浸渍纳米纤维素膜增强聚乙烯醇的研究

通过酸碱、机械相结合的处理方法从木粉中提取出高长径比纳米纤维素,再利用真空过滤的方法制备高强度透明纳米纤维素膜。所得纳米纤维素膜浸渍到聚乙烯醇水溶液后真空干燥制得纳米纤维素膜/聚乙烯醇复合膜。经检测,纳米纤维素膜增强型聚乙烯醇的弹性模量提高了200%;纳米纤维素膜的透光率为86.9%,复合膜的透光率高达84.8%。     

利用碱处理纳米纤维素制备三维网状水凝胶的研究

以樟子松木粉为原料,通过化学机械法制得纳米纤维素(CNF);将所得CNF溶液抽滤成湿膜后,置于不同浓度氢氧化钠(Na OH)溶液中处理得到CNF水凝胶,并测定水凝胶的收缩率、结晶结构、形貌特征和力学性能。X-射线衍射分析表明,当碱浓度大于12%(wt)时,水凝胶的晶型由纤维素Ⅰ转变为纤维素Ⅱ。扫描电镜观察表明,CNF湿膜经强碱处理后表面形貌发生较大改变,纳米纤维之间发生交错结合,呈现出连续缠结的三维网状结构和多孔结构。力学分析表明,制备高强度水凝胶的最佳Na OH浓度为18%(wt),可得拉伸强度为4.8 MPa,弹性模量为11.7 MPa,断裂伸长率为31.2%的高强度水凝胶。     

醋酸纤维素纳米纤维膜的改性及性能研究

在生产纳米纤维过程中最常用的方法是静电纺丝,另外纳米纤维优点是表面面积大,孔隙率高,在重金属离子吸附区域具有良好的应用前景。(CA)纳米纤维膜,来自乙酸纤维素的胺化纳米纤维膜和来自氨基纤维素的乙酸纤维素膜与碳纳米管的膜生产醋酸纤维素。因此,本文主要研究和分析了醋酸纤维素纳米纤维膜的改性和性能。     

酰胺化纳米晶纤维素提高乙烯-醋酸乙烯酯共聚物薄膜阻透性的研究

合成了三种酰胺化纳米晶纤维素,并采用溶液共混成膜法制备了酰胺化纳米晶纤维素（CNC）/乙烯醋酸乙烯醋共聚物(EVA)复合膜材料。通过紫外-可见分光光度计、电子万能试验机和透湿仪研究了酰胺化CNC/ EVA复合膜的光学性能、力学性能以及水蒸气阻隔性,并通过原子力显微镜研究热压处理的EVA复合膜的表面形貌。结果表明,添加三种不同碳链的酰胺化CNC都使 EVA膜的透光率有所降低,当添加量为5 %时,EVA膜透光率仍高达90%。一定程度的热压能够让酰胺化纳米晶纤维素在EVA基体中分散更均匀,使EVA复合膜的透光率提高了2%～3%;随着纳米晶纤维素含量的逐渐增加,三种酰胺化CNC/EVA膜的拉伸强度均逐渐增强,透湿率（WVTR值）均减小;酰胺化CNC含量相同时, 十六胺改性的纳米晶纤维素(CNC-N16)/EVA复合膜的力学性能和水蒸气阻隔效果优于相应的十二胺和正辛胺。     

蔗渣纤维素在离子液体中的溶解与再生

以蔗渣纤维素为原料,在1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)离子液体中,制备出蔗渣纤维素再生膜。通过偏光显微镜观察了蔗渣纤维素的溶解过程,采用红外光谱、扫描电镜、X射线衍射、热重及力学性能等分析测试手段,对蔗渣纤维素及再生膜进行表征,结果表明:未经活化的蔗渣纤维素可快速、直接溶解在离子液体中,再生前后蔗渣纤维素发生了从纤维素Ⅰ到纤维素Ⅱ的晶型转变,蔗渣纤维素再生膜具有致密的结构,热力学稳定性达到292℃,拉伸强度高达144MPa。     

黄麻纳米原纤增强壳聚糖膜的制备及表征

以黄麻为原料,先用化学处理得到黄麻纤维素,再用超微粉碎机处理,分离出黄麻纳米原纤,用黄麻纳米原纤增强壳聚糖膜得到复合膜。通过扫描电镜(SEM)、傅里叶变换红外吸收光谱(FTIR)、X射线衍射(XRD)、拉伸强度测试、紫外吸收光谱(UV)进行了表征及分析。结果表明,黄麻原纤在壳聚糖膜中具有良好的分散性与光透性,含黄麻原纤20%的壳聚糖复合膜具有较高的抗拉强度和模量,其分别为152.31 MPa和2.20 GPa,较纯壳聚糖膜提高了175.87%和168.29%。     

黄麻纳米原纤增强壳聚糖膜的制备及表征

以黄麻为原料,先用化学处理得到黄麻纤维素,再用超微粉碎机处理,分离出黄麻纳米原纤,用黄麻纳米原纤增强壳聚糖膜得到复合膜。通过扫描电镜(SEM)、傅里叶变换红外吸收光谱(FTIR)、X射线衍射(XRD)、拉伸强度测试、紫外吸收光谱(UV)进行了表征及分析。结果表明,黄麻原纤在壳聚糖膜中具有良好的分散性与光透性,含黄麻原纤20%的壳聚糖复合膜具有较高的抗拉强度和模量,其分别为152.31 MPa和2.20 GPa,较纯壳聚糖膜提高了175.87%和168.29%。     

纳米微晶纤维素增强羟丙基纤维素复合膜的力学性能和透光度的研究

采用酸碱处理竹原纤维并辅以超声分散制备纳米微晶纤维素（NCC）,采用溶液浇铸/水分挥发的成型方法制备了纳米微晶纤维素增强羟丙基纤维素（HPC）全纤维素纳米复合膜.研究了NCC/HPC复合膜的力学性能、透光度以及热稳定性.随着纳米微晶纤维素含量的增加,复合膜的拉伸强度、拉伸模量、储能模量和热稳定性逐渐增大,与纯羟丙基纤维素膜相比,当纳米微晶纤维素质量分数为60％时,纳米复合膜的拉伸强度提高了8.5倍,拉伸模量提高了3.9倍,储能模量提高了3.7倍,而NCC/HPC复合膜的透光度没有出现明显的下降.     

新型纳米纤维素/聚醚砜复合膜的性能研究

通过超声均匀分散纳米纤维素与聚醚砜共混,形成纳米纤维素/聚醚砜共混铸膜液。采用浸入沉淀相转化法制备纳米纤维素/聚醚砜复合膜。利用黏度法与荧光显微镜方法研究了共混铸膜液的性能;探讨了纳米纤维素和聚醚砜添加量对复合膜超滤性能的影响;利用扫描电镜观察了复合膜的截面孔结构。结果表明,共混铸膜液的黏度随纳米纤维素含量的增加,呈非线性增长;其相结构是以纳米纤维素为主的分散相分散在以聚醚砜为主的连续相中的"海岛结构";纳米纤维素的加入使复合膜的水通量显著增加;随着聚醚砜含量的增加,复合膜水通量下降。复合膜为典型的非对称膜孔结构。     

NCC/改性纳米SiO2/PVA共混膜的制备及表征

采用共混法制备了纳米纤维素(NCC)/改性纳米二氧化硅(SiO2)/聚乙烯醇(PVA)共混膜。傅里叶变换红外(FTIR)光谱分析结果表明NCC/改性纳米SiO2/PVA共混膜的共混模式为存在氢键作用力的简单物理共混。力学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较高的拉伸强度,其拉伸强度平均值为128.41 MPa。热学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较好的热稳定性,其最大热失重温度为238℃。扫描电子显微镜(SEM)图分析结果表明NCC/改性纳米SiO2/PVA共混膜样品的表面和断面形貌较规整。     

Aerocellulose based on all‐cellulose composites

Novel aerogels (or aerocellulose) based on all‐cellulose composites were prepared by partially dissolving microcrystalline cellulose (MCC) in an 8 wt % LiCl/DMAc solution. During this process, large MCC crystals and fiber fragments were progressively split into thinner crystals and cellulose fibrils. The extent of the transformation was controlled by using cellulose concentrations ranging from 5 to 20 wt % in the LiCl/DMAc solution. Cellulose gels were precipitated and then processed by freeze‐drying to maintain the openness of the structure. The density of aerocellulose increased with the initial cellulose concentration and ranged from 116 up to 350 kg m^?3. Aerocellulose with relatively high mechanical properties were successfully produced. The flexural strength of the materials reached 8.1 MPa and their stiffness was as high as 280 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Drawing of self‐reinforced cellulose films

Self‐reinforced cellulose films were prepared by incomplete dissolution of commercial microcrystalline cellulose in LiCl/DMAc solvent and subsequent coagulation of regenerated cellulose in the presence of undissolved microcrystalline cellulose. By drawing in wet conditions and subsequent drying, preferred orientation was introduced into the self‐reinforced cellulose films, resulting in significantly improved tensile strength of up to 430 MPa and modulus of elasticity of up to 33 GPa. A linear relationship was observed between applied draw, and the orientation of cellulose in the films, and the measured elastic modulus and tensile strength, respectively. The optically transparent drawn films significantly surpass the strength and modulus of elasticity of current all‐bio‐based planar materials and may therefore present a bio‐degradable alternative to nonbio‐based materials with similar performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2703–2708, 2007     

Influence of potassium permanganate pretreatment on mechanical properties and thermal behavior of moso bamboo particles reinforced PVC composites

To illustrate the mechanism of oxidizer treatment on wood cellulose reinforced plastic composites, moso bamboo particles were modified with potassium permanganate aqueous solutions and then filled in polyvinyl chloride (PVC) matrix. Mechanical properties and thermal behaviors of moso bamboo particles reinforced PVC composites (BPPC) were investigated. Results showed that tensile strength of BPPC achieved its maximum value of 13.79 MPa with 0.5% potassium permanganate treatment while modulus of rupture and modulus of elasticity reached their highest values of 30.36 MPa and 3261.89 MPa, respectively, at 0.2% concentration. Potassium permanganate treatment enhanced elongation at break and flexural deformation of BPPC. The melting temperature reached 190.8°C with 0.5% potassium permanganate treatment and the melting enthalpy of crystallization was reduced to 69.82 J/g with 0.2% potassium permanganate treatment. A uniform dispersion of moso bamboo particles in PVC matrix was obtained after potassium permanganate treatment. Low concentration potassium permanganate would oxidize hydroxyl groups of moso bamboo cellulose while too high concentration would degrade moso bamboo cellulose. POLYM. COMPOS., 35:1460–1465, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of cellulose carbamate membrane with high strength and transparency

In this study, cellulose carbamate was synthesized from alkali cellulose and urea by a low-cost solid–liquid phase method. Cellulose carbamate was dissolved in cuprammonium solution to form a regenerated cellulose membrane with high strength and high transparency. The mass fraction of cellulose dissolved was greatly increased (up to 17%), and the thermal stability of cellulose was retained. The surface of the membrane is compact and there are regular microchannels in it. The factors influencing the transparency and mechanical properties of regenerated cellulose membrane were discussed by the range analysis of orthogonal experiment. The light transmittance is 95.50%, the breaking strength is 98.35 MPa, the elongation at break is 21.74%. The ability of heat preservation and moisture preservation of regenerated cellulose membrane was tested, and the effect was close to that of conventional polyethylene membrane. The membrane material has broad application prospects in packaging, food preservation, agriculture, and other fields.     

无水石膏自流平地面材料的研制

利用无水石膏为主要原料，通过掺加激发剂、减水剂、保水剂、掺合料、骨料等进行改性处理，研制成功了一种流动性好、平整度高、凝结快速、强度高、耐水性好的自流平地面材料。试验表明，无水石膏自流平地面材料摊展度达到300mm以上，抗压、抗折强度分别达到15．01MPa和6．19MPa，粘结强度达0．53MPa，软化系数0．72，初凝和终凝时间分别为2．4h和9．1h，主要技术性能指标均达到或超过日本住宅公团标准要求，是一种理想的石膏基自流平地面材料，值得推广应用。     

Transparent,flexible, and high‐strength regenerated cellulose/saponite nanocomposite films with high gas barrier properties

Regenerated cellulose‐saponite nanocomposite films were prepared from LiOH/urea solutions, and exhibited high optical transparency and flexibility. The saponite platelets formed intercalated nanolayered structures in the composites. The longitudinal directions of both the cellulose II crystallites and the saponite platelets were preferentially oriented parallel to the film surface in the composites. The good nanodispersibility and high orientation of the saponite platelets in the composite films resulted in high mechanical strength, high Young's modulus, and good thermal dimensional stabilities, and gas barrier properties in the composites, compared with a reference cellulose film. Moreover, the tensile strength and Young's modulus of the composite film reached 241 MPa and 7.7 GPa, respectively, when a simple drawing process was applied to the wet composite film; this is probably owing to the improvement in the orientation of the cellulose II crystallites and saponite platelets in the composites. The composite films also showed high toughness and ductility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3168–3174, 2013     

Nitrile functionalized benzoxazine/bismaleimide blends and their glass cloth reinforced laminates

A novel high‐performance resin blend composed of nitrile functionalized benzoxazine (CNBZ) and bismaleimide (4,4′‐bismaleimidodiphenyl methane) (BMI) was prepared via solvent method. Its curing behaviors, thermal properties, and mechanical properties were studied by differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and universal testing machine, respectively. The results showed that the addition reaction between phenolic hydroxyl group and the double bond occurred except for the homopolymerization of CNBZ and BMI. When BMI content was more than 40%, the cured CNBZ/BMI blends exhibited higher glass transition temperatures (T_gs) than CNBZ and BMI homopolymers, which reached up to 334°C. Meanwhile, when BMI content was 40%, the tensile strength, flexural strength, and shearing strength reached up to 69, 235, and 12.9 MPa, respectively, which exhibited the comparable mechanical properties with BT resin. Furthermore, the glass cloth (GF) reinforced laminates based on these blends were prepared. The results showed that when BMI content was 40%, their tensile strength, flexural strength, and impact strength reached up to 334 MPa, 593 MPa, and 145 KJ m^?2, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41072.     

Acetylation of plant cellulose fiber in supercritical carbon dioxide

Natural cellulosic ramie fiber was acetylated using supercritical carbon dioxide (sc-CO₂) as a reaction medium. The structure and properties of the acetylated fibers were investigated using infrared spectroscopy, scanning electron microscopy, X-ray diffraction (including synchrotron microbeam X-ray diffraction), nano-Raman scattering, and a tensile test. The acetylation reaction proceeded without using an organic solvent, and it reached to the core part of the fiber within a short period while maintaining the fiber morphology. The crystallites of cellulose triacetate II and cellulose coexist in the fiber. The acetylated fiber with an average degree of substitution of 1.9 showed high modulus (34.5 GPa) and high strength (763 MPa), which are the highest values for cellulose diacetate so far reported to date.     

Preparation and characterization of poly(glycerol sebacate)/cellulose nanocrystals elastomeric composites

Poly(glycerol sebacate) (PGS) is one of the new elastomers used for soft tissue engineering, while improving its limited mechanical strength is the biggest challenge. In this work, a novel biodegradable elastomer composite PGS/cellulose nanocrystals (CNCs) was prepared by solution‐casting method and the mechanical properties, sol–gel contents, crosslink density, and hydrophilic performance were characterized. The thermal and degradation properties of composites were also investigated. Results show that the addition of CNCs into PGS resulted a significant improvement in tensile strength and modulus, as well as the crosslink density and the hydrophilicity of PGS. When the CNCs loading reached 4 wt %, the tensile strength and modulus of the composite reached 1.5 MPa and 1.9 MPa, respectively, resulting 204% and 158% increase compared to the pure PGS. Prolonging the curing time also improved the strength of both the neat PGS and PGS/CNCs composites according to the association and shift of hydroxy peaks around 3480 cm^?1. DSC results indicate that the addition of CNCs improved both the crystallization capacity and moving capability of PGS molecular chain. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42196.