Poly(lactic acid) E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Wiley Series on Plastics Engineering and Technology
• Sprache: Englisch

Seitenzahl: 1425

Veröffentlichungsjahr: 2011

Beschreibung

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.

Leseprobe

Contents

Cover

Wiley Series on Polymer Engineering and Technology

Title Page

Copyright

Preface

References

Contributors

Part I: Chemistry and Production of Lactic Acid, Lactide, and Poly(Lactic Acid)

Chapter 1: Production and Purification of Lactic Acid and Lactide

1.1 Introduction

1.2 Lactic Acid

1.3 Lactide

References

Chapter 2: Chemistry and Thermodynamic Properties of Lactic Acid and Lactide and Solvent Miscibility

2.1 General Properties

2.2 Thermodynamic Properties

2.3 Miscibility Properties of Lactic Acid and Lactide

References

Chapter 3: Industrial Production of High Molecular Weight Poly(Lactic Acid)

3.1 Introduction

3.2 Lactic Acid Based Polymers by Polycondensation

3.3 Lactic Acid Based Polymers by Chain Extension

3.4 Lactic Acid Based Polymers by Ring-Opening Polymerization

References

Chapter 4: Design and Synthesis of Different Types of Poly(Lactic Acid)

4.1 Introduction

4.2 Copolymerization

4.3 Properties of Copolymers

References

Chapter 5: Structure and Properties of Stereocomplex-Type Poly(lactic acid)

5.1 Introduction

5.2 Formation of Stereocomplex Crystals

5.3 Thermal Properties of sc-PLA

5.4 Crystal Structure of sc-PLA

5.5 Formation of sb-PLA

5.6 Applications of sc-PLA

References

Part II: Properties of Poly(Lactic Acid)

Chapter 6: Chemical Structure of Poly(lactic acid)

6.1 Introduction

6.2 Chain Structure and Configuration

6.3 Syndiotactic Polymerization and Syndiotacticity

6.4 Conformation

6.5 Amorphous Structure and Thermal Properties

6.6 Orientation Structure of PLA

6.7 Semicrystalline Structure

6.8 Frustrated Structure

6.9 Molecular Weight

6.10 Summary

References

Chapter 7: Chemical Compatibility of Poly(lactic acid): A Practical Framework Using Hansen Solubility Parameters

7.1 A Practical Framework

7.2 Solvent Compatibility

7.3 Plasticizers

7.4 Polymer Compatibility

7.5 Environmental Stress Cracking

7.6 Rational Composite Design

7.7 Diffusion and Barrier Properties

7.8 Pharmacological Transport

7.9 Summary

References

Chapter 8: Optical Properties

8.1 Introduction

8.2 Absorption and Transmission of UV–Vis Radiation

8.3 Refractive Index

8.4 Specific Optical Rotation

8.5 Infrared and Raman Spectroscopy

8.6 1H and 13C NMR Spectroscopy

References

Chapter 9: Crystallization and Thermal Properties

9.1 Introduction

9.2 Crystallinity and Crystallization

9.3 Crystallization Regime

9.4 Fibers

9.5 Hydrolytic Degradation

References

Chapter 10: Rheology of Poly(lactic acid)

10.1 Introduction

10.2 Fundamental Chain Properties from Dilute Solution Viscometry

10.3 Processing of PLA: General Considerations

10.4 Melt Rheology: An Overview

10.5 Processing of PLA: Rheological Properties

10.6 Conclusions

Appendix 10.A Description of the Software

References

Chapter 11: Mechanical Properties

11.1 Introduction

11.2 General Mechanical Properties and Molecular Weight Effect

11.3 Temperature Effect

11.4 Annealing

11.5 Orientation

11.6 Stereoregularity

11.7 Plasticization

11.8 Relaxation and Aging

11.9 Conclusions

References

Chapter 12: Permeation, Sorption, and Diffusion in Poly(lactic acid)

12.1 Introduction

12.2 Factors Affecting Permeability, Sorption, and Diffusion in PLA

12.3 Permeability, Sorption, and Diffusion of Pure PLA

12.4 Copolymers

12.5 PLA Blends

12.6 PLA Laminations

12.7 Coated PLA

12.8 PLA Composites and Fibers

12.9 PLA Nanocomposites

12.10 Future of PLA Membranes

References

Chapter 13: Migration

13.1 Migration Principles

13.2 Legislation

13.3 Migration and Toxicological Data of Lactic Acid, Lactide, Dimers, and Oligomers

13.4 EDI of Lactic Acid

13.5 Other Potential Migrants from PLA

13.6 Conclusions

References

Part III: Processing and Conversion of Poly(Lactic Acid)

Chapter 14: Processing of Poly(lactic acid)

14.1 Introduction

14.2 Properties of PLA Relevant to Processing

14.3 Modification of PLA Properties by Process Aids and Other Additives

14.4 Drying

14.5 Extrusion

14.6 Injection Molding

14.7 Film and Sheet Casting

14.8 Stretch Blow Molding

14.9 Extrusion Blown Film

14.10 Thermoforming

14.11 Electrospinning

14.12 Conclusion: Prospects of PLA Polymers

References

Chapter 15: Poly(lactic acid)/Starch Blends

15.1 Introduction

15.2 Blending Hydrophobic PLA with Hydrophilic Starch

15.3 Compatibilizers Used for Starch/PLA Blends

15.4 Enhancing Function of Compatibilizer by Controlling Compatibilizer Distribution

15.5 Reactive Blending

15.6 Summary

References

Chapter 16: Poly(lactic acid) Blends

16.1 Introduction

16.2 PLA/Nonbiodegradable Polymer Blends

16.3 PLA/Biodegradable Polymer Blends

16.4 Plasticization of PLA

16.5 Conclusion

References

Chapter 17: Foaming

17.1 Introduction

17.2 Plastic Foams

17.3 Foaming Agents

17.4 Formation of Cellular Plastics

17.5 Plastic Foams Expanded with Physical Foaming Agents

17.6 PLA Foamed with Chemical Foaming Agents

17.7 Mechanical Properties of PLA Foams

17.8 Foaming of PLA/Starch Blends

References

Chapter 18: Composites

18.1 Introduction

18.2 PLA Matrix

18.3 Reinforcements

18.4 Fiber/Matrix Adhesion

18.5 PLA Nanocomposites

18.6 Processing

18.7 Properties

18.8 Applications

18.9 Future Developments and Concluding Remarks

References

Chapter 19: Nanocomposites

19.1 Introduction

19.2 PLA Nanocomposites Based on Clay

19.3 PLA Nanocomposites Based on Carbon Nanotubes

19.4 PLA Nanocomposites Based on Various Other Nanoparticles

19.5 Properties of PLA-Based Nanocomposites

19.6 Biodegradability

19.7 Melt Rheology

19.8 Foam Processing

19.9 Possible Applications and Future Prospects

Acknowledgments

References

Chapter 20: Spinning of Poly(lactic acid) Fibers

20.1 Defining Fiber and Fiber Spinning

20.2 Melt Spinning Line

20.3 Fluid Dynamics During Spinning

20.4 Structure Development During Melt Spinning

20.5 Post-Spinning Operation

20.6 Structure Development During Drawing

20.7 Solution Spinning of PLLA

20.8 Mechanical Properties

References

Part IV: Degradation and Environmental Issues

Chapter 21: Hydrolytic Degradation

21.1 Introduction

21.2 Degradation Mechanism

21.3 Parameters for Hydrolytic Degradation

21.4 Structural and Property Changes During Hydrolytic Degradation

21.5 Applications of Hydrolytic Degradation

21.6 Conclusions

References

Chapter 22: Enzymatic Degradation

22.1 Introduction

22.2 Enzymatic Degradation of PLA Films

22.3 Enzymatic Degradation of Thin Films

22.4 Enzymatic Degradation of Lamellar Crystals

22.5 Future Perspectives

References

Chapter 23: Thermal Degradation

23.1 Introduction

23.2 Kinetic Analysis of Thermal Degradation

23.3 Thermal Degradation Behavior of PLA Based on Molecular Weight Change

23.4 Thermal Degradation Behavior of PLA Based on Weight Loss

23.5 Conclusions

References

Chapter 24: Photodegradation and Radiation Degradation

24.1 Introduction

24.2 Mechanisms of Photodegradation

24.3 Mechanism of Radiation Degradation

24.4 Photodegradation of PLA

24.5 Photosensitized Degradation of PLA

24.6 Radiation Effects on PLA

24.7 Modification of PLA by Irradiation

References

Chapter 25: Biodegradation

25.1 Introduction

25.2 Microbial Degradation

25.3 Poly(L-lactide) Degrading Enzymes

25.4 Conclusion and Future Prospects

References

Chapter 26: Cradle to Gate Environmental Footprint and Life Cycle Assessment of Poly(lactic acid)

26.1 Introduction to LCA and Environmental Footprints

26.2 Life Cycle Considerations for PLA

26.3 Review of Biopolymer LCA Studies

26.4 Improving PLA's Environmental Footprint

26.5 Further Reading on LCA

References

Part V: Applications

Chapter 27: Medical Applications

27.1 Introduction

27.2 Minimal Requirements for Medical Devices

27.3 Preclinical and Clinical Applications of PLA Devices

27.4 Conclusions

References

Chapter 28: Packaging and Other Commercial Applications

28.1 Introduction

28.2 Applications in Packaging and Containers

28.3 Other Commercial Applications

28.4 Conclusions

References

Chapter 29: Textile Applications

29.1 Introduction

29.2 Manufacturing, Properties, and Structure of PLA Fibers

29.3 Key Performance Features of PLA Fibers

29.4 Potential Applications

29.5 Conclusions

References

Chapter 30: Environmental Applications

30.1 Introduction

30.2 Application to Water and Wastewater Treatment

30.3 Application to Bioremediation

30.4 Concluding Remarks and Prospects

Acknowledgments

References

Index

Wiley Series on Polymer Engineering and Technology

Richard F. Grossman and Domasius Nwabunma, Series Editors

Polyolefin Blends

Edited by Domasius Nwabunma and Thein Kyu

Polyolefin Composites

Edited by Domasius Nwabunma and Thein Kyu

Handbook of Vinyl Formulating, Second Edition

Edited by Richard F. Grossman

Total Quality Process Control for Injection Molding, Second Edition

M. Joseph Gordon, Jr.

Microcellular Injection Molding

Jingyi Xu

Poly(lactic acid): Synthesis, Structures, Properties, Processing, and Applications

Edited by Rafael Auras, Loong-Tak Lim, Susan E.M. Selke, and Hideto Tsuji

Copyright © 2010 John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

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Library of Congress Cataloging-in-Publication Data:

Poly(lactic acid): synthesis, structures, properties, processing, and applications/ edited by Rafael Auras . . . [et al.].

p. cm.

Includes index.

ISBN 978-0-470-29366-9 (cloth)

1. Biodegradable plastics. 2. Lactic acid. 3. Polymers. I. Auras, Rafael.

TP1180.B55P65 2010

620.1'92323–dc22

2010006494

Preface

Poly(lactic acid) (PLA) cannot be considered as a new polymer. As early as 1845, PLA was synthesized by Théophile-Jules Pelouze by the condensation of lactic acid [1]. In 1932, Wallace Hume Carothers et al. developed a method to polymerize lactide to produce PLA that was later patented by DuPont in 1954 [2]. Although PLA existed for several decades, its use was limited to biomedical applications (e.g., biocompatible sutures, implants, biologically active controlled release devices) due to its high cost. The low molecular weight PLA polymers obtained also hampered their wide-ranging applications. The breakthrough occurred in the early 1990s when Cargill Inc. succeeded in polymerizing high molecular weight PLA using a commercially viable lactide ring opening reaction [3, 4]. In 1997, Cargill Dow LLC, a joint venture between Cargill Inc. and The Dow Chemical Company, was formed to begin truly commercially significant production of PLA resins under the trade name NatureWorks™. This is a major landmark in PLA's history because it signifies the beginning of a large-scale use of this bio-based polymer, transforming PLA from a specialty material to a commodity thermoplastic.

The increased availability of PLA stimulated an increased in its research and development activities. A survey of the literature revealed that the number of published articles related to PLA increased exponentially over the past decade, which can be also partly attributed to the escalating “green” movement that is stimulating the use of bio-based polymers. To date, the major PLA resin suppliers have been Cargill (in the United States known as Ingeo™), Mitsui Chemicals, Inc. (in Japan known as LACEA™), Purac (The Netherlands), and Teijin Limited (in Japan known as Biofront®). Other important events that took place pertaining to PLA are summarized in Figure P.1 and Table P.1.

Figure P.1 Number of works published since 1960 based on Scholars Portal Search (accessed on 28 Dec 09) using keywords “polylactide”, “poly(lactic acid)”, and “polylactic acid”.

Table P.1 Significant Events Related to PLA Production that Occurred over the Past Few Decades.

2010Jung et al. employed recombinant Escherichia coli to produce PLA [5]2009PURAC, Sulzer, and Synbra announced production of PLA from solid lactide for foamed products2009Galactic and Total Petrochemicals from Belgium created a joint venture, Futerro, to begin PLA production2009Cargill Inc. acquired full NatureWorks ownership from Teijin Limited2008Uhde Inventa Fischer and Pyramide Bioplastics announced large-scale production of PLA in Guben, Germany2008PURAC started to commercialize solid lactide monomers under PURALACT™2007Teijin launched heat-resistant stereocomplex PLA under Biofront™2007NatureWorks LLC and Teijin Limited formed 50–50 joint venture to market Ingeo™ bio-based thermoplastic resins2005Cargill Inc. acquired The Dow Chemical Company's share in Cargill Dow LLC 50–50 joint venture2003Toyota produced and developed PLA for automotive applications1997Formation of Cargill Dow LLC, a 50–50 joint venture of Cargill Inc. and The Dow Chemical Company, to commercialize PLA under the trade name NatureWorks™1997Fiberweb (now BBA, France) introduced melt-blown and spun-laid PLA fabrics under Deposa™ brand name1996Mitsui Chemicals, Inc. commercialized PLA produced by polycondensation route1994Kanebo Ltd. introduced Lactron® PLLA fiber and spun-laid nonwovens

While the information available in the literature is massive, at the inception of this volume, no reference book could be found that coherently assembled the scientific and technological knowledge about PLA. Our main motive for editing this book was to consolidate the most relevant information on PLA into a volume that serves as a one-source reference for readers who are keen on this unique biodegradable polymer.

Organized in five parts, Part I of this book covers several important topics, including chemistry and production of lactic acid (Chapter 1) and lactide (Chapter 2), which are the essential building blocks of PLA. Different polymerization reactions for the production of PLA are covered in Chapter 3. In view of certain shortcomings of PLA, copolymerization of PLA with other monomers and stereocomplexation with optimal enantiomer lactide ratios are gaining increased popularity as ways to enhance the material properties of the resulting polymer. These topics are covered in detail in Chapters 4 and 5, respectively. These chapters set the stage for discussions in Part II of this book, in which different material properties of PLA are covered in eight separate chapters. Chain configuration, tacticity, and crystal structure are discussed in Chapter 6 to illuminate how chain structure affects the material properties of PLA and its copolymers. Chapter 7 investigates the compatibility of PLA with solvents and other polymers, an important aspect that should be considered during end-use applications. The interaction of PLA with electromagnetic radiation for probing the molecular structure and interactions are discussed in Chapter 8. The essence of spectroscopy techniques for PLA analysis, including UV–VIS, FTIR, Raman, and NMR, is reviewed in this chapter. Crystallization, thermal, and rheological properties of PLA are discussed in Chapters 9 and 10, and these are important to elucidate the melt processing phenomena of PLA. In the remainder of Part II, Chapters 11, 12, and 13 deal with the mechanical, permeability, and migration behaviors of PLA, respectively, and will serve as handy references for designing and engineering PLA products for various end-use applications. In Part III, seven chapters are devoted to summarizing the state of the art of processing and conversion technologies for PLA, covering topics such as extrusion and molding (Chapter 14), polymer blending (Chapters 15 and 16), foaming (Chapter 17), preparation of micro- and nanocomposites (Chapters 18 and 19), and fiber spinning (Chapter 20). One of the hallmarks of PLA polymers is that they are degradable, which has been viewed as an attractive feature for certain applications. In Part IV, six chapters are included to discuss in great detail the various degradation modes of PLA, including hydrolytic degradation (Chapter 21), enzymatic degradation (Chapter 22), thermal degradation (Chapter 23), photodegradation (Chapter 25), and biodegradation (Chapter 25). This part ends with Chapter 26 in which the life cycle assessment and the environmental footprint of PLA are objectively discussed. Finally, in Part V, various applications for PLA are discussed, including medical items (Chapter 27), packaging (Chapter 28), textiles (Chapter 29), and environment-related applications (Chapter 30). Rather than eliminating all duplicate materials between chapters, we deliberately allowed some overlap in discussions to enable the chapters to stand alone to some extent.

This volume skillfully brings together the work of many contributors who are experts in their respective research areas. This volume would not have been possible without their help and contributions. We are indebted to them for their participation and patience during the preparation of this book and are grateful that they have entrusted us to edit their contributions as per the requirements of each chapter. We hope that readers will find this book useful. We are looking forward to receiving comments and constructive feedback regarding the content of this book [5]. Finally, we are indebted to our three academic institutions, Michigan State University, University of Guelph, and Toyohashi University of Technology, for allowing us to dedicate our effort and time to the completion of this edited book. Our most grateful thanks are to our colleagues for providing a sounding board to discuss ideas and explore new concepts about biodegradable polymers and materials in general; to our editor at John Wiley & Sons, Inc., Jonathan T. Rose, for supporting this proposal, and walking us through its completion; to Lisa Van Horn for coordinating the production of the book; and to Sanchari Sil, our project manager at Thomson Digital, for her invaluable patience to in answering our endless questions about the final proofing of the book. Overall, we could not put our effort into this task without the unconditional support of our families, so that our most special thanks go to all of them.

References

1. H. Benninga, A History of Lactic Acid Making, Springer, New York, 1990.

2. W. H. Carothers, G. L. Dorough, F. J. van Natta. J. Am. Chem. Soc. 1932, 54, 761–772.

3. P. R. Gruber, E. S. Hall, J. J. Kolstad, M. L. Iwen, R. D. Benson, R. L. Borchardt, U.S. Patent 6,326,458, 2001.

4. P. R. Gruber, E. S. Hall, J. J. Kolstad, M. L. Iwen, R. D. Benson, R. L. Borchardt, U.S. Patent 5,357,035, 1994.

5. Y. K. Jung, T. Y. Kim, S. J. Park, S. Y. Lee, Biotechnol. Bioeng. 2010, 105, 161–171.

RAFAEL AURAS

East Lansing, Michigan

LOONG-TAK LIM

Guelph, Ontario, Canada

SUSAN E. M. SELKE

East Lansing, Michigan

HIDETO TSUJI

Toyohashi, Aichi, JapanMay 2010

Contributors

Steven Abbott, Steven Abbott TCNF Ltd., Ipswich, England

Hideki Abe, Chemical Analysis Team, RIKEN Institute, Saitama, Japan

Seiichi Aiba, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan

Ashwini K. Agrawal, SMITA Labs, Department of Textile Technology, Indian Institute of Technology, New Delhi, India

Ann-Christine Albertsson, Department of Fiber and Polymer Technology, Royal Institute of Technology, Stockholm, Sweden

Eva Almenar, School of Packaging, Michigan State University, East Lansing, Michigan

Rafael Auras, School of Packaging, Michigan State University, East Lansing, Michigan

Sanchita Bandyopadhyay-Ghosh, Center for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Ontario, Canada

Buenaventurada P. Calabia, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan

Gian Domenico Cella, Novamont SpA, Novara, Italy

Kevin Cink, NatureWorks LLC, Minnetonka, Minnesota

João A. P. Coutinho, CICECO, Chemistry Department, University of Aveiro, Aveiro, Portugal

Katherine Dean, CSIRO, Materials Science and Engineering, Melbourne, Australia

Sukeewan Detyothin, School of Packaging, Michigan State University, East Lansing, Michigan; Department of Agroindustry, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok, Thailand

John R. Dorgan, Colorado School of Mines, Golden, Colorado

Luca Fambri, Department of Materials Engineering and Industrial Technologies and BIOtech Research Center, University of Trento, Trento, Italy

Anna Finne-Wistrand, Department of Fiber and Polymer Technology, Royal Institute of Technology, Stockholm, Sweden

Subrata Bandhu Ghosh, Center for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Ontario, Canada

Carla M. B. Gonçalves, CICECO, Chemistry Department, University of Aveiro, Aveiro, Portugal

Wim Groot, PURAC, Gorinchem, The Netherlands

Akira Hiraishi, Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan

Masayuki Hirata, Department of Biomolecular Engineering, Center for Fiber and Textile Science, Kyoto Institute of Technology, Kyoto, Japan

Dan Huang, Key Laboratory of Eco-textiles of Ministry of Education, College of Textile and Clothing, Jiangnan University, Wuxi, China

Yoshito Ikada, Faculty of Medicine, Nara Medical University, Nara, Japan

Tadahisa Iwata, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan

Waree Jaruwattanayon, School of Packaging, Michigan State University, East Lansing, Michigan; Thai Packaging Center, Thailand Institute of Scientific and Technological Research, Bangkok, Thailand

Xue Jiang, Key Laboratory of Eco-textiles of Ministry of Education, College of Textile and Clothing, Jiangnan University, Wuxi, China

Zhengyu Jin, School of Food Science and Technology, Jiangnan University, Wuxi, China

Ajay Kathuria, School of Packaging, Michigan State University, East Lansing, Michigan

Yoshihiro Kikkawa, Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan

Yoshiharu Kimura, Department of Biobased Materials Science, Center for Fiber and Textile Science, Kyoto Institute of Technology, Kyoto, Japan

Kamlesh Kumar, Center for Polymer Science and Engineering, Indian Institute of Technology, New Delhi, India

Amy E. Landis, Department of Civil and Environmental Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania

Loong-Tak Lim, Department of Food Science, University of Guelph, Guelph, Ontario, Canada

Hongshen Liu, CSIRO, Materials Science and Engineering, Melbourne, Australia; Center for Polymer from Renewable Resources, SCUT, Guangzhou, China

Bimlesh Lochab, Center for Polymer Science and Engineering, Indian Institute of Technology, New Delhi, India

Yan Luo, Department of Applied Chemistry, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, China

Isabel M. Marrucho, CICECO, Chemistry Department, University of Aveiro, Aveiro, Portugal; Instituto de Tecnologia Química e Biológica, ITQB2, Universidade Nova de Lisboa, Oeiras, Portugal

Laurent M. Matuana, School of Packaging, Michigan State University, East Lansing, Michigan

Claudio Migliaresi, Department of Materials Engineering and Industrial Technologies and BIOtech Research Center, University of Trento, Trento, Italy

Masatsugu Mochizuki, Center for Fiber and Textile Science, Kyoto Institute of Technology, Kyoto, Japan

Haruo Nishida, Eco-Town Collaborative R&D Center for the Environment and Recycling, Kyushu Institute of Technology, Fukuoka, Japan

Shoji Obuchi, Materials Laboratory, Mitsui Chemicals, Inc., Chiba, Japan

Shinji Ogawa, Process Technology Center, Mitsui Chemicals, Inc., Chiba, Japan

Gabriele Perego, Vanadis Srl, Colleretto Giacosa, Italy

Eustathios Petinakis, CSIRO, Materials Science and Engineering, Melbourne, Australia

Narendra Reddy, Department of Textiles, Clothing and Design, University of Nebraska-Lincoln, Lincoln, Nebraska

Mohini Sain, Center for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Ontario, Canada

Wataru Sakai, Macromolecular Science and Engineering, Kyoto Institute of Technology, Kyoto, Japan

Susan E. M. Selke, School of Packaging, Michigan State University, East Lansing, Michigan

Suprakas Sinha Ray, DST/CSIR Nanotechnology Innovation Center, National Center for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, Gauteng, Republic of South Africa

Olav Sliekers, PURAC, Gorinchem, The Netherlands

Herlinda Soto-Valdez, Centro de Investigación en Alimentació y Desarrollo A.C., Hermosillo, Sonora, México

Anders Södergaå rd, Laboratory of Polymer Technology, Åbo Akademi University, Turku, Finland

Mikael Stolt, Laboratory of Polymer Technology, Åbo Akademi University, Turku, Finland

Shuko Suzuki, Faculty of Medicine, Nara Medical University, Nara, Japan

Yaoqi Tian, School of Food Science and Technology, Jiangnan University, Wuxi, China

Xiuzhi Tian, Key Laboratory of Eco-textiles of Ministry of Education, College of Textile and Clothing, Jiangnan University, Wuxi, China

Yutaka Tokiwa, Okinawa Industrial Technology Center, Uruma, Okinawa, Japan

Hideto Tsuji, Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan

Naoto Tsutsumi, Macromolecular Science and Engineering, Kyoto Institute of Technology, Kyoto, Japan

Charles U. Ugwu, Okinawa Industrial Technology Center, Uruma, Okinawa, Japan

Jan van Krieken, PURAC, Gorinchem, The Netherlands

Tim Vanyo, NatureWorks LLC, Minnetonka, Minnesota

Indra Kumari Varma, Center for Polymer Science and Engineering, Indian Institute of Technology, New Delhi, India

Sicco de Vos, PURAC, Gorinchem, The Netherlands

Jinpeng Wang, School of Food Science and Technology, Jiangnan University, Wuxi, China

Yiqi Yang, Department of Textiles, Clothing and Design and Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska

Long Yu, CSIRO, Materials Science and Engineering, Melbourne, Australia; Center for Polymer from Renewable Resources, SCUT, Guangzhou, China

Part I

Chemistry and Production of Lactic Acid, Lactide, and Poly(Lactic Acid)

Chapter 1

Production and Purification of Lactic Acid and Lactide

Wim Groot, Jan van Krieken, Olav Sliekersl, and Sicco de Vos

1.1 Introduction

Natural polymers, biopolymers, and synthetic polymers based on annually renewable resources are the basis for the twenty-first-century portfolio of sustainable, eco-efficient plastics [1]. These biosourced materials will gradually replace the currently existing family of oil-based polymers as they become cost- and performance-wise competitive. Polylactide or poly(lactic acid) (PLA) is the front runner in the emerging bioplastics market with the best availability and the most attractive cost structure. The production of the aliphatic polyester from lactic acid, a naturally occurring acid and bulk produced food additive, is relatively straightforward. PLA is a thermoplastic material with rigidity and clarity similar to polystyrene (PS) or poly(ethylene terephthalate) (PET). End uses of PLA are in rigid packaging, flexible film packaging, cold drink cups, cutlery, apparel and staple fiber, bottles, injection molded products, extrusion coating, and so on [2]. PLA is bio-based, resorbable, and biodegradable under industrial composting conditions [1, 3, 4].

PLA can be produced by condensation polymerization directly from its basic building block lactic acid, which is derived by fermentation of sugars from carbohydrate sources such as corn, sugarcane, or tapioca, as will be discussed later in this chapter. Most commercial routes, however, utilize the more efficient conversion of lactide—the cyclic dimer of lactic acid—to PLA via ring-opening polymerization (ROP) catalyzed by a Sn(II)-based catalyst rather than polycondensation [2–6]. Both polymerization concepts rely on highly concentrated polymer-grade lactic acid of excellent quality for the production of high molecular weight polymers in high yield [2–4, 7].

Purification of lactic acid produced by industrial bacterial fermentation is therefore of decisive importance because crude lactic acid contains many impurities such as acids, alcohols, esters, metals, and traces of sugars and nutrients [4].

The lactide monomer for PLA is obtained from catalytic depolymerization of short PLA chains under reduced pressure [4]. This prepolymer is produced by dehydration and polycondensation of lactic acid under vacuum at high temperature. After purification, lactide is used for the production of PLA and lactide copolymers by ROP, which is conducted in bulk at temperatures above the melting point of the lactides and below temperatures that cause degradation of the formed PLA [4].

Processing, crystallization, and degradation behavior of PLA all depend on the structure and composition of the polymer chains, in particular the ratio of the L- to the D-isomer of lactic acid [2, 4, 6, 8, 9]. This stereochemical structure of PLA can be modified by copolymerization of mixtures of L-lactide and -, D-, or -lactide resulting in high molecular weight amorphous or semicrystalline polymers with a melting point in the range from 130 to 185°C [3, 4, 6–10].