Polymers EMonomers Polymerisation Degree of Polymerisation Different type of polymerisatio n reaction Char, of Polymers Uses Classification of Plastics Thermoplastic Materials Thermosetting Plastic Materials
Hello! Shankar Kumar B.Tech -Electronics&Telecommunication Cleared 2017 ESE written & Two times GATE Qualified. 4 Years of teaching experience
Characteristics of Polymers Uses of Polymers Classification of Plastics
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Characteristics of Polymer Polymers have long chain structures. Polymer's structure may be crystalline in simple material but generally they are noncrystalline solids at room temperature. Polymers pass through a viscous stage during formation. Polymers are light weight and they can be easily fabricated and shaped. They are poor conductors of electricity and their thermal conductivity is also low. Polymers are resistant to chemical attack and decay.
Uses of Polymer Polymers are widely used in indefinite no. of forms e.g: telephone sets, Paints, radio and tv cabinets, coatings, adhesive etc. Few notable developments in polymer materials are: Polymers materials are strong than steel acc. to weight to weight ratio. Polymer materials suitable for repairing damaged kidney or heart. Lining for spacecraft to withstand high temperature. Using polymers, under water tents have been prepared which allows a man to live and work.
Classification of Plastics 1. Thermoplastics 2. Thermosetting Plastics 1. Thermoplastics A Plastic which can be melted repeatedly by heating and which can be modulated again and again into different shapes with repeatedly melting is called thermoplastic. A thermoplastic become soft on heating and this property allows it to set in a desired shape again and again which it retains on cooling. The examples of thermoplastics are: 1. Polyethylene 3. Polystyrene 5. Nylon 2. Polyvinyl chloride (PVC) 4. Polycarbonate
Classification of Plastics 1. Thermoplastics 2. Thermosetting Plastics 1. Thermosetting Plastics It is a plastic substance which once set or moulded does not become soft on further heating. Instead of melting, it degrades on further heating. Thermosetting plastics are irreversible plastics which cannot be melted or softened once set of moduled into a given shape. The examples of thermosetting plastics are: 1. Bakelite 2. Melamine
Comparison b/w Thermoplastics & Thermosetting plastics Thermoplastics Thermosetting plastics They have long chain of polymers which are They have long chain of polymers which are not cross- linked. cross- linked. They become soft on heating. They become They cannot be remoulded on heating. remoulded on reheating. Examples: Polyethylene, polycarbonate and Examples: Bakelite & melamine. polyvinyl chloride. They can be reused or recycled. They cannot be reused or recycled. They are used for making () buckets, (ii) pipes, (i) carry bags, (iv) toys & (v) toilet goods etc. They are used for hot temperature applications such as (i) utensil handles, (ii) bodies of socket & plugs, (ii) furniture (iv) telephone bodies, (v) T-V cabinets & (vi) automobile parts etc.
Q.4 Statement (1) : Long chain polymers are weaker than most ceramics and metals. Statement (I): The molecular chains in long chain polymers are bonded to each other with Van der Waals bonds. (a) Both Statement (I) and Statement (l) are individually true and Statement (lI) is the correct explanation of Statement () Both Statement (I) and Statement (ll) are individually true, but Statement (lI) is not the correct explanation of Statement (l) (b) (c) Statement (I) is true, but Statement (II) is false (d) Statement (1) is false, but Statement (I) is true ESE: 2018] Ans. (a) The molecular chains in long chain polymers are bonded to each other with weak vander walls bonds and hence polymers are weaker than most ceramics and metals.
B.TECH | ELECTRONICS & TELECOMMUNICATION | ESE WRITTEN QUALIFIED | 4 YEARS OF TEACHING Experience..