Fungal biocomposites as a substitute for polystyrene packaging materials

Povišana mera plastičnega onesnaženja je pakirno industrijo prisilila v iskanje alternativnih, okolju bolj prijaznih materialov. V diplomi predstavljena rešitev temelji na glivnih biokompozitih, ki so produkt micelija preraščenega čez ostanke agroživilske verige. Micelij je vegetativno telo glive, ki z apikalnim podaljševanjem konic hif prodira skozi hranilen substrat. Pri produkciji biokompozitov micelij deluje kot lepilo, substrat popolnoma preraste, zapolni prazne prostore znotraj substrata ter ustvari solidno matrico, ki biokompozitu ohranjajo obliko. Da dobimo varen material, biokompozit toplotno obdelamo, s čimer inaktiviramo rast glive in živo maso pretvorimo v biološko neaktiven končni proizvod. V nasprotju s konvencionalnimi pakirnimi materiali, kot je polistiren, biokompozit poseduje hidrofobne lastnosti, je popolnoma razgradljiv in odporem proti visokim temperaturam. Estetsko in funkcionalno gledano je ekspandiran polistiren še vedno bolj smiselna izbira, vendar se z napredkom raziskav na področju glivnih biokompozitov slednje progresivno izboljšujejo. V okviru eksperimentalnega dela smo izdelali 9 različnih vrst glivnih biokompozitov. Razlikovali so se po substratu in uporabljeni glivni kulturi. Ovrednotili smo potreben čas za nastanek biokompozita, vizualni izgled, gostoto, poroznost, stični kot vode, tlačno trdnost in ognjevarnost. Ugotovili smo, da so biokompoziti na vseh področjih primerljivi z referencami. Za najboljši vzorec se je izkazal sev Ganoderma lucidum v kombinaciji z konopljinim pezdirjem (Rsh P)najnižja relativna gostota (177,45 kg/m3), najvišja poroznost (87,71 %), drugi najvišji povprečen stični kot vode (113,5°) in druga najvišja povprečna maksimalna sila pri 10% deformaciji vzorca (59 N).Increased levels of plastic pollution have forced the packaging industry to look for alternatives, more environmentally friendly materials. The solution presented in the thesis is based on fungal biocomposites, which are the product of mycelium growing over agri- cultural residues. Mycelium is the vegetative body part of a fungus that penetrates the nutrient substrate by apically extending the hyphae. In the production of biocomposites, the mycelium acts as an adhesive, completely outgrowing the substrate, filling the empty spaces within the substrate and creating a solid matrix that allows the biocomposite to maintain its shape. To obtain a safe material, the biocomposite is heat-treated in order to inactivate fungal growth and convert the living mass into a biologically inactive end product. Unlike conventional packaging materials, biocomposite possesses hydrophobic properties, is fully degradable and resists high temperatures. Aesthetically and functionally, EPS is still the more sensible choice, but with advances in research into fungal biocomposites, the two are progressively improving. In the experimental work, 9 different types of fungal biocomposites were produced. They differed in the substrate and the fungal culture used. The time required for biocomposite formation, visual appearance, density, porosity, water contact angle, compressive strength and fire resistance were evaluated. We have found that biocomposites are comparable to references in all areas. The best sample was a strain of Ganoderma lucidum in combination with hemp stalks (Rsh P)the lowest relative density (177.45 kg/m3), the highest porosity (87.71 %), the second highest average water contact angle (113.5°) and the second highest average maximum force at 10% sample strain (59 N)