Giganteus Stalks Research Articles

Assessment of the papermaking potential of processed Miscanthus × giganteus stalks using alkaline pre-treatment and hydrodynamic cavitation for delignification

One way of satisfying increased market demand and simultaneously achieving a reduced environmental load in the industrial paper production is the use of fibrous agricultural residues. The aims of this study were i) to investigate the effect of alkaline – hydrodynamic cavitation (HC) pre-treatments on the delignification of Miscanthus × giganteus stalks (MGS) and ii) establishing the suitability of MGS as feedstock and their exploitation in pulp and paper manufacturing. It was demonstrated that the proposed treatment is an efficient delignification method for the non-wood fiber sources, such as miscanthus. A significant outcome of this work was the observation that HC treatment preserved the fibres lengths and surface quality of raw MGS, but at the same time increased the amount of kinked and curled fibers present in cavitated miscanthus fibers. The average miscanthus fiber length was found to be relatively short at 0.45 (±0.28) mm, while the slenderness ratio, the flexibility coefficient and Runkel ratio values were calculated to be 28.13, 38.16 and 1.62, respectively. The estimated physical properties of MGS pulp hand-sheets were 24.88 (±3.09) N m g−1 as the tensile index, 0.92 (±0.06) kPa m2 g−1 as the burst index and 4.0 (±0.37) mN m2 g−1 as the tear index. Overall the current work demonstrated effective use of hydrodynamic cavitation for improving the processing in pulp and paper manufacturing.

Influence of cellulose particles on chemical resistance, mechanical and thermal properties of epoxy composites

Background: The technological developments for nanocellulose production from cheaper plant materials compared to wood, in particular, agricultural waste is an urgent task of nanobiophysics. The discovery of possibility of expanding the functional characteristics of materials in compositions with modified cellulose particles essentially stimulated the interest of researchers in cellulose composites. Surface modification of cellulose particles by functional materials, such as dyes, metal oxides, silicon, allows applying composites with modified cellulose in various areas of modern industry. A significant improvement in the operational performances of functionalized cellulose particles can be achieved by using them as filler in polymers. Epoxy resin compositions with modified and unmodified cellulose particles, studied in present work, are an example of hybrid biosystem. The interfacial interaction of filler particles with the epoxy matrix, their concentration and dispersion can change the physical and chemical properties of the biopolymer and the functional parameters of biocomposites. Studying the influence of external fields on the physical and chemical properties of epoxy resin-based biosystems and their influence on operational parameters seems to be an urgent problem of advanced and sustained materials science. Objectives: The purpose of this work was to develop an effective nanocellulose synthesis from plant materials and surface functionalization of micro- and nanocellulose particles with clathrochelate iron (ΙΙ) dye as well obtaining biocompositions of epoxy resin with functionalized and non-functionalized micro- and nanocellulose, and to explore of the morphology, chemical resistance, mechanical and thermal properties of epoxy composites with cellulose micro and nanoparticles. Materials and methods: The studying objects were the composites of epoxy resin Eposir-7120 with a polyethylene polyamine “PEPA” hardener in a ratio of 6.2:1 and 10% cellulose micro and nanoparticles. The microcellulose obtained from wood has been a commercial product. Nanocellulose has been synthesized from organosolv cellulose obtained from Miscanthus x giganteus stalks. Surface modification of micro- and nanocellulose was performed using the clathrochelate iron (ΙΙ) dye. The specific surface area of cellulose particles was determined using low-temperature nitrogen adsorption-desorption according to the Brunauer-Emmett-Teller method. Mechanical parameters were determined using universal Shopper and UMM-10 machines. Thermal analysis was performed using Q1500 analyzer. Swelling was determined by the gravimetric method. Results: Elastic modulus E, compressive strength σ and thermogravimetric parameters were determined. It was shown that in composites with micro and nanocellulose the E rises in 7.0–12.2% while the σ increases in 9.1% for composites with cellulose micro particles. The loading resin with nanocellulose and modified cellulose microparticles no affects the σ value of composites. The thermal stability of epoxy polymer (310°C) reduces after loading with micro and nanocellulose to 290 and 300°C, respectively. Chemical resistance of composites with both celluloses to 20% nitric acid reduces. In neutral medium swelling characterizes by rapid sorption to saturation of 15–20% acetone in 36 hours. Conclusions: Thus, the synthesis method of nanocellulose from plant materials and functionalization of its surface with clathrochelate iron (ΙΙ) were developed. Light response of dye was detected in visible spectral range. Epoxy resin composites with 10% micro and nanocellulose were obtained. The filling effect with micro- and nanocellulose at elastic modulus, compressive strength, and thermal stability of epoxycomposites was studied. The swelling processes run similarly in composites with cellulose micro and nanoparticles.

Comparison of Some Properties of Selected Non-Wood Plants and Wood Species and Unbleached Kraft Pulps from These Materials

ABSTRACT The different properties of hemp stalks, hemp woody-core, and Miscanthus × giganteus stalks cultivated in Poland and physical properties of unbleached kraft pulps from these materials were compared with the ones of pulps from pine, birch and wheat straw. Research performed showed that in terms of oven-dried material density, bulk density, yield, morphological, structural, and strength properties of pulps, hemp stalks and Miscanthus stalks are more similar to birch and pine than hemp woody-core and wheat straw. Thus, it can be stated that hemp and Miscanthus stalks should be better papermaking fibrous raw materials than hemp woody-core and wheat straw and could be used for the production of a broader range of papers and boards.

Miscanthus × giganteus stalks as a potential non-wood raw material for the pulp and paper industry. Influence of pulping and beating conditions on the fibre and paper properties

This manuscript describes the relationship between the method of processing (soda and kraft pulping) of Miscanthus × giganteus stalks into unbleached pulps of different residual lignin content (1.5–8.7 wt. %) and their beatability and properties. It was found that Miscanthus soda pulps with low residual lignin content need to be beaten for longer to achieve the same level of SR-freeness compared with kraft pulps. In order to obtain higher values of mechanical properties of handsheets prepared from soda and kraft Miscanthus pulps they have to be beaten to SR-freeness higher than 35 °SR. The mechanical properties of Miscanthus kraft pulps determined in static conditions (e.g. tensile strength) are better than those of soda pulps. A decrease in the kappa number of Miscanthus soda pulps below 20, lowers these properties distinctly. The tear index of Miscanthus pulps is good, while Gurley air-resistance is comparable with birch kraft pulp. Soda Miscanthus pulps having a higher content of residual lignin and kraft Miscanthus pulps of low and high residual lignin contents, due to the similarity of their properties with unbleached hardwood kraft pulps (birch, poplar, hornbeam), could probably replace the latter pulps in the production of packaging papers (e.g. sack paper).

Fractionation of Miscanthus x giganteus via modification of the Formacell process

Fractionation of Miscanthus x giganteus stalks (without core) using an organosolv system with carboxylic acids in two stages (Acetosolv+Formacell) produced highly purified pulps with kappa number values of 7.3–15.6 and viscosities above 750cm3/g. The pulp yields were approximately 52–57%, and the brightness suffered significant decreases (1.1–8.2%) in the second stage.The influence of process variables in the Formacell extended stage was analysed by means of factorial designs of experiments. Optimised operating variables yielded acceptable pulp properties at reasonable chemical costs and mild energetic conditions.A comparison was performed of four organosolv processes with carboxylic acids in two stages (Acetosolv+Formacell, Acetosolv+peroxyacetic acid, Acetosolv+ozone and peroxyformic acid in two stages as a modification of the Milox process), which exploit the solvent that impregnate the pulps after the first stage.

Delignification of Miscanthus × Giganteus by the Milox process

Miscanthus × giganteus stalks were subjected to delignification with formic acid–hydrogen peroxide–water in two stages. A face-centered experimental design was used to study the effects of different variables (formic acid and hydrogen peroxide concentrations, time and temperature) on yield, lignin content and viscosity of pulps on the first stage. Fitting equations described satisfactorily the system behaviour and showed that hydrogen peroxide concentration and temperature were the most influencing variables. A set of independent variables (90% formic acid, 1.5% hydrogen peroxide, 60 min, and 67 °C) produced a pulp with low lignin content (kappa 17.2) and high viscosity (899 cm 3/g), in the first stage. For the second stage a treatment time of 30 min was the more suitable, producing good quality pulps (kappa number 4.6, viscosity 788 cm 3/g). Phenolic hydroxyl and carboxyl group contents were higher lignins from the first stage.