Enhancing Paper Packaging's Wet Strength Using the Synergy between Chitosan and Nanofibrillated Cellulose Additives.

The demand for eco-friendly packaging materials has urged researchers to look for alternatives to petroleum-based polymers. In this regard, paper-based products have turned out to be a promising choice; however, their weak resistance to water has limited their application. The use of various additives to enhance paper's moisture resistance is a common practice. However, considering the growing global agenda for sustainable development, the search for new bio-based paper additives has become increasingly important. This study investigated the potential synergistic impact of the addition of nanofibrillated cellulose (NFC) and chitosan additives (CHIT) to different fiber combinations to improve paper's properties, in particular, their wet strength. The efficacy of the additive application order was examined and was found to be crucial in achieving the desired outcomes. The results showed that incorporating CHIT after NFC enhanced the paper's tensile and burst indicators, as well as the paper stretch in the dry state, by 35-70%, 35-55%, and 20-35%, respectively. In addition, the tensile index and stretch in the wet state improved 9-13 times and 2.5-5.5 times over, respectively. The air permeability decreased 2.5-12 times over. These findings demonstrate that the sequential addition of the NFC and CHIT additives yield a greater enhancement of paper's properties than using each additive separately.

Characterization of Self-Growing Biomaterials Made of Fungal Mycelium and Various Lignocellulose-Containing Ingredients.

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.

Characterization of Novel Biopolymer Blend Mycocel from Plant Cellulose and Fungal Fibers.

In this study unique blended biopolymer mycocel from naturally derived biomass was developed. Softwood Kraft (KF) or hemp (HF) cellulose fibers were mixed with fungal fibers (FF) in different ratios and the obtained materials were characterized regarding microstructure, air permeability, mechanical properties, and virus filtration efficiency. The fibers from screened Basidiomycota fungi Ganoderma applanatum (Ga), Fomes fomentarius (Ff), Agaricus bisporus (Ab), and Trametes versicolor (Tv) were applicable for blending with cellulose fibers. Fungi with trimitic hyphal system (Ga, Ff) in combinations with KF formed a microporous membrane with increased air permeability (>8820 mL/min) and limited mechanical strength (tensile index 9-14 Nm/g). HF combination with trimitic fungal hyphae formed a dense fibrillary net with low air permeability (77-115 mL/min) and higher strength 31-36 Nm/g. The hyphal bundles of monomitic fibers of Tv mycelium and Ab stipes made a tight structure with KF with increased strength (26-43 Nm/g) and limited air permeability (14-1630 mL/min). The blends KF FF (Ga) and KF FF (Tv) revealed relatively high virus filtration capacity: the log10 virus titer reduction values (LRV) corresponded to 4.54 LRV and 2.12 LRV, respectively. Mycocel biopolymers are biodegradable and have potential to be used in water microfiltration, food packaging, and virus filtration membranes.

Bio-Based Poly(butylene succinate)/Microcrystalline Cellulose/Nanofibrillated Cellulose-Based Sustainable Polymer Composites: Thermo-Mechanical and Biodegradation Studies.

Biodegradable polymer composites from renewable resources are the next-generation of wood-like materials and are crucial for the development of various industries to meet sustainability goals. Functional applications like packaging, medicine, automotive, construction and sustainable housing are just some that would greatly benefit. Some of the existing industries, like wood plastic composites, already encompass given examples but are dominated by fossil-based polymers that are unsustainable. Thus, there is a background to bring a new perspective approach for the combination of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) fillers in bio-based poly (butylene succinate) matrix (PBS). MCC, NFC and MCC/NFC filler total loading at 40 wt % was used to obtain more insights for wood-like composite applications. The ability to tailor the biodegradable characteristics and the mechanical properties of PBS composites is indispensable for extended applications. Five compositions have been prepared with MCC and NFC fillers using melt blending approach. Young's modulus in tensile test mode and storage modulus at 20 °C in thermo-mechanical analysis have increased about two-fold. Thermal degradation temperature was increased by approximately 60 °C compared to MCC and NFC. Additionally, to estimate the compatibility of the components and morphology of the composite's SEM analysis was performed for fractured surfaces. The contact angle measurements testified the developed matrix interphase. Differential scanning calorimetry evidenced the trans-crystallization of the polymer after filler incorporation; the crystallization temperature shifted to the higher temperature region. The MCC has a stronger effect on the crystallinity degree than NFC filler. PBS disintegrated under composting conditions in a period of 75 days. The NFC/MCC addition facilitated the specimens' decomposition rate up to 60 days.

Mechanical and Air Permeability Performance of Novel Biobased Materials from Fungal Hyphae and Cellulose Fibers.

Novel biobased materials from fungal hyphae and cellulose fibers have been proposed to address the increasing demand for natural materials in personal protective equipment (PPE). Materials containing commercially available kraft fibers (KF), laboratory-made highly fibrillated hemp fibers (HF) and fungal fibers (FF) obtained from fruiting bodies of lignicolous basidiomycetes growing in nature were prepared using paper production techniques and evaluated for their mechanical and air permeability properties. SEM and microscopy revealed the network structure of materials. The tensile index of materials was in the range of 8-60 Nm/g and air permeability ranged from 32-23,990 mL/min, depending on the composition of materials. HF was the key component for strength; however, the addition of FF to compositions resulted in higher air permeability. Chemical composition analysis (Fourier-transform infrared spectroscopy) revealed the presence of natural polysaccharides, mainly cellulose and chitin, as well as the appropriate elemental distribution of components C, H and N. Biodegradation potential was proven by a 30-day-long composting in substrate, which resulted in an 8-62% drop in the C/N ratio. Conclusions were drawn about the appropriateness of fungal hyphae for use in papermaking-like technologies together with cellulose fibers. Developed materials can be considered as an alternative to synthetic melt and spun-blown materials for PPE.

Highly Loaded Cellulose/Poly (butylene succinate) Sustainable Composites for Woody-Like Advanced Materials Application.

We report the manufacturing and characterization of poly (butylene succinate) (PBS) and micro cellulose (MCC) woody-like composites. These composites can be applied as a sustainable woody-like composite alternative to conventional fossil polymer-based wood-plastic composites (WPC). The PBS/MCC composites were prepared by using a melt blending of 70 wt% of MCC processed from bleached softwood. MCC was modified to enhance dispersion and compatibility by way of carbodiimide (CDI), polyhydroxy amides (PHA), alkyl ester (EST), (3-Aminopropyl) trimethoxysilane (APTMS), maleic acid anhydride (MAH), and polymeric diphenylmethane diisocyanate (PMDI). The addition of filler into PBS led to a 4.5-fold improvement of Young's modulus E for the MCC composite, in comparison to neat PBS. The 1.6-fold increase of E was obtained for CDI modified composition in comparison to the unmodified MCC composite. At room temperature, the storage modulus E' was found to improve by almost 4-fold for the APTMS composite. The EST composite showed a pronounced enhancement in viscoelasticity properties due to the introduction of flexible long alkyl chains in comparison to other compositions. The glass transition temperature was directly affected by the composition and its value was -15 °C for PBS, -30 °C for EST, and -10 °C for MAH composites. FTIR indicated the generation of strong bonding between the polymer and cellulose components in the composite. Scanning electron microscopy analysis evidenced the agglomeration of the MCC in the PBS/MCC composites. PMDI, APTMS, and CDI composites were characterized by the uniform dispersion of MCC particles and a decrease of polymer crystallinity. MCC chemical modification induced the enhancement of the thermal stability of MCC composites.

Cellulose synthesis by Komagataeibacter rhaeticus strain P 1463 isolated from Kombucha.

Isolate B17 from Kombucha was estimated to be an efficient producer of bacterial cellulose (BC). The isolate was deposited under the number P 1463 and identified as Komagataeibacter rhaeticus by comparing a generated amplified fragment length polymorphism (AFLP™) DNA fingerprint against a reference database. Static cultivation of the K. rhaeticus strain P 1463 in Hestrin and Schramm (HS) medium resulted in 4.40 ± 0.22 g/L BC being produced, corresponding to a BC yield from glucose of 25.30 ± 1.78 %, when the inoculum was made with a modified HS medium containing 10 g/L glucose. Fermentations for 5 days using media containing apple juice with analogous carbon source concentrations resulted in 4.77 ± 0.24 g/L BC being synthesised, corresponding to a yield from the consumed sugars (glucose, fructose and sucrose) of 37.00 ± 2.61 %. The capacity of K. rhaeticus strain P 1463 to synthesise BC was found to be much higher than that of two reference strains for cellulose production, Komagataeibacter xylinus DSM 46604 and Komagataeibacter hansenii DSM 5602T, and was also considerably higher than that of K. hansenii strain B22, isolated from another Kombucha sample. The BC synthesised by K. rhaeticus strain P 1463 after 40 days of cultivation in HS medium with additional glucose supplemented to the cell culture during cultivation was shown to have a degree of polymerization of 3300.0 ± 122.1 glucose units, a tensile strength of 65.50 ± 3.27 MPa and a length at break of 16.50 ± 0.83 km. For the other strains, these properties did not exceed 25.60 ± 1.28 MPa and 15.20 ± 0.76 km.

Characterisation of films and nanopaper obtained from cellulose synthesised by acetic acid bacteria.

Bacterial cellulose (BC) samples were obtained using two culture media (glucose and glucose+fructose) and two bacteria (Komagataeibacter rhaeticus and Komagataeibacter hansenii). Nanopaper was obtained from the BC through oxidation and both were studied to determine the impact of culture media and bacteria strain on nanofiber structure and mechanical properties. AFM and SEM were used to investigate fibre dimensions and network morphology; FTIR and XRD to determine cellulose purity and crystallinity; carboxyl content, degree of polymerisation and zeta potential were used to characterise nanofibers. Tensile testing showed that nanopaper has up to 24 times higher Young's modulus (7.39GPa) than BC (0.3GPa). BC displayed high water retention values (86-95%) and a degree of polymerisation up to 2540. Nanofibers obtained were 80-120nm wide and 600-1200nm long with up to 15% higher crystallinity than the original BC. It was concluded that BC is an excellent source for easily obtainable, highly crystalline and strong nanofibers.