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
Which factor imparts crystalline nature to a polymer like nylon?
Strong intermolecular forces like hydrogen bonding and linear structure that lead to close packing of chains and hence, imparts crystalline character. e.g., nylon
Name the polymer used in laminating sheets and give the name of monomeric units involved in its formation.
Urea formaldehyde resin is used for laminated sheets. The monomer of this resin is urea $\left(\mathrm{NH}_2 \mathrm{CoNH}_2\right)$ and formaldehyde $(\mathrm{HCHO})$
