1. Synthesis of Polylactic acid

2. Production Direct condensation of lactic acid – single step
Ring opening polymerization- Multi step process

3. Feasible process for the commercial production of PLA
by Direct Condensation
Equilibrium between free acid , Water, and polyesters
Difficulty in removing the trace amount of water in the
late stages of polymerization generally limit the ultimate
molecular weight achievable by this approach
To overcome the above
Kinetic control over the reaction
Efficient removal of Water : Reletively high temperatures
Reduced pressure
Entraining agent such as various solvents
Suppresion of Depolymerization

4. Catalysts employed : Protonic acids Metals Metal Oxides Metal halides
Organic salts of metals

5. General properties of Polylactic acid O [CH-C-O]n CH3
Transperancy
Glass Transition temperature C
Melting Point C
Crystallinity : %
Tensile Strength : 4-6 Kg/mm2
Elongation : 3-4 %, brittle
Flexural Strength : 9~11 Kg/mm2
Impact Strength :~50 Kg-cm/cm2

6. Bio-Polymer Production (Cargill-Dow, USA)
Production of Polylactic acid (PLA) polymer from corn sugar replaces petroleum feedstock.
PLA can replace PET, polyesters and polystyrene.
PLA is compostable.
PLA is carbon neutral – CO2 is recycled.
In the future, PLA will be made from ligno-cellulosic biomass.

7. Used for 30 years in medicine:
Background on P.L.A.
Used for 30 years in medicine:
Encapsulation of vaccines
Carrier for slow release medication - treatment of prostate cancer and infertility

8. Polylactic Acid (PLA)
A polymer made from cornstarch fermentation, declared a new generic fiber by the US FTC
Competitive in price and performance with fossil fuel derived polymers: PE, PS, PP, polyester
Can be engineered to be biodegradable
Can be used in carpet tiles
Cargill Dow's new facility in Blair, Nebraska, will use up to 40,000 bushels of corn each day and can produce more than 300 million pounds of PLA each year

9. Cargill-Dow LLC Plant. Blair, Nebraska. November, 2001. Completed
August, 2001
August, 2001
September, 2001
The School of
Packaging
Mechanical, Physical and Barrier
Properties of Poly(Lactic Acid)
RAA, © 2002

10. Main Producers Producer Cargill – Dow LLC 16 300 Mitsui Chemicals 1.3
2000
Million lb/yr*
2001
Million lb/yr **
2002
Million lb/yr**
Cargill – Dow LLC 16
300
Mitsui Chemicals
1.3
Cost U$S / lb
1.5/2.0
1.0
0.5
* Chemical Week V162, 2000 & Plastics Week, Jan17, 2000

11. Polylactic acid (PLA) for plastics production
Corn
Starch
Unrefined
Dextrose
Lactic Acid
Fermentation
Lactide
Monomer Production
Polymer Grades
Fiber
Film
Thermoforming
Bottle
Woven
Non-woven
Etc.
Polymer
Modification
Polymer
Production
PLA

12. Polymerization scheme of copolymers
from L-lactic acid and D-lactic acid

13. Recent development of biodegradable sutures

14. Non-Solvent Process to Prepare PLA
Fermentation
By heating catalyst.
Lactide Formation
Lactic
Acid
Prepolymer
Distillation
Unconverted Polymer
Meso
Lactide
Dextrose
PLA
Polymer
Polymerization
Distillation
Coordination / Insertion Propagation
Low D
Lactide
Corn
Cargill Dow LLC Process. Gruber, et. al

15. Biodegradable polymers approved
for medical applications

17. PGA – Polyglycolic acid, PLA – Polylactic acid, PLGA – Copolymer of PLA & PGA

18. Initial cost of PLA was too high that has limited its
packaging applications to high value films, thermoformed
containers, and coated papers .
PLA has a largest potential market because it is a compostable
and biodegradable thermoplastic.
Derived from annually renewable agricultural resources .
New technologies for mass production of PLA promise
to lower its cost and widen its packaging applications,
to include food packaging .
PLA can be fabricated on a variety of familiar processes .
There is a need to better understand its behavior and properties
to be fully adapted in packaging applications.

19. Scheme 1 : Generalized flow sheet for the production of PLA from agricultural waste. 

26. Synthesis of Polylactic acid over
Solid acid catalyst

27. Characterization of Polylactic acid :
Experimental Section
Lactic acid (LA) is a 85% aqueous solution of the monomer
Catalyst Tungastophosphoric acid H3 [ P(W3O10) 4 ] x H2O (HPA) is
heated at 1500C for 3 hours.
The following products were used without any further treatment
Chloroform-d1 with TMS (1%) (deuteration degree not less than 99.5%) from Merck
for NMR measurements.
Characterization of Polylactic acid :
IR, TGA, DSC 13C NMR and GPC

28. Schematic Representation
10 gms of Lactic Acid
40 mg of HPA
H3 [ P(W3O10) 4 ]
Vessel with Dean Stark Trap
Continuous flow of N2
Stirred at 1500C for 3 hrs
Viscous liqiud
Poured into 100ml of methanol
Precipitate
Filterd & Dried
PLA

29. Experimental set up for the synthesis of polylactic acid
Dean stark trap
Water removed through dean stark trap
Continuous purging of N2 gas

30. Infrared Spectral Analysis of PLA
-C=O
-C-O
1759
1092

31. 13C NMR Analysis of PLA
CDCl3

32. 13C NMR Analysis of PLA δ 169.5 ( δ 69.0 ( O=C O C H-) δ 16.6 (
CDCl3
13C NMR of PLA ( Solvent CDCl3)
δ (
δ ( O=C O C H-)
δ (
C=O )
CH3 )

33. Thermo Gravimetric Analysis of PLA
PLA prepared at 1500C

34. Differential Scanning Calorimetric Analysis of PLA
Tg = 560 C
Tm = 1300C

35. Thermo Gravimetric Analysis of PLA prepared at 1800C

36. Gel Permeation Chromatography Analysis
Wt Molecular weight

37. Polymerization of lactic acid by using various catalysts

38. Comparison with conventional catalyst
Temperature
(0C)
Mw(g/mol)
GPC
H2SO4*
(Conventional)
HPW#
180
200
220
150
31000
30600
32600
42496
* reaction duration -12 h
# reaction duration -3 h

39. Condensation polymerization
Table 1 Summary of the catalysts used for polymerization of Lactic acid
Condensation polymerization
S.No
Catalyst
Weight % of catalysts
Temp K
MW(g/mol) 1 2 3 4 5 6
Tolune sulphonic acid
Sulphuric acid
Boric acid
Phosphoric acid
Nafion-H
Methyl sulphonic acid
1,2.5
0.1to 1.5,2.5
0.1,2.5
2.0
2.5
,403
373,403
453,473,
433
403
1458
100000
31000,65000
3800,6500
4000
20000

40. Ringopening polymerization1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
ZnCl2
Al(acac)
Sn(II)octoate
Sb2O3
Ti(IV)butylate
Ti(IV)isopropylate
Dibutyltin dilaurate (DBTL)
Stannous octoate
Tetraphenyltin Mg Al Zn Sn
TiO2
ZnO
GeO2
ZrO2
SnO
SnCl2
SnCl4
Mn(AcO)2
Fe2(LA)3
Co(AcO)2
Ni (AcO)2
Cu (AcO)2
Zn(LA)2
Y(OA)3
Al(iPrO)3
Ti (BuO)4
TiO(acac)2
(Bu)2SnO
0.1
0.05
0.01
0.5
0.83
0.62
0.72
0.68
0.57
0.80
1.10
1.57
1.70
1.50
1.51
2.75
1.86
2.92
3.79
3.55
2.74
1.05
353
451
433
403
4700
3600
8000
10800
15000
9000
6700
,000
,000
2100
5400
35000
230000
1600
20000
1300
1500
29000
19000
27000
32000
1900
7000
13000

41. Table .2. Typical applications of PLA
Processes
End Products
Non woven fibres
Personal hygiene, protective clothing, filtration
Oriented films
Container labels, tape
Extrusion coatings
Dinnerware, food packaging, mulch film
Flexible film
Food wrap, trash bags, shrink wrap
Cast sheet
Delivery trays
Injection moulding
Rigid containers, Dairy containers
foam
Clam shells, meat trays

42. Salient features
Developed process utilizes a noncorrosive, environmentally friendly
Solid acid catalyst
The reaction temperature is decreased from 1800C to 1500C
The reaction duration is three hours – obtained required
Molecular weight
The solid acid can be completely recovered and regenerated.
The physico-chemical properties of PLA can be widely tunned according
to the requirements i.e by changing various solid acid strength