How is the following resin intermediate prepared and which polymers is formed by this monomer unit?
Reaction between melamine and formaldehyde can be shown as
Melamine-formaldehyde polymer is formed by this monomer unit.
To have practical applications why are cross links quetioined in rubber?
Cross links in rubber required for increasing the elasticity of rubber.
Why does cis-polyisoprene posses elastic property?
cis-polyisoprene is also known as natural rubber. Its elastic property is due to the existence of weak van der Waals' interactions between their various polymer chains.
What is the structural difference between HDP and LDP? How does the structure account for different behaviour and nature, hence use of a polymer?
HDP (high density polymer) consists of linear molecule and has a high density due to close packing. It is a translucent polymer. While LDP (Iow density polymer) has highly branched structure and hence, does not pack well resulting in low density. It is a transparent material.
What is the role of benzoyl peroxide in addition polymerisation of alkenes? Explain its mode of action with the help of an example.
Role of benzoyl peroxide is to initiate the free radical polymerization reaction which can be easily understood by taking an example of polymerization of ethene to polyethene.
(i) Chain initiation
(ii) Chain propagation
(iii) Chain terminator step
