Slide 1

Polymers

• Introduction to polymers
• Definition of polymers
• Types of polymers
• Classification based on source
• Classification based on structure

Slide 2

Addition Polymers

• Definition of addition polymers
• Examples of addition polymers
  • Polyethylene
  • Polypropylene
  • Polyvinyl chloride (PVC)
  • Poly(acrylonitrile)
  • Polyethylene terephthalate (PET)

Slide 3

Condensation Polymers

• Definition of condensation polymers
• Examples of condensation polymers
  • Polyamides
  • Polyesters
  • Polycarbonates
  • Polyurethanes

Slide 4

Polymerization

• Definition of polymerization
• Types of polymerization
  • Addition polymerization
  • Condensation polymerization
• Steps involved in polymerization
  1. Initiation
  2. Propagation
  3. Termination

Slide 5

Monomers

• Definition of monomers
• Types of monomers
  • Homopolymerization
  • Copolymerization
• Examples of monomers
  • Ethylene
  • Vinyl chloride
  • Acrylonitrile
  • Glycol and terephthalic acid

Slide 6

Polymer Properties

• Physical properties
  • Melting point
  • Density
  • Solubility
  • Transparency
• Chemical properties
  • Reactivity
  • Stability
  • Flammability

Slide 7

Polymer Processing

• Extrusion
• Injection molding
• Blow molding
• Calendering
• Compression molding

Slide 8

Polymer Additives

• Plasticizers
• Stabilizers
• Flame retardants
• Colorants
• Fillers

Slide 9

Polymer Structure

• Linear polymers
• Branched polymers
• Cross-linked polymers
• Network polymers

Slide 10

Polymer Applications

• Plastics
• Elastomers
• Fibers
• Adhesives
• Coatings

Classification of Polymers

• Thermoplastics
  • Can be melted and re-molded multiple times
  • Examples: Polyethylene, Polypropylene
• Thermosetting plastics
  • Cannot be melted and re-molded once set
  • Examples: Melamine, Bakelite
• Elastomers
  • Exhibits high elasticity and can undergo large deformations
  • Examples: Natural rubber, Silicone rubber
• Fibers
  • Long and thin polymers with high tensile strength
  • Examples: Nylon, Polyester
• Biodegradable polymers
  • Capable of decomposing naturally in the environment
  • Examples: Polylactic acid (PLA), Polyhydroxyalkanoates (PHA)

Polymer Structure

• Polymer chains
  • Composed of repeating units called monomers
  • Example: Polyethylene – (-CH2-CH2-)n
• Covalent bonds
  • Provide strength and stability to the polymer structure
• Intermolecular forces
  • Van der Waals forces or hydrogen bonding between polymer chains
• Cross-linking
  • Formation of chemical bonds between polymer chains
• Copolymers
  • Combination of two or more different monomers in a polymer chain

Polymer Characterization Techniques

• Molecular weight determination
  • Gel permeation chromatography (GPC)
  • Viscometry
• Thermal analysis
  • Differential scanning calorimetry (DSC)
  • Thermogravimetric analysis (TGA)
• Spectroscopic techniques
  • Infrared spectroscopy (IR)
  • Nuclear magnetic resonance (NMR)
• Microscopy
  • Scanning electron microscopy (SEM)
  • Atomic force microscopy (AFM)
• Mechanical testing
  • Tensile strength
  • Young’s modulus

Polymer Degradation and Recycling

• Degradation mechanism
  • Thermal degradation
  • Photo degradation
  • Chemical degradation
• Factors affecting degradation
  • Temperature
  • Oxygen exposure
  • pH
• Recycling methods
  • Mechanical recycling
  • Chemical recycling
  • Energy recovery
• Importance of recycling
  • Reduce waste generation
  • Conservation of resources
  • Environmental sustainability

Polymer Crystallinity

• Crystalline polymers
  • Repeating units are closely packed in an ordered arrangement
  • Stronger and more rigid than amorphous polymers
  • Examples: Polyethylene, Polypropylene
• Amorphous polymers
  • Repeating units have no long-range order
  • Weaker and less rigid than crystalline polymers
  • Examples: Polystyrene, Polymethyl methacrylate (PMMA)
• Degree of crystallinity
  • Measure of the extent of crystalline regions in a polymer

Polymerization Techniques: Addition Polymerization

• Free radical initiation
  • Initiation: Formation of free radicals
  • Propagation: Growth of polymer chains through addition reactions
  • Termination: Combination or disproportionation of free radicals
• Examples of addition polymerization reactions
  • Ethylene polymerization to form polyethylene
  • Styrene polymerization to form polystyrene
  • Acrylonitrile polymerization to form polyacrylonitrile

Polymerization Techniques: Condensation Polymerization

• Formation of polymers by repeated condensation reactions
• Formation of by-products (water, alcohol, etc.)
• Examples of condensation polymerization reactions
  • Polyamide formation from adipic acid and hexamethylenediamine
  • Polyester formation from terephthalic acid and ethylene glycol
  • Polyurethane formation from isocyanates and polyols

Polymer Additives: Plasticizers

• Improve flexibility and workability of polymers
• Reduce glass transition temperature (Tg)
• Examples: Phthalates, adipates, citrates Polymer Additives: Stabilizers
• Prevent degradation of polymers by heat and UV radiation
• Examples: Hindered phenols, UV absorbers

Polymer Additives: Flame Retardants

• Reduce flammability of polymers and delay ignition
• Examples: Brominated flame retardants, phosphorous compounds Polymer Additives: Colorants
• Add color to polymers
• Examples: Pigments, dyes Polymer Additives: Fillers
• Improve strength, stiffness, and dimensional stability of polymers
• Examples: Glass fibers, carbon black, calcium carbonate

Polymer Applications: Plastics

• Packaging materials (bottles, containers)
• Automotive components
• Electronic devices
• Toys and sports equipment Polymer Applications: Elastomers
• Tires and rubber products
• Seals and gaskets
• Conveyor belts
• Elastic bands Polymer Applications: Fibers
• Clothing and textiles
• Carpets and rugs
• Industrial applications (ropes, nets)
• Composite materials

Polymer Applications: Adhesives

• Bonding materials together
• Examples: Epoxy adhesives, Cyanoacrylate adhesives Polymer Applications: Coatings
• Protective and decorative layers on surfaces
• Examples: Paints, Varnishes Polymer Applications: Biomaterials
• Medical implants and devices
• Drug delivery systems

Thermoplastics

• Can be melted and re-molded multiple times
• Examples:
  • Polyethylene: Used in packaging materials and containers
  • Polypropylene: Used in automotive components and household products Thermosetting Plastics
• Cannot be melted and re-molded once set
• Examples:
  • Melamine: Used in tableware and laminates
  • Bakelite: Used in electrical insulators and handles

Elastomers

• Exhibits high elasticity and can undergo large deformations
• Examples:
  • Natural rubber: Used in tires and rubber products
  • Silicone rubber: Used in seals and medical devices Fibers
• Long and thin polymers with high tensile strength
• Examples:
  • Nylon: Used in clothing and carpets
  • Polyester: Used in textiles and bottles

Biodegradable Polymers

• Capable of decomposing naturally in the environment
• Examples:
  • Polylactic acid (PLA): Used in packaging and disposable cutlery
  • Polyhydroxyalkanoates (PHA): Used in agricultural films and sutures Polymer Chains
• Composed of repeating units called monomers
• Example: Polyethylene – (-CH2-CH2-)n

Covalent Bonds

• Provide strength and stability to the polymer structure
• Formed by sharing of electrons between atoms Intermolecular Forces
• Van der Waals forces or hydrogen bonding between polymer chains
• Determines polymer properties such as solubility and mechanical strength

Cross-Linking

• Formation of chemical bonds between polymer chains
• Increases strength and rigidity of polymers
• Examples: Vulcanization of rubber, Cross-linking of epoxy resins Copolymers
• Combination of two or more different monomers in a polymer chain
• Example: Styrene-butadiene rubber (SBR)

Molecular Weight Determination

• Gel permeation chromatography (GPC)
• Viscometry Thermal Analysis
• Differential scanning calorimetry (DSC)
• Thermogravimetric analysis (TGA)

Spectroscopic Techniques

• Infrared spectroscopy (IR)
• Nuclear magnetic resonance (NMR) Microscopy
• Scanning electron microscopy (SEM)
• Atomic force microscopy (AFM)

Mechanical Testing

• Tensile strength
• Young’s modulus
• Impact resistance Polymer Degradation Mechanism
• Thermal degradation
• Photo degradation
• Chemical degradation

Factors Affecting Degradation

• Temperature
• Oxygen exposure
• pH Recycling Methods
• Mechanical recycling
• Chemical recycling
• Energy recovery