In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II.

In this paper three newly synthesized imidazolium ionic liquids with different structures of cations were used for hydrolysis of cellulose. It was found that type of the cation has a great influence on particle size and dispersity of produced cellulosic materials. The use of an ionic liquid with a cation with an aliphatic substituent resulted in filler characterized with wide dispersity range and some particles larger than 2 µm. Introduction of methyl group into imidazolium ring was responsible for production of particles below 350 nm. Such particles were obtained also during hydrolysis of cellulose with ionic liquid containing a benzyl substituent with that difference that in this case particles had definitely narrower dispersity range. Moreover, type of the ionic liquid used affected crystallinity degree of the produced celluloses. Produced cellulosic materials were used as fillers for chitosan matrix. A relationship between mechanical properties of polymer composites and the particle size as well as dispersity of cellulose, controlled by chemical modifications of cellulose with innovative ionic liquids was evaluated. Incorporation of filler with established dispersive properties made it possible to form composites characterized by the assumed properties, for example with high values of Young’s modulus, tensile strength or elongation at break. Understanding the dependence between the structure of ionic liquids and dispersive properties of cellulose is an important step toward the design of composite materials with optimal mechanical properties.

In this paper, silica–lignin hybrid materials were used as fillers for a polylactide (PLA) matrix. In order to simulate biodegradation, PLA/hybrid filler composite films were kept in soil of neutral pH for six months. Differential scanning calorimetry (DSC) allowed analysis of nonisothermal crystallization behavior of composites, thermal analysis provided information about their thermal stability, and scanning electron microscopy (SEM) was applied to define morphology of films. The influence of biodegradation was also investigated in terms of changes in mechanical properties and color of samples. It was found that application of silica–lignin hybrids as fillers for PLA matrix may be interesting not only in terms of increasing thermal stability, but also controlled biodegradation. To the best knowledge of the authors, this is the first publication regarding biodegradation of PLA composites loaded with silica–lignin hybrid fillers.

Inorganic–organic hybrids are a group of materials that have recently become the subject of intense scientific research. They exhibit some of the specific properties of both highly durable inorganic materials (e.g., titanium dioxide, zinc) and organic products with divergent physicochemical traits (e.g., lignin, chitin). This combination results in improved physicochemical, thermal or mechanical properties. Hybrids with defined characteristics can be used as fillers for polymer composites. In this study, three types of filler with different MgO/lignin ratio were used as fillers for polypropylene (PP). The effectiveness of MgO-lignin binding was confirmed using Fourier transform infrared spectroscopy. The fillers were also tested in terms of thermal stability, dispersive-morphological properties as well as porous structure. Polymer composites containing 3 wt.% of each filler were subjected to wide angle X-ray diffraction tests, differential scanning calorimetry and microscopic studies to define their structure, morphology and thermal properties. Additionally, tensile tests of the composites were performed. It was established that the composition of the filler has a significant influence on the crystallization of polypropylene—either spherulites or transcrystalline layers were formed. The value of Young’s modulus and tensile strength remained unaffected by filler type. However, composites with hybrid fillers exhibited lower elongation at break than unfilled polypropylene.

In this work, the influence of the supermolecular structure of cellulosic fillers in chitosan matrix on the process of adsorption of calcium, magnesium and iron metal ion was analyzed, while using techniques such as: X-ray diffraction, flame atomic absorption spectrometry, FTIR spectroscopy, particle size analysis, and wettability angle. It has been shown that polymorphic form of cellulose significantly affects its particle size. The introduction of cellulosic filler into polymer matrix was responsible for changes in the sorption efficiency of chitosan composites. It was found that materials with nanocellulose II were characterized with the highest efficiency of adsorption. This interesting relationship has not been reported in the literature, yet. It is important especially in terms of designing composite materials with high adsorption capacity. In the presented paper this issue was discussed, taking into account crystallographic aspects as well as changes in the hydrophilicity of the surface of composite materials. Composite materials were also subjected to mechanical tests which showed some interesting increase in tensile strength when compared to the unfilled polymer.

Currently, the fundamental activity that will allow for the development of an economy with closed circulation is the management of food waste and production waste for the preparation of biocomposites. The use of waste materials of natural origin allows for the creation of innovative composites with improved physicochemical and functional properties. The present investigation concerns the use of coffee grounds (2.5–20 wt.%) and oak sawdust (2.5–20 wt.%) as effective fillers of rigid polyurethane foam. Innovative composite materials, previously indebted in the literature, were subjected to the necessary analyses to determine the application abilities: processing times, free density, water absorption, dimensional stability, mechanical properties (compressive strength), thermal conductivity, morphology, and flame resistance. The results with respect to the mechanical tests turned out to be the key. Increasing the number of coffee additives has a positive effect on the compressive strength. The addition of this filler in the range of 5–15 wt.% increased the compressive strength of the composites, 136–139 kPa, compared to the reference sample, 127 kPa. The key parameter analysed was thermal conductivity. The results obtained were in range of the requirements, that is, 0.022–0.024 W/m·K for all used amounts of fillers 2.5–20 wt.%. This is extremely important since these materials are used for insulation purposes. The results of the burning-behaviour test have confirmed that the addition of renewable materials does not negatively affect the fire resistance of the received foams; the results were obtained analogously to those obtained from the reference sample without the addition of fillers. The height of the flame did not exceed 17 cm, while the flame decay time was 17 s for the reference sample and the composite with coffee grounds and 18 s for the composite with oak sawdust. In this work, the practical application of bioorganic waste as an innovative filler for the insulation of flooded polyurethane foam is described for the first time. The introduction of fillers of natural origin into the polymer matrix is a promising method to improve the physicochemical and functional properties of rigid polyurethane foams. Composites modified with coffee grounds and sawdust are interesting from a technological, ecological, and economic point of view, significantly increasing the range of use of foam in various industries.