Question 32 (Textile Engineering & Fibre Science)
Consider the following assertion [a] and reason [r]and choose the most appropriate answer.
[a] In the case of consideration polymerization of PET, diethylene glycol terephthalate (DGT) is prepared first
[r] In consideration polymerization, it is important to have a correct stoichiometric balance of comonomers
| (A) | [a] is right [r] is wrong |
| (B) | [a] is right [r] is right |
| (C) | [a] is wrong [r] is wrong |
| (D) | [a] is wrong [r] is wrong |
[Show Answer]
Option B
Frequently Asked Questions | FAQs
How is condensation polymerisation formed?
Condensation polymerization, also known as step-growth polymerization or polycondensation, is a type of polymerization reaction in which a polymer is formed by the repeated condensation reactions between two or more monomers. The reaction involves the elimination of a small molecule, such as water or methanol, as a byproduct during each step of the polymerization process.
The general steps involved in condensation polymerization are as follows:
Monomer Activation: The monomers, which are typically bifunctional or multifunctional molecules with reactive functional groups, are activated by some external stimulus, such as heat, pressure, or a catalyst. This activation allows the functional groups to become chemically reactive and capable of forming covalent bonds with other monomers.
Condensation Reaction: The activated monomers react with each other, forming covalent bonds and eliminating a small molecule, such as water or methanol, as a byproduct. This condensation reaction results in the formation of a polymer chain, which grows through the repeated addition of monomers and the elimination of byproducts.
Chain Growth and Termination: The polymer chain continues to grow as monomers are added and byproducts are eliminated. The reaction continues until the monomers are fully consumed or until the polymer reaches the desired molecular weight or chain length. At this point, the polymerization can be terminated by stopping the addition of monomers or by quenching the reaction using appropriate methods.
Polymerization Kinetics: The rate and progress of the condensation polymerization reaction depend on various factors, such as the reactivity of the monomers, the temperature, the presence of catalysts, and the concentration of reactants. The reaction may proceed slowly due to the formation of byproducts or the need for high temperatures to activate the monomers, and it may require careful control to achieve the desired polymer properties.
Polymer Structure: The structure and properties of the resulting polymer depend on the monomers used, the reaction conditions, and the degree of polymerization. Condensation polymerization can produce a wide variety of polymer structures, including linear, branched, and cross-linked polymers, with a range of properties such as mechanical strength, thermal stability, and chemical resistance.
Examples of common condensation polymers include polyesters, polyamides (nylons), polyurethanes, and phenol-formaldehyde resins. These polymers are widely used in a variety of applications, such as plastics, fibers, coatings, adhesives, and composites, due to their diverse properties and versatility.
Why polyesters are condensation polymers?
Polyesters are condensation polymers because they are formed through a condensation polymerization reaction. Condensation polymerization is a type of polymerization in which two or more monomers react to form a polymer by eliminating a small molecule, such as water or methanol, as a byproduct during each step of the polymerization process.
In the case of polyesters, the monomers involved are typically bifunctional molecules with reactive functional groups, such as carboxylic acids (COOH) and alcohols (OH). These monomers react with each other through a condensation reaction, where the carboxylic acid group of one monomer reacts with the alcohol group of another monomer, forming an ester bond (COO) and eliminating a water molecule (H2O) as a byproduct. This process is repeated, with the ester bond acting as a reactive site for further polymerization, resulting in the formation of a polymer chain.
The general chemical equation for the condensation polymerization of a polyester can be represented as follows:
n HOOC-R-COOH + n HO-R’-OH → [-OOC-R-COO-R’-]n + n H2O
Where R and R’ represent the organic moieties of the monomers, and n represents the degree of polymerization or the number of monomer units incorporated into the polymer chain.
Polyesters are widely used in various applications, such as fibers, films, packaging materials, coatings, and adhesives, due to their desirable properties, including high strength, durability, chemical resistance, and thermal stability. The ability to control the polymerization process and tailor the properties of polyesters by varying the monomer composition, reaction conditions, and degree of polymerization makes them versatile materials with a wide range of applications in various industries.