Explain about the biodgradable plastics

Explanation

(i) Synthetic polymers are non-deradable and pollute the soil and when burnt add dioxin in the environment which cause cancer.
(ii) So, efforts were taken to provide an alternative eco-friendly biopolymers.
(iii) Polyhydroxyalkanoates (PHAs) and polyhydroxybutyrate (PHB) are group of degradable biopolymers which have several medical applications such as drug delivery , scaffold and heart valves . PHAs are biological macromolecules and thermoplastics which are biodegradable and biocompatible .
(iv) Sereral microorganisms have been utilized to produce different types of PHA sin cluding Gram-positive like Bacillus megaterium , Bacillus subtilis and Corynebacterium glutamicum , Gram-negative bacteria like group of Pseudomonas sp . and Alcaligenes eutrophus .
(v) Polylactic acid or polylactide (PLA) is a biodegradable and bioactive thermoplastic .
It is an aliphatic polyester derived from renewable resources , such as corn starch , cassave root , chips or starch or sugarcane .
(vii) For the production of PLA, two main monomers are used lactic acid , and the cyclic diester , lactiede .
(viii) The most common route is the ring opening polymerization of lactide with metal cataysts like tin octoate in solution .
(ix) The metal-catalyzed reaction results in equal amount of d and polylactic acid