BIOBUILD D4.5 Report on bio-composite mechanical and physical properties

This deliverable reports the results obtained by the physical, mechanical and biological characterization of bio-composites prepared with adhesives of natural origin as linseed oil, lignosulfonate and fungal mycelium. It was characterized three different methodologies, without synthetic glue, for performing bio-composites based on Norway spruce wood fibres impregnated with bio-PCM ethyl ester palmitate. The biological and physical mechanical characterization were performed on the best combination of three different thesis based on the results obtained by thermal proprieties. Only about SQIM bio-composites, mycelia based on, we received 4 theses, respectively impregnated non pressed (I_NP) and pressed (I_P) and non-impregnated non pressed (NI_NP) and pressed (NP_P). For this reason, due principally to the scaling fabrication with respect to lab scaling of CNR we characterized by all point of view, biological and physical mechanical, only the SQIM bio-composites, nevertheless the evaluation and results obtained in the WP3 from CNR, are resulted di great importance to know the performance of a fungus, found and characterized and used for preparing different bio-composites with hardwood and softwood species impregnate with bio-PCM. The influence of bio-PCM on these characteristics it is the aim of this deliverable. In fact, the wallboards could be susceptible of biological attacks especially insects due to indoor environment and principally moulds if there are put in service condition the development of humidity. The indoor environment of a building is, in accordance with CEN EN 335, standard use classes 1 and 2. The only biological risk are insect coleoptera and in case of Norway spruce Hylotrupes bajulus, subterranean European termites Reticulitermes lucifugus and moulds that are developing in the house if the moisture reach high values. The resistance of the wood-boring beetle Hylotrupes bajulus was evaluated in accordance with EN 47:2016. Larvae of category two, weighing 50 to 150 mg, were used, with one larva per sample. Results showed that only the reference specimens and lignosulfonate without PCM reached 12 weeks, while bio-composites with linseed oil, citric acid, and oxalic acid demonstrated resistance to H. bajulus after 4 weeks with impregnation and only one week without. Radiographic imaging was conducted using a Gilardoni Radiolight X-ray source, and results were evaluated based on larval survival, gallery formation, and structural degradation. Tests on lignosulfonate adhesives are still pending. The test with mycelia bio-composites is still running and it is waiting for the first check, after 1 month trough RX analyses. The only mycelium thesis test that was stopped before the ending, due the death of all larvae was the I_NP. For the other thesis on mycelium bio-composites the larvae resulted very active after one month since beginning of test and at the moment the tests are ongoing until the first decade of September 2026. The termites biological test was performed in according to CEN EN 2017 and the results showed that the bio-composites, independently from the adhesive used is not so much suitable for these insects, independently from the presence of bio-PCM, only in some case it was observed some attempts or light attack but not more, such as lignosulfonate without bio-PCM and NI_NP. 6(67) BIOBUILD D4.5 Report on bio-composite mechanical and physical properties The mould tests concluded showed, for test already concluded at the date of this deliverable, that in most cases, a good resistance o very slight susceptibility to mould but a changing of dimension due to the swollen under effect of high moisture environment with formation of water condensation. As observed in the physical tests carried out in the laboratory, the impregnation with bio-PCM of the bio-composites fibres leads to a decrease in its mechanical properties and its integrity, also depending on the panel and its composition. The test that decreases more the properties due to the bio-PCM affecting above all is the internal bond test. However, the data collected permit of defining which types of panels have the greatest affinity with the final use of the project, i.e. interior cladding, which will then be linked with the thermal characterization data. We have been able to see that modified linseed oil is a natural adhesive that is more effective in terms of physical and mechanical characteristics than lignin; in fact, the OX and AC specimens recorded higher values in all the tests in which there was a comparison with the samples with lignin. The AC batch, combining the results of all the tests, is the one with the best characteristics and most similar for the final purpose. The mycelia bio-composites, seems by physical mechanical point of view the solution with the less performance and even in this case it was found a decreasing of an order of magnitude with the presence of bio-PCM with respect to bio-composites without it independently by compression or not.