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.