Toward Sustainable, Economic, and Tailored Production of Cellulose Nanomaterials

This paper introduces a concentrated di-carboxylic acid(DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals(CNCs) and cellulose nanofibrils(CNFs). The DCA hydrolysis process addressed several issues associated with mineral acid hydrolysis for CNC production, such as cellulose loss and acid recovery. The surface and morphological properties of the cellulose nanomaterials resulting from the DCA hydrolysis process can be tailored simply by controlling the severity of DCA hydrolysis. To further reduce cost, a lowtemperature(≤80℃) hydrotropic chemical process using p-toluenesulfonic acid(p-Ts OH) was also introduced to rapidly fractionate raw lignocelluloses for the production of lignin containing cellulose nanofibrils(LCNFs) and lignin nanoparticles(LNPs). The LCNF surface hydrophobicity and morphology can be tailored by controlling the fractionation severity, i.e., the extent of delignification. The lignin also improved the thermal stability of LCNFs. LNPs can be easily separated by diluting the spent acid liquor to below the p-Ts OH minimal hydrotropic concentration of approximately 10%. p-Ts OH can also be easily recovered by re-concentrating the diluted spent liquor after lignin precipitation. We believe that these two novel processes presented here have the potential to achieve true sustainable, economic, and tailored production of cellulose nanomaterials, suitable for a variety of applications.     

旋涂法制备银纳米线透明导电薄膜

以商用银纳米线分散液为原料,利用旋涂法在载玻片上制备透明导电薄膜,并测试其可见光波段透过率,分析银纳米线分散液浓度、旋涂转速和热处理对银纳米线透明导电薄膜性能的影响。实验结果表明,银纳米线分散液浓度为2 mg/mL,旋涂转速为7500 rpm时,制得的银纳米线透明导电薄膜透过率可达98 %,电阻为120 Ω;120 ℃热处理10 min后银纳米线透明导电薄膜的透过率降低至91%,电阻降低至70 Ω。通过旋涂法制备了具有较好光电性能的透明导电薄膜,有望应用于触控设备和有机发光二极管(OLED)等领域。     

Fluorescent digital image correlation techniques in experimental mechanics

White light has often been used for surface illumination to acquire images for digital image correlation(DIC) analysis. In recent years, fluorescent imaging technique has been introduced for illumination, surface deformation and topography measurements with applications on various materials including biomaterials(biofilms, etc.) at the microscale. Traditional imaging, with the use of white light, encounters technical issues such as specular reflection owing to moisture or smooth shiny surfaces(e.g., metallic or glass surfaces). As an alternative to white light, fluorescent imaging serves as a solution to resolve the issues of specular reflection.Fluorescent DIC techniques, especially the fluorescent stereo DIC, allow 3 D surface profilometry and deformation measurements at the microscale and submicron scale. Fluorescent stereo imaging under a microscope utilizes emission wavelengths that are different from illumination wavelengths to ensure clear images on any surface that might give reflections at certain angles when white light is used, allowing accurate metrology and deformation measurement. In addition microscopic fluorescent imaging provides nanoscale resolutions surpassing Abbe's diffraction limit. This paper provides a review of the recent advances in fluorescent DIC.     

改性漆酶协同谷氨酸改善二次纤维微观结构及性能的研究

采用L-苯丙氨酸甲酯盐酸盐对漆酶氨基酸残基末端的羧基进行改性,研究改性漆酶-谷氨酸体系对旧瓦楞箱纸板(OCC)浆纤维微观结构及性能的影响。研究结果表明,与未改性漆酶-谷氨酸相比,经过改性漆酶-谷氨酸体系处理后OCC浆纤维表面呈层叠状紧密黏连,细纤维化程度更高;改性漆酶催化氧化木素,使纤维微孔结构瓦解并逐渐扩大为中孔,纤维BET比表面积和平均孔径增大;谷氨酸通过迈克尔加成反应嫁接到木素上使纤维羧基含量进一步提升,与OCC原浆相比纤维羧基含量提高了26.9%;显著改善纸浆的打浆性能,降低了打浆能耗;对纸浆的增强作用更加明显。