Bibliography - Leander Bakker

Material Studies

Introduction

This project revolves around the growing of architecture by application of mycelium. Mycelium is the vegetative part of fungi. This biological tissue/ material is composed from tube-like fibers. These fibers are called hypha and are approximately 1 lm in diameter. Hypha grow by elogation of the apical tip. Which means that the fibers grow faster in the tips than in its branches. On occasion these fibers branch out and merge with other hyphae. As a consequence a random fibernetwork structure is formed; The mycelium (Lull et al., 2005).

Mycelium can be grown in multiple forms, (pure) mycelium, synthetic mycelium and composite mycelium. The last one will be the main focus of this material study since this is the form that is most used within the product development and the built environment. The composite is a mixture of mycelium mixed with a organic substrate most preferably a lignocellulosic biomass. Mycelium than forms it's network of hyphae on and through the substrate by (partly) consuming the substrate. It then transforms the substrates biomass into chitine (up to 45%), Protein and polysacharides. As a result of this process mycelium and the substrate are bonded into the mycelium composite (Tazelaar, 2017).

Biological Properties

Lifecycle of fungi

Since fungi is a living organism the species goes through the cycle of life. In order to produce and reproduce mycelium knowledge of it's cycle is required. The image below portaits the lifecycle of the fungi.

This image is based on a image from (Lull et al., 2005)

Bakker, L. (2019). Fungi Lifecycle. Own Image

Species

The taxonomical kingdom of fungi is vast. Within the this kingdom you can find species that act as food, produce medicine or in case of this research as building material. Form all the different taxonomical divisions on division is particularly intressting, this is the basidiomycota division. The reason why this division is so intressting is because of its ability to break down long and complex organic moleculs. The species that are most often used within this field are the Oyster mushroom (Pleurotus ostreatus, "Oesterzwam" (NL)), the Split Gill (Schizophyllum commune, "Waaiertje" (NL)), Lingzhi mushroom (Ganoderma lucidum, Reishi, "Gesteelde lakzwam"(NL)) and the Turkey tail (Trametes versicolor, "Gewoon elfenbankje" (NL)). The choices for these fungi are chosen due to their benifitial properties towards growth, strenght and ability to consume specific nutritions for example (Tazelaar, 2017).

Pleurotus Ostreatus

Schizophyllum Commune

Ganoderma Lucidum

Trametes Versicolor

Source Pleurotus Ostreatus image: File:2010-10-28 Pleurotus ostreatus (Jacq.) P. Kumm 116409 cropped.jpg - Wikimedia Commons [Photograph]. (2010, October 28). Retrieved March 26, 2019, from https://commons.wikimedia.org/wiki/File:2010-10-28_Pleurotus_ostreatus_(Jacq.)_P._Kumm_116409_cropped.jpg

Source Schizophyllum Commune image: File:Schizophyllum commune (849610).jpg - Wikimedia Commons [Photograph]. (2018, February 24). Retrieved March 26, 2019, from https://commons.wikimedia.org/wiki/File:Schizophyllum_commune_(849610).jpg

Source Ganoderma Lucidum image: Reishi - Ganoderma lucidum [Photograph]. (n.d.). Retrieved March 26, 2019, from https://gluckspilze.com/Reishi-Ganoderma-lucidum-China-Strain-Indoor-Spawn-Bag-for-organic-growing-acc-to-regulation-EC-834-2007-AND-889-2008-AT-BIO-701

Source Trametes Versicolor image: Phil Bendle. (2018, May 25). Trametes versicolor, Turkey-tail porebracket - Friends of Te Henui - Kete New Plymouth [Photograph]. Retrieved March 26, 2019, from http://ketenewplymouth.peoplesnetworknz.info/friends_of_te_henui/images/show/26954-trametes-versicolor-turkey-tail-porebracket

Growth properties

Fungi is a living organism which means it needs nutrients and energy to grow. These required nutrients consist Carbon (C), Nitrogen (N), Phosphorus (P), Suplphur (S), Potassium (K), Calcium (Ca), Magnesium (Mg), Hydrogen (H), Oxygen (O) and various more elements in trace amounts, like Iron (Fe), Zinc (Zn), Copper (Cu) and Manganese (Mn). Most of therse nutrients can be found in the form of sucrose, ammonium salts, inorganinic ion, carbohydrates and proteins. In order to grow the fungi assimilates sucrose. This organic compound can be obtained through different processes. For example by deconstruction of glucan polymers form plant residues. In order to assimiliate molecules fungi requires oxygen. Some fungi contain enzymes which enables them to break down almost all naturally occurring carbon polymers and as well as some manmade carbon polymers including plastics. Most of the fungi have a simple nutrient requirements. Some are just sufficient by consuming a carbon source. While others have few additional needs for organic compounds. These compounds are actively and inactively obtained by the fungi from it's environment (Watkinson, Boddy, & Money, 2016 ;Blauwhoff, 2016).

In order to stimulate maximum growth the environmental aspects need to be optimum. To achieve this most fungi require warm tempertures around 25ºC with a humity of 65%. Furthermore the the environment needs to contain enough oxygen and food scources to stimulate growth. In order to increase growth even more environment of the fungi should be a little acidic, approximatly between pH 4 and 6. But since every species of fungi is different the optimum growing conditions differ for each species(Watkinson et al, 2016).

Fungi have also been observed to contain xenobiotics. Which basically means that compounds are found within organism that do not naturally ocor their, neither by natural production nor other natural ways. These compounds can for example be hormones form one organism taken up by another. Research has found that fungi is able to breakdown xenobiotic compounds like polycyclic aromatic hydrocabons (PAH), halogenated solvents, endocrine-disrupting agents, metals, metalloids, organometallics and radionuclides. Most of these xenobiotics are toxic or harmfull to the environment in another way. Within this observation it became clear that fungi contain enzymes which break down xenobiotics, like drugs, pharmaceuticals, polyaromatic hydrocarbons and radionuclides into unharmfull compounds. Therefor fungi is suitable for detoxication through bioremediation(Watkinson et al, 2016).

Structural Properties

Structural properties

The usage of mycelium as a building component is relatively new. Therefor there is not much research available involving this subject. Besides that mycelium is a biocomposite with many different possibilities for substrate, that fact makes it even more harder to determine average structural properties. In the table below structural properties are shown of mycelium in comparrision to EPS and concrete. EPS is shown since the characteristics of mycelium and EPS are very similiar as are their usages within product development. While concrete is shown as it is a widely used within the build environment.

As seen the structural properties are very similair when it comes down to their compressive strengths. While the young's modulus shows that mycelium is more flexible than EPS. With the mycelium flexibility it is also able to better deal with flexural forces than EPS. But the best the reason why mycelium is better for usages than EPS is its low energy consumption for production and it's biodegradable properties.

	Mycelium Composite	EPS	Concrete (C53/65)
Density [Kg/m³]	122	20	2500
Compressive strength 10% [MPa]	0,12	0,10	65
Tensile strength [MPa]	-	0,15	2,13
Flexural strength [MPa]	0,23	0,15	4,30
Young's modulus [MPa]	1,14	6,00	37300

This table is based on information from (Cement&BetonCentrum, n.d.;Tazelaar, 2017)

Composites Enhancement

As previously mentioned mycelium is often created as biocomposite material. That means fungi get inoculated into a substrate. This substrate is therefor very important for the quality of the mycelium composite.

Joining of materials

To create large objects made from mycelium it is necessary to join mycelium together. While bricks for example need mortar in order to join multiple bricks together mycelium is different. In order to join mycelium together it is important to join mycelium components while it is still alive. To join mycelium the different components can simply be stacked upon one another. As a consequence both hyphe networks will grow and join together into one hyphea network. But this can only be done with fungi from the same species. When mycelium form different species are placed on top of one another the weaker one tends to get consumed by the stronger species. Therefor the result is two misformed components that are not properly joined together.

Environmental Properties

Vezel Emissie broeikasgas [t CO2/t vezel] Primair gebruik energie [GJ/t] Carbon 1,7 290 Glas 2,2 35 Vlas/Hennep 0,714286 5-10

Waterproof

Windproof

Fire safety

Jones et all (2018) did a research into the fire safety of mycelium components. decomposition temperatures, residual char, and gases evolved during pyrolysis. The thermal degradation and fire safety of mycelium and mycelium-wheat grain composites have been characterised using various experimental techniques. Thermogravimetric analysis revealed that the growth time has no discernible effect on the thermal degradation characteristics of mycelium. FTIR and GCMS analysis have identified the complex thermal degradation patterns accompanied by the release of multiple flammable and non-flammable gaseous products. The fibrous structure of mycelium is retained following pyrolysis, albeit with a reduction in its diameter. The fire reaction properties of mycelium have found to be superior to other competing thermoplastic polymers (PMMA and PLA) due to its tendency to form relatively higher char yields. The presence of mycelium is responsible for an improvement in the fire reaction properties of wheat grains. However, beyond 6 d, the growth time has been found to have no significant effect on the fire reaction properties of mycelium-wheat grain composites. Mycelium has been found to possess certain flame-retardant properties (e.g. high char residue and release of water vapour) and could be used as an economical, sustainable and fire-safer alternative to synthetic polymers for binding matrices.

Acoustics

Insulation

0,04 W/MK Mycelium 2,60 W/MK Concrete

Resistance to Toxins

Biodegradation

Effect on the ecosystem

Comperision to concrete, styrofoam. Usage of waste streams.

Waste production.

In order to produce mycelium based products.

Patterns

Machine Alterations

Product lifecycle

Pure mycellium and composite mycelium
Aerial Hyphae and Conidiophores Fungal colonies cultured on agar medium often cover themselves with a forest of aerial hyphae. This tangle of filaments can fill the airspace above the agar and squash itself by extending against the lid. Extension of these aerial hyphae is driven by the same mechanisms described in the previous section, but the cells encounter a different set of environmental challenges. Hyphae-penetrating agar must exert substantial force to push through the gel matrix and do so by loosening the cross-links between polymers in the apical cell wall, thereby applying a proportion of their internal turgor pressure against their surroundings. The requirement for force generation is greatly reduced for a cell extending into the air, but internal pressure is necessary to support the vertical orientation of the cell. This is obvious, based on the observed collapse of aerial hyphae when they are exposed to dry air. Before hyphae can reach the air above the colony, they must overcome the surface tension of the air–water interface. This problem seems to be addressed by a combination of the continued exertion of turgor-derived force and the secretion of hydrophobic proteins called hydrophobins that reduce the surface tension at the interface. Hydrophobins are small, cysteine-rich, water-repellant proteins that are secreted on the surface of aerial hyphae and fruit bodies. They have been studied in the mushroom-forming basidiomycete, Schizophyllum commune. Targeted deletion of one of the hydrophobin genes in this fungus, SC3, results in the resulting mutant’s inability to produce aerial hyphae. The protein, SC3, operates as a surfactant, self-assembling as a monolayer at an air–water interface and reducing the surface tension of the water. The reduction in surface tension may allow hyphae of the fungus to escape a fluid environment and grow into the air. Secretion of the protein continues with the extension of the aerial hyphae, coating them with a hydrophobic layer. Hydrophobin secretion is also important in facilitating the attachment of hyphae to hydrophobic surfaces. In many species, aerial hyphae differentiate into conidiophores (spore stalks) that produce asexual spores, or conidia. We will return to the process of conidium formation, or conidiogenesis, in the next chapter. The secretion of hydrophobins onto the surface of developing mushrooms (basidiomata) is important in cementing hyphae together, waterproofing the surface of the reproductive organ, and supporting gas exchange by preventing tissues from becoming saturated with water. (Watkinson et al., 2016)

project04:Material Study