Mechanical properties of mycelium based mdf

Abstract

Keywords: Mycelium composites; MDF; white-rot fungi; mechanical properties; physical properties.

1. Introduction

Mycelium composites have been popular recently worldwide in terms of research interest and commercialization. Mycelium composites are biodegradable, produced renewable materials, environmentally friendly and show low density, good insulation properties, both related to acoustic and thermal aspects. However, mechanical properties of mycelium composites are obviously lower than alternative materials such as expanded polystyrene. Mycelium is the vegetative part of a fungus or fungus-like bacterial colony, consisting of a mass of branching, thread-like hyphae. Mycelium binds organic matter through a network of hyphal microfilaments in a natural biological process able to be exploited to produce both low-value materials, such as packaging, and higher-value composite materials from problematic agricultural and industrial waste materials with little or no commercial value [1]. Mycelium composite materials such as foams, packaging materials, accessory materials, insulation boards etc., have been developed and some of them are available in the market in recent years. For example, Dell uses mycelium foams for packaging of business servers and IKEA has also expressed interest in adopting mycelium*

Corresponding Author: e-mail: gezer@ktu.edu.tr, tel: (462) 377 15 32 135

E.D. Gezer, E. Gümüşkaya, E. Uçar, D. Ustaömer / Sigma J Eng & Nat Sci 11 (2), 135-140, 2020

based packaging [1]. However, there are not many studies about mycelium based medium density fiberboards (MDF) in the literature. In addition, as is known, urea formaldehyde adhesive is commonly used in MDF production. It is also known that the formaldehyde emission from MDF containing formaldehyde above the standard amounts has a negative impact on the environment and human health. Formaldehyde emission causes severe allergic reactions in the skin, eye and respiratory system, weakens the immune system, and causes cancer like health problems depending on the con centration in the environment, exposure time and shape [2]. Therefore, so many scientists are still trying to find a way to decrease/lower or eliminate the formaldehyde emissions from MDF. In order to solve this formaldehyde emission problem from MDF, mycelium based MDF production might be a very good option. The objectives of this study were to produce mycelium based MDF either without using any adhesive or with using only 6% phenol formaldehyde adhesive and to determine some mechanical and physical properties of the mycelium based MDF.

2. Material And Methods

Mixture of hardwood and softwood fibers (50/50%) was obtained from Kastamonu Integrated Wood Industry Company. Commercial urea-formaldehyde (UF) resin was provided by Camsan Wood Industries and Trade. Fibers were then moisturized around 70% and pH was adjusted to around 7 before the sterilization. White-rot fungus culture was obtained from USDA Forest Products Laboratory, Wisconsin, USA. Fibers contained around 70% moisture content were put in polyethylene bags and sterilized at 121°C for 30 mins. The bags were then placed and cooled off in the laminar flow inoculation cabinet. A white-rot fungus mycelium was inoculated and then the bags were then incubated in a climate cabinet at 25 °C and 70% relative humidity for 15 and 30 days. One group of the incubated fibers was subjected to MDF production without using any resin while other group of the incubated fibers was dried to 2% initial moisture content before resin blending. The calculated quantities of the components were mixed. A UF resin (6 % solid resin based on wood oven-dry weight and 2% catalyst was applied based on wood oven-dry weight) were applied directly to the wood fibers using an air-pressure spray nozzle. The blended fibers were formed on steel caulplates into one-layer mats of 40 mm x 40 mm (Figure 1). The mats were manually pre-pressed. These mats were pressed at a temperature of 180 °C for 7 min in a computer-controlled press (Figure 2) and conditioned in a climate room until they reached equilibrium moisture content. After climatizing of MDF panels, the specimens were cut from these panels to determine some physical and mechanical properties.

Figure 2. Production of mycelium based MDF Some physical and mechanical properties of mycelium based MDF panels were determined according to EN 310 (1993) [3], EN 317 (1993) [4], EN 319 (1993) [5] and EN 319 (1993) [6] standards (Figure 3).

E.D. Gezer, E. Gümüşkaya, E. Uçar, D. Ustaömer / Sigma J Eng & Nat Sci 11 (2), 135-140, 2020

3. Results And Discussion

The results section should detail the main findings and outcomes of your study. You should use tables only to improve conciseness or where the information cannot be given satisfactorily in other ways such as histograms or graphs. Tables and figures should be numbered serially and referred to in the text by number.

4. Conclusion

The results showed that the MOE, MOR and IB values of the mycelium based MDF were low and did not meet the minimum required strength values given in the standards. However, these boards may still be used as insulation materials.

Acknowledgments

This study has been funded by TUBITAK (Project no: 118O145).

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