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| 首页 >> 中国造纸杂志社 >> 国际造纸 >> 摘要 >> 《Paper and Biomaterials》2021年第1期摘要 |
| | Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp | | Gong Xiaoqi,Zhang Zongwei,Ni Yonghao,Ouyang Xinhua,Chen Lihui,Huang Liulian,Hu Huichao | | 2021,6(1):1-10.DOI:10.12103/j.issn.2096-2355.2021.01.001 | | Hemicellulose has a wide range of applications, including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films. Hemicellulose is usually present as a spent liquor, such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers. Due to its dilute nature, hemicellulose needs to be dried for practical utilization, and this is challenging. In this study, cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process. Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process. The effects of drying time and drying temperature were determined. Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose, as revealed by detailed Fourier transform infrared and X-ray diffraction analyses. The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method, and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose. The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films. | | [Abstract] [PDF] | |
| | Synthesis of Reprocessable Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks | | Xue Danwei,Xue Bailiang,Tang Rui,Shen Chao,Li Xinping,Zhao Wei | | 2021,6(1):11-21.DOI:10.12103/j.issn.2096-2355.2021.01.002 | | In this study, an environmentally friendly and non-toxic route to synthesize lignin-based non-isocyanate poly(imine-hydroxyurethane)s networks was explored. Specifically, the NH2-terminated polyhydroxyurethanes (NPHUs) prepolymer was first synthesized from bis(6-membered cyclic carbonate) (BCC) and diamine via the ring-opening reaction. Subsequently, the corresponding lignin-based non-isocyanate polyurethanes (NIPUs) with tunable properties were synthesized from NPHUs and levulinate lignin derivatives containing ketone groups via the Schiff base reaction. The structural, mechanical, and thermal properties of NIPUs with different stoichiometric feed ratios of BCC and levulinate lignin were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicated that the tensile strength, Young's modulus, toughness, storage modulus, glass transition temperature, and thermal stability of lignin-based NIPUs gradually increased with increasing lignin content, and the highest Young's modulus of 41.1 MPa was obtained when lignin content reached 45.53%. With good reprocessing properties, this synthetic framework of lignin-based NIPUs also provides sustainable non-isocyanate-based substitutions to traditional polyurethane networks. | | [Abstract] [PDF] | |
| | Carboxyethylated Microfibrillated Cellulose Fibers Prepared from Different Raw Materials | | Chen Jinghuan,Liu Jingang,Hou Leilei,Xu Zehong | | 2021,6(1):22-32.DOI:10.12103/j.issn.2096-2355.2021.01.003 | | Carboxyethylation pretreatment was used to prepare microfibrillated cellulose (MFC) in this study. In order to evaluate the adaptability of this pretreatment method, carboxyethylated MFC was prepared from six different cellulosic materials. The carboxyl content, degree of polymerization, water retention value, charge density, chemical structure, size distribution, and micromorphology of the materials before and after pretreatment and grinding were studied and compared. The viscosity, ultraviolet (UV) transmittance, and thermal stability of the MFC samples at a certain concentration were determined. The results showed that the carboxyl content, water retention value, charge density, degree of polymerization, size distribution, and micromorphology of the pretreated and ground samples varied with those of the raw materials. The initial viscosity varied based on the type of raw material used. The MFC suspension prepared from cotton linter pulp had the highest UV transmittance, while the MFC prepared from bleached softwood kraft pulp had the highest viscosity at a low shear rate. After thermal degradation, the amount of residual char from the MFC prepared with the thermo-mechanical pulp was slightly higher than that of the other MFCs. This study demonstrates that carboxyethylation is an effective pretreatment method for different cellulosic materials. | | [Abstract] [PDF] | |
| | Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties | | Zhang Ruijuan,Su Yanqun,Liu Jingang | | 2021,6(1):33-40.DOI:10.12103/j.issn.2096-2355.2021.01.004 | | In this study, we investigated the barrier properties of different kinds of microfibrillated cellulose (MFC) coating layers. The air, oxygen, and water vapor permeability, as well as the water contact angles (WCA), were measured to quantify the barrier efficacy of the applied coatings. The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards. However, different MFC coatings realize different oxygen transmission rates (OTRs) and water vapor transmission rates (WVTRs). The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment (MFCCBP) gave the best oxygen and water vapor barrier performances. The OTR of the virgin cardboard (>16500 cm3/(m2·24 h)) decreased to 4638 cm3/(m2·24 h) after coating with the MFCCBP. The WVTR similarly decreased from 1016.7 g/(m2·24 h) to 603.2 g/(m2·24 h). | | [Abstract] [PDF] | |
| | Preparation of Chitosan-based Microspheres for Rapid Hemostasis | | Fang Yan,Li Peiyuan,Zhou Weikang | | 2021,6(1):41-49.DOI:10.12103/j.issn.2096-2355.2021.01.005 | | Rapid control of heavy hemorrhaging is critical to save the life of injured individuals. Herein, we developed a novel hemostat employing chitosan-based microspheres, which was prepared by sequential microemulsion of chitosan solution, sol-gel phase transition, and surface modification by 3,4-dihydroxyhydrocinnamic acid (HCA). HCA-modified chitosan microspheres (CSMS-HCA) displayed a porous structure, with a high specific surface area (~211.3 m2/g), accelerating their rapid absorption of blood and concentrating red cells and platelets. The CSMS-HCA exhibited much better in vitro and in vivo hemostatic efficacy than porous chitosan microspheres did. Such a rapid hemostat in the form of microspheres is highly effective in treating deep and irregular wounds, owing to easy accessibility to injured sites. | | [Abstract] [PDF] | |
| | Adsorption of Cu2+ by Crosslinked Graft Copolymers of Starch | | Cai Xue,Lin Tao,Zhang Neng,Wei Xiaoyao,Yin Xuefeng | | 2021,6(1):50-60.DOI:10.12103/j.issn.2096-2355.2021.01.006 | | With the use of acrylic acid (AA) as a monomer, humic acid (HA) and starch as raw materials, potassium persulfate (KPS) as initiator, and N,N-dimethylacrylamide (MBA) as a cross-linking agent, AA/HA/Starch graft copolymer was prepared and characterized by SEM and FT-IR. The effects of temperature, adsorption time, adsorbent dosage, pH value and Cu2+ initial concentration of the solution on the adsorption performance of the crosslinked graft copolymer were also investigated. The results showed that the Cu2+ adsorption capacity of the AA/HA/Starch graft copolymer increased firstly and then decreased with increasing adsorbent dosage and the initial pH value of Cu2+ solution. With the increase of Cu2+ initial concentration and the extension of adsorption time, the adsorption amount of Cu2+ increased rapidly and then stabilized. And it decreased slightly with the increase of temperature. At pH value of 5.5, temperature of 298 K, adsorbent dosage of 50 mg, adsorption time of 125 min, and 100 mL Cu2+ solution with Cu2+ initial concentration of 100 mg/L, the Cu2+ adsorption capacity of the crosslinked graft copolymer was 238 mg/g. The adsorption of Cu2+ by the adsorbent followed the pseudo-second-order kinetic equation and Langmuir isothermal adsorption model, and the adsorption was attached to monolayer chemical adsorption. This study proved that AA/HA/Starch graft copolymer could be used as an efficient adsorbent for the removal of harmful and toxic metal cations such as Cu2+ from industrial wastewater. | | [Abstract] [PDF] | |
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