X Contents 2.3 Kinetics of Step-Growth Polymerization. 49 2.3.1 Catalyzed step-Growth Reactions..50 2.3.2 How Should Experimental Data Be Compared with Theoretical Rate Laws?....52 2.3.3 Uncatalyzed Step-Growth Reactions....53 2.4 Distribution of Molecular Sizes.............. 55 2.4.1 Mole Fractions of Species.... 56 2.4.2 Weight Fractions of Species .58 2.5 Polyesters 60 2.6 Polyamides. …64 2.7 Stoichiometric Imbalance. 67 2.8 Chapter Summary....... 71 Problems....... 71 References.... 76 Further Readings......... 76 3 Chain-Growth Polymerization..77 3.1 Introduction......... 77 3.2 Chain-Growth and Step-Growth Polymerizations:Some Comparisons.................77 3.3 nitiati0n............. .79 3.3.1 Initiation Reactions................ 80 3.3.2 Fate of Free Radicals....... 81 3.3.3 Kinetics of Initiation. 82 3.3.4 Photochemical Initiation.84 3.3.5 Temperature Dependence of Initiation Rates.....85 3.4 Termination. .86 3.4.1 Combination and Disproportionation...... 86 3.4.2 Effect of Termination on Conversion to Polymer...... 88 3.4.3 Stationary-State Radical Concentration............. .89 3.5 Propagation .90 3.5.1 Rate Laws for Propagation....... 91 3.5.2 Temperature Dependence of Propagation Rates... .92 3.5.3 Kinetic Chain Length.................. .94 3.6 Radical Lifetime........... .96 3.7 Distribution of Molecular Weights..99 3.7.1 Distribution of i-mers:Termination by Disproportionation.................99 3.7.2 Distribution of i-mers:Termination by Combination............102 3.8 Chain 3.8.1 Chain Transfer Reactions..105 3.8.2 Evaluation of Chain Transfer Constants..106 3.8.3 Chain Transfer to Polymer.108 3.8.4 Suppressing Polymerization.109 3.9 Chapter Summary. .110 Problems… .110 References.… .114 Further Readings.... .1152.3 Kinetics of Step-Growth Polymerization ...................................................................... 49 2.3.1 Catalyzed Step-Growth Reactions.....................................................................50 2.3.2 How Should Experimental Data Be Compared with Theoretical Rate Laws? .....................................................................................52 2.3.3 Uncatalyzed Step-Growth Reactions.................................................................53 2.4 Distribution of Molecular Sizes .................................................................................... 55 2.4.1 Mole Fractions of Species .................................................................................56 2.4.2 Weight Fractions of Species..............................................................................58 2.5 Polyesters ....................................................................................................................... 60 2.6 Polyamides ..................................................................................................................... 64 2.7 Stoichiometric Imbalance .............................................................................................. 67 2.8 Chapter Summary .......................................................................................................... 71 Problems .................................................................................................................................. 71 References................................................................................................................................ 76 Further Readings...................................................................................................................... 76 3 Chain-Growth Polymerization....................................................................77 3.1 Introduction.................................................................................................................... 77 3.2 Chain-Growth and Step-Growth Polymerizations: Some Comparisons....................... 77 3.3 Initiation......................................................................................................................... 79 3.3.1 Initiation Reactions............................................................................................80 3.3.2 Fate of Free Radicals.........................................................................................81 3.3.3 Kinetics of Initiation..........................................................................................82 3.3.4 Photochemical Initiation....................................................................................84 3.3.5 Temperature Dependence of Initiation Rates....................................................85 3.4 Termination.................................................................................................................... 86 3.4.1 Combination and Disproportionation ................................................................86 3.4.2 Effect of Termination on Conversion to Polymer ............................................88 3.4.3 Stationary-State Radical Concentration ............................................................89 3.5 Propagation .................................................................................................................... 90 3.5.1 Rate Laws for Propagation ................................................................................91 3.5.2 Temperature Dependence of Propagation Rates...............................................92 3.5.3 Kinetic Chain Length.........................................................................................94 3.6 Radical Lifetime ............................................................................................................ 96 3.7 Distribution of Molecular Weights................................................................................ 99 3.7.1 Distribution of i-mers: Termination by Disproportionation .............................99 3.7.2 Distribution of i-mers: Termination by Combination.....................................102 3.8 Chain Transfer ............................................................................................................. 104 3.8.1 Chain Transfer Reactions ................................................................................105 3.8.2 Evaluation of Chain Transfer Constants .........................................................106 3.8.3 Chain Transfer to Polymer ..............................................................................108 3.8.4 Suppressing Polymerization ............................................................................109 3.9 Chapter Summary ........................................................................................................ 110 Problems ................................................................................................................................ 110 References.............................................................................................................................. 114 Further Readings.................................................................................................................... 115 Hiemenz/ Polymer Chemistry, 2nd Edition DK4670_C000 Final Proof page x 5.11.2007 8:20pm Compositor Name: JGanesan x Contents