Plastics, the synthetic material
We have learnt about materials of various kinds and their properties. we’ve got also learnt about fibres and also plastics. we are going to learn more about them during this chapter.
Natural Fibres: Natural fibres come from natural sources like plants and animals. Cotton, linen, hemp, jute, flax, rhea, plant fibre (sambal), coir et al. come from plants. Wool and silk are the common fibres from animals. Synthetic Fibres: Synthetic fibres are man-made fibres. Synthetic fibres are made of different chemicals hence each reasonably synthetic fibre or material has its own properties. The synthetic material is thought of as plastic. the sole limitation with synthetic fibres is that they’re poor (not good) absorbent of moisture.
Hot wax, wet clay and soft metals (sheets and wires) are natural materials that show plasticity. These materials are often moulded to any desired shape. they continue to be within the given shape till remoulded to a different shape. In our day-to-day life, we don’t describe wax, clay or metals as plastics. Term plastic is being employed just for synthetic plastics.
Monomers and Polymers:
All substances are made from molecules. a substance having one molecule structure forming its particle is termed a monomer. An example is a glucose. A molecule of glucose is CHO Each molecule of glucose exists independently as one molecule (monomer). In certain substances, molecules get linked up chemically to make an oversized molecule, generally a series of molecules. this massive molecule is named a polymer, and therefore the action forming a series or a bunch of molecules could be a called polymerization. Polymers could also be natural or synthetic. A molecule of starch, polymerized from glucose, is (C,H,On. ‘n’ is that the number of molecules lying in an exceedingly chain forming a polymer. Similarly, proteins are polymers of amino acids. The simplest amino acid is glycine and its molecule is C,H,O,N. A protein from glycine is (C,H,O,N)n, a polymer. Natural polymers might not be plastic in nature.
Synthetic polymers. Scientists evolved a mechanism to polymerize the monomers of certain substances like rubber, silicone, rosin (obtained from resin exuded from pine trees) and petroleum products like ethane, propane, benzene, toluene, styrene, esters et al. of these are the raw materials for synthetic plastics.
For example, ethylene (gas) could be a monomer with the chemical formula: CH, CH, or (CH). During polymerisation the bonding (link) changes to make an extended chain of molecules, as follows:
Plastics are a group of synthetic substances that will be moulded to any desired form or shape by applying heat and pressure.
TYPES OF PLASTICS
There are two main groups of plastics:
(a) Thermoset plastics are hard and rigid. An example is a bakelite. Thermoset is often moulded to the line in any shape but it can not be remoulded. it’s dark in colour, hard and proof against heat and electricity. it’s being widely used for the handles of kettles and pans. it’s also getting used as part of fibreglass sheet within the making of helmets. Melamine could be a quite thermoset plastic utilized in good quality tableware.
(b) Thermoplastics are soft and versatile. they’re not elastic like rubber and steel springs. a number of the higher known thermoplastics are nylon ( polyamide), polyesters, polyethene, polystyrene, vinyl polymer (PVC), acrylic, polyacetal, polyurethane, polypropylene (PP), poly-tetra-fluoro-ethylene (PTFE) et al..
Their Properties and User there’s an excellent style of plastics made of different chemicals. Property and use of every reasonably plastic depend upon the fabric getting used for its synthesis (polymerization).
Some Common Properties of Synthetic Plastics are:
1. They’re non-biodegradable.
2. Chemical resistant: they’re not laid low with strong acids and alkalies.
3.Toughness: Plastic is hard and may withstand high. it’s stretchable and its enduringness is, again and again, the fibre. Even a fine synthetic fibre isn’t easily breakable.
4. Easy moulding: Plastic is well moulded to any shape or maybe more responsible for a fine pore forming a fibre.
5. Colouring: Plastics are colourless, white or could also be given any colour to suit the necessity.
6. To light plastics could also be transparent, translucent or opaque.
7. Insulation: Plastics are non-conductors of warmth and electricity and hence used as insulators.
8. Plastics form a component of the paints for walls and wood. they’re utilized in making water-and weather-proof paints that protect wood and walls.
Some Disadvantages of Synthetic Plastics
1. Plastics are poor absorbers of moisture, hence fabric made of pure plastics aren’t good for wearing. they’re not airy also. to beat this disadvantage synthetic fibres are blended with natural fibres (cotton and wool).
2. Plastics may melt or turn on the heating, hence synthetic materials should be kept far from fire ( except thermosets). it’s risky for the housewives to figure within the kitchen while wearing synthetic wears.
3. Plastics while rubbing with our body develop static charge upon them which is harmful to the skin. you would possibly have observed sparks jumping between the material (shirt) and therefore the body while starting off
the shirt. Sparks also give out crackling sound. Plastic isn’t bio-degradable, hence a pollutant.
4. On burning it emits a foul smell and poisonous gases.