Thermoplastic, Thermoset, and Elastomer Polymers: A Comprehensive Guide

Posted on Oct 5, 2024 in Technology

Thermoplastics

Polyethylene (PE)

Repeating Chemical Structural Unit:

Pf: 110-137 º C

Types of Polyethylene:

1. Low Density (LDPE): Branched chain structure.
   • Low degree of crystallinity, density, and strength.
2. High Density Polyethylene (HDPE): Straight chain structure.
   • High degree of crystallinity and resistance.
3. Linear Low Density (LLDPE): Linear structure with short, oblique lateral branches.

Properties:

1. Low cost.
2. Toughness and low ambient temperature resistance.
3. Good flexibility.
4. Excellent corrosion resistance.
5. Very good insulating properties.
6. Colorless, tasteless, and low water-vapor transmission.

Applications:

1. Containers.
2. Chemical applications.
3. Coating of wells, weirs, and reservoirs.

Polyvinyl Chloride (PVC)

Repeating Chemical Structural Unit:

Mp: 204 ° C

Properties:

1. High chemical and flame resistance.
2. Easily mixed with additives.
3. Amorphous and does not recrystallize.
4. Low flexibility.
5. High strength and considerable fragility.
6. Good electrical properties.
7. High resistance to dissolution.

Types of Polyvinyl Chloride:

1. Rigid PVC: Difficult to process and low impact resistance.
   • Applications: Pipes and gutters.
2. Plasticized PVC: Produces plasticity, flexibility, and extensibility.
   • Applications: Furniture and car upholstery, shoes, etc.

Polypropylene (PP)

Repeating Chemical Structural Unit:

Pf: 165-177 º C

Properties:

1. Stronger and less flexible than PE.
2. Higher glass transition temperature than PE.
3. Good resistance to moisture and heat.
4. Low density.
5. Good surface hardness and stability.
6. Remarkable flexibility.

Applications:

1. Household products.
2. Laboratory utensils.
3. Thermal conductivity applications.

Polystyrene (PS)

Repeating Chemical Structural Unit:

Pf: 150-243 º C

Types:

1. Unmodified Polystyrene: Transparent, odorless, and fragile plastic.
2. Rubber-Modified Polystyrene: Impact resistant.
3. Expandable Polystyrene:

Properties:

1. Good dimensional stability.
2. Low shrinkage in molding and easy processing.
3. Susceptible to weathering.
4. Sensitive to organic solvents and oils.
5. Good electrical insulator.
6. Appropriate mechanical properties.
7. Stiffness, brightness, clarity.

Applications:

1. Automotive interior coating.
2. Appliances.
3. Cooking utensils.

Polyacrylonitrile (PAN)

Repeating Chemical Structural Unit:

Properties:

1. High resistance.
2. Good resistance to moisture and solvents.

Applications:

1. Fibers used in wool sweaters and blankets.

Acrylonitrile Butadiene Styrene (ABS)

Structural Chemical Units:

Properties:

• Acrylonitrile:
  1. Good chemical and heat resistance.
  2. Good tenacity.
• Butadiene:
  1. Impact resistance.
  2. Low retention property.
• Styrene:
  1. Surface brightness.
  2. Stiffness.
  3. Easy processing.

Applications:

1. Pipes and tools.
2. Door coatings.
3. Computer housings and covers.

Polymethyl Methacrylate (PMMA)

Repeating Chemical Structural Unit:

Mp: 160 ° C

Properties:

1. Hard, rigid, and transparent.
2. Good weather resistance.
3. More impact resistant than glass.
4. High transparency to visible light.
5. Good chemical resistance in outdoor environments.

Applications:

1. Aircraft glazing.
2. Advertising signs.
3. Rear car windows.

Drawback: It scratches easily.

Polyamide (Nylon)

Repeating Chemical Structural Unit for Nylon 6.6:

Pf: 250-266 º C

Properties:

1. Highly crystallized.
2. High strength.
3. High deflection temperature.
4. Good chemical resistance.
5. Good tenacity.
6. Low friction surface.
7. Good friction resistance.

Applications:

1. Non-lubricated bearings.
2. Stands.
3. Antifriction parts.

Polycarbonate (PC)

Repeating Chemical Structural Unit:

Mp: 270 ° C

Properties:

1. High strength, toughness, and dimensional stability.
2. Very rigid molecular structure.
3. High impact resistance.
4. Good electrical insulating properties and transparency.
5. Resistant to chemicals but attacked by some solvents.

Applications:

1. Security screens.
2. Helmets.
3. Window glass.

Thermosets

Epoxy Resins

Repeating Chemical Structural Unit:

Properties depend on the degree of crosslinking, chemical structure, and type of curing agent.

Properties:

1. High molecular mobility during processing.
2. High hardness and chemical resistance.
3. Low shrinkage during crosslinking.
4. High adhesion.

Applications:

1. Protective and decorative coatings.
2. High voltage insulators.
3. Crack sealing in concrete.

Phenolic Resin (Bakelite)

Chemistry:

Properties:

1. Low cost.
2. Good thermal and sound insulation properties.
3. Good mechanical properties.
4. Easy molding.
5. Limited color options (black and brown).
6. High hardness, stiffness, and strength.
7. Good chemical resistance.

Applications:

1. Electrical switches.
2. Steering brakes.
3. Laminated wood.

Elastomers

Natural Rubber

Raw material: Latex

Structure:

* Cis-1, 4 polyisoprene: * trans-1, 4 polyisoprene:

Vulcanization: The chemical process where polymer molecules cross-link to form larger molecules, restricting molecular motion.

Properties:

1. Low tensile strength.
2. High elongation.

Synthetic Rubber

1. Styrene butadiene rubber (SBR).
2. Nitrile rubber.
3. Polychloroprene (neoprene).
4. Silicone Rubber:

Repetitive Structural Unit:

Properties:

1. Usable over a wide temperature range.

Applications:

1. Sealing.
2. Material boards.
3. Electrical insulators.