Assertion (A) Polytetrafluoroethene is used in making non-stick cookwares.
Reason (R) Fluorine has highest electronegativity.
Synthetic polymers do not degrade in the environment for a long time. How can biodegradable synthetic polymers be made. Differentiate between biopolymers and biodegradable polymers and give examples of each type.
Synthetic polymers are quite resistant to environmental degradation process and are responsible for accumulation of polymer solid waste material. New biodegradable synthetic polymers have been designed and developed. These polymers contain similar functional groups as present in biopolymers.
e.g., aliphatic polyesters
Biopolymer, are polymers of amino acid or carbohydrates which are linked to each other by peptide or glycosidic linkages as shown below
Biopolymer can or can't be biodegradable.
e.g., protein, starch etc, are biodegradable but keratin are non-biodegradable. Biodegradable polymer are polymers which can be degradable always. e.g., DHBV nylon-2, Nylon-6
Differentiate between rubbers and plastics on the basis of intermolecular forces.
Rubber is a natural polymer which possess elastic properties. Natural polymer is a linear polymer of isoprene (2-methyl-1, 3-butadiene).
In natural rubber cis-polyisoprene molecules consists of various chains held together by weak van der Waals' interaction and has coiling structure. So, it can be stretched like a spring.
Plastics are generally polymer of ethene known as polythene. Polythene is thermoplastic polymer which may be linear (HDP) or branched (LDP) these type of polymers. Possesses intermediate intermolecular forces of attraction. It has linear, structure that can be moulded but can't be regained on its original shape after stretching.
Phenol and formaldehyde undergo condensation to give a polymar (A) which on heating with formaldehyde gives a thermosetting polymer (B). Name the polymers. Write the reactions involved in the formation of (A). What is the structural difference between two polymers?
Phenol and formaldehyde undergo condensation to give a polymer novolac $(A)$ which on heating with formaldehyde gives bakelite $(B)$ as a thermosetting polymer.
Sequence of the reaction can be written as
Structural difference in between these two is that novolac is a linear polymer while bakelite is a cross linked polymer.
Low density polythene and high density polythene, both are polymers of ethene but there is marked difference in their properties. Explain.
Low density and high density polythenes are obtained under different conditions. These differ in their structural features. Low density polythenes are highly branched structures while high density polythene consists of closely packed linear molecules. Close packing increases the density.