Puu-0.4300 New Fibre Materials: Biocomposites

Introduction & historical background Mark Hughes 11th January 2016

Today • Course outline • Passing the course! • • • •

What is a composites? What are “biocomposites”? Historical viewpoint What are the opportunities?

Why this course? • To underpin the development of new fibre (reinforced) materials an excellent understanding of composite materials is essential. Within other spheres of fibre reinforced composites (e.g. aerospace and automotive), the science and technology of these materials is well understood and continues to develop. Much can be learnt from these sectors and applied to composite reinforced with natural fibres, or their derivatives • Through this course you will understand how natural fibres can be used to reinforce polymers and form the basis for other composite materials. You will also understand relevant composites theory, the raw materials used, manufacturing processes and the applications envisioned • This is the last time that this course will be run! It will be replaced by CHEM-E2200 Polymer blends and composites (5 cr), which will run for the first time in Period I of the 2016-2017 academic year

Learning outcomes of the course • Understand the principles of composite reinforcement and the influence of reinforcement ‘architecture’ on composite properties • To be able to apply knowledge about fibre and matrix properties to predict composite properties • To understand the range of materials that can be used as matrix and the processing routes that can be employed • Can apply knowledge of fibre properties, polymer technology and materials science and composites theory in the design of new materials

Content • Composites theory – – – –

Reinforcement and matrix Load sharing Stress transfer mechanisms Fibre architecture

• Raw materials (fibres and matrices) – Wood and non-wood fibres: sources and properties – Polymers, virgin, recycled, fossil-based, biopolymers

• Processes – Composites processing for thermoplastics and thermosetting resins – Fibre processing, including modification

• Applications

Passing the course! • • • •

5 weeks in Period III 3 credit course 2 x 2 hour sessions per week Assessment: – Literature-based project: – Examination:

50% 50%

Schedule Week

Day

Date

Activity

Person

3

Mon

11.1

Lecture: Introduction & historical background

MH

Thurs

14.1

Lecture: Reinforcement, matrix and interface

MH

Mon

18.1

Lecture: Reinforcement processes

MH

Thurs

21.1

Lecture: Matrices

PP

Mon

25.1

Lecture: Fibres for reinforcement

MH

Thurs

28.1

Lecture: Manufacturing processes

MH

Mon

1.2

Lecture: Fibre architecture and composite properties

MH

Thurs

4.2

Excursion to polymer technology

PP(MH)

Mon

8.2

Lecture: Applications and future trends

MH

Thurs

11.2

Project evaluations

MH(PP)

4

5

6

7

Project • Completed individually • Base on approx. 10-15 peer-review literature sources + others as appropriate • This is a ‘desk-based’ research project. The information that you use will come form e.g. – Scientific literature (principally) – Internet (try to be critical about the information that you obtain) – Direct contact with companies (if appropriate)

• Assessment: – Report (around 10 pages of text in length) – Presentation and discussion (in final lecture)

Topics • Choose one of the following topics: – – – – – – – – – – – – – –

Applications in construction Applications in transportation Applications in another field (please confirm other field with me) Biopolymers for biocomposites Recycled materials for biocomposites (Sara) Additives used in biocomposite (Mikko) Production technologies for biocomposites Fibres for biocomposites (Niko) Textiles for biocomposites Micromechanics in biocomposites Mechanical properties of biocomposites Life Cycle Assessment (LCA) of biocomposites Bast fibers and polypropylene (PP) composites (Antti Eloranta) Own topic (please confirm with me before starting)

• Please email me to reserve your topic. Topics will be allocated on a first come, first served basis • Deadline for submission of report: Monday 29th February 2016

Other matters • Will keep MyCourses up to date with any new information that becomes available • Slides will be in MyCourses

Who is involved? • Mark Hughes (Forest Products Technology) • Pirjo Pietikäinen (Polymer Technology)

Reading • General introduction to materials: – JE Gordon. “The New Science of Strong Materials or Why You Don't Fall Through the Floor” (Princeton Science Library). BUY IT!

• Many books covering composite materials science: – D. Hull, and T. W. Clyne. “An Introduction to Composite Materials” (Cambridge Solid State Science Series) – available from Amazon – M.R. Piggott. “Load bearing fibre composites” (available on ebrary)

• Green composites: – Caroline Baillie. “Green Composites” Woodhead Publishing Ltd (available on ebrary)

• Others relating to composites

What is a composite?

“The whole is greater than the sum of its parts” - Aristotle • A composite is a material composed of two or more distinct constituents (or phases) separated by an identifiable interface • Generally (but not always) the phases have different physical and/or chemical properties • The properties of the resulting composite can be entirely different from those of the original components • For example GRP (Glass-fibre Reinforced Plastic) is composed of (brittle) glass and (also brittle) thermosetting polymer, but the resulting composite is very ‘tough’ (the fracture energy is about 103 to 104 times greater) • Why is this? Structure (and particularly microstructure)

Mechanical properties For many real-life engineering applications it is often desirable to have a blend of properties: • Good stiffness: – resistance to deflection under short-term loading

• Adequate strength: – how much force can be sustained before it breaks

• Toughness: – the ability to resist the propagation of cracks (arguably the most important property of an engineering material)

Stress, strain, stiffness, strength

(Source: Wikipedia)

• Stress: load/cross-sectional area • Strain: extension/original length • Poisson’s ratio: ratio of transverse to axial strain • Stiffness: Young’s modulus, E, stress/strain (in linear elastic region – Hooke’s law) • Strength: stress at ultimate load (tension or compression)

The range of properties that Nature can achieve

(Source: J.E. Gordon: “Structures”)

Toughening polymers with nanocellulose

PLA + 1% nanocellulose x10 work of fracture (Bulota, M. & Hughes, M. (2012). J Mater Sci 47:5517–5523)

Composite materials • Composite materials are nowadays widely used by humankind in many diverse applications • Nature also uses composites extensively and many elegant hierarchical composite structures have evolved that are far more complex than any synthetic equivalents – we can learn a lot from these natural materials! • Natural composites have been, and are, used extensively by humankind • Many of the earliest forms of composite were based on natural materials

Composites: natural, synthetic and naturalsynthetic hybrids….. • FRPs - Fibre Reinforced Plastics: carbon, glass, aramid fibre: epoxy, phenolic, unsaturated polyester resin • Metal matrix composites - MMC • Wood: cellulose embedded in hemicellulose and lignin • Bone: hard crystalline mineral, hydroxyapatite, embedded in a matrix of collagen • Teeth, skin….. almost all biological materials are composites of one sort or another…. • “Biocomposites” (the first manmade composites) combine at least one “natural” component

Natural composites used by humans

Biocomposites: what are they?

Biocomposites • “Bio-composites”, “eco-composites”, “green composites” • “Materials composed wholly, or in part, of constituents which come, ultimately, from a renewable resource” – This definition applies to both the reinforcement and matrix phases of the composite – Within this definition of ‘fibres from renewable resources’ are regenerated cellulose fibres – rayon or viscose (as ultimately these come from biomass) as well as natural ‘nano fibrils’ of cellulose and chitin – Matrices could be of either an organic or inorganic nature. Organic matrices may be polymers themselves derived from renewable resources or may be a synthetic, fossil derived polymer and may be either ‘virgin’ or recycled

Range of biocomposites • Current “biocomposites” fall into two broad categories: • Wood Plastic Composites (WPCs)

– Wood fibre or another agricultural fibre combined with a plastic such as polyethylene or polypropylene (or a range of other polymers

• Natural fibre reinforced composites

– Range of natural fibres grown specifically for their good properties, combined with a polymer resin or plastic to form a composite material

• Broad classification and the distinction between the types is not always so clear

Wood Plastic Composites • Now in commercial production in many countries, especially in N. America • Europe slow to take-off, but now strong interest. E.g. UPM ProFi and UPM Formi products • Applications are mainly in the construction sector, where they can replace materials such as treated timber, but are extending into other areas including biomedical and other consumer applications

Wood Plastic Composites • Also in other applications such as furniture…..

(source: www.lammhults.se)

Natural fibre reinforced composites • Automotive components • Most manufacturers nowadays incorporate several kilos (5-10) of natural fibre reinforced polymer matrix composites in their cars • In excess of 50 k tonnes per year in EU

Drivers • Much wood and fibre traditionally went to landfill – WPCs provide a way of diverting fibre and adding value to waste • Similar story for plastics – a large volume of post industrial and post consumer waste plastics end up in landfill • Desire to develop and diversify farming practices have led to the concept of non-food crops, i.e. crops grown for the purpose of providing raw materials such as fibre and polymers – the raw materials for composites • In short, making more environmentally conscious materials – sustainable composites

Plastics and resin polymers • Biocomposites also need some form of a “matrix” material, which is generally a polymer • Can be either: – Thermoplastic (e.g. polypropylene; polyethylene; nylon; PVC……) – Thermosetting (e.g. phenol formaldehyde; unsaturated polyester; vinyl ester; epoxy etc)

• Polymers can be also: – Fossil based (i.e. petrochemical based) – Renewable resource based (i.e. manufactured from non-food crops, such as vegetable oils or starch….. or a number of other staring materials like furfural alcohol)

• Further, the polymers may be biodegradable or not (irrespective of whether they are fossil- or bio-based)

Biocomposites: historical viewpoint

Composites in history • Hemp fibre found in ancient pottery from China dating back to 10 000 BC • Straw reinforced mud bricks of ancient times • Really begins with the advent of synthetic resins during the early part of twentieth century • Examples of biocomposites before then. For instance, in America in the 1850s, shellac (a resin secreted by the female lac bug) was being compounded with wood flour to mould Union cases to display early photographs, whilst Lepage worked in France with albumen and wood flour to produce decorative Bois Durci plaques

Bakelite • Invention of Bakelite (phenol formaldehyde) in 1909 • Wood flour or waste string and rags used as reinforcement to form the earliest synthetic composites • Applications in consumer items such as radio and speaker cases

Gordon Aerolite • Early work had been carried out by Caldwell and Clay in 1924, into the use of fabric reinforced synthetic resins for airscrews • Not really taken seriously until a Dr Norman DeBruyne became interested in the 1930’s • Much of the development work was the result of a search to find new lighter and stronger materials that could be used in aircraft structures

Gordon Aerolite • Development began in 1936 with work undertaken by De Bruyne to utilise cotton fabric, as reinforcement in phenolic mouldings • A composite consisting of unidirectionally aligned unbleached flax thread impregnated with phenolic resin • A number of prototype aircraft structural components were produced from Gordon Aerolite. One of the first of these was a wing spar for the Bristol Blenheim Bristol Blenheim (Image from:http://www.pilotfriend.com/photo_albums/timeline/ww2/Bristol%20Blenheim.htm)

Gordon Aerolite • Produced by laying up strips of resin impregnated unbleached flax yarn to form a cross-ply laminate structure, or unidirectional bar or strip of material • Heated and pressed to form the composite • Around 75% by volume was fibre, held together with resin which formed the remaining 25% • Ultimate tensile strength and Young’s modulus of longitudinally loaded material were around 480 MPa and 48 GPa respectively

Other early biocomposites • Henry Ford first raised the possibility of using hemp fibre reinforced soybean resin in cars! • The body panels of the Trabant were produced from cotton reinforced unsaturated polyester resin

Demise of natural fibre reinforced composites and resurgence • Rapid developments in cold cure resin systems such as unsaturated polyester and epoxy resin together with glass fibre in the 1940’s led to the decline in the interest in natural fibre reinforced composites (NFRC) • Resurgent interest with the oil crisis in the early 1970s • Much work was conducted in the late 1980s and early 1990s, leading to the current use of biocomposites (wood-fibre plastic composites and natural fibre reinforced composites)

Opportunities

Opportunities for the forest products sector • New high performance materials – Harness the properties of the microfibril

• Different functionalities – Surface properties – ‘Tailored’ biodegradability

• New markets – Consumer items, leisure, transportation

• Different production technologies – Compounding, extrusion, injection moulding

Further reading • Historical aspect covered in Chapter 14 of ‘Green Composites’ • Callum Hill and Mark Hughes (2010). Natural Fibre Reinforced Composites: Opportunities and Challenges. Journal of Biobased Materials and Bioenergy, 4: 1–11 • Faruk, O, Bledzki, AK, Fink, HP and Sain, M. (2012) Biocomposites reinforced with natural fibers: 2000-2010. Progress in Polymer Science 37(11): 1552-1596 (DOI: 10.1016/j.progpolymsci.2012.04.003)