Stemergy: Renewable Fibre Technology

Flax Fiber Composite

A rapidly expanding application for flax fiber is as a reinforcement and filler in the production of flax fiber composites. The binding materials range from thermoplastics such as polypropylene to thermoset resins such as polyester or polyurethane. Typical applications include automotive interior substrates, furniture and other flax fiber based consumer products.

Flax fiber is also being used to produce mineral based composites, in much the same way polypropylene or glass fiber is used to reinforce cement or plaster. The rising price of energy, particularly petroleum, is making these other reinforcing fibers more expensive and the excellent properties and cost of flax fiber are opening up new applications everyday.

Flax Fiber Composites for Automotive Reinforcements:

Presently, one large use for flax fiber composites is for automotive products. There are a number of ways flax fiber can be used to create a biofiber based composite for automotive applications. A common application is to blend the primary flax fiber with polypropylene in a nonwoven (felt) mat that is then compression molded to form a three dimensional flax fiber composite based part.

In the case of a flax fiber composite made from a blend of flax fiber and a thermoplastic such as polypropylene, the flax fiber based mat is heated to the melting point of the plastic, then placed into a matched metal mold, and compressed under pressure. The molded flax fiber composite part is removed from the mold, cooled and further attachments or finishings are added to the part. The flax fiber composite part would typically be used for interior trim applications such as a door panel, window pillar, package tray or trunk liner.

In the case of a flax fiber composite made from a blend of flax fiber and a thermoset resin such as polyester or polyurethane, the flax fiber based mat is placed into a heated matched metal mold, sprayed with the thermoset resin, and then compressed under pressure. The molded flax fiber composite part is finished in the same way as other compression molded materials. There are a number of thermoset resins that are compatible with flax fiber to produce flax fiber composite products. Some of these are plant based, so that a 100% biocomposite is feasible. An example is a flax fiber composite utilizing a soy based binder for the production of automotive headliners.

In addition to flax fiber composites from nonwoven materials it is also possible to make other flax fiber composites using thermoplastic and extrusion based technologies. The use of injection molding technology is possible using flax fiber as a reinforcing material. There are compounding systems that can blend flax fiber with different thermoplastics and extrude them for use in injection molding, thus allowing flax fiber composites to be produced in more complex shapes and structures at very high capacities

The use of plant fibers like flax fiber as a cost and performance effective reinforcement was developed in Europe in the early 1990's and has been embraced by North American car makers. Flax fiber composites are of interest to automotive and other applications due to the following features:

Flax Fiber Composites for Consumer Product Reinforcements:

Many of the technologies developed for automotive applications can be used to make consumer products from flax fiber composites. It is possible to use compression molding, injection molding, simple hand lay-ups or hybrid technologies to produce consumer goods from flax fiber composites. Such products include furniture (chair backs or seats), sporting goods and recreational products, luggage, musical instruments and sound reinforcement gear.

In most applications if the product uses glass fiber, then flax fiber most likely could be substituted as reinforcement in the product.

Flax Fiber Composites for Building Materials:

Beyond automotive, the use of flax fiber composites and other biofiber materials are expected to make large in-roads into home and commercial construction products in the years to come. The applications are numerous and flax fiber composites can help innovative companies achieve their goals of implementing sustainable and environmentally sound building practices that are both cost effective with superior features. Some of the products that are in the works include panel materials, utilizing flax fiber and earth-friendly binders as an alternative to wood-based panels such as flax plywood. New systems for blending flax fiber with concrete and stucco are already in place. Flax fiber based insulation is available in Europe and soon to be available in North America.

Flax Fiber Composites Using Flax Core (Shives):

While most of the reinforcing applications previously described utilize the primary flax fiber, there are also a number of applications that can use the flax core fiber (often called flax shives) to produce additional flax fiber composites. These would typically include blending the flax core fiber (shive) as a powder with various plastic or cement based products. One example would be a flax core fiber composite blended with polypropylene to make an extruded composite decking product. Since the flax core fiber (shive) can be produced in different particle sizes it is highly versatile and easy to use.

A Bright Future for Flax Fiber Composites:

In the era of volatile and rising oil and energy prices and with changing environmental standards effecting traditional materials, the future is bright for flax fiber composites. The growing demand for flax fibre has and will continue to spur on innovation at all levels of the value chain. This will occur all the way from advancements in plant breeding to improve fibre yields and properties through to process and conversion technology optimization based around flax fiber composites.

Stemergy is here to help you to find a way to implement flax fiber into your project or product. We have years of experience in this area and are more than pleased to help.

Flax Core Fiber – also called flax shives - (left) shown with flax fiber composite decking material blended with polypropylene.

Flax Core Fiber – also called flax shives - (left) shown with flax fiber composite decking material blended with polypropylene.

Flax Fiber Composite molded brief case made with flax fiber and polypropylene compression molded nonwoven material.

Flax Fiber Composite molded brief case made with flax fiber and polypropylene compression molded nonwoven material.

Flax Fiber based automotive interior trim part shown with flax fiber composite substrate and plastic inserts for fastening.

Flax Fiber based automotive interior trim part shown with flax fiber composite substrate and plastic inserts for fastening.