Bulk and Solution Polymerization

It consists classification of polymerization techniques. What is bulk polymerization, how will the reaction proceed, and what are the advantages, disadvantages, and applications. Similarly, what is solution polymerization and how it will be carried out, what are the advantages, disadvantages, and applications behind it everything is explained in detail. Some of the related questions are also included for practice. All the contents taken from different websites and books are also mentioned.

1. BULK & SOLUTION Polymerization PRESENTED BY : K. MUTHU KANNAN II M.Sc., Chemistry S.B.K.College Aruppukottai-626101

2. Can be carried out in solid, liquid and gaseous states. Solid state polymerization reactions are slow, therefore these are not much practical use. Gaseous polymerization do not occur under normal conditions, it requires high temperature. Almost all commercial polymerization processes are carried out in liquid state. 2 HOW POLYMERIZATION REACTION CARRIED OUT ?

3. BULK POLYMERIZATION SOLUTION POLYMERIZATION EMULSION POLYMERIZATION SUSPENSION POLYMERIZATION HOMOGENEOUS SYSTEM HETEROGENEOUS SYSTEM POLYMERIZATION TECHNICQUES 3 WHAT ARE THE POLYMERIZATION TECHNICQUES ?

4. BULK POLYMERIZATION 4

5. BULK POLYMERIZATION In mass polymerization, t he whole system remains in a homogeneous phase , because the monomer is taken in the liquid state , the initiator is dissolved in the monomer and the chain transfer agent (if used to control the molecular weight) is also dissolved in the monomer liquid. The reaction mixture is heated or exposed to a UV radiation source for initiating the polymerization and is kept on a rotatory shaker for proper mixing the mass and uniform heat transfer. Only the initiator and the chain transfer agent is used therefore, the product formed has a high degree of purity , i.e., without any contamination of reactant components. 5

6. BULK POLYMERIZATION 6 Polymerization Polymer Monomers Initiators Chain transfer agents Agitator

7. ADVANTAGES It is quite simple and requires simple equipment. Direct utility of the polymer with no isolation requirement. P olymers are of high purity obtained. M inimum chances of contamination. No requirement of additives other than the initiators and the chain transfer agent. Excellent colour and clarity can be obtained. 7

8. DISADVANTAGES V iscosity of the reaction medium increases and its mixing becomes very difficult. D iffusibility of the growing polymer chain gets restricted. Trommsdorff -Norrish effect (Auto-acceleration). P robability of chain collision becomes less and termination causes difficulty. Typically conversion rate is less than 80%. E xcessive heat due to exothermic reaction may lead to an explosion. 8

9. APPLICATIONS 9 Low molecular weight polymers obtained by this method, are used as adhesives, plasticizers and lubricants. Used in casting formulations. Production of methyl methacrylate (MMA) (suspension also), polyamides, polycarbonates, polyethylene (low-density), terephthalate, polycaprolactam (nylon 6). polyamides Polyterephthalate polycaprolactam Poly carbonates

10. SOLUTION POLYMERIZATION 10

11. SOLUTION POLYMERIZATION 11 T he whole system is in a homogeneous phase, because the monomer, chain transfer agent (if used) and initiator are dissolved in an inert suitable solvent , while the ionic or coordination catalysts can either be dissolved or suspended in the solvent medium. The temperature is easily controlled because of the fact that the monomers are dissolved in solvent and the upper limit of the whole system depends upon the boiling point of the solvent. After the reaction is over the polymer is used as such in the form of polymer solution or isolated by evaporating the solvent.

12. SOLUTION POLYMERIZATION 12 Polymerization Polymer Monomers + inert solvent Initiators Chain transfer agents Agitator Ionic or coordination catalyst

13. ADVANTAGES 13 Heat removal is accomplished via solvent reflux. I nert solvent medium helps to control viscosity and promote a uniform heat transfer. Solvent reduces viscosity, making processing easier. Heating and stirring are much easier than the bulk polymerization. Conversion of monomer to polymer is high and typically about 80% - 90%.

14. DISADVANTAGES 14 The method is costly since it uses costly solvents. The polymer produced is low average molecular weight (here solvents act as chain terminators ) and is always contaminated with traces of the solvent. P olymer will also have to be isolated from the solution either by precipitation or by evaporation of the solvent. Environmental pollution due to solvent release. Purity of product is also not as high as that of bulk polymerization.

15. APPLICATIONS 15 P roduction of polyacrylonitrile by free-radical polymerization and also polyisobutylene by cationic polymerization. Exclusively used in the production of block co-polymers. In the solution form, it can be directly u sed as adhesives and coatings. Polyethylene (high density) , polybutadiene, polypropylene, butyl rubber, polystyrene, polyisoprene and polyformaldehyde are produced this way. polypropylene polyformaldehyde polyisoprene polybutadiene

16. QUESTIONS 16 QUESTION: 1 Which of the following monomer mixture is used in bulk polymerization? Undiluted monomer Monomer – solvent mixture Monomer – water mixture None of th e above QUESTION: 2 How is the solvent in solution polymerization, more useful to overcome the disadvantages of bulk polymerization? It reduces the viscosity gain Increases the rate of the reaction Causes chain transfer All of the mentioned

17. QUESTION: 3 Which of the following demerits of solution polymerization? Handling of inflammable solvents Recovery of solvents Chain transfer to solvents All of the mentioned QUESTIONS QUESTION: 4 Which of the following polymerization systems prepared by solution polymerization, is heterogeneous in character? Methyl methacrylate in solvent Acrylonitrile in organic solvents Amides in organic solvent All of the mentioned 17

18. QUESTION: 5 Why does heat dissipation in bulk polymerization becomes progressively difficult with high conversions? Increase in medium viscosity Solubilization of polymer in the monomer Precipitation of polymer in the monomer All of the mentioned QUESTIONS 18 QUESTION: 6 What is disadvantages of bulk polymerization? Hi gh temperature Heat control Need catalyst All of the me ntioned

19. REFERENCES Organic polymer chemistry (2 nd edition) by K.J.SAUNDERS Polymer chemistry (2010 edition) by Alka L. Gupta https://www.researchgate.net/publication/330304320_Solution_Bulk_polymerization https://en.wikipedia.org/wiki/Bulk_polymerization#:~:text=Bulk%20polymerization%20or%20mass%20polymerization,the%20mixture%20becomes%20more%20viscous . https://youtu.be/-5xwKbtThzY https://saylordotorg.github.io/text_general-chemistry-principles-patterns-and-applications-v1.0/s16-08-polymeric-solids.html https://youtu.be/RPwsHgeuL10 https://gacbe.ac.in/pdf/ematerial/18BCH35S-U4.pdf https://www.sanfoundry.com/polymer-engineering-questions-answers-techniques-polymerization1/ https://www.sanfoundry.com/unit-processes-questions-answers-methods-polymerization/ 19

20. Thank you