Views: 28
INTRODUCTION
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are mouldable.
Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.
Synthetic resins may be phenol, formaldehyde, cellulose vinyl, alkyl, etc.
They are made from simplest substances consisting of one primary chemical are known as the monomers or monoliths. They are combined or synthesized to form polymers by the process known as the polymerization.
PROPERTIES OF PLASTICS
The following properties are common with most of the plastics.
- They are light in weight.
- They have good resistance to most of the chemical.
- They have high electrical resistance.
- They have good corrossive resistance.
- Plastics can be moulded to any desired shape and size.
- They can be made transparent or color.
- They are cheap compared to metals.
- Operations like drilling ,sawing, punching can be done on plastics.
- Painting and polishing is not necessary.
- The plastics posses excellent electric insulating properties.
- The plastics, have low specific gravity, the average being 1.3 to 1.40
ADVANTAGES OF PLASTICS OVER OTHER MATERIALS:
1.They can be molded into finished products at a relatively low cost, compared to the machining and fabricating costs for wood and metal.
- They resist chemicals.
- They pose a high strength to weight ratio.
- They does not rust like iron
DISADVANTAGE OF PLASTICS:
- It has low modulus of elasticity.
- It is not reliable with respect to weathering