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picture1_Bulk Polymerization Example 91561 | Fispol6


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File: Bulk Polymerization Example 91561 | Fispol6
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 ...

icon picture PDF Filetype PDF | Posted on 16 Sep 2022 | 3 years ago
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           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
                                           
 
            	
                 
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...Chapter polymerization conditions and polymer reactions in homogeneous systems heterogeneous reaction engineering chemical of polymers the techniques involve pure monomer or solutions is a solvent these can be divided into methods bulk solution polymerizations advantages simplest technique produces highest purity only soluble initiator chain transfer agent to control molecular weight are used this method practiced widely manufacture condensation continued easy recovery for cast final product forms viscosity mixture still low allow ready mixing heat bubble elimination disadvantages free radical typically highly exothermic an increase temperature will pol n rate generate dissipation tendency develop localized hot spots near end very high difficult as trapped inside termination overall production autoacceleration process trommsdroff gel effect seldom commercial e g ps pmm...

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