Chapter 6. Polymerization conditions and 
           polymer reactions
           6.1. Polymerization in homogeneous systems
           6.2. Polymerization in heterogeneous systems
           6.3. Polymerization reaction engineering
           6.4. Chemical reactions of polymers       
                                 
 
         
	
          
                                 
 
         
	
          
             6.1. Polymerization in homogeneous systems
             The homogeneous polymerization techniques involve pure monomer
             or homogeneous solutions of monomer and polymer is a solvent.
             These techniques can be divided into 2 methods: the bulk and the
             solution polymerizations.
             6.1.1. Bulk polymerization
             Advantages:
             • Bulk polymerizations is the simplest technique and produces the
              highest-purity polymers. 
             • Only monomer, a monomer-soluble initiator (& chain transfer agent 
              to control the molecular weight) are used.
             • This method is practiced widely in the manufacture of condensation 
              polymers. 
                                           
 
            
	
                 
           Advantages:  (continued)
           • Easy polymer recovery and easy for cast polymerization into final
             product forms.
           • The viscosity of the mixture is still low to allow ready mixing, heat transfer,
             and bubble elimination.
           Disadvantages:
           • Free-radical polymerizations are typically highly exothermic. 
           • An increase temperature will increase the pol’n rate, generate heat
             dissipation and a tendency to develop of localized “hot spots”.
           • Near the end of pol’n, the viscosity is very high and difficult to control
             the rate as the heat is “trapped” inside          the termination rate <<<<,
             the propagation rate >>>>, the overall pol’n >>>>, heat production >>>.
                 autoacceleration process (Trommsdroff or gel effect).
           This method is seldom used in commercial manufacture.
           E.g. PS and PMM