The annual rate of decomposition in five soil types of tundra situated in the Fugleberget drainage area (Hornsund Fjord, South Spitsbergen) was investigated by use of the method of standard cellulose samples. The rate of decomposition varied from 15% to over 65% a year and was closely connected with a contents of nitrogen in soil, amount of which varied from 0.33% to 3.44%. The results presently obtained are much higher than those obtained by the same method in other polar regions.
This paper presents the findings of a study of gas emissivity and the volumetric gas flow rate from a patented modified cellulose mix used
in production of disposable sand casting moulds. The modified cellulose mix with such additives as expanded perlite, expanded
vermiculite and microspheres was used as the study material. The results for gas emissivity and the gas flow rate for the modified cellulose
mix were compared with the gas emissivity of the commercial material used in gating systems in disposable sand casting moulds. The
results have shown that the modified cellulose mix is characterized by a lower gas emissivity by as much as 50% and lower gas flow rate
per unit mass during the process of thermal degradation at the temperature of 900°C, compared to the commercial mix. It was also noted
that the amount of microspheres considerably affected the amount of gas produced.
The use of ammonium nitrate due to its high nitrogen content (> 26%) has made it the most utilized fertilizer in agricultural areas. However, being easily accessible with this feature encouraged its use for different purposes. Ammonium nitrate is usually produced with large tonnage (> 50 ton/h) and high cost (> $20 million) production processes. Therefore, any changes that can be made in the process must be applied in the process so that the result can be achieved easily without increasing the cost in any way. In this study, it is aimed to reduce the explosion sensitivity of ammonium nitrate used for explosive purposes in terrorist attacks. Thus, it was aimed to solve the problem by adding various chemicals to the ammonium nitrate production process so that it can only be used for agricultural purposes. For this purpose, the production process was examined by adding carboxymethyl cellulose and polyethylene glycol to the ammonium nitrate production process and the accuracy of the results was tested by instrumental analysis methods.
The study investigates the effect of the organic compound representing the cellulose derivative - sodium salt of carboxymethyl cellulose (CMC/Na) on the structure of the main component of bentonite (B) - montmorillonite (MMT). Structural analysis revealed that the CMC/Na of different viscosity interacts with the mineral only via surface adsorption, causing at the same time partial or full delamination of its layered structure. This was confirmed by the XRD diffraction tests. Such polymer destructive influence on the structure of the modified main component of the bentonite limits the use of its composites as an independent binder in moulding sand technology, but does not exclude it from acting as an additive being a lustrous carbon carrier. According to the IR spectra of the B/CMC/Na materials, it can be stated that the interaction between the organic and inorganic parts is based on the formation of hydrogen bonds. That kind of the interpretation applies especially to the MMT modified in the bentonite with a lower viscosity polymer. The characteristics of the main IR absorption bands for composites with a higher viscosity polymer indicates the formation of less stable structures suggesting the random nature of the hydrogen bonds formation.
Results for microcrystalline cellulose pyrolysis are presented, which includes thermogravimetric measurements and kinetic analysis of experimental data. The effect of sample mass size and heating rate on estimated values of activation energy and pre-exponential factor is demonstrated and a simple modification of procedure is proposed that allows for the correct values of kinetic parameters regardless of the experimental conditions. The efficiency of the proposed method is confirmed for two endothermic chemical reactions. A method of nonlinear regression is used for calculation of kinetic parameters for a single or TG curve or several curves simultaneously.
The paper includes the TG-DTG thermogravimetric air-testing of a cellulose mixture modified with the additives of expanded vermiculite or expanded perlite. A thermal degradation test was carried out at 1000°C with a simultaneous qualitative analysis of the emitted gases. During the thermal degradation process, the thermal effects were also measured. The research results indicate that expanded vermiculite or expanded perlite do not emit toxic gases during thermal degradation. The cellulose mixture modification, with the additives of expanded vermiculite or perlite, does not result in the creation of new gaseous compounds in the process of thermal degradation. A s investigated below, the mixtures tested in this article find application in gating systems for supplying liquid metal in no-bake moulds. Such cellulose-based material solutions shall allow the foundry industry to introduce less gas vaporising technologies within the entire casting production process.
The parenchyma cellulose isolated from bagasse pith was used as an alternative resource for preparation of water-soluble cellouronic acid sodium salt (CAS). The influence of ultrasound treatment on the cellulose was investigated for obtaining CAS by regioselective oxidization using 4-acetamide-TEMPO and NaClO with NaClO2 as a primary oxidant in an aqueous buffer at pH 6.0. The yield, carboxylate content and polymerization degree (DP) of CAS were measured as a function of ultrasonic power, agitating time and cellulose consistency by an orthogonal test. The ultrasound-treated conditions were further improved by discussion of ultrasonic power, the most important factor influencing the yield and DP. An optimized CAS yield of 72.9% with DP value (DPv) of 212 was found when the ultrasonic strength is 550 W, agitating time is 3 h and cellulose consistency is 2.0%. The oxidation reactivity of cellulose was improved by ultrasonic irradiation, whereas no significant changes in crystallinity of cellulose were measured after ultrasonic treatment. Moreover, the ultrasound treatment has a greater effect on yielding CAS from parenchyma cellulose than from bagasse fibrous' one. The CAS was further characterized by Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM).
The herein paper contains the results of investigations on a new type of cellulose blend used for the manufacture of profiles applied in the
process of making gating systems in the foundry industry. A standard cellulose profile was subjected to an experiment. During the
experiment the profile was filled with a liquid cast iron and at the same time the temperatures of the liquid metal crystallizing inside the
profile were measured as well as the temperature of the outer layer of the profile was controlled. Further, the microstructure of the cast
iron, which crystallized out inside the cellulose profile, was analysed and the cellulose, thermally degraded after the experiment, was
verified with the use of the chemical analysis method. Moreover, a quality analysis of the original as well as the degraded cellulose profile
was run with the use of the FTIR infrared spectroscopy. The presented results revealed that the cellulose blend is aluminium silicate
enriched and contains organic binder additives. The cast iron, which crystallized out, tended to have an equilibrium pearlitic structure with
the release of graphite and carbides. The generation of disequilibrium ausferrite phases was also observed in the structure.