Define thermoplastics and thermosetting polymers with two examples of each.

(N/A) $Thermoplastic$ polymers are linear or slightly branched long-chain polymers that can be repeatedly softened and hardened upon heating. Hence,they can be reshaped multiple times. Examples include $Polythene$ and $Polystyrene$.
$Thermosetting$ polymers are cross-linked or heavily branched polymers that undergo extensive cross-linking during the molding process,becoming permanently hard. These plastics cannot be softened again upon heating. Examples include $Bakelite$ and $Urea-formaldehyde$ resins.