Reinforcing and stiffening
Forces act on materials all the time - even if a material appears stationary it still has a force acting on it. There are five terms used to describe what type of force can act on a material:
- Pulling force exerted by each end of an object such as a string or rope. - a pulling force
- Being squashed. - a pushing force
- A bending force is applied at an angle causing a material to be in compression and tension at the same time. - forces at an angle to the material
- A twisting force. - a twisting force
- A force across a material, eg scissors cut by applying a shear force. - forces acting across the material
It is very difficult to generalise on the properties of A polymer is a large molecule formed from many identical smaller molecules (monomers). Polymers can be natural or synthetic. Plastics are long chains of polymers. as there are so many. There are seven types of plastic - six are common and are used for everyday objects, and the last type (not listed below) covers the substantial variations remaining that are not common.
| Common polymer | Shorthand | Common use |
| Polyethylene terephthalate | PET | Plastic water bottles |
| High density polythene | HDPE | Fabric conditioner bottle |
| Polyvinyl chloride | PVC | Plastic toys, cling film, blister packs |
| Low density polythene | LDPE | Bread bags |
| Polypropylene | PP | Yoghurt pots and pen lids |
| Polystyrene | PS | Packaging and coffee cups |
| Common polymer | Polyethylene terephthalate |
|---|---|
| Shorthand | PET |
| Common use | Plastic water bottles |
| Common polymer | High density polythene |
|---|---|
| Shorthand | HDPE |
| Common use | Fabric conditioner bottle |
| Common polymer | Polyvinyl chloride |
|---|---|
| Shorthand | PVC |
| Common use | Plastic toys, cling film, blister packs |
| Common polymer | Low density polythene |
|---|---|
| Shorthand | LDPE |
| Common use | Bread bags |
| Common polymer | Polypropylene |
|---|---|
| Shorthand | PP |
| Common use | Yoghurt pots and pen lids |
| Common polymer | Polystyrene |
|---|---|
| Shorthand | PS |
| Common use | Packaging and coffee cups |
Each polymer type from the table above will cope with a force in a different way. If a polymer doesn’t withstand the force needed, a new type of polymer could be created by a A person who develops materials using the principles of science and maths.. It is important to understand the characteristics of each polymer available to see if it is fit for the intended purpose.
The stiffness and strength of thermoforming and thermosetting plastic polymers depend upon the type of plastic, the An end view or area of a 3D form. area and the depth of the section. Different forms of Single, hair-like strands that derive from either natural or synthetic sources. can also affect the strength of thermosetting plastics and can act as reinforcement against tension. Plastics can also be strengthened by Bonding layers of material together to improve strength., ie layering sheets together to improve strength and stability.
