JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 48

reinforcement
devices.

Tab. 1: Silks in comparison to plant and glass fibres [8]

Properties

Silk fibresa

Annual global production
of fibres [kt]

(150)

Cost of commercial
raw fibre [£/kg]

(2.0-30.0)

0.5-1.5

1.3-20.0

Chemical nature

protein-based

cellulose-based

silica-based

Fibre length

continuous

discrete

continuous

15-600 (15-50)

5-25

1.35-1.55

2.40-2.70

Fibre diameter [μm]
Density [gcm ]
-3

Moisture absorption [%]
Softening temperature [°C]

1-15

31,000

(8-15)

1.25-1.35
5-35

Plant fibresb

(20-35)

170-220

7-25

(600)

(7-10)

Glass fibresc
4,000

0-1

190-230

700-1,100

30-80 (50-80)

As part of projects funded by the European Research
Council (ERC) and the Air Force Office of Scientific
Research (AFOSR), the Oxford Silk Group is also
investigating the potential of silkworm silks as sustainable alternative reinforcements for engineering
(i.e. non-biomedical) composites. This timely work
is in the context of the growing research interest and
industrial acceptance of natural fibre composites as
sustainable material solutions to help industry meet
environmental legislations in the short term, and to
help develop a circular, green economy in the long
term.

70-85

Table 1 and Figure 2 compare some technical
properties of natural silks with natural plant fibres
(the more widely studied natural reinforcement)
Specific tensile stiffness
4-20
(4-12)
20-60 (30-60)
27-34
and synthetic glass fibres (the more commonly used
[GPa/gcm-3]
reinforcement). In general, the primary disadvan0.2-1.8 (0.3-0.6)
0.4-1.5 (0.5-0.9)
2.0-3.7
Tensile strength [GPa]
tages of silks in comparison to plant and glass fibres
Specific tensile strength
are: i) higher cost (of processed fabrics), ii) higher
0.1-1.5 (0.3-0.7) 0.3-1.1 (0.3-0.7)
0.7-1.5
[GPa/gcm-3]
moisture absorption (than even plant fibres), iii)
lower softening (and therefore processing) tempera15-60
(15-25)
2-30
(2-4)
2.5-5.3
Tensile failure strain [%]
tures, and iv) poor stiffness. However, silks possess
-3
25-250
(70)
5-35
(7-14)
40-50
Toughness [MJm ]
i) lower density (than even plant fibres), ii) natural
Specific toughness
flame resistance, iii) moderate strength, iv) unpa20-185
(50-55)
3-26
(4-10)
16-19
[MJm-3/gcm-3]
ralleled toughness, and iv) a favourable environa
Includes silks from various spiders and silkworms. As most of the commercial silk is cultivated from
mental profile of the raw material. As the silk textile
the Bombyx mori silkmoth, typical properties of this variety of silk are presented in brackets.
industry is well-established, common technical
b
Includes bast, leaf and seed fibres. Typical properties of flax fibre are presented in brackets.
c
Includes E- and S-glass fibres. Properties for E-glass are in the lower range.
textile precursors for composites are not difficult to
produce or source. In addition, the Oxford Silk Group
has recently shown that the higher compactibility of silk
preforms in comparison to both plant and glass fibre textiles
provides a unique opportunity to produce high fibre content
natural fibre composites using conventional manufacturing
processes [7].
Tensile stiffness [GPa]

5-25

(5-15)

As part of its research, the group first conducted a comprehensive literature review on silk composites and simultaneously
worked on the "design of silk fibre composites" noting the
apparent differences between the traditionally used brittle-stiff
reinforcing fibres and ductile-compliant silk fibres. This paper
presents some results from a subsequent cross-comparative
study evaluating the properties of nonwoven and woven silk
composites against similar flax and glass composites.
Fig. 2: Ashby plot comparing natural silks with other natural fibres (gold
balloons) and their building blocks (pink), and synthetic fibres (green) -
Adapted from [9]

and bone repair [3-6]. Indeed, the companies spun out of
the Oxford Silk Group (see www.oxfordbiomaterials.com)
are developing many such silk-based biocomposite medical

Composite manufacture
All composite laminates were manufactured using vacuum
infusion in a rigid aluminium mould. Silk composites were
fabricated using specially produced nonwoven mat and biaxial
woven fabric reinforcements at fibre volume fractions of 36%
and 45%, respectively (Figure 3) [8]. The nonwoven silk mat
is unique as the low-cost fabrication process employed (des-

48 jec composites magazine / No92 October - November 2014


http://www.oxfordbiomaterials.com

JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014

Cover
Edito
Point of view: oil & gas
Contents
COMPANY & BUSINESS In Brief
Recycling
Biocomposites
Spin-off
Agenda of Events
APPLICATIONS
Sustainability
Defense
Automotive
MARKET
Biocomposites
Inside the factory
SPECIAL JEC AMERICAS - FALL EDITION
Gain insight into the JEC 2014 I.C.S. Americas Program
JEC Americas Innovation Awards Program
Maintenance - Certified composite repair system for pipelines
Carbon fabrics - Successful first flight test for the VX-1 KittyHawk C-PlyTM aircraft model
Design - Composite aerostructure development in high-performance enterprises
RESEARCH & DEVELOPMENT
Reinforcement
Process
TECHNOLOGY & INNOVATIONS
NDT
Tooling
Infusion
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Cover
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 2
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Edito
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Point of view: oil & gas
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 5
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Contents
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 7
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - COMPANY & BUSINESS In Brief
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Biocomposites
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Recycling
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Spin-off
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 12
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 13
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Ad1
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Ad2
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 15
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Sustainability
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 17
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 18
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 19
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Defense
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 21
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Automotive
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Biocomposites
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 24
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 25
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 26
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 27
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Inside the factory
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 29
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 30
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - SPECIAL JEC AMERICAS - FALL EDITION
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Gain insight into the JEC 2014 I.C.S. Americas Program
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 33
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 34
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 35
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 36
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - JEC Americas Innovation Awards Program
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 38
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 39
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 40
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 41
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Maintenance - Certified composite repair system for pipelines
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Carbon fabrics - Successful first flight test for the VX-1 KittyHawk C-PlyTM aircraft model
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Design - Composite aerostructure development in high-performance enterprises
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 45
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 46
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Reinforcement
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 48
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 49
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 50
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Process
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 52
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 53
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 54
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - NDT
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 56
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 57
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Tooling
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 59
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 60
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 61
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Infusion
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 63
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 64
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - Index
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - In the world
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 67
JEC COMPOSITES MAGAZINE - Issue #92 - October/November 2014 - 68
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