Materials Science Forum Vol. 1071

Abstract: Tall oils are a second-generation feedstock with perspective use in polyurethane materials. This study compared crude tall oil and tall oil fatty acid bio-polyols to determine whether crude tall oil could be used for polyurethane foam production making the production more cost-effective. Polyols were synthesized in a two-step process. At first, double bond epoxidation followed by oxirane ring-opening, and transesterification with multifunctional alcohols. The epoxidation process was studied with acid value and relative conversion to oxirane analysis. The obtained polyols were analyzed for acid value, hydroxyl value, viscosity, and with Fourier transform infrared spectroscopy analysis. The results showed suitable hydroxyl values for almost all polyols, including crude tall oil polyols, but the high viscosity limits the use of most of the polyols.

Abstract: Birch outer bark is a byproduct accumulated from birch tree (Betula pendula Roth. and Betula pubescens Ehrh.) processing and contains up to 50 wt% suberin. Suberin is a biopolyester built mostly from α,ω-bifunctional fatty acids (suberinic acids) which after depolymerization together with lignocarbohydrate complex is a potential adhesive for obtaining particleboard composites. These composites can be made in hot-pressing process at around 225 °C temperature. The high hot-pressing temperature for suberinic acid-based adhesive is a disadvantage compared to hot-pressing temperatures for conventional resins such as urea-formaldehyde and phenol-formaldehyde (120–130 °C and 170–180 °C respectively). In this study we looked into possible ways to improve the properties (modulus of elasticity (MOE), bending strength (MOR) of suberinic acid-based particleboards by utilization of catalysts (additives) for SA-based adhesive polymerization, thus reducing hot-pressing temperature by potentially achieving the same mechanical properties as for the catalyst-untreated boards hot-pressed at higher temperature. The suitability of potential protonic acid, Lewis acid, as well as tin-based and basic catalyst was studied with differential scanning calorimetry (DSC) by quantifying specific enthalpy of the exothermic peak with an onset temperature of ≈185 °C. Based on DSC results, six catalysts (mixtures) were chosen (sulfanilic acid, p-toluenesulfonic acid, Al₂(SO₄)₃, SnCl₂, SnCl₂/p-toluenesulfonic acid, dibutyltin oxide) for further studies on the effects of mechanical properties of particleboards. Treatment with 5 wt% sulfanilic acid, 5 wt% p-toluenesulfonic acid (free suberinic acid basis) significantly improved both MOE and MOR values. 6 wt% Al₂(SO₄)₃ significantly improved MOE value.

Abstract: In this study, Computational Fluid Dynamics (CFD), applied to a non-Newtonian fluid, was developed to characterize gas-liquid interaction and mixing process in a 15 m³ (working volume) bioreactor. The bioreactor was equipped with four arrangements of standard Rushton, Pitch-blade and Scaba® impellers. Gas-liquid hydrodynamics was estimated based on CFD results. The chosen operating conditions were defined by the settings used for production of xanthan gum via fermentation route by Xanthomonas campestris. The mixing process was simulated by using the k-epsilon turbulence model, Multiple Reference Frame and Population Balance Model approaches. The simulation results have been compared and analyzed by isosurfaces, volume fractions, velocity graphs, torques and flow analysis calculations. Obtained results revealed that for the Pitched-Pitched-Pitched arrangement to avoid the constraint-imposed overload torque limitations impeller diameter size should be reduced by 10%. The use of Rushton-Rushton-Rushton impeller arrangement was discouraged for non-Newtonian pseudoplastic fluid mixing, whereas Pitched-Rushton-Scaba and Scaba-Rushton-Pitched impeller arrangements were both acceptable.

Abstract: 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.

Abstract: Necessity for reduction of greenhouse gases emissions, the growing demand for improvement of biorefinery technologies and the development of new biorefining concepts, oblige us as a society, mainly scientists, to develop novel biorefinery approaches. The aim of this research was to comprehensively characterize lignocellulosic biomass that was obtained after 2-furaldehyde production, in terms of further valorization of this resource. This research shows that birch wood chips can be used in the new biorefinery processing chain for production of 2-furaldehyde, acetic acid and subsequent cellulose pulp obtaining, using thermomechanical and alkaline peroxide mechanical pulping process. In addition, obtained lignocellulosic residue was also characterized. Unique bench-scale reactor system was used to obtain a lignocellulosic material without pentoses and with maximum preservation of cellulose fiber for further use. Studies on the deacetylation and dehydration of birch wood hemicelluloses of pentose monosaccharides to 2-furaldehyde and acetic acid using orthophosphoric acid as a catalyst were carried out. Results showed that depending on the used pretreatment conditions the 2-furaldehyde yield was from 0.04 to 10.84 % o.d.m., the acetic acid yield was from 0.51 to 6.50 % o.d.m. and the lignocellulose residue yield was from 68.13 to 98.07 % o.d.m. with minimal content of admixtures. In addition, experimentally the optimal 2-furaldehyde production conditions regarding to purity and usability of cellulose in leftover of lignocellulosic material were developed. Best results in terms of both 2-furaldehyde yield and purity of residual lignocellulose were obtained in experiment where catalyst concentration was 70%, catalyst amount 4 wt.%, reaction temperature 175 °C and treatment time 60 min. By performing alkaline peroxide mechanical pulping of the relevant LC residue, it was possible to obtain pulp with tensile index comparable to standard printing paper, indicating that it is possible to perform stepwise 2-furaldehyde production with subsequent pulping to obtain various value added products.

Abstract: This study is devoted to clay modification with a corn starch biopolymer. Authors given the assessment of three different starch thermal modifications (cold, hot and combined), as well as their effect on the clay composite. Described the principle of starch thermal modification and its structural transformations during heat treatment. Incorporation of the gelated starch into clay body contributes to the strength increasing of the clay composite up 18% to 126% for gelatinized and retrograded starch, respectively. Due to its covering properties, the gelled and retrograded starch hydrogel integrates well into the structure of the clay composite and has a positive effect on both its mechanical and physical properties. Also, the obtained clay composite is ecological due to its natural components.

Abstract: The focus of this research paper is the preparation of inorganic foam glass-ceramic with the utilization of waste diatomite as a raw material. The waste diatomite was first comprehensively characterized by the analysis of the chemical and mineralogical composition, particle size, thermal analyses, and microstructure by scanning electron microscopy. Followed by the pretreatment of the mixtures with the addition of a foaming agent which was sodium hydroxide. The mixtures were then formed by pressing them into pellets and fired by a powder sintering method. The pretreatment drying temperatures and firing temperatures of the prepared mixtures were evaluated. After firing, the resulting properties of the foam glass-ceramic were investigated with the utilization of an X-ray diffraction analysis, bulk density, and compressive strength. The possibility of utilization of waste diatomite in raw material mixtures for the preparation of inorganic foam glass-ceramic was investigated.

Abstract: The influence of microstructure on the resulting physico-mechanical and refractory properties of refractory forsterite–spinel ceramics was investigated in this paper. The raw materials were milled, mixed into four different raw material mixtures and sintered for two hours at 1550°C. The microstructure of the samples was examined by scanning electron microscopy and X-ray diffraction analysis was used to determine the mineralogical composition of the sintered samples. Physico-mechanical properties such as porosity, water absorption, bulk density, and modulus of rupture were also determined. Thermomechanical characteristics were assessed by the determination of refractoriness, refractoriness under load, thermal shock resistance and corrosion resistance to various metals. The results showed that a higher amount of spinel leads to improved microstructure, thermal shock resistance and that all mixtures have high corrosion resistance to all tested materials.

Abstract: This paper explores the possibilities of utilization of waste diatomite in foam glass production. Chemical and mineralogical composition, granulometry and high temperature behaviour of waste diatomite were characterized. Different possibilities of waste diatomite utilization in foam glass production were explored mainly via means of thermal analysis and hot stage microscopy. The effects of diatomite addition to waste glass were evaluated. Possibility of using NaOH as a foaming agent for foam glass production from waste diatomite and the effects of NaOH amount and reaction time on waste diatomite were investigated. Partial conversion of diatomite and clay to hydrates due to the reaction with NaOH lead to the decrease of the melting temperature and foaming of the melt was observed via hot stage microscopy. 30 wt. % NaOH addition allowed foaming of waste diatomite in the temperature ranges typical for foam glass production. Increased reaction time led to the intensification of the foaming process.

Abstract: This article is focused to investigate the corrosion resistance of LCC, ULCC and NCC. Castables microstructure is one of the key factors influencing corrosion resistance, therefore new fine matrix was designed. Potassium carbonate was used as a corrosive medium using static crucible method for tested castables. The corrosion mechanism was evaluated by Scanning Electron Microscopy (SEM) with EDX probe. The experimental results disclosed that corrosion resistance was improved with decreasing calcium oxide content of tested castables.