纤维素硝酸酯真空热脱水工艺设备的优化设计

针对原纤维素硝酸酯真空热脱水设备在生产过程中,干物料产能受原料透水性能和环境温度的影响较大问题,分析问题产生的原因和影响因素的作用机理,提出提高滤水段滤水比重、保持棉饼温度的设备改进方法。介绍了优化的布料系统、真空-压榨滤水机构和滤水段棉饼保温机构的设计及工作原理。结果表明:该方法显著提高设备滤水能力,降低能源消耗,并减少硝化棉的分解量,使生产过程安全性更高。     

DNA disPLAY: Programmable Bioactive Materials Using CNC Patterning

2D, 3D and 4D printing are fertile areas for design and material experimentation, and thus the architectural detail in the future. Here Skylar Tibbits , along with his collaborators - Lina Kara'in (MIT Self-Assembly Lab) , Jose Gomez-Marquez, Anna Young and Joaquin Navarro (Little Devices Lab, MIT), Lee Gehrke, Helena de Puig and Justina Tam (Gehrke Lab, MIT), and Joseph Schaeffer and Carlos Olguin (Autodesk Inc) - describe the development of DNAdisPLAY: a project that created a physical prototype and design workflow for 2D bioprinting, resulting in the development of software, hardware and printed DNA patterns on paper.     

纳米二氧化硅改性对硝基木器涂料力学及光学性能的影响

硝基涂料是典型的挥发型涂料,室温下就可以固化,固含量低因此涂膜薄,耐水性、耐久性和耐化学药品性能不好本文利用纳米二氧化硅(SiO_2)的优越稳定性、补强性及增稠性等特性来改善硝基涂料的不足,研究改性前后复合涂层的力学性能和光学性能的变化。研究结果表明:当纳米SiO_2添加量为0.1 g时,涂层的磨耗值最小,其值为0.077 g,相比未添加纳米SiO_2的硝基涂层磨耗值降低了46.4%,并且在此添加量下,涂层硬度达到最大在添加纳米SiO_2改性剂后,涂层附着力仍保持1级水平当纳米SiO_2添加量从0提高到0.1 g时,涂层的光泽度从47.3%显著下降到13.8%,添加纳米SiO_2符合木器涂料亚光改性的需求     

喷墨打印水转印过渡层的性能研究

实验研究了过渡层对喷墨打印水转印转印膜伸长率及转印效果的影响。 结果表明:水转印膜伸长率随着硝化纤维的增加、丙烯酸树脂的减少而减小;初始接触角随表面活性剂纳米二氧化硅的增加而减小,提高了过渡层对水性油墨的吸附性能。     

含氟丙烯酸酯改性水性硝化纤维乳液的制备及其性能

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)、丙烯酸(AA)、丙烯酸羟乙酯(HEMA)、全氟辛基乙基丙烯酸酯(FA)、三乙胺(TEA)为主要原料,采用自乳化法制备含氟丙烯酸酯改性水性硝化纤维乳液(WNC)。通过傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、纳米粒度仪、动态流变仪以及视频光学接触角测定仪对所制乳液及薄膜进行了结构和性能表征,并考察了单体聚合温度、n(AA)∶n(HEMA)、含氟丙烯酸酯质量分数(占反应物AA、HEMA、NC、IPDI总质量的百分数)对乳液及其薄膜性能的影响。结果表明,所得WNC乳液性能稳定,乳液胶粒呈球形,具有核-壳结构。当单体聚合温度为60℃,n(AA)∶n(HEMA)=3∶1,含氟丙烯酸酯用量为1.0%时,所得乳液粒径较小且分布窄,平均粒径和分散系数分别是54 nm和0.023;改性后的乳液薄膜吸水率降低至2.0%,薄膜接触角增加至120°,相比较未改性的WNC乳液,改性后的WNC乳液薄膜具有优异的耐水性。     

X-ray Diffraction Study of Single-base Propellant Ageing（英）

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Hygroscopicity of nitrocellulose with different nitrogen content

Research on the hygroscopic behavior of NC is essential because it affects the mechanical properties, combustion properties, and safe storage of NC-based products. In this study, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) are used to characterize the chemical structure, crystal structure, and microscopic morphology of NC, respectively. The moisture adsorption isotherms of NC fibers with different nitrogen content are determined by dynamic vapor sorption (DVS) and fitted with Hailwood-Horrobin (H−H) and Guggenheim-Anderson-de Boer (GAB) models. The specific surface area and surface energy of NC are also measured by inverse gas chromatography (IGC). The results show that as the nitrogen content of NC increases, the intensity of the −OH characteristic absorption peak is weakened, the crystallinity does not change much, the number of cracks and pores on the NC fiber surface increases, and the equilibrium moisture content (EMC) of the NC decreases in general. In addition, the fitting results based on the H−H and GAB models show that, under low humidity conditions, the EMC value of NC is determined by the adsorbed water content of the monolayer, which is mainly related to the −OH content in NC. However, with the increase of humidity, the EMC value of NC is gradually determined by the multilayer adsorbed water content, which is influenced by both the nitrogen content and the fiber cleavage structure. Meanwhile, the IGC results show that the surface energy of the NC consists mainly of the dispersive surface energy (values >46 mJ m⁻²), with the specific surface energy contributing approximately 25 mJ m⁻². The total surface energy of NC and the bonding strength between NC molecules and water molecules decrease with increasing nitrogen content.     

基于两段法及改变落球高度的硝化棉落球粘度测量

为提高落球法测量硝化棉粘度的精确性，减小因小球在落球距离内做非匀速运动造成的误差，提出了一种基于两段法及改变落球高度的精确测量方法。采用PLC、光电传感器设计实验装置，选取5种粘度的试液，获得不同落球高度的计时值，拟合数据得到适宜落球高度。对比了传统固定高度与适宜落球高度方法的测量误差。实验表明，适宜落球高度和试液粘度之间存在负相关性；粘度大于60 300 mPa·s时，落球管口处即为适宜落球高度；粘度小于60 300 mPa·s时，在适宜落球高度释放小球能减小测量误差；粘度越低误差减小效果越明显。