1. Figure5. SEM images and mapping of biocomposite Tchestnut_G
Development and characterization of a natural, fungi based, biocomposite
A.Rebelo 1, ,J. Santana1, V. de Zea Bermudez 2,4, G. Marques3, P.L. Silva1,2.
1 Engineering Department, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal
2 CQ-VR, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal
3 CITAB-Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal
4 Chemistry Department, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal
Introduction
Chemical analysis made to the substrate, prior to inoculation, showed that there is a larger amount of carbon compared to other macronutrients. However, there is a deficiency of calcium, important for mycelial growth. Considering micronutrients analysis, iron appears in greater quantity, and this is essential for enzyme activity and fungal intermediary metabolism. The C/N ratio is of the order of 27.59, and is within the range favorable to fungi growth (between 20 and 50: 1).
SEM images represents two different locations of the substrate: interface and bulk. In both, it is possible to see great hyphae colonization and how the fungal colony is protected creating the observed surface layer (melanin concentrations). Mapping presents how nutrients: carbon (green), oxygen (red), magnesium (purple), phosphorus (cyan), potassium (blue), are dispersed throughout substrate.
Being incorporated in the petrochemical industry, polymer industry's main raw material is oil [1]. Resorting to oil for these materials production, problems arise in terms of environmental sustainability, as their operation and subsequent use, contributes to the increase of greenhouse effect [2].
One of the most common polymers is Expanded Polystyrene (EPS), known as Styrofoam [3]. Styrofoam has been banned in some cities, around the world, mainly due to chlorofluorocarbons gases (CFCs), used as blowing agents. The most recent prohibitions were due to the impact of the disposal of food packaging, in dumps at open sky and in the sea, as well as, in human health [4] [5].
Due to the harmful effects of EPS various types of biodegradable composites have been studied and developed in the last years .
This study aimed to develop a biodegradable biocomposite with a biomass matrix and fungi as the dispersed phase, exhibiting characteristics similar to EPS, in terms of properties or applications.
Figure3. XDR and FTIR of biocomposite Tchestnut_G
Materials and methods
Three basidiomycete strains were used: Pleurotus ostreatus, Ganoderma lucidum and Lentinula edodes for colonization of the wood biomass (sawdust of pine, chestnut, beech, oak and mixed woods). Natural additives were also tested.
After a few weeks, when the substrate is well colonized by the fungus, biocomposites were temperature treated (60ºC, overnight) in order to inhibit the fungus growth and prevent subsequent fructification.
Biocomposites characterization was made by several techniques:
X-Ray diffraction.
FTIR
Substrate chemical composition analyses
SEM and mapping
Conclusions
From all composites, the Tchestnut_G was the one that presented more promising results, although XRD diffraction pattern showed reduced crystallinity. However, SEM images demonstrate good fungal colonization of the substrate, providing the desired rigidity and consistency. Mapping indicate that the main nutrients for fungal growth spread evenly, ensuring homogeneity of Tchestnut_G. Chemical analyzes points the possibility of improving biocomposite time production by increasing calcium content.
Figure4. Macro and Micronutrients and ratio C/N of the substrate before inoculation of biocomposite Tchestnut_G
REFERENCES
[1] Silva, L. F. d. et al., Produção biotecnológica de poli-hidroxialcanoatos para a geração de polímeros biodegradáveis no Brasil. Química Nova, Volume 30, pp
[2] Murali M. Reddy Singaravelu, V. M., Biobased Plastics and Bionanocomposites: Current Status and Future Opportunities. Progress in Polymer Science, 1 June, pp
[3] Lucas, E. F., Soares, B. G. & Monteiro, E. E. C., Caracterização de Polímeros: Determinação de Peso Molecular e Análise Térmica. Rio de Janeiro, Brasil: e-papers.
[4] The Way To Go, isites.harvard.edu. [Online] Available at: [Acedido em 2 Junho 2015].
[5] Harvad University, Polystyrene Fast Facts. USA, Copyright.
Figure 1. Isolation process from a fruiting Pleurotus ostreatus.
Figure5. SEM images and mapping of biocomposite Tchestnut_G
Results
Discussion
FTIR shows valleys in the range of 3400cm-1, due to O-H vibrations, corresponding to the sample water content. The 2930cm-1 valley presents C-H stretching vibrations which may be attached to cellulose molecules from the CH2 organic radical. At 1640cm -1 it is possible to detect O-H vibration. Finally, the 1377cm-1 valley is representative of the symmetrical angular aliphatic deformation of CH3, hydrocarbon from Ganoderma.
Alexandra Rebelo
UTAD
Figure2. Final result of the biocomposite Tchestnut_G