Thermoplastics vs Thermosetting Plastics

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Questions and Answers

What primarily determines the conductivity of extrinsically conducting polymers?

Externally added ingredients (correct)

The molecular weight of the polymer

Intrinsic properties of the polymer itself

Presence of heat during processing

Which of the following is NOT a characteristic of conductive element filled polymers?

They are prone to high costs (correct)

They are lightweight and strong

They have good bulk conductivity

They can be in different shapes

What is an example of the size range that defines nanoparticles?

1 nanometer to 100 nanometers (correct)

1 micron to 10 microns

100 nanometers to 1000 nanometers

0.1 millimeter to 1 millimeter

What is a key advantage of blended conducting polymers?

Improved physical, chemical, and mechanical strength Signup and view all the answers

What is the approximate width defined as 1 nanometer in meters?

$10^{-9}$ m Signup and view all the answers

What type of compound is Bakelite classified as?

Thermosetting plastic Signup and view all the answers

Which property makes Bakelite susceptible to damage?

Presence of –OH groups Signup and view all the answers

Which of the following is NOT a use of Bakelite?

Pigments in paints Signup and view all the answers

What limits the use of conductive polymers?

Poor mechanical strength Signup and view all the answers

Which factor is NOT mentioned as affecting conductivity in polymers?

Thickness of the material Signup and view all the answers

Which type of conducting polymer involves a combination of two different polymers for enhanced properties?

Blended conducting polymers Signup and view all the answers

What is the role of a bifunctional linker in conductive polymers?

To connect dissimilar polymers Signup and view all the answers

What is a characteristic of intrinsically conducting polymers (ICP)?

They show conductivity without any additives. Signup and view all the answers

What is a characteristic of thermosetting resins compared to thermoplastics?

They retain their shape and structure after heating. Signup and view all the answers

Which of the following statements is true regarding ABS plastics?

ABS is opaque and amorphous. Signup and view all the answers

What happens to thermoplastics when subjected to heat or pressure?

They can be softened, reshaped, and reused. Signup and view all the answers

Which of the following is an example of a thermosetting resin?

Bakelite. Signup and view all the answers

What is a defining property of phenolic resins?

They contain strong bonds and cross-linking. Signup and view all the answers

Which application is NOT commonly associated with ABS plastics?

Electrical insulators for high voltage applications. Signup and view all the answers

What is a common feature of thermoplastics?

They can be reclaimed from waste. Signup and view all the answers

What is the role of Formaldehyde in the production of phenolic resins?

It reacts with phenol to form Monomethylnol phenol. Signup and view all the answers

What is the primary purpose of calcination in sol-gel processing?

To produce the final product from the gel Signup and view all the answers

What occurs during the hydrolysis step of sol-gel processing?

Release of alcohol Signup and view all the answers

Which of the following is NOT a disadvantage of sol-gel processing?

High temperatures required for synthesis Signup and view all the answers

If gels are aged for more than 7 days, what issue must be prevented?

Cracks in the gels Signup and view all the answers

What is a significant advantage of the sol-gel process over traditional ceramic methods?

Ability to synthesize ceramics at low temperatures Signup and view all the answers

Which properties distinguish quantum dots from metals?

They are semiconductors with a band gap energy of 3.4 eV. Signup and view all the answers

What is a fundamental characteristic of nanoparticles fabrication techniques?

They aim for uniform size distribution of particles. Signup and view all the answers

Which of the following is not a top-down approach in nanoparticles preparation?

Gas Condensation Processing Signup and view all the answers

What aspect should be identical in nanoparticles for effective applications?

Chemical composition and crystal structure Signup and view all the answers

What is a key advantage of the 'bottom-up' synthesis process over the 'top-down' approach?

It results in more economical production. Signup and view all the answers

Which milling technique is utilized for particle size reduction?

Mechanical milling Signup and view all the answers

Which characteristic is true regarding quantum dots?

They are hard and tough with high tensile strength. Signup and view all the answers

What type of nanoparticles does wet ball milling primarily produce?

Hard and brittle materials Signup and view all the answers

Which process would be least effective for creating nano-scale structures?

Bulk heating Signup and view all the answers

Which of the following is often associated with the properties of quantum dots?

Their colors change based on their size. Signup and view all the answers

Study Notes

Thermoplastics

Can be softened and reshaped by heating
Usually soft, weak, and less brittle
Can be reclaimed from waste
Usually soluble in some organic solvents
Examples: PVC, Teflon, ABS (Acrylonitrile Butadiene Styrene)

Thermosetting Resins

Retain shape and structure even when heated
Cannot be reshaped
Usually hard, strong, and brittle
Cannot be reclaimed from waste
Due to strong bonds and cross-linking, insoluble in almost all organic solvents
Examples: Phenolic resins (Novolac, Bakelite)

ABS Plastics (Acrylonitrile Butadiene Styrene)

Opaque, thermoplastic, amorphous polymer
Easily recycled and relatively non-toxic
Strong resistance to corrosive chemicals and physical impacts
Easy to mold
Low melting temperature, ideal for injection molding
Applications: Computer keys, power tool housing, wall sockets, LEGO toys, 3D printing, camera housings, protective housings

Thermosetting Plastics: Phenolic Resins (Phenoplasts) - Novolac and Bakelite

Condensation polymerization products of phenol derivatives and aldehydes
Phenol reacts with formaldehyde in the presence of acidic/alkaline catalysts to form monomethylnol phenol
Monomethylol phenol reacts with phenol to form a linear polymer called “Novolac”
Water is removed as a byproduct during Novolac formation
Further addition of HCHO at high temperature and pressure converts Novolac into cross-linked Bakelite
Bakelite is hard and insoluble

Bakelite

Resistant to acids, salts, and most organic solvents, but attacked by alkalis
Excellent electrical insulating property
Difficult to recycle
Applications: Plywood laminations, grinding wheels, paints, varnishes, electrical insulator parts (plugs, switches, heater handles), paper laminated products, thermally insulation foams

Conducting Polymers

Polymers, especially those with a conjugated p-bond structure, often show higher conductivity when doped with conductive materials
Limited use due to poor mechanical strength
Combining mechanical and electrical properties is crucial for applications
Bifunctional linkers can be doped to increase conductivity
Examples: Polyaniline (PANI) for conductivity and polycaprolactum (PCL) for mechanical strength
Applications: Antistatic and electromagnetic shielding

Mechanism of Conduction in Polymers

Conjugation of -electrons enhances conductivity
Undoped polymers are insulating
Doped polymers are conducting
Dopant anions (A-) provide charge neutrality

Types of Conducting Polymers

Intrinsically conducting polymers (ICP)
Doped conducting polymers
Extrinsically conducting polymers (ECP)

Factors Affecting Conductivity

Density of charge carriers
Their mobility
The direction of movement
Presence of doping materials (additives)
Temperature

Extrinsically Conducting Polymers

Conductivity due to presence of external ingredients
Two types:
- Conductive element filled polymer: Contains carbon black, metallic fibers, metal oxides etc., polymer acts as a binder, good for bulk conductivity
- Blended conducting polymers: Combination of a conventional polymer with a conducting polymer, good for physical, chemical, and mechanical strength

Nanomaterials

Entities with a width of a few nanometers to a few hundred, containing tens to thousands of atoms
Range of 1-100nm
One nanometer is a millionth part of the size of the tip of a needle (1nm = 10^-6 mm = 10^-9m
Examples: Proteins, DNA, inorganic nanoparticles

Categories of Nanomaterials

Carbon-based nanomaterials (fullerenes, carbon nanotubes, graphene)
Metal/metal oxide nanoparticles
Semiconductor quantum dots

Quantum Dots (QDs)

Semiconductor particles of a few nanometers
Quantum dots emit light when excited
Color of light emitted depends on the size of the quantum dot
Applications: Displays, solar cells, bioimaging

Quantum Dots vs. Gold Nanoparticles

Gold nanoparticles: Metallic, yellow in bulk, good conductors of heat and electricity, high density, high melting point, hard and tough, resistant to stretching and breakage, inert
Quantum dots: Semiconductors with a band gap energy of 3.4 eV, good catalysts, relatively low melting point,

Nanomaterial Synthesis Techniques

Top-down: High-energy ball milling, chemical oxidation, electrochemical oxidation, lithography, etching, coating, atomization
Bottom-up: Gas condensation processing, chemical vapor condensation, atomic/molecular condensation, laser ablation, supercritical fluid synthesis, wet chemical synthesis, precipitation, spinning, self-assembly, DNA origami

Advantages of Bottom-up Synthesis

Lower temperatures compared to traditional methods
Monosized nanoparticles possible

Disadvantages of Bottom-up Synthesis

Controlling particle growth and preventing agglomeration
Ensuring complete reaction and removal of unwanted reactants
Slow production rates

Sol-gel Processing

Hydrolysis and condensation of alkoxide-based precursors (e.g., TEOS)
Steps: Sol, gel, ageing, drying, dehydration, densification and decomposition
Controls particle size and shape
Calcination of gel produces the product
Advantages: Low temperature synthesis, monosized nanoparticles possible
Disadvantages: Controlling particle growth and preventing agglomeration, ensuring complete reaction and removal of unwanted reactants, slow production rates

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Description

This quiz explores the characteristics and applications of thermoplastics and thermosetting plastics. You will learn about different types like ABS and phenolic resins, their properties, and usage in various industries. Test your knowledge on plastic materials and their classifications!