Materials Science: Polymers and Vulcanization

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Questions and Answers

What is a primary use of polyester?

Garments for men, women, and children (correct)

Insulating wires

Damping in cosmetics

Conducting polymers

What is a characteristic feature of synthetic rubbers like SBR?

It cannot stretch beyond its original length

It stretches to at least twice its length and returns to original shape (correct)

It is made exclusively from natural resources

It is not suitable for making tyres

What type of adhesive is commonly used in laminated plastics?

Silicone resin

Polyethylene glycol

Urea-formaldehyde (correct)

Polyvinyl chloride

Which of the following materials can be blended with wool?

Polyester Signup and view all the answers

What is laminated glass used for?

Bulletproof applications Signup and view all the answers

Which conducting polymer type is involved in the manufacture of sensors?

Blended conducting polymer Signup and view all the answers

What is the primary characteristic of plywood?

Odd numbers of layers with alternating grain orientation Signup and view all the answers

In which application are conducting polymers NOT typically used?

Thermal insulation Signup and view all the answers

What is the primary purpose of vulcanization in rubber processing?

To improve the properties of natural rubber Signup and view all the answers

What type of polyethylene is produced using high pressure methods?

LDPE Signup and view all the answers

Which catalyst is used in the production of polypropylene?

Ziegler-Natta Catalyst Signup and view all the answers

What is a major application of polytetrafluoroethylene (TEFLON)?

Non-stick cookware coatings Signup and view all the answers

Which thermosetting polymer is commonly used as an insulator in the electrical industry?

Epoxy resin Signup and view all the answers

What is the primary component that reacts with acetylene to produce vinyl chloride?

Hydrochloric acid Signup and view all the answers

What is Terylene, also known as Dacron, primarily made from?

Ethylene glycol and terephthalic acid Signup and view all the answers

What characterizes polyurethanes in comparison to other thermoplastics?

They have a spongy, crosslinked structure Signup and view all the answers

Study Notes

Vulcanization of Rubber

Charles Goodyear discovered vulcanization in 1839.
Vulcanization improves the properties of natural rubber.

Thermoplastics

Polyethylene is a polymer of ethylene.
Ethylene is a colorless gas at room temperature.
It is prepared by dehydrating ethanol at 160°C using concentrated sulfuric acid.
Low-density polyethylene (LDPE) is produced using high-pressure methods (1050-2000 kgf/cm2) with free radical initiators.
High-density polyethylene (HDPE) is produced using low-pressure methods (31 kgf/cm2) with ionic catalysts.

Polypropylene

It is obtained by polymerizing propylene in the presence of Ziegler-Natta catalyst.
It is used for packaging pharmaceuticals and cosmetics, making sterilizable hospital equipment, washing machine parts, pipes, TVs, radios, molded luggage, and colorful furniture.

Polyvinyl Chloride (PVC)

Vinyl chloride is the monomer for PVC.
It is produced by direct addition of HCl to acetylene at 60-80°C.
It is one of the most widely used plastics.
PVC has high rigidity and chemical resistance but is brittle.
Its primary use is in making cables, water hoses, raincoats, and pipes for the petroleum industry.

Polytetrafluoroethylene (Teflon)

Obtained by polymerizing water-emulsion of tetrafluoroethylene under pressure and in the presence of benzoyl peroxide catalyst.
Non-stick cookware coatings are made of Teflon.
It is used for making gaskets, pump parts, tank linings, non-lubricating bearings, and non-reactive coatings.

Polyurethanes

These are crosslinked polymers made from a polyol and an isocyanate.
Used as insulating material in refrigerators.
Its spongy nature makes it suitable for pillows and mattresses.

Thermosetting Plastics

Epoxy Resins

They are obtained from the polycondensation of epichlorohydrin with polyphenols or polyalcohols.
Used as major constituents of adhesives in the paint industry and as insulators in the electrical industry.

Polyester

Terylene is the British name for Dacron, obtained by condensation of ethylene glycol and terephthalic acid.
Mostly used for making synthetic fibers for garments.
It can be blended with wool for carpets, blankets, upholsteries, and quilts.

Silicones

Have alternating silicon-oxygen bonds and organic radicals attached to silicon atoms.
Used as damping agents in cosmetics, silicone-glass laminates for high-temperature applications, etc.

Synthetic Rubbers

Artificially produced rubber-like polymers that stretch to at least twice their length and return to their original shape/size when released.
Styrene Butadiene Rubber (SBR) is similar in processing and finished product to natural rubber.
It is mainly used for manufacturing tires, soles and other components of shoes, insulating wires and cables, adhesives, and lining for vessels.

Miscellaneous Polymers

Laminates

Created by joining two or more layers of solid materials with an adhesive.

Plywood

Odd numbers of wood layers (0.5-10 mm thick) bonded with grains of alternate layers at right angles (cross-laminate).
Used for making railway coaches, cabinets, false ceilings, and other house building purposes.

Laminated Plastics

Paper, cloth, asbestos fiber, glass, metal, etc. are impregnated with thermosetting resin like phenol-formaldehyde or urea-formaldehyde solution in solvent.
Used for electrical and insulating materials, pump parts, etc.
Also used for decorative purposes on table tops and wall panels.

Laminated Glasses

Two glass sheets joined with a plastic sheet in between.
Polyvinyl-butyl resin can be used as an adhesive for transparency.
Bulletproof or splinter proof laminated glass is obtained by curing the laminates in an oven under heat and pressure.

Conducting Polymers

These are classified into:
- pi-electrons conducting polymer
- Conducting element-filled polymer
- Inorganic polymer
- Doped-conducting polymer
- Blended conducting polymer

Conducting Polymers Uses

Making:
- Button cells
- Photovoltaic devices
- Sensors
- Biomedical devices

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Description

This quiz covers key concepts related to the vulcanization of rubber, various thermoplastics, polypropylene, and polyvinyl chloride (PVC). You'll explore chemical processes, properties, and applications of these important materials. Test your knowledge on the discoveries and advancements in materials science.