The pool balls shown are manufactured from the thermosetting polymer phenol formaldehyde resin (PF) - Leaving Cert Engineering - Question a - 2016

The manufacturing process suitable for thermoset products is Compression Moulding.

Process Overview

1. Mold Preparation: A split mould is formed into the desired shape of the product.

2. Material Loading: A measured amount of phenol formaldehyde resin is loaded into the mould cavity, typically in a powder or ‘slug’ form.

3. Heating and Pressurizing: The mould is then closed, and heat and pressure are applied, causing the polymer to soften and fill the mould completely.

4. Cross-linking: As the temperature rises, the resin undergoes a chemical reaction leading to cross-linking, which solidifies the material.

5. Cooling and Removal: Once cooled, the mould is opened, and the finished component is ejected. The removal of any excess material, known as ‘flash’, is also performed.

Diagram

   +-------------------------+
   |        Upper Mold       |
   |                         |
   |                         |
   +-------------------------+
        ||         ||
        ||         ||
   +-------------------------+
   |       Lower Mold        |
   |                         |
   +-------------------------+

This process ensures high-quality finishes and is suitable for manufacturing various thermoset products.

1. Complex Shapes: Injection moulding allows for the production of objects with various shapes and cross-sections, such as the intricate design of a kicking tee.

2. Mass Production: The process facilitates the mass production of thermoplastic items, ensuring that multiple kicking tees can be manufactured efficiently in a short period.

The principle of an injection moulding machine involves several key stages:

1. Feeding: Plastic granules are fed from a hopper into the machine.
2. Melting: These granules are heated until they melt into a liquid state under controlled temperature and pressure.
3. Injection: The molten plastic is injected into a mould through a nozzle, filling all cavities and spaces.
4. Cooling: The plastic is cooled in the mould to solidify.
5. Ejection: Once set, the finished component is ejected from the mould, typically using ejector pins.

The flexibility of a kicking tee can be improved by adding plasticisers to the polymer during the moulding process. Plasticisers enhance the material's properties by making it softer and more deformable. Adjusting the thickness of the tee can also help; a thinner design typically results in a more flexible product, balancing strength with flexibility to prevent breakage.

Synthetic rubber refers to a type of elastomer that is artificially produced through the polymerization of monomers such as isoprene. Unlike natural rubber derived from latex, synthetic rubber offers tailored properties such as improved resistance to heat, chemicals, and ozone. This customization makes it suitable for various applications, including tires and industrial products.

Properties:

• Elasticity: Elastomers exhibit significant elasticity at room temperature, allowing them to stretch and return to their original shape.
• Flexibility: They are soft and deformable, making them ideal for applications requiring resilience.
• Durability: They possess good resistance to wear, weather, and aging.

Internal Structure: Elastomers consist of long, coiled polymer chains connected through weak intermolecular forces. These chains can be stretched but return to their coiled form when the stress is removed, enabling the material's elastic properties. The internal structure often includes cross-linking to enhance strength and stability.