SPE THERMOSET TOPCONFebruary 20, 2018

Natural Fiber Composites: Design, Testing and Engineering

Trey Riddle, PhDsunstrands.com

Introduction

Where are we now?How far do we

want to go?vs.

* M. Abbey

BIGthink BIG

impact

profit people planet

Industrial BioMaterials:

Compatibility is Key

BioBased:Rapidly Renewable

Traditional:Energy/Oil Intensive

Bio-Composite

Manufacturers Interests

Low cost

Weight reductions

End of Life (Landfill)

Increased surface area

Reduced environmental hazards

Additional Value of Biomaterials

Attractive

Meet performance metrics

(Eco) Marketing appealNew revenue streamsMarketing leverage

The Sustainable Materials Company

Sunstrand is not just building a company, We’re building an industry

Attractive Intersection of

Science & Ag

Value InTransparency

• I am 5th generation American Farmer • I grew up farming cattle, wheat, corn and

alfalfa hay• I am a US Navy Veteran. I served on warships

in the South Pacific & Middle East• I grow hemp and kenaf in rural Kentucky

Environmental Credentials

• Net negative carbon emissions compared to glass fiber which produces ~1,900lb of CO2 per ton

• Rapidly renewable and sustainable• Weight reductions increase fuel economy

Biomaterial Supply Chain

Customer

End UsePlastics

InputsProducts

Main Fiber Line Area Dry (Mil) Processing

PackagingDrying LineWet (Reactor) Processing

Processing capacity of bamboo, hemp, kenaf, flax and others

Industrial Plant in

Louisville, KY

The USA is ahead…

• USA uses more composite materials than any other country

…and behind

• The USA uses a negligible amount of natural fibers in the US

Europe: Market Leaders

Bioplastics/Biocomposites market • 2014: $543M• CAGR of 20% since 2008• $5.8B by 2030

Auto industry in 2014• Before peak auto• Natural fiber usage = ~100MM lb• NA manufactures 4X more vehicles

Fiber Properties

Where Do Natural Fibers Come

From?

• Primary fibers: Flax, Hemp, Kenaf, Jute• Members of the Bast family

“Bast” Fiber~25%

Core, Hurd, Shive ~75%

Filament Testing:Fiber Bundles

• Testing is generally of fiber bundles• Cellulose fibers held together by lignin• Can still follow typical ASTM filament specs• Inherent variability in fiber response

Fiber Engineering (Mechanical)

Properties

Fiber Density(g/m3)

Length(mm)

Diameter(µm)

Elongationat break

(%)

Tensilestrength*

(MPa)

Cotton 1.21 15–56 12–35 2–10 287–597Coir 0.3–3.0 7–30 15–25Flax 1.38 10–65 5–38 1.2–3 343–1035Jute 1.23 0.8–6 5–35 1.5–3.1 187–773Sisal 1.20 0.8–8 7–47 1.9–3 507–855Hemp 1.35 5–55 10–51 1.6–4.5 580–1110Henequen 1.4 8–33 3–4.7 430–580Ramie 1.44 40–250 18–80 2–4 400–938Kenaf (bast) 1.2 1.4–11 12–36 2.7–6.9 295–930Kenaf (core) 0.31 0.4–1.1 18–37Pineapple 1.5 3–8 8–41 1–3 170–1627Bagasse 1.2 0.8–2.8 10–34 0.9 20–290Southern yellow pine 0.51 2.7–4.6 32–43Douglas fir 0.48 2.7–4.6 32–43Aspen 0.39 0.7–1.6 20–30

Mechanical Properties

Comparison to Glass Fiber

• Natural fibers are not as stiff or strong as glass fibers• Natural fibers are very light: 1.0-1.4 SG• Good specific properties

Design Approach

Composite Testing

• Testing of bio-fiber composites is the same as traditional composites

• Failure mechanism also similar• Matrix cracking, debonding, fiber

breakage, etc

Composite Design

Opportunities to match glass fiber composite response• Requires increasing Vf

Composite Response

Rule of mixtures• Match stiffness with reduced weight by

adding Vf

• Stiffness in particular, sometimes strength

Example of Modulus Matching

Design Considerations

Short Fiber

• Natural fibers are inherently short• Well suited for discontinuous systems• Compounding, non-wovens

• Continuous strand systems are available, but at higher costs

• Similar to carbon fiber prices

Matrix Bonding & Critical Length

• Polar fibers do not bond with non-polar resins• Increase mechanical locking through refining

(fibrillation) but reduce strength• Sizings (coupling) or resin additives can be used• “Knockdown factors” can be empirically derived

and used in modeling• Interfacial Shear Strength requires critical length

Manufacturing Considerations

• Lignocellulosic materials are hydrophilic• Can be mitigated

• Temperature effects• Possible degradation at temps above 390F (200C)

• Weight (handling) issues• Fibers are very light, nearly ½ glass

• Clumping• Fuzzy fibers can cling each other

Application Examples

Products/Compatible Manufacturing

Processes

Short (< 4in) Discontinuous fibers• Nonwovens – Veils/Chopped Strand Mat

• Open mold infusion• Sheet molding• Pultrusion

• Bulk molding compound• Thermoplastic compounding

Yarn Systems• Typical fabrics for laminates• Pultrusion• Filament Winding

Industry First Biomaterial

Spray-up

• Core material for complex sandwich panels geometries• Compatible with chopper gun systems• Large complex molds

• Opportunities to decrease weight & density

• Opportunities to increase flexural stiffness and strength

• Reduce costs

Large Scale 3-D Printing

• 3D printed pavilion that used Sunstrand’s bamboo fiber• 1/3 of the embodied energy and an order of magnitude

less carbon footprint of carbon fiber –resin systems normally used in large scale additive manufacturing

Final Thoughts

• Leverage marketing • There are some issues• Match stiffness and in some cases strength • Possibilities for cost and weight reduction• Goal is “near” drop-in compatibility• Consistent materials systems are available

www.sunstrands.com1401 Locust StreetLouisville, KY 40206

Sunstrand: The Sustainable Materials Company

WE are changing the way YOUR stuff is made