This book describes the synthesis, properties, and processing methods of poly(lactic acid) (PLA), an important family of degradable plastics. As the need for environmentally-friendly packaging materials increases, consumers and companies are in search for new materials that are largely produced from renewable resources, and are recyclable. To that end, an overall theme of the book is the biodegradability, recycling, and sustainability benefits of PLA. The chapters, from a base of international expert contributors, describe specific processing methods, spectroscopy techniques for PLA analysis, and and applications in medical items, packaging, and environmental use.

Table of Contents:
Preface xvii Contributors xxi Part I Chemistry and Production of Lactic Acid, Lactide, and Poly(Lactic Acid) 1 1 Production and Purification of Lactic Acid and Lactide 3 Wim Groot, Jan van Krieken, Olav Sliekersl, and Sicco de Vos 1.1 Introduction 3 1.2 Lactic Acid 4 1.2.1 History of Lactic Acid 4 1.2.2 Physical Properties of Lactic Acid 4 1.2.3 Chemistry of Lactic Acid 4 1.2.4 Production of Lactic Acid by Fermentation 5 1.2.5 Downstream Processing/Purification of Lactic Acid 8 1.2.6 Quality/Specifications of Lactic Acid 10 1.3 Lactide 10 1.3.1 Physical Properties of Lactide 10 1.3.2 Production of Lactide 11 1.3.3 Purification of Lactide 13 1.3.4 Quality and Specifications of Polymer-Grade Lactide 14 1.3.5 Concluding Remarks on Polymer-Grade Lactide 16 References 16 2 Chemistry and Thermodynamic Properties of Lactic Acid and Lactide and Solvent Miscibility 19 Zhengyu Jin, Yaoqi Tian, and Jinpeng Wang 2.1 General Properties 19 2.1.1 Physical and Chemistry Properties of Lactic Acid 19 2.1.2 Physical and Chemical Properties of Lactide 19 2.2 Thermodynamic Properties 19 2.2.1 Vapor Pressures of Lactic Acids at Different Temperatures 19 2.2.2 Temperature Dependence of Densities of Lactic Acid 20 2.2.3 Temperature Dependence of Viscosity of Lactic Acid 20 2.2.4 Thermodynamic Properties 21 2.3 Miscibility Properties of Lactic Acid and Lactide 21 2.3.1 Miscibility of Lactic Acid with Different Solvents 21 2.3.2 Miscibility of Lactic Acid with Modifiers in Diluents 21 2.3.3 Physical and Chemical Equilibrium of Lactic Acid 22 2.3.4 Miscibility of Lactide with Solvents 25 References 25 3 Industrial Production of High Molecular Weight Poly(Lactic Acid) 27 Anders Södergård and Mikael Stolt 3.1 Introduction 27 3.2 Lactic Acid Based Polymers by Polycondensation 28 3.2.1 Direct Condensation 29 3.2.2 Solid-State Polycondensation 30 3.2.3 Azeotropic Dehydration 31 3.3 Lactic Acid Based Polymers by Chain Extension 32 3.3.1 Chain Extension with Diisocyanates 32 3.3.2 Chain Extension with Bis-2-oxazoline 33 3.3.3 Dual Linking Processes 34 3.3.4 Chain Extension with Bis-epoxies 34 3.4 Lactic Acid Based Polymers by Ring-Opening Polymerization 34 3.4.1 Polycondensation Processes 35 3.4.2 Lactide Manufacturing 35 3.4.3 Ring-Opening Polymerization 36 References 37 4 Design and Synthesis of Different Types of Poly(Lactic Acid) 43 Ann-Christine Albertsson, Indra Kumari Varma, Bimlesh Lochab, Anna Finne-Wistrand, and Kamlesh Kumar 4.1 Introduction 43 4.2 Copolymerization 43 4.2.1 Synthesis of Copolymers of Lactic Acid: Glycolic Acid 44 4.2.2 Synthesis of Copolymers of Lactic Acid: Poly(ethylene glycol) 44 4.2.3 Synthesis of Copolymers of Lactic Acid: d-Valerolactone and Lactic Acid: b-Butyrolactone 45 4.2.4 Synthesis of Copolymers of Lactic Acid: e-Caprolactone 46 4.2.5 Synthesis of Copolymers of Lactic Acid: 1,5-Dioxepan-2-one 46 4.2.6 Synthesis of Copolymers of Lactic Acid: Trimethylene Carbonate 46 4.2.7 Synthesis of Copolymers of Lactic Acid: Poly(N-isopropylacrylamide) 47 4.2.8 Synthesis of LA: Alkylthiophene (P3AT) Copolymers 47 4.2.9 Functional Poly(lactic acid) 47 4.2.10 Branched Copolymers 48 4.3 Properties of Copolymers 53 4.3.1 Degradation of Homo- and Copolymers 54 4.3.2 Drug Delivery from PLLA Copolymers 54 4.3.3 Radiation Effects 55 References 55 5 Structure and Properties of Stereocomplex-Type Poly(lactic acid) 59 Masayuki Hirata and Yoshiharu Kimura 5.1 Introduction 59 5.2 Formation of Stereocomplex Crystals 59 5.3 Thermal Properties of sc-PLA 60 5.4 Crystal Structure of sc-PLA 60 5.4.1 Unit Cell Parameters and Molecular Conformation of sc-PLA 60 5.4.2 Density and Heat of Fusion of Sccrystals 60 5.5 Formation of sb-PLA 61 5.5.1 ROP Routes to Diblock and Multiblock sb-PLA 61 5.5.2 SSP Routes to Multiblock sb-PLA 63 5.6 Applications of sc-PLA 64 References 65 Part II Properties of Poly(Lactic Acid) 67 6 Chemical Structure of Poly(lactic acid) 69 Xue Jiang, Yan Luo, Xiuzhi Tian, Dan Huang, Narendra Reddy, and Yiqi Yang 6.1 Introduction 69 6.2 Chain Structure and Configuration 69 6.2.1 Chain Structure 69 6.2.2 Configuration 70 6.2.3 Interlocked Structure, Polymer Blend, and Resistance to Hydrolysis 71 6.3 Syndiotactic Polymerization and Syndiotacticity 72 6.4 Conformation 74 6.5 Amorphous Structure and Thermal Properties 74 6.5.1 Amorphous and Three-Phase Models 74 6.5.2 Glass Transition 75 6.6 Orientation Structure of PLA 77 6.6.1 Mechanical Orientation by Stretching or Compression 77 6.6.2 Thermal Orientation (Phase Transition) 77 6.7 Semicrystalline Structure 78 6.7.1 General 78 6.7.2 Three Forms (a, b and c) of the Crystal Structure 78 6.8 Frustrated Structure 79 6.9 Molecular Weight 80 6.10 Summary 80 References 80 7 Chemical Compatibility of Poly(lactic acid): A Practical Framework Using Hansen Solubility Parameters 83 Steven Abbott 7.1 A Practical Framework 83 7.1.1 Thermodynamics Versus Kinetics 83 7.1.2 Hansen Solubility Parameters 83 7.2 Solvent Compatibility 84 7.3 Plasticizers 86 7.4 Polymer Compatibility 87 7.5 Environmental Stress Cracking 89 7.6 Rational Composite Design 89 7.7 Diffusion and Barrier Properties 90 7.7.1 Gases 91 7.7.2 Water 91 7.8 Pharmacological Transport 93 7.9 Summary 93 References 94 8 Optical Properties 97 Carla M. B. Gonçalves, João A. P. Coutinho, and Isabel M. Marrucho 8.1 Introduction 97 8.2 Absorption and Transmission of UV-Vis Radiation 97 8.3 Refractive Index 99 8.4 Specific Optical Rotation 100 8.5 Infrared and Raman Spectroscopy 100 8.5.1 Infrared Spectroscopy 101 8.5.2 Raman Spectroscopy 105 8.6 1H and 13C NMR Spectroscopy 108 References 111 9 Crystallization and Thermal Properties 113 Luca Fambri and Claudio Migliaresi 9.1 Introduction 113 9.2 Crystallinity and Crystallization 114 9.3 Crystallization Regime 118 9.4 Fibers 119 9.5 Hydrolytic Degradation 121 References 123 10 Rheology of Poly(lactic acid) 125 John R. Dorgan 10.1 Introduction 125 10.2 Fundamental Chain Properties from Dilute Solution Viscometry 126 10.2.1 Unperturbed Chain Dimensions 126 10.2.2 Real Chains 126 10.2.3 Solution Viscometry 127 10.2.4 Viscometry of PLA 128 10.3 Processing of PLA: General Considerations 130 10.4 Melt Rheology: An Overview 131 10.5 Processing of PLA: Rheological Properties 132 10.6 Conclusions 137 Appendix 10.A Description of the Software 138 References 138 11 Mechanical Properties 141 Gabriele Perego and Gian Domenico Cella 11.1 Introduction 141 11.2 General Mechanical Properties and Molecular Weight Effect 141 11.2.1 Tensile and Flexural Properties 141 11.2.2 Impact Resistance 143 11.2.3 Hardness 143 11.3 Temperature Effect 143 11.4 Annealing 144 11.5 Orientation 147 11.6 Stereoregularity 148 11.7 Plasticization 149 11.8 Relaxation and Aging 151 11.9 Conclusions 152 References 152 12 Permeation, Sorption, and Diffusion in Poly(lactic acid) 155 Eva Almenar and Rafael Auras 12.1 Introduction 155 12.2 Factors Affecting Permeability, Sorption, and Diffusion in PLA 157 12.2.1 L-Lactide Unit Content 157 12.2.2 Plasticizers 158 12.2.3 Crystallization 159 12.2.4 Orientation 160 12.2.5 Free volume 160 12.2.6 Branching 160 12.2.7 Environmental Factors 161 12.3 Permeability, Sorption, and Diffusion of Pure PLA 163 12.3.1 Gases 163 12.3.2 Water Vapor 165 12.3.3 Organics 167 12.4 Copolymers 169 12.5 PLA Blends 169 12.5.1 PLA/Starch Blends 169 12.5.2 PLA/Poly(€-caprolactone) Blends 170 12.5.3 PLA/Chitosan Blends 171 12.5.4 PLA/Poly((R)-3-hydroxybutyrate) Blends 171 12.6 PLA Laminations 171 12.7 Coated PLA 171 12.8 PLA Composites and Fibers 171 12.8.1 PLA Composites 172 12.8.2 Fiber-Reinforced PLA 172 12.9 PLA Nanocomposites 172 12.10 Future of PLA Membranes 176 References 176 13 Migration 181 Herlinda Soto-Valdez 13.1 Migration Principles 181 13.2 Legislation 182 13.3 Migration and Toxicological Data of Lactic Acid, Lactide, Dimers and Oligomers 182 13.3.1 Lactic Acid 182 13.3.2 Lactide 186 13.3.3 Oligomers 186 13.4 EDI of Lactic Acid 187 13.5 Other Potential Migrants from PLA 187 13.6 Conclusions 187 References 188 Part III Processing and Conversion of Poly(Lactic Acid) 189 14 Processing of Poly(lactic acid) 191 Loong-Tak Lim, Kevin Cink, and Tim Vanyo 14.1 Introduction 191 14.2 Properties of PLA Relevant to Processing 191 14.3 Modification of PLA Properties by Process Aids and Other Additives 193 14.4 Drying 194 14.5 Extrusion 195 14.6 Injection Molding 196 14.7 Film and Sheet Casting 201 14.8 Stretch Blow Molding 204 14.9 Extrusion Blown Film 207 14.10 Thermoforming 208 14.11 Electrospinning 209 14.12 Conclusion: Prospects of PLA Polymers 211 References 213 15 Poly(lactic acid)/Starch Blends 217 Long Yu, Eustathios Petinakis, Katherine Dean, and Hongshen Liu 15.1 Introduction 217 15.2 Blending Hydrophobic PLA with Hydrophilic Starch 218 15.3 Compatibilizers Used for Starch/PLA Blends 219 15.4 Enhancing Function of Compatibilizer by Controlling Compatibilizer Distribution 220 15.5 Reactive Blending 223 15.6 Summary 225 References 225 16 Poly(lactic acid) Blends 227 Sukeewan Detyothin, Ajay Kathuria, Waree Jaruwattanayon, Susan E. M. Selke, and Rafael Auras 16.1 Introduction 227 16.2 PLA/Nonbiodegradable Polymer Blends 227 16.2.1 Polyolefins 228 16.2.2 Vinyl and Vinylidene Polymers and Copolymers 229 16.2.3 Elastomers and Rubbers 238 16.2.4 PMMA/PLA Blends 239 16.3 PLA/Biodegradable Polymer Blends 240 16.3.1 Polyanhydrides 240 16.3.2 Vinyl and Vinylidene Polymers and Copolymers 242 16.3.3 Aliphatic Polyesters and Copolyesters 244 16.3.4 Aliphatic-Aromatic Copolyester 255 16.3.5 Elastomers and Rubbers 257 16.3.6 Poly(ester amide) 258 16.3.7 Polyethers and Copolymer 258 16.3.8 Annually Renewable Biodegradable Materials 261 16.4 Plasticization of PLA 264 16.5 Conclusion 266 References 266 17 Foaming 273 Laurent M. Matuana 17.1 Introduction 273 17.2 Plastic Foams 273 17.3 Foaming Agents 274 17.3.1 Physical Foaming Agents 274 17.3.2 Chemical Foaming Agents 274 17.4 Formation of Cellular Plastics 275 17.4.1 Dissolution of Blowing Agent in Polymer 275 17.4.2 Bubble Formation 275 17.4.3 Bubble Growth and Stabilization 276 17.5 Plastic Foams Expanded with Physical Foaming Agents 276 17.5.1 Microcellular Foamed Polymers 276 17.5.2 Solid State Batch Microcellular Foaming Process 277 17.5.3 Microcellular Foaming in a Continuous Process 282 17.6 PLA Foamed with Chemical Foaming Agents 286 17.6.1 Effect of CFA Content 286 17.6.2 Effect of Processing Conditions 287 17.7 Mechanical Properties of PLA Foams 288 17.7.1 Batch Microcellular Foamed PLA 288 17.7.2 Microcellular Extrusion of PLA 288 17.7.3 Microcellular Injection Molding of PLA 288 17.8 Foaming of PLA/starch Blends 289 References 289 18 Composites 293 Subrata Bandhu Ghosh, Sanchita Bandyopadhyay-Ghosh, and Mohini Sain 18.1 Introduction 293 18.2 PLA Matrix 293 18.3 Reinforcements 294 18.3.1 Natural Fiber Reinforcement 294 18.3.2 Synthetic Fiber Reinforcement 295 18.3.3 Organic Filler Reinforcement 296 18.3.4 Inorganic Filler Reinforcement 298 18.4 Fiber/Matrix Adhesion 298 18.4.1 Surface Modification 298 18.4.2 Compatibilizing Agent 299 18.5 PLA Nanocomposites 299 18.6 Processing 300 18.7 Properties 300 18.7.1 Mechanical Properties 300 18.7.2 Thermal Properties 303 18.7.3 Degradation 304 18.8 Applications 305 18.8.1 Biomedical Applications 305 18.8.2 Packaging Applications 306 18.8.3 Automotive Applications 306 18.8.4 Electronic Applications 307 18.9 Future Developments and Concluding Remarks 307 References 307 19 Nanocomposites 311 Suprakas Sinha Ray 19.1 Introduction 311 19.2 PLA Nanocomposites Based on Clay 312 19.2.1 Structure and Properties of Clay 312 19.2.2 Preparation and Characterization of PLA/Clay Nanocomposites 312 19.3 PLA Nanocomposites Based on Carbon Nanotubes 314 19.4 PLA Nanocomposites Based on Various Other Nanoparticles 315 19.5 Properties of PLA-Based Nanocomposites 316 19.6 Biodegradability 317 19.7 Melt Rheology 318 19.8 Foam Processing 319 19.9 Possible Applications and Future Prospects 320 Acknowledgments 321 References 321 20 Spinning of Poly(lactic acid) Fibers 323 Ashwini K. Agrawal 20.1 Defining Fiber and Fiber Spinning 323 20.2 Melt Spinning Line 323 20.3 Fluid Dynamics During Spinning 326 20.3.1 Instabilities During Flow Through Spinneret 326 20.3.2 Instabilities in the Spinning Zone: Draw Resonance 327 20.4 Structure Development During Melt Spinning 328 20.4.1 Spinning at Low Speeds 328 20.4.2 Spinning at High Speeds 328 20.5 Post-Spinning Operation 330 20.5.1 Drawing 330 20.5.2 Finish Application 330 20.5.3 Crimping 330 20.5.4 Heat Setting 330 20.6 Structure Development During Drawing 331 20.7 Solution Spinning of PLLA 333 20.7.1 Wet Spinning 334 20.7.2 Dry Spinning 335 20.7.3 Factors Affecting Solution Spinning 335 20.7.4 Dry-Jet Wet Spinning 337 20.7.5 Solution Spinning of Stereocomplex Fiber 337 20.8 Mechanical Properties 338 20.8.1 Melt-Spun PLLA 338 20.8.2 Solution-Spun PLLA 339 20.8.3 Stereocomplex Fiber 341 References 341 Part IV Degradation and Environmental Issues 343 21 Hydrolytic Degradation 345 Hideto Tsuji 21.1 Introduction 345 21.2 Degradation Mechanism 345 21.2.1 Molecular Degradation Mechanism 346 21.2.2 Material Degradation Mechanism 355 21.2.3 Degradation of Crystalline Residues 360 21.3 Parameters for Hydrolytic Degradation 362 21.3.1 Effects of Surrounding Media 362 21.3.2 Effects of Material Parameters 365 21.4 Structural and Property Changes During Hydrolytic Degradation 371 21.4.1 Fractions of Components 371 21.4.2 Crystallization 371 21.4.3 Mechanical Properties 372 21.4.4 Thermal Properties 372 21.4.5 Surface Properties 372 21.4.6 Morphology 373 21.5 Applications of Hydrolytic Degradation 373 21.5.1 Material Preparation 373 21.5.2 Recycling of PLA to Its Monomer 375 21.5.3 Miscellaneous Applications 376 21.6 Conclusions 376 References 376 22 Enzymatic Degradation 383 Tadahisa Iwata, Hideki Abe, and Yoshihiro Kikkawa 22.1 Introduction 383 22.1.1 Definition of Biodegradable Plastics 383 22.1.2 Enzymatic Degradation 383 22.2 Enzymatic Degradation of PLA Films 384 22.2.1 Structure and Substrate Specificity of Proteinase K 385 22.2.2 Enzymatic Degradability of PLLA Films 385 22.2.3 Enzymatic Degradability of PLA Stereoisomers and Their Blends 386 22.2.4 Effects of Surface Properties on Enzymatic Degradability of PLLA Films 388 22.3 Enzymatic Degradation of Thin Films 390 22.3.1 Thin Films and Analytical Techniques 390 22.3.2 Crystalline Morphologies of Thin Films 391 22.3.3 Enzymatic Adsorption and Degradation Rate of Thin Films 391 22.3.4 Enzymatic Degradation of LB Film 394 22.3.5 Application of Selective Enzymatic Degradation 394 22.4 Enzymatic Degradation of Lamellar Crystals 395 22.4.1 Enzymatic Degradation of PLLA Single Crystals 395 22.4.2 Thermal Treatment and Enzymatic Degradation of PLLA Single Crystals 396 22.4.3 Single Crystals of PLA Stereocomplex 397 22.5 Future Perspectives 397 References 398 23 Thermal Degradation 401 Haruo Nishida 23.1 Introduction 401 23.2 Kinetic Analysis of Thermal Degradation 401 23.2.1 Changes in Molecular Weight 401 23.2.2 Thermogravimetry 402 23.3 Thermal Degradation Behavior of PLA Based on Molecular Weight Change 403 23.4 Thermal Degradation Behavior of PLA Based on Weight Loss 403 23.4.1 Diverse Mechanisms of PLA Pyrolysis 403 23.4.2 Effects of Polymerization Catalyst Residues 404 23.4.3 Effects of Chain-End Structures 406 23.4.4 Thermal Degradation Catalysts 406 23.4.5 Thermal Degradation Behavior of PLA Stereocomplex: sc-PLA 408 23.4.6 Control of Racemization 409 23.4.7 Selective Depolymerization of PLA in Blends 409 23.5 Conclusions 410 References 410 24 Photodegradation and Radiation Degradation 413 Wataru Sakai and Naoto Tsutsumi 24.1 Introduction 413 24.2 Mechanisms of Photodegradation 413 24.2.1 Photon 413 24.2.2 Photon Absorption 414 24.2.3 Photochemical Reaction of Carbonyl Groups 415 24.3 Mechanism of Radiation Degradation 415 24.3.1 High Energy Radiation 415 24.3.2 Basic Mechanism of Radiation Degradation 415 24.4 Photodegradation of PLA 416 24.5 Photosensitized Degradation of PLA 418 24.6 Radiation Effects on PLA 419 24.7 Modification of PLA by Irradiation 420 References 420 25 Biodegradation 423 Buenaventurada P. Calabia, Yutaka Tokiwa, Charles U. Ugwu, and Seiichi Aiba 25.1 Introduction 423 25.2 Microbial Degradation 423 25.2.1 Field Test 423 25.2.2 ISO and ASTM Standards 424 25.2.3 PLLA Degrading Microorganisms 424 25.3 Poly(L-Lactide) Degrading Enzymes 426 25.3.1 Proteinase K 426 25.3.2 PLLA-Degrading Enzyme of Amycolatopsis sp. 426 25.3.3 Induction of PLLA Degrading Enzymes with Natural Substrates 426 25.3.4 Other Serine Proteases 426 25.3.5 Lipase 426 25.3.6 Enzymatic Degradation in Organic Solvents 427 25.3.7 Evolution of PLA Degrading Enzymes 428 25.4 Conclusion and Future Prospects 428 References 429 26 Cradle to Gate Environmental Footprint and Life Cycle Assessment of Poly(lactic acid) 431 Amy E. Landis 26.1 Introduction to LCA and Environmental Footprints 431 26.1.1 Life Cycle Assessment 431 26.1.2 Uncertainty in LCA 432 26.2 Life Cycle Considerations for PLA 432 26.2.1 The Life Cycle of PLA 432 26.2.2 Energy USE and Global Warming 433 26.2.3 Environmental Trade-Offs 434 26.3 Review of Biopolymer LCA Studies 434 26.4 Improving PLA’s Environmental Footprint 438 26.4.1 Agricultural Management 438 26.4.2 Feedstock Choice 439 26.4.3 Energy 439 Further Reading on LCA 440 References 440 Part V Applications 443 27 Medical Applications 445 Shuko Suzuki and Yoshito Ikada 27.1 Introduction 445 27.2 Minimal Requirements for Medical Devices 445 27.2.1 General 445 27.2.2 PLA as Medical Implants 446 27.3 Preclinical and Clinical Applications of PLA Devices 447 27.3.1 Fibers 447 27.3.2 Meshes 448 27.3.3 Bone Fixation Devices 448 27.3.4 Microspheres, Microcapsules, and Thin Coatings 453 27.4 Conclusions 454 References 454 28 Packaging and Other Commercial Applications 457 Shoji Obuchi and Shinji Ogawa 28.1 Introduction 457 28.2 Applications in Packaging and Containers 457 28.2.1 Oriented Film 457 28.2.2 Flexible Film 458 28.2.3 Shrink Labels and Film 461 28.2.4 Thermoforming 462 28.2.5 Lamination 462 28.3 Other Commercial Applications 462 28.3.1 Agricultural and Engineering Materials 462 28.3.2 Electrical Appliances 463 28.3.3 Automotive Materials 466 28.4 Conclusions 467 References 467 29 Textile Applications 469 Masatsugu Mochizuki 29.1 Introduction 469 29.2 Manufacturing, Properties, and Structure of PLA Fibers 469 29.2.1 PLA Fiber Manufacture 469 29.2.2 PLA Fibers and Textile Properties 469 29.2.3 Effects of Structure on Properties 470 29.2.4 PLA Stereocomplex Fibers 471 29.3 Key Performance Features of PLA Fibers 471 29.3.1 Biodegradability and the Biodegradation Mechanism 471 29.3.2 Moisture Management 472 29.3.3 Antibacterial/Antifungal Properties 472 29.3.4 Low Flammability 473 29.3.5 Weathering Stability 474 29.4 Potential Applications 474 29.4.1 Geotextiles 474 29.4.2 Industrial Fabrics 475 29.4.3 Filters 475 29.4.4 Towels and Wipes 475 29.4.5 Home Furnishings 475 29.4.6 Clothing and Personal Belongings 475 29.5 Conclusions 475 References 476 30 Environmental Applications 477 Akira Hiraishi 30.1 Introduction 477 30.2 Application to Water and Wastewater Treatment 477 30.2.1 Application as Sorbents 477 30.2.2 Application to Nitrogen Removal 479 30.3 Application to Bioremediation 482 30.3.1 Significance of PLA Use 482 30.3.2 Bioremediation of Organohalogen Pollution 482 30.3.3 Other Applications 483 30.4 Concluding Remarks and Prospects 484 Acknowledgments 484 References 484 Index 487