Coating of a lignocellulosic aggregate with pectin/polyethylenimin mixtures: Effects on flax shive and cement-shive composite properties

Lignocellulosic lightweight concretes are a potential contributor to sustainable development. However, lignocellulosic aggregates are not always fully compatible with cement matrices leading to setting delays, significant dimensional variations and low mechanical strengths. An aggregate treatment, reducing water absorption and water-soluble molecule release, can avoid or reduce these drawbacks. In this study a coating treatment, using a pectin/polyethylenimin (PP) mixture, was applied to flax shives, which is a lignocellulosic by-product. Before shive coating, a dilution with distilled water or a micro-wave heating were conducted to decrease PP mixture viscosity.The PP treatment involved a decrease in shive water absorption. Compared to standard shive concrete, treated shive concrete exhibited a decrease in setting delay with an increase in cement hydration enthalpy, an increase in mechanical strengths and a significant reduction in dimensional variations. Although a slight increase in thermal conductivity and bulk density was measured, the cement-shive composite obtained still belongs to the insulating concrete category.     

选择性磨浆对杨木P-RC APMP制浆过程的优化

利用纤维束筛分仪将一段高浓磨后的半成品化机浆筛分为纤维束和浆A,将纤维束用盘磨磨浆至不同游离度后回添至浆A中,制备化机浆(浆C),实施化机浆生产的选择性磨浆。研究了选择性磨浆对杨木P-RC APMP成纸性能及磨浆能耗的影响。结果表明,采用选择性磨浆,可以降低化机浆生产过程的磨浆能耗。在与对比浆游离度基本一致的情况下,对出一段高浓磨半成品浆料中的纤维束实施选择性磨浆,当纤维束磨浆至170 mL,即浆C的游离度为305 mL时,二段磨浆能耗降低13.1%,成纸松厚度提高11.6%,撕裂指数升高1.7%,但抗张指数降低10.5%,内结合强度降低16.8%。纤维束的选择性磨浆,可通过控制纤维束磨浆后的特性,调整化机浆成纸性能。     

高得率制浆工艺对去除浆中纤维束的影响

介绍了高得率制浆工艺对消除浆中纤维束的影响,论述了降低纤维束含量从而提高纸浆质量及成纸印刷适性的措施。     

Production of fiberboards from shives collected after continuous fiber mechanical extraction from oleaginous flax

In this study, fiberboards were produced from shives collected after continuous fiber mechanical extraction from oleaginous flax straw. Fiberboards were produced through thermo-pressing, and their mechanical and thermomechanical properties were studied, as well as their water resistance. The influence of two pretreatments for shives and lignin addition was investigated on the different properties. Boards obtained were all cohesive hardboards. The optimal board was obtained from fibers extruded from the shives and without addition of any supplementary lignin amount. Looking at its characteristics and standard NF EN 312, the latter perfectly complied with the requirements for type P1 boards, i.e., boards for general uses in dry conditions.     

Extraction and purification of ferulic acid from flax shives,wheat and corn bran by alkaline hydrolysis and pressurised solvents

Extraction of ferulic acid and vanillin from flax shives, wheat bran and corn bran were carried out using two extraction methods, non-pressurised alkaline hydrolysis (0.5 M NaOH) and pressurised solvents (0.5 M NaOH, water, ethanol and ammonia). There were no differences in the content of products extracted with non-pressurised and pressurised 0.5 M NaOH solution yielding mostly ferulic acid, p-coumaric acid and small amounts of vanillin. Pressurised low-polarity water (PLPW), pressurised aqueous ethanol (PAE) and pressurised aqueous ammonia (PAA) were efficient in the one-step production of vanillin from ferulic acid in flax shives (guaiacyl-rich), wheat bran and corn bran (ferulic acid-rich). Vanillin was produced from the bound-ferulic acid via cleavage of the aliphatic double bond under the pressurised conditions. Higher content of ferulic acid in the corn bran yielded higher amounts of vanillin compared to wheat bran and flax shives. A simple and efficient purification procedure for ferulic acid from the alkaline extracts is presented. This procedure exploits the solubility of ferulic acid at different ethanol concentrations.     

Properties of Hemp–Flax Composites for Use in the Building Industry

This article presents the results of research concerning lightweight composites produced on the basis of lime, cement, and clay binders, with the addition of perlite, hemp shives, and flax straw. Tests of physical and mechanical properties of composites were performed and their basic characteristics were determined, i.e. absorptivity, density, thermal conductivity coefficient, and compressive and flexural strength. The study was conducted to determine the use of hemp and flax composites to fill the frames of a wooden house. The results prove that the composites have low thermal conductivity, apparent density, and low strength properties compared with conventional building materials.     

Effect of aluminium sulphate-catalysed hydrolysis process on furfural yield and cellulose degradation of Cannabis sativa L. shives

Commercially, furfural is produced from pentosan-rich biomass using mineral acids as homogeneous catalysts. This study investigated a novel hydrolysis method that allows to obtain furfural from hemp shives with high yield and also to preserve the cellulose in the remaining biomass for other bioconversion processes. To date, hemp shives have not been investigated for furfural production. Cannabis sativa L. (“Bialobrzeskie” variety) shives were used as a feedstock due to the high content of pentosan (17.6% of oven-dried biomass). It means that the theoretically possible amount of furfural was 12.8% of oven-dried hemp shives. The effect of temperature (140–180 °C), the amount of catalyst (3–7% of oven-dried biomass) and the treatment time (10–90 min) on the furfural formation were studied. Whereas, the effect of the same temperature and the amount of catalyst on the changes of lignocellulose were studied after 90 min treatment time. Al₂(SO₄)₃*18H₂O was used as a catalyst for the conversion of C5-sugars to furfural. To show the catalytic properties of Al₂(SO₄)₃*18H₂O, autocatalysis was performed as a reference process using the same parameters. The highest yield of furfural, 73.7% of the theoretical yield, was obtained at 180 °C, 5% Al₂(SO₄)₃*18H₂O of oven-dried mass and 90 min. From the biorefinery perspective, the optimal hydrolysis parameters were 160 °C, 5% Al₂(SO₄)₃*18H₂O of oven-dried mass and 90 min. With these parameters, the yield of furfural was 62.7% of the theoretical yield, 99.2% of hemicelluloses were removed and 95.8% of cellulose was preserved and slightly depolymerized.     

Characteristics of lignin from flax shives as affected by extraction conditions

Lignin, a polyphenolic molecule, is a major constituent of flax shives. This polyphenolic molecular structure renders lignin a potential source of a variety of commercially viable products such as fine chemicals. This work compares the performance of different lignin isolation methods. Lignin from flax shive was isolated using both conventional alkaline extraction method and a novel experimental pressurized low polarity water (PLPW) extraction process. The lignin yields and chemical composition of the lignin fractions were determined. The conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h, extracted 92 g lignin per kg flax shives, while lignin yields from the PLPW extracts ranged from 27 to 241 g lignin per kg flax shives. The purity and monomeric composition of the lignins obtained from the different extraction conditions was assessed via UV spectroscopy and alkaline nitrobenzene oxidation. Lignin obtained from conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h was of low purity and exhibited the lowest yields of nitrobenzene oxidation products. With respect to alkali assisted PLPW extractions, temperature created an opposing effect on lignin yield and nitrobenzene oxidation products. More lignin was extracted as temperature increased, yet the yield of nitrobenzene oxidation products decreased. The low yield of nitrobenzene oxidation products may be attributed to either the formation of condensed structures or the selective dissolution of condensed structures of lignin during the pressurized alkaline high temperature treatment. Analytical pyrolysis, using pyroprobe GC-MS, was used to investigate the molecular composition of the lignin samples. The total yield of pyrolysis lignin products was 13.3, 64.7, and 30.5% for the 1.25 M NaOH extracted lignin, alkaline assisted PLPW extracted lignin, and the unprocessed flax shives, respectively. Key lignin derived compounds such as guaiacol, 4-vinyl guaiacol, 4-methyl guaiacol, syringol, eugenol, isoeugenol, catechol, homocatechol, and vanillin were detected in all of the samples.     

Effects of Humic Substances Obtained from Shives on Flax Yield Characteristics

The effects of humic substances (HS) extracted from flax shives on the fiber and seed yield of fiber flax were examined during 3 years field experiment. HS from shives consists of humic acids—5.3 gL^?1 and fulvic acids—0.7 gL^?1 were applied (6·10^–2 gL^?1 concentration, with 300 Lha^?1 of spraying liquid) in “herring-bone” stage (BBCH 13 growth stage). The HS action was evaluated in different climatic conditions and in three varieties. Application of HS on early stage of vegetation of flax plants increased fiber yield (exceeding control on 16.0–28.1%) and quality (5% of cellulose content), protein and oil content in seeds (up to 1.9–4.2% and 1.6–3.5%, respectively). Positive reply of flax plants on HS from flax shives in tested cultivars allows saying about prospects of this type of humic substances.     

MuST筛在SGW浆筛选中的应用

介绍了齐齐哈尔造纸有限公司的带预筛的多段压力筛在SGW机械浆中的应用情况。该压力筛的使用，很好地适应了Opti优化概念纸机对SGW浆的要求。