Definitions [19]
Answer the following in one sentence.
Define the term: Monomer
Small molecules that are interlinked together to form polymers are called as monomers.
Define fibres.
Polymeric solids which form threads are called fibres.
Define elastomer.
Polymers having the property of elasticity in which a substance gets stretched by external force and restores its original shape on the release of that force are called elastomers.
Answer the following in one sentence.
Define the term: Synthetic fibres
The man-made fibres prepared by polymerization of one monomer or copolymerization of two or more monomers are called synthetic fibres.
Define Polymer.
A polymer is a large molecule of very high molecular mass formed by the repeated combination of a very large number of one or more types of small molecules called monomers.
Define rubber.
Polymers which are elastic in nature are called rubber.
Answer the following in one sentence.
Define the term: Vulcanization
The process by which a network of cross-links is introduced into an elastomer is called vulcanization.
The synthetic polymer obtained by addition polymerization of tetrafluoroethylene and having high chemical inertness and heat resistance is called polytetrafluoroethylene (Teflon).
The synthetic polymer formed by addition polymerization of acrylonitrile in presence of a peroxide initiator is called polyacrylonitrile.
The synthetic linear polymer containing repeating amide (–CO–NH–) linkages formed by condensation of dicarboxylic acids and diamines or by ring opening of lactams is called polyamide (nylon).
The polymer containing repeating ester (–COO–) linkages formed by condensation of dicarboxylic acids and diols is called polyester.
The polyester formed by condensation polymerization of ethylene glycol and terephthalic acid is called terylene (dacron).
The thermoplastic polyester obtained from ethylene glycol and terephthalic acid and widely used in packaging is called polyethylene terephthalate (PET).
The thermosetting polymer formed by condensation polymerization of phenol and formaldehyde in presence of acid or base catalyst is called bakelite.
The synthetic rubber formed by addition polymerization of chloroprene (2-chloro-1,3-butadiene) is called neoprene.
The semisynthetic fibre obtained by regeneration of cellulose from wood pulp through chemical treatment is called viscose rayon.
Chemically polymers are complex, giant macromolecules made from the repeating units which are derived from small molecules called 'monomers'.
The term ''polymer' originates from Greek word 'poly' meaning many and 'mer' meaning. part or unit. Interlinking of many units constitutes polymers.
Key Points
| Type of Polymer | Definition | Source | Method of Preparation | Examples |
|---|---|---|---|---|
| Natural Polymer | Polymers obtained from natural sources. | Plants and Animals | Occur naturally in nature | Cotton, Wool, Silk, Natural rubber |
| Plant Polymer | Natural polymers derived from plants. | Cotton plant, Flax plant, Rubber tree | Extracted from plant materials | Cotton, Linen, Natural rubber |
| Animal Polymer | Natural polymers derived from animals. | Sheep, Silkworm | Obtained from animal products | Wool, Silk |
| Synthetic Polymer | Man-made polymers formed by polymerization of monomers. | Chemical industries | Polymerization or copolymerization process | Nylon, Terylene, Neoprene |
| Semisynthetic Polymer | Polymers produced by chemical modification of natural polymers. | Natural polymers (e.g., cellulose) | Chemical treatment of natural fibres | Rayon, Cellulose acetate, Cellulose nitrate |
| Type of Polymer | Structural Arrangement | Nature of Monomers | Key Feature | Examples |
|---|---|---|---|---|
| Linear (Straight chain) Polymer | Monomer units joined in a single continuous chain | Bifunctional monomers or alkenes | Forms long straight chains | PVC, High density polythene (HDPE) |
| Branched Chain Polymer | Main chain with side chains attached | Monomers having trifunctional groups or branching tendency | Presence of side chains | Low density polythene (LDPE) |
| Cross-linked Polymer | Chains interconnected forming a network structure | Polyfunctional monomers | Cross-links between linear chains | Bakelite, Melamine |
| Type of Polymerization | Alternative Name | Basic Process | Key Characteristic | Examples |
|---|---|---|---|---|
| Addition Polymerization | Chain growth polymerization | Monomers add together without elimination of small molecules | Repeating unit has same elemental composition as monomer | Polyethylene, PVC, Polystyrene |
| Condensation Polymerization | Step growth polymerization | Polymer forms with elimination of small molecules like H₂O, HCl, NH₃ | Repeating unit differs in composition from original monomers | Nylon-6,6; Terylene |
| Ring Opening Polymerization | Ring cleavage polymerization | Cyclic monomers open and join to form long chain polymers | No small molecule eliminated; proceeds via ring opening step | Nylon-6 (from caprolactam) |
| Type of Polymer | Property | Nature of Intermolecular Forces | Key Characteristic | Examples |
|---|---|---|---|---|
| Elastomers | High elasticity | Very weak van der Waals forces with few cross-links | Can be stretched and regain original shape | Vulcanized rubber, Buna-S, Neoprene |
| Fibres | High tensile strength | Strong hydrogen bonding and dipole–dipole forces | Crystalline nature and high resistance to breaking | Nylon-6,6; Terylene |
| Thermoplastic Polymers | Plasticity | Moderately strong intermolecular forces | Soften on heating and harden on cooling | Polythene, Polystyrene, PVC |
| Thermosetting Polymers | Rigidity | Extensive covalent cross-linking | Do not soften on heating; become infusible | Bakelite, Urea-formaldehyde resin |
| Feature | Low Density Polythene (LDPE) | High Density Polythene (HDPE) |
|---|---|---|
| Method of Preparation | Polymerization of ethene by free radical addition | Polymerization of ethene using Ziegler–Natta catalyst |
| Reaction Conditions | 1000–2000 atm pressure, 350–570 K temperature, traces of peroxide/oxygen | 333–343 K temperature, 6–7 atm pressure, TiCl₄ + triethyl aluminium catalyst |
| Structure | Highly branched chains | Linear chains with close packing |
| Key Properties | Flexible, low density, chemically inert, poor conductor of electricity | Hard, crystalline, high density, strong and more chemical resistant |
| Major Uses | Films, sheets, squeeze bottles, cable insulation | Buckets, pipes, bottles, toys, laboratory ware |
Important Questions [21]
- How are polymers classified on the basis of polymerisation process?
- Write the preparation of nylon 6, 6.
- Write classification of polymers on the basis of structure.
- Write the Chemical Reaction to Prepare Novolac Polymer.
- Explain the Following Term: Homopolymers
- Bakelite is the Polymer of
- Write the Formulae of the Raw Materials Used for Preparation Of Dextran.
- The Zieglar-natta Catalyst is Used in the Preparation of
- Write the structure of melamine.
- Write any ‘two’ uses of terylene.
- Draw the Structures of Veronal and Thymine.
- Answer the following in one sentence. Define the term: Vulcanization
- Write a chemical reaction for the preparation of the following polymer. polyacrylonitrile
- The monomer used in preparation of teflon is ______.
- Write the structure and name of monomer of Natural rubber.
- Write the reactions involved in the preparation of PVC
- Write the structure and name of the monomer of Nylon-6.
- The monomer of natural rubber is ______.
- Write the name of biodegradable polyamide copolymer.
- Write Chemical Reaction to Prepare the Following Polymer : Teflon
- Write the reactions involved in the preparation of Teflon.
