polymer reaction engineering

Polymer Reaction Engineering Edited by José M. Asua Professor of Chemical Engineering Institute for Polymer Materials (POLYMAT) The University of the Basque Country, Spain Polymer Reaction Engineering Polymer Reaction Engineering Edited by José M. Asua Professor of Chemical Engineering Institute for Polymer Materials (POLYMAT) The University of the Basque Country, Spain ©2007 by Blackwell Publishing Ltd Blackwell Publishing Editorial Offices: Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK Tel: +44 (0)1865 776868 Blackwell Publishing Professional, 2121 State Avenue, Ames, Iowa 50014-8300, USA Tel: +1 515 292 0140 Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia Tel: +61 (0)3 8359 1011 The right of the Author to be identified as the Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. First published 2007 by Blackwell Publishing Ltd ISBN: 978-1-4051-4442-1 Library of Congress Cataloging-in-Publication Data Polymer reaction engineering / edited by José M. Asua. p. cm. Includes bibliographical references and index. ISBN-13: 978-1-4051-4442-1 (alk. paper) ISBN-10: 1-4051-4442-4 (alk. paper) 1. Polymerization. 2. Polymers. I. Asua, José M. TP1087.P653 2007 668.9  2–dc22 2007060685 A catalogue record for this title is available from the British Library Set in 10/12 Minion by Newgen Imaging Systems (P) Ltd, Chennai, India Printed and bound in Malaysia by KHL Printing Co Sdn Bhd The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. For further information on Blackwell Publishing, visit our website: www.blackwellpublishing.com Contents Contributors xi Preface xiii Notation xv Acronyms xxi 1 Introduction to Polymerization Processes 1 José M. Asua 1.1 Microstructural features of polymers and their effect on properties 1 1.1.1 Chemical composition and monomer sequence distribution 1 1.1.2 Molecular weight distribution 2 1.1.3 Polymer architecture 4 1.1.4 Chain configuration 7 1.1.5 Morphology 7 1.1.6 Effect of processing and compounding on the microstructure of the polymeric materials 8 1.2 Classes of polymerizations 9 1.2.1 Chain-growth polymerization 9 1.2.2 Step-growth polymerization 14 1.3 Polymerization techniques 16 1.4 Main commercial polymers 18 1.4.1 Polyolefins 18 1.4.2 Styrenic polymers 20 1.4.3 Poly(vinyl chloride) 21 1.4.4 Waterborne dispersed polymers 21 1.4.5 Polyesters and polyamides 22 1.4.6 Thermosets 22 1.5 Polymerization reactors 23 References 27 vi Contents 2 Coordination Polymerization 29 João B.P. Soares, Timothy McKenna and C.P. Che ng 2.1 Polyolefin types: microstructural classification and analytical techniques 30 2.1.1 Polyethylene types 31 2.1.2 Polypropylene types 36 2.1.3 Polyolefin microstructural characterization techniques 39 2.2 Catalysts for olefin polymerization 43 2.2.1 Coordination catalyst types 43 2.2.2 Polymerization mechanism 49 2.3 Polymerization kinetics for sing le- and multiple-site catalysts 54 2.3.1 Homopolymerization 57 2.3.2 Copolymerization 75 2.3.3 Long-chain branch formation 83 2.4 Inter- and intraparticle mass and heat transfer resistances 86 2.4.1 Particle fragmentation and morphology control 87 2.4.2 Single particle models: inter- and intraparticle mass and heat transfer 90 2.5 Industrial olefin polymerization reactors 99 2.5.1 Reactor configurations and designs 100 2.5.2 Polyethylene manufacturing processes 104 2.5.3 Polypropylene manufacturing processes 109 2.5.4 Mathematical models for industrial reactors 112 Acknowledgments 115 References 115 3 Free-Radical Polymer ization: Homogeneous Systems 118 Robin A. Hutchinson and Alexander Penlidis 3.1 Free-radical polymers: properties and applications 118 3.2 FRP mechanisms and kinetics 119 3.2.1 Homopolymerization 119 3.2.2 Copolymerization 137 3.2.3 Diffusion-controlled reactions 144 3.2.4 Kinetic balances for modeling polymer MWs 147 3.3 Controlled radical polymerization 151 3.3.1 Stable free-radical polymerization 153 3.3.2 Atom transfer radical polymerization 154 3.3.3 Reverse addition-fragmentation chain transfer polymerization 155 3.4 Polymer reaction engineering aspects 156 3.4.1 Heat removal and temperature programming 156 3.4.2 Batch reactors 159 3.4.3 Semibatch (semicontinuous) reactors 161 3.4.4 Continuous stirred-tank reactors 163 3.4.5 Tubular reactors 168 Contents vii 3.5 A “roadmap” for mathematical modeling 171 References 174 4 Free-Radical Polymerization: Heterogeneous Systems 179 Gregorio R. Meira and Costas Kiparissides 4.1 Introduction 179 4.2 High-impact polystyrene 179 4.2.1 Interrelationship between microstructure and application properties 182 4.2.2 Modeling HIPS polymerization 187 4.2.3 Optimizing final properties: melt flow index in a continuous HIPS process 194 4.2.4 Final remarks for HIPS 195 4.3 Vinyl chloride monomer bulk polymerization 195 4.3.1 Kinetic mechanism 197 4.3.2 PVC morphology 201 Acknowledgments 206 References 206 5 Suspension Polymerization 209 Costas Kotoulas and Costas Kiparissides 5.1 Introduction 209 5.2 Surface active agents 212 5.3 Mixing phenomena 214 5.4 The “bead” suspension polymerization process 216 5.5 The “powder” suspension polymerization process 217 5.6 Population balance modeling 220 5.6.1 The drop breakage process 220 5.6.2 The drop coalescence process 223 5.6.3 Numerical solution of the PBE 224 5.7 Physical properties and phase equilibrium calculations 224 5.7.1 Physical and transport properties 224 5.7.2 Phase equilibrium calculations 225 5.8 Effect of operating conditions on PSD 227 5.9 Scale-up of suspension polymerization reactors 227 References 230 6 Emulsion Poly merization 233 María J. Barandiaran, José C. de la Cal and José M. Asua 6.1 Main products and markets 233 6.2 Microstructural features and their effect on properties 234 6.3 Emulsion polymerization fundamentals 236 6.3.1 Description of the process 236 6.3.2 Mechanisms, thermodynamics and kinetics 240 viii Contents 6.4 Reactor engineering 256 6.4.1 Emulsion polymerization reactors 256 6.4.2 Predicting the performance of emulsion polymerization reactors 258 6.4.3 Implementation of emulsion polymerization 261 6.4.4 Residual monomer and VOC removal 265 6.4.5 Scale-up 267 6.5 Related processes 267 6.5.1 Inverse emulsion polymerization 267 6.5.2 Miniemulsion polymerization 268 6.5.3 Microemulsion polymerization 268 6.5.4 Dispersion polymerization 268 References 269 7 Step-Growth Polymerization 273 Kyu Yong Choi and Kim B. McAuley 7.1 Introduction 273 7.1.1 Examples of commercially important polymers produced by step-growth polymerization 273 7.1.2 Basic properties of step-growth polymerization processes 276 7.2 Polymerization kinetics and modeling 278 7.2.1 Reaction kinetics and the most probable distribution 279 7.2.2 Effect of non-stoichiometric composition 282 7.2.3 Molecular weight development in non-linear step-growth polymerization 285 7.3 Industrial step-growth products, processes and modeling 290 7.3.1 Poly(ethylene terephthalate) production and modeling 291 7.3.2 Polyamide production processes and modeling 300 7.4 Summary 312 References 313 8 Control of Polymerization Reactors 315 José R. Leiza and José C. Pinto 8.1 Characterization of the control problem 315 8.2 Classical polymerization reaction control problems 316 8.2.1 Control of reaction rates and of reactor temperature 316 8.2.2 Control of monomer conversion and polymer production 318 8.2.3 Control of molecular weight averages and MWDs 319 8.2.4 Control of copolymer composition 320 8.2.5 Control of particle size and PSDs 320 8.2.6 Control of other reaction parameters 321 8.3 On-line monitoring 322 8.3.1 Introduction 322 8.3.2 On-line sensors for monitoring polymer quality 323 8.3.3 State estimation 330 [...]... of polymerizations Table 1.3 summarizes the different types of polymerizations [8] Chain-growth polymerization involves chain growth by reaction of an active polymer chain with single monomer molecules In step-growth polymerization, polymer growth involves reactions between macromolecules In addition, non-polymeric byproducts may be formed in both types of polymerization However, condensative chain polymerization... of blocks of varying monomer composition The blocks forming the block copolymer can be different homopolymers, a combination of homopolymers and copolymers or copolymers of different chemical composition A gradient copolymer is formed by polymer chains whose composition changes gradually along the chain A graft copolymer is a polymer comprising molecules with one or more blocks connected to the backbone... dead polymer chains of length n [mol] dead polymer chains of length n with b branching points [mol] dead polymer chains of length n with terminal insaturation [mol] dead polymer chain with an internal double bond [mol] number-average degree of polymerization instantaneous number average degree of polymerization number-average degree of polymerization of branched polymers weight-average degree of polymerization... the polymer The reaction of monomers to form a polymer is termed polymerization The molecular and morphological characteristics of the polymer depend on the formulation (monomers, catalysts, initiators, etc.), the polymerization process (reactor, polymerization technique) and the process conditions (concentrations, temperature, time) 1.1.1 Chemical composition and monomer sequence distribution Homopolymers... in the production of polymeric materials Copolymers differ in the sequence arrangements of the monomer units in the copolymer chain In terms of MSD, different classes of copolymers can be distinguished (Table 1.1) Statistical copolymers are copolymers in which the sequential distribution of the monomeric units obeys known statistical laws Strictly speaking, random copolymers are copolymers formed following... coordination polymerization, which is the highest tonnage polymerization process, is discussed first The following chapters present the production of polymers by free-radical polymerization in homogeneous, heterogeneous and dispersed (suspension and emulsion) media Afterwards, the reaction engineering of step-growth polymerization is discussed The last chapter is devoted to the control of polymerization... architecture, polymers can be classified as linear, branched and crosslinked polymers (Table 1.2) In the linear polymers, the structural units are arranged in a linear sequence Branched polymers may have short and long branches Branched polymers include comblike and star polymers Extensive branching may lead to a dendritic structure Introduction to Polymerization Processes 5 Table 1.2 Polymer architectures... vast majority of the polymers are produced using a few classes of polymerizations (coordination polymerization, free-radical polymerization and step-growth polymerization) The type of polymerization determines not only the kind of polymer obtained, but also the reactor configuration and the way in which the process is conducted Therefore, the book is organized according to the type of polymerization The... active center: • • • • Coordination polymerization (active center is an active site of a catalyst) Free-radical polymerization (active center is a radical) Anionic polymerization (active center is an anion) Cationic polymerization (active center is a cation) Table 1.3 Types of polymerizations Chain-growth polymerization Step-growth polymerization Pn + M → Pn+1 (chain polymerization) polystyrene Pn + Pm... Graft Controlled radical polymerization (CRP) Free-radical polymerization Styrene/acrylonitrile, polybutadiene Ionic polymerization Free-radical polymerization Free-radical polymerization Polymerization method Examples Styrene, butyl acrylate Styrene, butadiene Styrene, maleic anhydride Methyl methacrylate, butyl acrylate Comonomers/reactants a For unspecified or unknown copolymers the name is poly(monomer . Polymer Reaction Engineering Edited by José M. Asua Professor of Chemical Engineering Institute for Polymer Materials (POLYMAT) The University of the Basque Country, Spain Polymer Reaction Engineering Polymer. classes of polymerizations (coordination polymerization, free-radical polymerization and step-growth polymeriza- tion). The type of polymerization determines not only the kind of polymer obtained,. 9 1.2.1 Chain-growth polymerization 9 1.2.2 Step-growth polymerization 14 1.3 Polymerization techniques 16 1.4 Main commercial polymers 18 1.4.1 Polyolefins 18 1.4.2 Styrenic polymers 20 1.4.3 Poly(vinyl