Biodegradable polymers are those polymers which get decomposed by the process of biodegradation. Biodegradation is defined as a process carried out by biological systems (usually fungi or bacteria) wherein a polymer chair is cleaved via enzymatic activity.And it is called BIODEGRADABLE POLYMERS.
There are essentially following three elements for the biodegradation process which needs to
be simultaneously present :
(a) Micro-organisms. The micro-organisms must exist with the appropriate biochemical
machinery to synthesize enzymes specific for the target polymer to initiate the
depolymerization process.
(b) Environment. The following environmental factors must be tuned environment .within the window of acceptability for the organisms producing the appropriate enzymes to degrade the target polymer :
(1) Temperature,
(ii) Pressure,
(iii) Moisture
(iv) Oxygen
(v) Type and concentration of salts,
(vi) Light etc.
(C) Substrate. Here the substrate refers to biodegradable polymer. And it must following essential features for biodegradation process to be successful :
(1) Suitable functional groups. BIODEGRADABLE POLYMERS chain must contain suitable function groups or linkages (like ester groups) .which are susceptible to hydrolysis oxidation by micro-organisms (or enzymes) for the initiation of biodegradation process.
(ii) Hydrophilicity. Greater the hydrophilicity of the polymer and usually larger is the
rate of biodegradation.
(iii) Low molecular weights. Polymers with low molecular weights are more
susceptible towards biodegradation.
(iv) Less crystallinity. As the crystalline domains are difficult to be accessed by the enzymes for the degradation process to start.
types of biodegradable polymers
Broadly ,BIODEGRADABLE POLYMERS can be classified into two types : Natural and Synthetic. In general, naturally occurring polymers are more biodegradable than synthetic polymers.
(1) Natural BIODEGRADABLE POLYMERS= collagen,natural rubber, lignin, poly- (gamma glutamic acid) are some of the examples of natural biodegradable polymers.
(ii) Synthetic Biodegradable Polymers. Polyvinyl alcohol, polyanhydrides, poly-(3-Hydroxybutyrate-CO-3-Hydroxyvalerate) or PHBV are some of the examples of synthetic biodegradable polymers.
biodegradable polymers example
The best example of BIODEGRADABLE POLYMER are polyhdroxy butyrate ,polyhydroxy butyrates-co-beta or PHVB and some of the examples are natural rubber, lignin and etc.
NATURAL POLYMERS EXAMPLES ARE= collagen,nature polymer, lignin and etc.
SYNTHETIC POLYMERS EXAMPLE ARE= polyvinyl alcohol,polyanhydrides and PHVB etc.
Poly-β-hydroxybutyrate-CO-β- hydroxyvalerate (PHBV) is a biodegradable aliphatic polyester.
biodegradable polymers is
Need for Biodegradable Polymers
The problems with traditional and non-biodegradable polymers are :
(1) Solid waste problems, particularly with regard to decreasing availability of land fills.
(ii) Litter problems, and
(iii) Entrapment or ingenious hazards to marine life.
Biodegradable polymers are a particularly attractive option for addressing the solid waste and marine pollution concerns. And Biodegradable polymers do not need to be land filled and they re-enter normal geochemical cycles over time and many of the polymers are derived renewable resources.
Applications of Biodegradable Polymers
(1) Poly (B-hydroxy butyrate) or PHB. And PHB is used in the manufacture of shampoo bottles.
(ii) B-hydroxybutyrate-ß-hydroxy valerate or HB-HV copolymers. The HB-HV copolymers are suitable as matrices for controlled release of drugs. due to their favorable biocompatibility and biodegradation properties.
(iii) Poly (lactic acid) or PLA. As PLA breaks down in the environment back to lactic acid and which can be metabolized. but it has found commercial use in medical applications such as sutures, drug-delivery systems and wound clips. It is also used in some agricultural applications, such as timed-release coatings for fertilizers and pesticides.
limitations of biodegradable polymers
(1) Biodegradation and recycling are two major approaches to plastic waste management. However, biodegradable polymers are not suitable candidates in the recycling of commingled plastics.
(ii) Generally, biodegradable polymers are very expensive.
(iii) Broadly speaking, biodegradable polymers are not easily available.
(iv) In order to store potentially hazardous materials and landfills are built to be free of moisture and air. These anaerobic conditions which serve to guard against the release of hazardous chemicals from landfills and also retard biodegradation.
biodegradable polymers used in orthopaedic device given in this vedio.
for more information about biodegradable polymers click here
https://en.wikipedia.org/wiki/Biodegradable_polymer
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