As a final blog I would like to represent to you a paper which contains the relevance of my thesis to the environment. I explain in this paper the importance of recycling and how using natural fiber composites can help to reduce the landfills.
In next link you will find my statement paper.
The properties of flax fiber are remarkable and it is proven that flax reinforced materials perform better than unfilled polymers(polymer foams). This is shown in graph 1.The lower the density (X-axsis) and the higher the Youngs-modulus (Y-axsis) the better the composite. What we also see that these flax filled composites do worse than most engineering composites. This indicates that when an application that requires fiber filled composites is needed, flax fibers aren’t the first choice. But for applications where unfilled polymers are not stiff enough and engineering composites are overkill, flax fiber reinforced polymers can be used. The advantage of a flax fiber filled composite lies in processing properties. To give the flax fiber filled composites an extra advantage is to make them100% biodegradable.
Graph 1: Positioning of flax fibre composites as function of Young’s modulus and density versus a variety of materials . The dashed line gives the design criterion for a stiff light plate.
So the goal for the future is to develop composites that are 100% biodegradable. This is done by using flax within composites that use natural resins only. A large advantage of these composites is that the good recyclability of the fiber allows the reutilization of the material (eg. Cellulose paper). Another advantage is that bio-refining processes are being explored. This new development still needs a lot of research.
Source: I. Van de Weyenberg, “Flax Fibres as a Reinforcement for Epoxy Composites”. 2005.
In previous blogs I have been talking about composites and I briefly explained in my first blog what a composite is. To repeat a composite is a combination of fibers and a matrix (ex. epoxy)). In composites the matrix is not only used as a binder and load transfer media but also as a fiber “shield” to protect it from early degradation and exterior aggressions. Today I will go deeper in on this subject. Composite materials are known for their durability, high strength, excellent quality, low maintenance and low weight. Composites are widely used in automotive, construction, transport, aerospace,…
When you go through my previous blogs you can see that carbon fiber and glass fiber composites are the most popular composites for the moment.
Carbon fiber composite materials are ten times stronger than steel and eight times that of aluminum, along with being much lighter than both materials. Carbon fiber composites have found their way into the manufacturing of aircraft and spacecraft parts, automobile springs, golf club shafts, racing car bodies and more.
The advantages of carbon fiber materials are significant. First of all carbon fibers are very light fibers resulting in lightweight structures. Furthermore, one can chose between stiff or strong fibers depending on the composite part being produced and the type of carbon fiber material required. Another major advantage is its thermal expansion is basically zero – this means that a metal for instance is expanding when heated, carbon fiber remains in its basic form. The material also has disadvantages, carbon fiber is fairly expensive compared to other materials and the manufacturing process for composite components can be more labor intensive than metallic parts.
Fiberglass is a versatile material that provides potential over conventional materials such as wood, aluminum and steel. Fiberglass is produced by using less energy and is used in products which result in less carbon emissions. Fiberglass offers advantages of being light weight yet has high mechanical strength, impact resistant, is chemical, fire and corrosion resistant, and a good thermal and electrical insulator( “recycling composite materials”, Johnson, z.d.). Due to economic reasons, the material will remain the main choice in many sectors due to the significant price advantage in relation to higher performing fibers.
You maybe will think when reading all of these advantages of current composites “why do we want to use bio-composites? Why put so much time and effort in developing this product?”
Well is is correct that current composites have good qualities, but like I mentioned in my previous blog “Recyclability” the main disadvantage of these non bio-composites is that they are not biodegradable. So when “end-of-life” components aren’t recycled they pollute our earth. That is why we need to do research for bio-composites so that they can replace the composites in components where no high properties are wanted.
The flax plant is grown for flax fibers and flaxseeds. The flax fibers are used in the textile and composite industry. The flaxseeds are used as a food source. The flaxseed carries one of the biggest nutrient payloads on the planet. Flaxseed may help reduce your risk of heart disease, cancer, stroke, and diabetes. flaxseed contains all sorts of healthy components, it owes its primary healthy reputation to: (“What is flaxseed? What are the benefits of flaxseed? – Medical News Today”, 2013)
- Omega-3 essential fatty acids, “good” fats that have been shown to have heart-healthy effects. Each tablespoon of ground flaxseed contains about 1.8 grams of plant omega-3s.
- Lignans, which have both, plant estrogen and antioxidant qualities. Flaxseed contains 75 to 800 times more lignans than other plant foods.
- Fiber, Flaxseed contains both the soluble and insoluble types.
(“Flaxseed Health Benefits, Food Sources, Recipes, and Tips for Using It”, Magee, z.d.)
Besides all of these good qualities, flax seed has a very low amount of carbohydrates, making it ideal for people who limit their intake of starches and sugars. Also people on a diet can use flaxseeds because of its combination of healthy fat and high fiber content. Many dieters have found that flax seed has been a key to keeping them feeling satisfied(“Flax Seed Health Benefits and Safety Issues – Flax Seed Nutrition”, Dolson, z.d.).
So you see that there is more than only flax fibers on this flax plant. It is a multi-faceted plant that serves people not only as a building material but also as nutrition.
With my previous blog I ended the explanation of why we should use flax! Now I want you to get acquainted with the historical culture of flax in Belgium. Whenever you are in the mood for some culture in Belgium, you need to make a visit in Courtray. Here you will find the museum of flax! Due to the river the Leie, flax processing in this region was the biggest and best in the world. Flax processing was the main industry of the south of West Flanders in a large part of the 19th and 20th centuries. Since 1964 a vzw is founded to preserve and collect anything related to the historical evolution of the flax industry. The association started with a small exhibition of flax in the left Broeltoren, but it was not until 1981 that the museum was founded. Since then the museum received high praise and in 2000 the museum was handed over to city of Courtray. It is a beautiful museum were flax processing comes to life. Wax puppets portray the flax process from seed to textile (see picture). The museum organizes activities like Kortrijks Kantatelier that cherishes the art craft of lacemaking. I want to know your opinion on what you think of this innitiative! Please fill in next poll.
Figure 1: From linseed to textile
The fourth main advantage is recyclability. There are very limited commercial recycling operations for main stream composite materials due to technological and economic constraints. The most used recycling methods are grinding and thermal recycling. Both of these methods consume a lot of energy.
Even though fiberglass is extremely useful because of their good properties, an “end of life solution” is needed. Current fiber reinforced plastic composites with thermoset resins do not biodegrade. For many applications where fiberglass is used, this is a good thing. However, in landfills, this is not.
The recycled fiberglass finds its way in various industries and can be used in various end products like concrete. It can also be used as a filler in resin, which can increase mechanical properties in certain applications.
Recycling Carbon Fiber
With the current annual worldwide carbon fiber consumption being at 30,000 tonnes, most waste goes to the landfill. For the composites that don’t go to landfill, the high value carbon fibers from end-of-life components are extracted by breaking down resins in a pyrolytic process at relatively high temperatures. This requires a high amount of energy which has a direct correlation to the high recycling costs.
When summing everything up, we see that the main disadvantage when recycling glass- or carbon fibers is that they are not biodegradable. This means they will not disappear when thrown on the landfill. When we do recycle these composites it takes a lot of energy to recycle them properly. The use of a lot of energy means a lot of money wasted. That is where natural fibers come into the picture. They are biodegradable and do not cost as much as glass or carbon fibers.
A beautiful example of recycling biocomposites is bioplastic polyhydroxy-butyrate (PHB). Unlike carbon and glass fibers that can sit in landfills for years, hemp-PHB biocomposites decompose a few weeks after burial. As they degrade, they release methane gas that can be captured and burned for energy recovery or re-used to make more biocomposites.
“symbol recycling carbon”
Source: Recycling technologies for thermoset composite materials—current status”, Pickering, 2006.
Recycling Composite Materials”, Johnson, z.d.
Biodegradable composites for the building industry | Stanford Woods Institute”, Shwartz, z.d.
Flax is a plant that tolerates a range of soils and climates (Buchanan, 1995). The soils most suitable for flax are alluvium, deep loams (soil composed of sand, silt, and clay in relatively even proportions 40-40-20%). These soils must contain a large proportion of organic matter. Heavy clays are unsuitable, as are soils of a gravelly or dry sandy nature. It is important to choose a site in full sun, with deep, fertile, well-drained soil, and prepare it as you would for growing vegetables or flowers. Flax is planted as soon as the soils begin to warm (typically April) and can be harvested in August, well before the early frosts (“Growing Flax: Production tips, economics, and more”,z.d.). Within 8 weeks of sowing, the plant will reach 10–15 cm in height, and will grow several centimeters per day under its optimal growth conditions reaching 70–80 cm within fifteen days. Farming flax requires few fertilizers or pesticides (“How to Grow Flax | Backyard Gardening Blog”, z.d.).
Because of the ease of cultivating the flax fiber is used in textile and automotive industry. Due to this they can be grown almost everywhere the costs of producing flax can be kept low.
And to be honest isn’t the view of a flax field in bloom not wonderful!
Field of flax