Plastic is nothing but a synthetic organic high polymer. It is important to know the general excellent properties of plastics in order to make the best use of an engineering material. It should also be noted that each plastic material has its own unique properties to suit different uses. Therefore the success of plastics as an engineering material for a particular purpose will depend on the right choice of variety.
properties of plastic materials
Following are the general properties of plastics.
Plastics are sufficiently strong and can be used for load bearing structural members. The strength of the plastic can be further increased by reinforcing the plastic with various fibrous materials.
Plastics have not gained much popularity as a structural material due to the following resins.
- high cost of construction
- high temperature sensitivity
- poor hardness
- to be subject to creep under constant load
2. weather resistance
Plastics made from phenolic resins are only good at resisting the effects of weather. Some plastics are seriously affected by ultraviolet light.
Being organic in nature, plastics are flammable. But the resistance to fire temperature depends on the composition of the plastic.
- Cellulose acetal plastic burns slowly.
- Polyvinyl chloride (PVC) plastics are non-flammable.
- Phenol formaldehyde and urea formaldehyde plastics are used as fireproof materials.
Plastics generally have sufficient durability, provided they provide sufficient surface hardness. Thermoplastic varieties are attacked by termites and rodents.
5. dimensional stability
The plastic easily maintains its shape and is not subject to plastic deformations.
6. chemical resistance
Plastics offer great resistance to moisture, chemicals and solvents. Excellent corrosion resistance is found in many plastics. Plastics are used to convey chemicals.
7. thermal resistance
Plastics have low thermal conductivity and therefore foamed or expanded varieties of plastics are used as thermal insulators.
8. working conditions
All operations like drilling, sawing, punching, clamping etc. are easily performed on plastics just like wood.
9. moisture resistant
This property depends on the variety of plastic used, for example, cellulose plastics are strongly affected by the presence of moisture, whereas polyvinyl chloride plastics offer higher resistance to moisture.
Plastics generally have low ductility and therefore structural members of the plastic can fail without early warning.
1 1 miscellaneous properties
In addition to the above properties, plastics have the following properties.
- Plastic is available in a variety of colors, both opaque and transparent.
- Plastic has excellent insulating properties, so it is used as an electrical insulator.
- Plastics are clean, light and shiny, so they don’t require any finishing touches like painting, polishing, etc.
- Thermo-plastics generally have a low melting point and cannot be used if the temperature or heat conditions are maintained.
- They have good optical and sound absorption properties.