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Plastic waste is an ever-growing concern, causing harm to many ecological and human health aspects, one of the major contributors to this problem being packaging. Mycelium composites (MC) are ecologically safe materials, well suited for the short-life usage as packaging materials. In our study we made MC using fine and coarse granulometry hemp shives applying them in 3 substrate variants – with added bran, with added bran and birch bark, and as the sole substrate. We assessed material's water absorption and mechanical properties, chemical decomposition, biodegradability, mold resistance and fungal biomass. Granulometric effect was observed only when using shives as the sole substrate, where larger particle size gave poorer results. Bran did not significantly improve mechanical properties or water uptake. Bark reduced water uptake by ~200 %, but lowered mechanical properties, and provided no benefits to mold resistance which was low for all specimens. Overall, hemp MC showed complete biodegradability after 12 weeks, mechanical properties up to 0,235 MPa, compatible with expanded polystyrene, but very high water uptake of up to 1000 %. Future studies are needed to reduce water absorption and improve mold resistance, as well as invent consensus methodology for better cross-study comparison.

Kraft cooking of juniper wood with NaOH/Na2S aqueous solution has been used in the study for partial delignification at the temperature of 165°C for different residence time (0-40 min) following by thermal compression for densification under a pressure of 5 MPa at 100°C for 24 hours. The densified and natural juniper wood samples were characterized by chemical composition and mechanical properties. The results show that the density of densified juniper wood was increased by 96-127% reaching the value of 1170 kg/m3 that is similar to conventional bone implants (1090 kg/m3). Modulus of rupture and modulus of elasticity of densified juniper wood were increased by 85% and 621%, respectively, demonstrating a high potential of the material to be used as bone implants.

Cellulose modification is a challenge due to molecules characteristics – equatorial conformation, hydrogen bonds both withing molecule and among neighboring molecules etc. Esterification of cellulose hydroxyl groups (-OH) with dicarboxylic compounds is challenging. In presented study simple modification with maleic anhydride is performed in an anhydrous environment. Scanning electron microscopy reveals clean fibers of cellulose-maleic anhydride derivatives. FTIR proves unique peak at 1735cm-1 that corresponds to ester carbonyl groups. Titration of carboxylic (-COOH) groups solidifies that one part of anhydride has bonded with cellulose and other carboxylic groups is accessible for further development.

In this study, novel blends of mycelium biocomposites (MB) were developed. Various combinations of birch sawdust and hemp shives with birch bark (BB) and wheat bran (WB) additives were inoculated with basidiomycete Trametes versicolor to produce self-growing biomaterials. MB were characterized according to mycelial biomass increment in final samples, changes in chemical composition, elemental (C, H, N) analyses, granulometry of substrates, water-related and mechanical properties, as well as mold resistance and biodegradability. The mycelial biomass in manufactured MB increased by ~100% and ~50% in hemp and sawdust substrates, respectively. The lignocellulose ingredients during fungal growth were degraded as follows: cellulose up to 7% and 28% in sawdust and hemp substrates, respectively, and lignin in the range of 13% in both substrates. A larger granulometric fraction in hemp MB ensured higher strength property but weakened water absorption (600–880%) performance. Perspective MB combinations regarding strength performance were hemp/BB and pure hemp MB (σ10 0.19–0.20 MPa; E 2.9 MPa), as well as sawdust/WB combination (σ10 0.23 MPa; E 2.9 MPa). WB positively affected fungal biomass yield, but elevated water absorption ability. WB improved compressive strength in the sawdust samples but decreased it in the hemp samples. BB supplement reduced water absorption by more than 100% and increased the density of sawdust and hemp samples. All MB samples were susceptible to mold contamination after full water immersion, with identified fungal genera Rhizopus, Trichoderma and Achremonium. The MB exhibited high biodegradability after 12 weeks’ exposure in compost, and are therefore competitive with non-biodegradable synthetic foam materials.

Lignocellulosic biomass (LCB)-based thermal insulation materials available in the market are more expensive than conventional ones and consist mainly of wood or agricultural bast fibers which are primarily used in construction and textile industries. Therefore, it is crucial to develop LCB-based thermal insulation materials from cheap and available raw materials. The study investigates new thermal insulation materials from locally available residues of annual plants like wheat straw, reeds and corn stalks. The treatment of raw materials was performed by mechanical crushing and defibration by steam explosion process. Optimization of thermal conductivity of the obtained loose-fill thermal insulation materials was investigated at different bulk density levels (30–45–60–75–90 kg m−3). The obtained thermal conductivity varies in range of 0.0401–0.0538 W m−1 K−1 depending on raw material, treatment mode and a target density. The changes of thermal conductivity depending on density were described by the second order polynomial models. In most cases, the optimal thermal conductivity was revealed for the materials with the density of 60 kg m−3. The obtained results suggest the adjustment of density to achieve an optimal thermal conductivity of LCB-based thermal insulation materials. The study also approves the suitability of used annual plants for further investigation towards sustainable LCB-based thermal insulation materials.

For reinforcing of paper, nanoparticle gels from black alder, birch and pine bark were obtained. Non-extracted bark and that extracted in biorefinery were used. For producing nanoparticles, the materials were destructed using the thermocatalytic destruction method and then dispersed in water medium in a ball mill. At a sufficient concentration, gel-like dispersions were obtained, which contained nanoparticles with the size ~300 nm. The effect of nanoparticle gels on the properties of paper sheets was investigated by introducing the dissolved gels in paper furnish and by covering both sides of paper sheets with nanoparticle gel coatings. It has been established that the nanoparticle fillers increase the tensile and burst strength. The nanoparticle fillers from extracted bark increase the mechanical indices to a higher extent. The coatings from nanoparticle gels considerably improve the Gurley air resistance of paper and increase the mechanical indices of paper sheets, especially burst strength. The effect of nanoparticle gel coatings is dependent on the coating thickness and gel concentration. The coatings decrease the tensile strength in a wet state.

The study of converting grey alder (Alnus incana) chips and silver birch (Betula pendula) flakes – residues from plywood manufacture – into blow-in insulation material by steam explosion (SE) is reported. The SE was conducted at temperatures between 200 and 235°C, for 0–5 min at pressures between 16 and 32 MPa. The severity parameters (logR 0) of the SE was calculated, from which logR 0≈3.6 was the most appropriate for production of blow-in materials. Thermal conductivity of the obtained insulating material was found to be in the range of 0.053–0.057 W m−1·K−1.