JEC COMPOSITES MAGAZINE - Issue #71 - March 2012 - 32

natural fibre
wood) is an average 210,000 MT/year. France is therefore Europe’s leading natural fibre producer, accounting for 80% of total production (Figure 1). suits the required properties. Certain extraction processes help significantly to improve the mechanical performance (Table 1).
Tab.1: Average tensile properties for single flax fibres from optimized extraction processes (Source: FRD)

Available natural fibre reinforcements

Natural fibres for composites
Given the growing interest in natural fibres for composite materials, the industrial players involved are faced with a natural fibre value chain that is insufficiently structured for technical markets. FRD acts as a platform for the natural fibre industry and proposes a catalogue of appropriate solutions for the different composite processes, including cut fibres, powders, aggregates, compounds and natural fibre based reinforcements. FRD makes use of its expertise and knowledge of the plants, fibres, and extraction/ converting processes used to develop the best plant-based product for material manufacturers’ individual specifications.

Mechanical property Young’s modulus Breaking stress Elongation at break

Average value
32 GPa

935 MPa

3%

ture of products with isotropic properties and in a wide The types of natural fibre variety of thicknesses and textile reinforcements for densities (50-2,500 g/m²); thermoplastic or thermoset - fabrics similar to the marcomposites are very similar ket’s available glass solutions to synthetic-fibre ones (see in terms of weight and weave; Figure 2). - unidirectional materials There is a very broad range of designed for mechanical proindustrially available reinforce- perties in a single direction; ments that covers plant-based - multiaxials with multiple products such as: plies of unidirectional fibres - rovings (low-twist contiplaced in two or more direcnuous filament) in a wide tions and stitched together variety of thicknesses from to ensure good mechanical 100 to 2,000 tex; properties in several different - nonwovens from different directions; technologies for the manufac- - prepreg, opening the field to

Tab. 2: Performance of natural fibre reinforced composites (Source: FRD)

Matrix Reinforcement Reinforcement composition Density Fraction Mechanicals characteristics Traction Maximum stress (MPa) (direction 0°)
Strain (%) Elastic modulus (GPa) Elastic modulus (GPa)
Values 17.6 147 1.1 15.3 258 3.6

EPIKOTE Epoxy Resin 828 LVEL Multiaxial
flax 100% 1640 g/m² 49% SD 1 14 0.1 1.6 33 0.5

UD
flax 100% 1500 g/m² 46% Values 26.3 284.2 1.4 20.1 301.2 3.0 SD 0.8 12.4 0.1 1.0 11.0 0.1

Non-woven
flax 100% 1500 g/m² 33% Values 5.8 53 1.21 3.6 89 2.7 SD 0.2 3 0.07 0.9 8 0.3

Mechanical performance
Humans have been cultivating these natural fibres since time immemorial. Flax is the oldest textile in the world, with more than 7,000 years of history behind it. Paradoxically, our level of knowledge of these fibres for technical applications still requires a great deal of research to better understand the parameters that influence the performance of these natural fibres, in order to optimize them. What we do know about these fibres is that the process used to extract the fibres from the plant has an effect on the mechanical performance of the fibre. FRD studies these impacts, specifically on flax and hemp, in order to identify the process that

Flexural Maximum stress (MPa) (direction 0°)
Strain (%)

Matrix Reinforcement Reinforcement composition Density Fraction Mechanicals characteristics Traction Maximum stress (MPa) (direction 0°)
Strain (%) Elastic modulus (GPa) Elastic modulus (GPa)
Values 13.3 125 1.3 14.7 155 4.9

NORESTER Polyester resin RM822 Multiaxial
flax 100% 1640 g/m² 51% SD 0.5 6 0.1 0.9 25 2.6

UD
flax 100% 1500 g/m² 44% Values 25.0 290.0 1.5 21.1 309.0 3.3 SD 0.3 8.5 0.1 0.8 7.5 0.1

Non-woven
flax 100% 1500 g/m² 29% Values 7.6 66 1.3 4.9 110 3.1 SD 0.3 4 0.1 0.6 9 0.2

Flexural Maximum stress (MPa) (direction 0°)
Strain (%)

32 jec composites magazine / No71 March 2012
JEC COMPOSITES MAGAZINE - Issue #71 - March 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #71 - March 2012
