Bio-Degradable Polymers

1. Bio-Degradable Polymers CORPORATE TRAINING AND PLANNING

2. Introduction Although there certainly has never been a great incentive for making unstable polymers, the idea of making degradable polymers has long existed due to its environmental significance, and quite a bit of effort has gone into research along these lines. There are three important ways of making a degradable to polymeric material. 1.Thermal degradation 2.photo degradation 3.Biodegradation CORPORATE TRAINING AND PLANNING

3. Degradation: Degradation is nothing but loose the properties of polymer due to external sources. Thermal Degradation: Polymaric materials will loose the properties because of over thermal conditions. Photodegradation One is to make the polymer sensitive to sunlight, which fractures its chemical bonds and breaks it down by photodegradation. To make plastics photodegradable, a material can be implanted that will absorb sunlight and becomes sufficiently reactive to attack the polymer molecules from which the material is composed. CORPORATE TRAINING AND PLANNING

4. Continue….. One other means of photodegradation is to incorporate in the polymer backbone suitable groups, e.g., carbonyl groups that absorb the ultraviolet (UV) component of the sunlight to form excited states energetic enough to undergo bond cleavage. . CORPORATE TRAINING AND PLANNING

5. Bio-degradation Biodegradation lies in the possibility to create an environment (as in a landfill) completely different from that encountered under normal storage conditions; e.g., microorganisms that can destroy organic polymers may be added to a landfill. Biodegaradation is understood about the molecular-level interaction between polymers and microorganisms. For example Esterases (ester hydrolyzing enzymes) and some microorganisms are known to biodegrade polyester at a reaction rate depending upon the polyester structure. While many aliphatic polyesters, specifically poly(hydroxy fatty acids), are suited for biodegradation, the aromatic polyester (e.g., PET) do not possess this property. Poly(vinyl alcohol) is the most readily biodegraded, compared to other vinyl polymers CORPORATE TRAINING AND PLANNING

6. Natural Bio-degradable polymers: Example for natural biodegradable polymers are Cellulose, Polysaccharides, Starch, PVOH etc. Cellulose Plastics Cellulose is a natural polymer produced from wood via wood pulp.Woven grade cotton contains about 90% cellulose while an average wood has about 50% and the balance is composed of lignin and polysaccharides. The cellulose are prepared by reacting chemical cellulose with organic acids and anhydrides using sulfuric acid as a catalyst. CORPORATE TRAINING AND PLANNING

7. POLYVINYL ALCOHOL: Vinyl alcohol does not exist in the free state and all attempts to prepare it have led instead to the production from acetaldehyde. Poly(viny1 alcohol) is thus prepared by alcoholysis of a poly(viny1 ester) and methonal is used The presence of hydroxyl groups attached to the main chain has a number of significant effects. The first effect is that the polymer is hydrophilic and will dissolve in water to a greater or lesser extent according to the degree of ‘hydrolysis’ and the temperature. CORPORATE TRAINING AND PLANNING

8. Water Soluble polymers: Water soluble polymers cover a wide range of highly varied families of products of natural or synthetic origin, and have numerous uses. The separation of solids in a liquid medium takes place rapidly when the density of the particles is markedly different from that of the liquid medium. Either the particles settle out or they float on top of the liquid. Among these families, synthetic polymers, and more particularly coagulants and flocculants, are used mainly for facilitating the separation of materials in suspension in aqueous media. CORPORATE TRAINING AND PLANNING

9. Synthetic Polymers • Degradable, synthetic polymers that are commonly known in the medical field include poly(a-hydroxy esters), poly(3-caprolactone), poly(ortho esters), polyanhydrides, poly(3-hydroxy butyrate), polyphosphazenes, polydioxanones, polyoxalates, and poly(amino acids). • The linear aliphatic polyester, PLA (XIV) is chemically synthesized by condensation polymerization of the free acid or catalytic ring-opening polymerization of the lactide (dilactone of lactic acid). • The ester linkages in the polymer are sensitive to both enzymatic and chemical hydrolysis. PLA is hydrolyzed by many enzymes including pronase, proteinase K, bromalin, ficin, esterase, and trypsin. • The degradation rate of PLA also varies with varying pH. CORPORATE TRAINING AND PLANNING

10. Continue…. • The amount of lactic acid released during the course of PLA degradation is very small but increases rapidly as PLA is broken down to low molecular weight oligomers. • PLA is primarily considered for medical implants and drug delivery, but broader applications in packaging and consumer goods are also targeted. • An attractive feature of this material is the relatively low cost of the monomer, lactic acid, which can be derived from biomass (fermentation), coal, petroleum, or natural gas. CORPORATE TRAINING AND PLANNING

11. In 1927, Eastman Kodak Co. commercialized cellulose acetate into photographic film base. • Molding grade of CA was introduced in 1935. • In 1938, Eastman introduced CAB. • CAP was introduced in 1960. CORPORATE TRAINING AND PLANNING

12. Polymerization The cellulose esters are prepared by reacting chemical cellulose with organic acids and anhydrides using sulfuric acid as a catalyst. In the standard synthesis of CA, the reaction proceeds with acetic acid and acetic anhydride to the triester stage. CA is prepared by hydrolyzing the triester to remove some of its acetyl groups. Plastic grade CA contains 38 to 40% acetyl. CORPORATE TRAINING AND PLANNING

13. The propionate and butyrate esters are made by substituting propionic acid and propionic anhydride or butyric acid and butyric anhydride for some of the acetic acid and acetic anhydride. • Plastic granules of CAP contain 39 to 47% propionyl and 2 to 9% acetyl. CAB contains 26 to 39% butyryl and 12 to 15% acetyl. CORPORATE TRAINING AND PLANNING

14. When A is and B is Plastic is H H Cellulose —C—CH3 —C—CH3 Cellulose acetate || || O O —C—CH3 —C—CH2—CH3 Cellulose acetate propionate || || O O —C—CH3 —C—CH2—CH2—CH3 Cellulose acetate butyrate || || O O —C—CH2—CH3 —C—CH2—CH3 Cellulose propionate || || O O —CH2—CH3 —CH2—CH3 Ethyl cellulose —NO2 —NO2 Cellulose Nitrate CORPORATE TRAINING AND PLANNING

15. Cellulose Esters Cellulose Acetate Introduction Manufacturing of cellulose acetate was done in 1865 using a process in which cotton was heated with acetic anhydride in sealed tube at 130-1400C but the process was difficult to control. With further research various new techniques of manufacturing of cellulose acetate are developed. CORPORATE TRAINING AND PLANNING

16. One of the methods available today is homogenous acetylation. • In this process cellulose is pretreated with glacial acetic acid to open up the cellulosic matter. • After pretreating, acetylation is done by mixing pretreated cellulose with acetylating agent like acetic anhydride, a catalyst like concentrated sulphuric acid and acetic acid as diluent. CORPORATE TRAINING AND PLANNING

17. Properties - High water absorption - Poor electrical insulation characteristics - Limited aging resistance - Limited heat resistance - Dissolved by wide variety of reagents CORPORATE TRAINING AND PLANNING

18. Properties of Cellulose acetate CORPORATE TRAINING AND PLANNING

19. Applications CA Different applications Spectacles Tool handles CORPORATE TRAINING AND PLANNING

20. Cellulose Acetate Butyrate (CAB) Bleached Wood Pulp + 40-50% H2SO4 Pretreated for 12 hours Drying with Acetic acid Etherification of treated cellulose with mixture of Butyric acid and acetic anhydride + H2SO4 ( Catalyst) Cellulose acetate butyrate CORPORATE TRAINING AND PLANNING

21. Properties -Good toughness - Excellent appearance - Giving good coating with hard glossy surface - Lower water absorption - Better flow properties - Lower density CORPORATE TRAINING AND PLANNING

22. Properties of Cellulose Acetate Butyrate CORPORATE TRAINING AND PLANNING

23. Applications - Toys, tools handles, tabular keys, telephone housing, pipes for conveying water, outdoor display signs, vacuum formed products and protective coating for metals. CORPORATE TRAINING AND PLANNING

24. Cellulose Acetate Propionate - Cellulose Acetate Propionate having shorter side chain and it is harder stiffer, and posses higher tensile strength than Cellulose Acetate Butyrate. - Easy to vacuum form and also tend to be used for applications like tool handles, safety lockers, steering wheels, etc. CORPORATE TRAINING AND PLANNING

25. Properties - Cellulose Acetate Propionate have shorter side chain and it is harder, stiffer and possess higher tensile strength than Cellulose Acetate Butyrate. Like cellulose acetate butyrate, this is easy to vacuum form and also tends to be used for applications like tool handles, safety lockers, steering wheels, etc. CORPORATE TRAINING AND PLANNING

26. Cellulose Nitrate -Cellulose Nitrate is manufactured by the reaction between cellulose, nitric acid and sulphuric acid. - It is possible to vary degree of etherification according to the root hydroxyl group which is replaced by nitrate group. - Fully nitrated cellulose, cellulose tri-nitriate is an explosive. - Cellulose nitrate is precipiticised with camphor in order to make it easy processable. CORPORATE TRAINING AND PLANNING

27. Properties of Cellulose Nitrate Good rigidity Water white transparency Poor chemical resistance Reasonable toughness Capable of forming highly attractive multi-coloured sheeting Highly inflammable. CORPORATE TRAINING AND PLANNING

28. Applications The one time important application was in photographic film. Today the principal outlet are knife handles,table tennis ball and spectacle frames. CORPORATE TRAINING AND PLANNING