Sustainable Production of Levulinic Acid from the Cellulosic Fraction of Pinus Pinaster Wood: Operation in Aqueous Media Under Microwave Irradiation

The fractionation of the structural components of lignocellulosic biomass (cellulose, hemicelluloses, and lignin) and the separate utilization of the resulting fractions for specific purposes, according to the philosophy of biorefineries, enables the development of sustainable processes for biomass utilization. In this work, Pinus pinaster wood was subjected to aqueous processing to remove water-soluble extractives and hemicelluloses, and the resulting solid was subjected to pulping with HCl-catalyzed acetic acid solutions (Acetosolv method). The pulp was employed as a substrate for levulinic acid manufacture by reaction in acidic media under microwave irradiation. The effects of the major operational variables (temperature, reaction time, and acid concentration) on the levulinic acid yield were established by statistical modeling of experimental data. Operating under the best reaction conditions (at 191.2°C for 18.9 min in aqueous media containing 1.10% HCl), the levulinic acid yield accounted for 56.4% of the stoichiometric value.     

Lignin liquefaction under microwave heating

Organosolv lignin from olive tree pruning was subjected to liquefaction under microwave heating and modifying the experimental conditions (time, temperature, and concentration of catalyst) according to an experimental design. The organosolv lignin and obtained polyols were characterized using attenuated‐total reflection infrared spectroscopy (ATR‐IR), thermogravimetric analysis (TGA), gel permeation chromatography, and another parameter such as the hydroxyl number (I_OH). The ATR‐IR and the TGA results showed that the solvents (polyethylene glycol #400 and glycerol) reacted with the lignin being present in the final product. The optimal polyol showed a liquefaction yield of 99.07% that was obtained in 5 min of reaction at 155°C with 1% of sulphuric acid. The liquefaction product showed a hydroxyl number of 811.8 mg KOH/g, suitable to be used as a precursor in polyurethane foam synthesis. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3292–3298, 2013     

Enhanced mechanical properties of epoxy composites using cellulose micro- and nano-crystals

Epoxy polymers are commonly utilized in structural applications due to their high bearing capacity and excellent chemical resistance. However, their inherent brittleness poses a significant challenge for their use in high shock and fracture strength products. To address this shortcoming, fillers can be incorporated into the polymer during preparation. In this study, we aimed to investigate the effect of incorporating cellulose-based fillers, namely cellulose nanocrystals (CNCs) and microcrystalline cellulose (MCC), on the mechanical properties of epoxy polymer composites. The study evaluated the impact of various factors, including filler concentration, particle size, and moisture content, on the mechanical properties of the composites. The results demonstrated that the incorporation of CNC or MCC powders at concentrations below 5% could enhance the mechanical properties of the resulting epoxy composites without adversely affecting their surface and thermal properties. The maximum tensile strength and fracture toughness of the filler-based epoxy composites were achieved at 2 and 4 wt% for CNCs and MCC, respectively. CNCs with a smaller particle size distribution were found to be much more effective than MCC in improving the mechanical properties of the epoxy composites. Furthermore, utilizing dried fillers resulted in a higher improvement in tensile strength, which was achieved at lower filler concentrations.     

Novel Nitrocellulose Made from Bacterial Cellulose

Nitrocellulose (NC) is useful in several industrial segments, especially in the production of gun, rocket, and missile propellants. The conventional way to prepare NC is done through the nitration of plant cellulose with nitric acid. In this work, bacterial cellulose nitrate (NBC) is synthesized by bacterial cellulose (BC) and nitro-sulfric acid under heterogeneous conditions. NBC with the degree of substitution (DS) of 1–2.85 was obtained, and the effects of sulfuric to nitric ratio, reaction temperature, and reaction time on the value of DS of NBC are discussed. The samples are also characterized by elemental analysis, thermal analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction.     

New equipment for measurement of the force of adhesion of mucoadhesive films

A better recognition of the properties of materials is of great interest in pharmaceutical technology, and especially in the development of modern solid dosage forms. As an example, a knowledge of the force of adhesion of a mucoadhesive preparation is of considerable importance. The aim of the present study was to develop the calibrated equipment suitable for determination of the force of adhesion and for following the process of film deformation during testing. A new instrument is introduced, and the results are presented.     

植物纤维组分在聚氨酯中的应用

植物纤维原料及其组分可部分替代多元醇用于聚氨酯的制备中,其中的纤维素、木质素及其衍生物均可在其中作为多元醇组分或者填料。这种多元醇组分既可由纤维素、半纤维素或木质素直接充当,也可以通过液化手段制得。植物生物质基多元醇与异氰酸酯反应可制成聚氨酯;植物纤维原料及其组分作为填料时,可以改善聚氨酯的热稳定性及机械性能。文章综述了植物纤维以及植物纤维组分在聚氨酯中的应用,介绍了液化过程中植物纤维原料、液化试剂、催化剂等的使用方法。     

Ice-microsphere templating to produce highly porous nanocomposite PLA matrix scaffolds with pores selectively lined by bacterial cellulose nano-whiskers

The production of 3D scaffolds for tissue engineering with provision of a controlled nano-topography remains a significant challenge. Here we have combined an ice-microsphere templating technique with thermally induced phase separation, and by taking advantage of interactions between hydrophilic and hydrophobic phases, lined the pore walls with bacterial cellulose nano-whiskers. The cryogenic technique we have developed not only allows the decoration of the pore walls of 3D porous forms with nano-whiskers but also enables the pore structure, interconnects and surface area to be controlled. Moreover our novel combined solvent extraction and ice sublimation route presented herein preserves the frozen-in structure.     

NMMO工艺天然高分子绿色复合膜的制备和表征

以纤维索、木质索和淀粉为原料,以N-甲基吗琳-N-氧化物(NMMO)为洛剂,制备了天然高分子绿色复合膜。利用傅里叶红外光谱和X射线衍射测试了复合薄膜的结钩,采用电子显微镜和轻敲模式原子力显微镜观察了该模型薄膜的表明形貌,并测定了薄膜力学性能。结果表明,通过NMMO工艺技术,3种天然高分子打破了原有的结晶结钩,重组形成了具有一定塑性的均相复合薄膜;该薄膜具有较高的拉伸强度(17. 25 MPa)和断裂伸长率(80.90%),表现出较好的耐水性能。     

Surfactant-Assisted Preparation of Nanoscale Cyclotrimethylenetrinitramine (RDX) Film Explosives in a Bacterial Cellulose Gelatin Matrix

Cyclotrimethylenetrinitramine (RDX) is a nitroamine explosive widely used in military applications because of its good explosive and safety properties. Using bacterial cellulose (BC) gelatin with a three-dimensional network as a carrier and sodium dodecyl benzene sulfonate (SDBS) and p-octyl polyethylene glycol phenylether (OP) as surfactants, nanoscale RDX films were prepared by a solvent/nonsolvent method. It was found that the granularity distribution of RDX in the films in the presence of SDBS and OP in the RDX solution was very uniform compared to the granularity distribution in the absence of surfactant. The surfactants also improved the dispersion of RDX in the film and the adhesion of RDX onto the network of BC gelatin, leading to an increase of RDX content in the film. Corresponding contents of RDX in the presence of SDBS and OP are 82.59 and 84.47% in the films, respectively, increasing RDX content by 7.23 and 9.11% over the films without surfactants.     

罩面金属氟碳涂料的配方设计及应用

介绍了氟碳金属涂料和氟碳罩面清漆的参考配方、生产工艺,探讨了罩面金属氟碳涂料配方的设计及喷涂效果,表明金属氟碳漆罩清漆效果良。