Biopolymers

New Materials for Sustainable Films and Coatings

David Plackett

• Publisher: Wiley
• Year: 2011
• Print ISBN: 9780470683415
• eBook ISBN: 9781119995791
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

As an area of high topical interest, Biopolymers – New materials for Sustainable Films and Coatings covers the development and utilization of polymers derived from bioresources, with a particular focus on film and coating applications.

With growing concern for the environment and the rising price of crude oil, there is increasing demand for non-petroleum-based polymers from renewable resources. Leading research groups worldwide in industry and academe are working on such technology with the objective of applying the latest advances in the field.

Written by well-respected experts, this text systematically covers the extraction and production of selected biopolymers as well as their properties and application as films or coatings in a variety of uses. The areas addressed include food packaging, edible coatings, paper coatings and agricultural films.

Intended for researchers and students, this book will also be of interest to industry, especially in terms of the practical applications.

Part I

Chapter 1

Introductory Overview

David Plackett

Ris

National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde, Denmark

1.1 Introduction

This book presents the latest knowledge about the synthesis and properties of bio-derived polymers in terms of practical film and coating applications. These biopolymers include starch, polyactides (PLAs), polyhydroxyalkanoates (PHAs), chitosan, proteins, hemicelluloses, cellulose and furan polymers. The contents are divided into two parts: Part 1 in which the synthesis or production and properties of biopolymers are discussed and Part 2 in which specific applications are covered. With this structure, the objective of the book is to provide the reader with an up-to-date summary of current knowledge concerning individual biopolymers and then to discuss the state of their development and uptake in a number of key fields, including packaging, edible films and coatings, paper and paperboard, and agronomy. A further chapter deals with specialized uses of biopolymers in optoelectronics and sensor technologies, a field which is still very much in its infancy. In this introductory overview, biopolymers and the question of sustainability are discussed in the context of total world markets for plastics and resins.

1.2 Worldwide Markets for Films and Coatings

1.2.1 Total Polymer Production and Use

In order to set the scene for this book, it is useful to get a sense of the total volumes and types of polymer used worldwide as well as in use specifically in films and coatings. This includes such everyday materials as kitchen films, grocery carrier bags and garbage bags, and many types of industrial and specialty films, as well as industrial or architectural paints and coatings. Since polymer production and consumption is reported in various ways, it can be difficult to separate out uses in films and coatings from total polymer usage; however, some insights can be gained through reports from industry associations and other sources.

A RAPRA report from 2004 [1] states that in 2003 the total global consumption of polymers in solid form (i.e., not adhesives, paints, binders) was 160 million tonnes and, of this amount, about 40 million tonnes was in the form of films. Information presented by Ambekar et al. [2] illustrates the steady increase in total plastics consumption over the past 50–60 years and indicates that this figure reached 260 million tonnes in 2007, of which about one-third was used in packaging. Volumes of plastics produced worldwide according to figures for 2007 are shown in Figure 1.1. According to the American Chemistry Council (http://www.americanchemistry.com), US production of thermoset resins in 2009 was 12.7 billion pounds on a dry weight basis, down nearly 16% from 2008, probably as a result of the impact of the economic crisis on construction activity. The corresponding figure for thermoplastic production in 2009 was 86 billion pounds which reflected only a 0.5% decrease over 2008, possibly because of the greater diversity of markets for thermoplastics as compared with thermosets.

Figure 1.1 Volumes of plastics produced worldwide in 2007. Figures in brackets are millions of tonnes (Source: Plastics Europe Market Research Group)

A report by the consulting company Accenture discusses polymer consumption by market sector in 2006 and consumption figures predicted for 2016 [3]. A summary of the relevant data is shown in Table 1.1.

Table 1.1 World polymer consumption in 2006 and projected consumption for 2016 (thousands of metric tonnes) [3]. Adapted from Accenture report “Trends in manufacturing polymers: Achieving high performance in a multi-polar world”, 2008.

Market sector	2006	2016
Construction	45 886	72 919
Plastic products	43 500	78 361
Food	42 025	71 774
Textiles	32 176	51 630
Electrical/electronic	13 810	25 499
Furniture	13 687	22 993
Vehicles and parts	10 746	15 625
Machinery	2397	3658
Fabricated metals	1519	2259
Printing	780	1220
Other transportation	9330	16 181
Other equipment	3852	6334
Other manufacturing	21 238	33569
Total	240 947	402 022

1.2.2 Total Production and Use of Plastic Films

The world market for plastic films is dominated by polyethylene (PE) and polypropylene (PP), which together comprise some 34 million tonnes per annum. These polyolefins are subject to increasing demand as the main materials used in packaging films, particularly in the developing areas of the world. Besides PE and PP, polyethylene terephthalate (PET) film is used in packaging and in a wide range of industrial and specialty products, such as in electrical (e.g., transformer insulation films, thermal printing tapes) and imaging products (e.g., microfilm, x-ray films, business graphics). Polyvinyl chloride (PVC) films are found in consumer goods and medical applications and polyvinyl butyrate (PVB), because of its optical clarity, toughness, flexibility and ability to bind to many surfaces, is mainly used in automotive and construction applications as glazing protection. Polystyrene (PS) films are also used in packaging and a variety of other medical, commercial and consumer goods. The primary types of plastics used in films, their properties and various applications are shown in Table 1.2. Polymer films as a whole are a massive market sector with Europe and North America each consuming about 30% of total world production and increasing volumes being consumed in the growing economies.

Table 1.2 Commodity thermoplastic films – their properties and applications (∗ in addition, trays produced by thermoforming films of PET, PE and other thermoplastics are widely used in the packaging industry). PET = polyethylene terephthalate, HDPE = high-density polyethylene, LDPE = low-density polyethylene, PP = polypropylene, PS = polystyrene, PVC = polyvinyl chloride, PVB = polyvinyl butyral.

Polymer type	Properties	Applications∗
PET	Clear and optically smooth surfaces, barrier to oxygen, water and carbon dioxide, heat resistance for hot filling, chemical resistance	Oveneable films and microwave trays, packaging films, industrial and specialty films
HDPE	Solvent resistance, higher tensile strength than other PEs	Grocery bags, cereal box liners, wire and cable coverings
LDPE	Resistance to acids, bases and vegetable oils, good properties for heat-sealing packaging	Bags for dry cleaning, newspapers, frozen bread, fresh produce and household garbage, shrink wrap and stretch film, coatings for paper milk cartons, and hot and cold beverage cups, wire and cable coverings
PP	Excellent optical clarity in BOPP films, low water vapour transmission, inert to acids, bases and most solvents	Packaging, electronics, kitchen laminates, furniture, ceiling and wall panels
PS	Excellent water barrier for short shelf-life products, good optical clarity, hard wearing	Packaging, electronic housings, medical products, interior furnishing panels
PVC	Biologically and chemically resistant	Packaging films, wire and cable coverings, waterproof clothing, roofing membranes
PVB	Adheres well to various surfaces, optically clear, tough and flexible	Laminated safety glass for use in automotive and architectural applications

Regardless of polymer type, packaging is the main end use for plastic films. In this context, films are generally defined as being planar materials less than 10 mils or ∼250 μm in thickness (i.e., thick enough to be self-supporting but thin enough to be flexed, folded and/or creased without cracking). Above this thickness, the term sheet is frequently used instead of film. Data from Plastics Europe (http://www.plasticseurope.org) confirm that packaging is the biggest end-use for plastics (38%), followed by building and construction (21%), automotive (7%), and electrical and electronic (6%). Other applications for plastics, which include medical and leisure, use 28% of the total production volume (Figure 1.2).

Figure 1.2 Plastics demand by converters in Europe in 2008. Total demand was 48.5 million tonnes (Source: Plastics Europe Market Research Group)

In addition to packaging, the myriad applications of polymer films include decorative wrap, form-fill-seal, blood bags, flexible printed circuits, bed sheeting, diapers, and in-mould decorating of car parts (to replace painting and provide a more durable surface coating) to name just a few. Carrier bags and garbage bags are big markets with significant imports into Europe. In construction, films are used in glazing, damp proofing, tarpaulins, and geomembranes.

Multi-material or mutli-layer films account for around seven million tonnes annually, with about 95% of this volume going into packaging. Multi-layer materials are attractive because they permit custom adaptation of properties such as barrier and strength. As well as the possibility to colour or print, and produce single or multi-layered products, films are also often combined with other materials such as aluminum or paper. An example is the aseptic packaging manufactured by Tetra Pak (Lund, Sweden) which contains layers of PE, paper and a very thin layer of aluminum acting as a water vapour and gas barrier. The introduction of technology such as orientation of PP films has also contributed significantly to the availability of more valuable film materials. In particular,...

Table of contents

• Cover
• Title Page
• Copyright
• Preface
• About the Editor
• List of Contributors
• Part I
• Part II
• Index