethane (Perlon U)


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Polyurethanes - Properties1. It possesses excellent flexibility even at sub-zero

temperature2. It is less stable than polyamides

3. It is easily affected by moisture. Any moisture present reacts with the diisocyanate to producean unstable intermediate

4. It is characterised by excellent resistance toabrasion and solvents

5. These may be cast to produce gaskets, seals and printing rolls


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Polyurethanes - Uses

Polyurethanes are used as coatings, films,foams, adhesives and elastomersThey are used to produce gaskets and seals

They are used in defence, oceanographicresearch, mountaineering, plastic foam (ex. coir foam, thermocole, etc.)Resilient polyurethane fibres (spandex) are usedfor foundation garments and swim suitsThey also find use as a leather substitute(corfam)


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Applications of Polyurethane


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Applications of Polyurethane


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Polyurethane being used as an insulator in house construction


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Polyurethane used as Flooring solution


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Industrial polyurethane application


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Polyester - Polyethylene terephthalate (PET) - Preparation


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Polyethylene Terephthalate - Properties

1. It has a symmetrical structure and can beconverted into fibres

2. It is a good fibre-forming material and isconverted into commercial fibres3. The fibres possess high stretch-resistance and

wrinkle-resistance4. It is highly resistant to mineral and organic

acids, but is less resistant to alkalis


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Polyethylene Terephthalate - Uses1. It is used for making synthetic fibres like

terylene, dacron, etc.

2. It is used for blending with wool to impart better wrinkle resistance

3. It is used as glass reinforcing material in safetyhelmets, aircrafts, battery boxes, etc.

4. PET is highly resistant to mineral and organicacids, but is less resistant alkalis.


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Applications of PET


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Preparation of Nylon 6


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Preparation of Nylon 6,6


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N ylon 6 and N ylon 6 6 - Preparation


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Nylon 11 - Preparation

n H 2 N (CH 2)10 COOH ( N (CH 2)10 C ) nS elf condensation

H O

[ - A mino undecanoic acid Nylon 11


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Polyamides (Nylon) - Properties1. Nylons are translucent, whitest and high

melting polymers2. They possess high temperature stability

and good abrasion-resistance3. They are insoluble in common organic

solvents and soluble in phenol and formicacid

4. Nylon can be sterilized with steam or boiling water, so it is suitable for manymedical applications.


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Polyamides (Nylon) - Uses1. Nylons are used for making filaments for

ropes, bristles for tooth-brushes and films,tyre cords, etc.

2. Nylon 6 and Nylone 11 are mainlyused for moulding purposes for gears,

bearings, electrical mounting etc.

3. Nylon 6 6 is used for fibres, which is usedin making socks, dresses, carpets, etc.4. It used in making rollers, textile

machineries


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-form.

Mechanical,


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Applications of Nylon


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Free radical mechanism Addition polymerisation


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Poly styrene


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S tructure of Polythene


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S tructure of Polythene


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S tructure of Polyvinyl Chloride

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