all ppts chem

POLYMERIC MATERIALS Overview

  • Presented by Micko Galicia, Amir Garcia, Angelito Felizardo, Louis Joya

Introduction to Polymers

  • Polymers are large molecules formed from hundreds of monomers.

  • The term "polymer" derives from Greek: "poly" means many, and "mer" means part.

  • All plastics are polymers, but not all polymers are plastics.

Types of Polymers

1. Natural Polymers

  • Occur in nature and are often water-based.

  • Examples: Silk, wool, DNA, cellulose, proteins.

2. Homopolymers

  • Made of identical repeating units of a single type of monomer.

  • Formed through addition polymerization.

3. Copolymers

  • Made from two or more different types of monomers.

  • Created through copolymerization.

Types of Copolymers:

  • Statistical Copolymer

  • Alternating Copolymer

  • Block Copolymer

  • Graft Copolymer

4. Thermoplastics

  • Can be softened by heating and reshaped.

  • Processing methods: Extrusion, injection molding, thermoforming, blow molding.

5. Thermosetting Polymers

  • Become permanently hard when heated or cured.

  • Cannot be softened again after setting.

6. Long Chain Polymers

  • Large molecules with repeating monomers in a continuous chain.

  • Properties depend on monomer type, bonding, and chain arrangement.

Classification of Polymers by Origin

1. Natural Polymers

  • Found in nature (e.g., proteins, cellulose).

2. Semi-Synthetic Polymers

  • Modified natural polymers (e.g., rayon).

3. Synthetic Polymers

  • Fully artificial, produced in labs (e.g., plastics).

Classification by Structure

1. Linear Polymers

  • Repeating units in a straight line.

2. Branched Chain Polymers

  • Linear with side chains.

3. Cross-Linked Polymers

  • Chains connected by covalent bonds.

Classification by Molecular Forces

  • Elastomers: Rubber-like polymers that return to form.

  • Fibers: Long, flexible polymers used in textiles.

  • Thermoplastics: Can be reheated and reshaped.

  • Thermosetting Polymers: Harden permanently when set.

Classification by Polymerization Method

1. Addition Polymers

  • Form without producing byproducts.

2. Condensation Polymers

  • Form through condensation reactions (e.g., water).

Plastics and Their Types

Definition

  • Plastics are polymers with specific properties: structure, flexibility, moldability, durability.

Types of Plastics

  • Polyethylene Terephthalate (PET)

  • High-Density Polyethylene (HDPE)

  • Polyvinyl Chloride (PVC)

  • Low-Density Polyethylene (LDPE)

  • Polypropylene (PP)

  • Polystyrene (PS)

Key Types of PET

  • Widely used for bottles, containers; lightweight and moisture-resistant.

Key Types of PVC

  • Used in construction, plumbing; durable and resistant to chemicals.

Key Types of HDPE

  • Chemical containers; good chemical resistance.

Key Types of LDPE

  • Flexible for packaging applications.

Key Types of PP

  • Widely used in various industries for its cost-effectiveness.

Key Types of PS

  • Generates various products due to its moldable properties.

Fiber and Cement

Fiber

  • Natural or artificial material longer than it is wide; finds use in composites for strengthening.

Types of Fibers

  1. Natural Fibers: Eco-friendly, e.g., flax, jute.

  2. Synthetic Fibers: Made from laboratory-produced polymers, e.g., nylon, polyester.

Cement

  • Binders in construction made from materials like limestone and gypsum; used to create concrete.

Types of Cement

  1. Hydraulic Cement: Hardens with moisture.

  2. Non-Hydraulic Cement: Hardens in dry conditions.

  3. Specialty Cement: Modified Portland for specific applications.

  4. Geopolymer Cement: Made from fly ash; resistant to heat and chemicals.

Earth's Atmosphere

Overview

  • Earth's atmosphere protects from solar radiation, mainly consists of nitrogen (78%) and oxygen (21%).

Layers of the Atmosphere

  1. Troposphere: Temperature decreases with altitude; primary layer for weather.

  2. Stratosphere: Contains the ozone layer; temperature increases with altitude.

  3. Mesosphere: Coldest layer; meteor disintegration occurs here.

  4. Thermosphere: High temperatures; ionized air molecules.

  5. Exosphere: Outermost layer; where satellites orbit.

Key Points on Temperature Variations and Transition Layers

  • Tropopause: Layer separating troposphere and stratosphere; acts as a limit for vertical atmospheric circulation.

  • Stratopause: Separates the stratosphere and mesosphere.

Summary

  • The atmosphere consists of multiple layers, each with distinct properties and phenomena.