多壁碳纳米管/两亲性嵌段聚合物复合材料的制备

采用两亲性三嵌段聚合物PAN-PEG-PAN的DMF溶液分散MWNTs,通过静电纺丝制备MWNTs/PAN-PEG-PAN复合纤维.采用流变仪与SEM分析了MWNTs的分散性以及MWNTs对复合材料的结构性能的影响.结果表明:MWNTs/PAN-PEG-PAN溶液的模量与粘度随着MWNTs的质量分数的增加而增加,当MW...     

基于高速相位调制的菲涅耳场相位恢复

多强度相位恢复方法通过改变光学成像系统中的物理参数获得不同的编码衍射图案,实现相位的最佳收敛和高精度重建,无需额外的先验知识等优点;但现有多强度相位恢复方法在获取不同测量的过程中,往往需要不断改变成像系统的物理结构,从而导致成像结构较为复杂,需要精确移动或调整部分光学元件的空间位置,反复地对齐与校准,显著增加了相应的工作量。针对上述问题,本文提出基于高速相位调制的菲涅耳场相位恢复方法,该方法主要使用两种纯相位空间光调制器(电可调透镜/纯相位型硅基液晶)来进行相位的快速动态调制,然后通过自由空间传播到记录平面,被探测器所获取强度信息,不需要透镜装置或者改变成像系统的物理结构,使得成像结构更为紧凑和简单,避免了反复对齐与校准的过程;在重建阶段使用WF算法从获取的多幅编码衍射图案中同时重建光场的振幅和相位。仿真实验验证了本文方法的有效性和鲁棒性。本文方法的成像结构更为紧凑和简单,避免了反复对齐与校准的工作量,具有重要的应用潜力,尤其是电可调透镜调制方案,可适用于高分辨率场景的高速记录。     

泡沫胶凝法制备轻质钙长石耐火材料的工艺研究

以煅烧矾土、煅烧高岭土、硅灰石、蛋白质发泡剂、明胶、聚乙烯醇、硅溶胶和聚合硫酸铝为原料,采用泡沫胶凝法制备了轻质钙长石材料,主要研究了蛋白质发泡剂加入量、明胶加入量、硅溶胶和聚合硫酸铝的加入时机以及硅溶胶加入量等对泡沫胶凝成型工艺的影响,并分析了烧成后轻质钙长石材料的物相组成、显微结构和性能。结果表明:1)蛋白质发泡剂-水泡沫体系中蛋白质发泡剂的体积分数为15%时,体系的发泡倍数达到最大;每100 mL蛋白质发泡剂-水泡沫体系中加入1.2 g明胶时,泡沫的沉陷率最小,稳定性最好;将聚合硫酸铝促凝剂分散到黏稠泥浆中,制成泡沫泥浆后,在高速搅拌下按1 L泡沫泥浆加入137 mL硅溶胶的比例缓缓加入硅溶胶,搅拌结束15 m in后体系发生胶凝。2)按试验确定的最佳工艺成型并于1 280℃保温0.5 h烧成后的轻质钙长石材料,以钙长石为主晶相,并有少量刚玉相;烧成后的轻质钙长石材料为多孔结构,其气孔多为封闭气孔,且分布较均匀,平均孔径约200μm;烧成后的轻质钙长石材料的性能参数已达到,有的甚至已超过德国的Jm23砖。     

The formation of a dual-layer carbon film on silicon carbide using a combination of carbide-derived carbon process and chemical vapor deposition in a CCl4 – containing atmosphere

The synthesis of a dual-layer carbon film on SiC is reported using a combination of carbide-derived carbon (CDC) process and chemical vapor deposition (CVD) in a CCl₄ – containing atmosphere. The film is composed of a CDC sub-layer formed by chlorination of the SiC and a CVD top-layer by pyrolyzing CCl₄. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and thermogravimetric analysis are employed to analyze the film. The formation mechanism of the dual-layer film is proposed as two simultaneous and competitive processes, namely, the chlorination of SiC and the growth of CVD layer.     

A-O法生物脱氮技术在蒸氨废水中的应用

为解决外排焦化污水中COD和氨氮的超标问题，在对蒸氨系统进行改造的同时，将生化处理装置与A－O法生物脱氮工艺相结合，使外排废水全面达标排放。     

对-(月桂基)苄基聚氧乙烯醚羧酸甜菜碱的合成与表面活性

以月桂酸、苯、聚乙二醇为原料,合成了4种具有不同氧乙烯数(分别为1,2,3,4)的对-(月桂基)苄基聚氧乙烯醚羧酸甜菜碱两性离子表面活性剂。用FTIR,1HNMR和ESI-MS对产物进行了结构鉴定。用吊片法测定了30℃时它们在水溶液中的临界胶束浓度(cmc)和表面张力(γcmc)。结果表明,水溶液中它们的cmc都达到了10-6mol·L-1,γcmc为29～35 mN·m-1;随着聚氧乙烯单元的增多,4种表面活性剂的cmc先变化不大后开始减小,而饱和吸附量则先增大后减小,分子在溶液表面的极限占有面积先减小后增大,相应的γcmc先减小后增大。     

Thermo-mechanical properties of MWCNT-g-poly (l-lactide)/poly (l-lactide) nanocomposites

The thermo-mechanical properties of poly (l-lactide) (PLLA) biodegradable polymer reinforced with PLLA grafted from multiwalled carbon nanotubes (MWCNT-g-PLLA)s are characterized. The crystallinity of PLLA polymer matrix affected by MWCNT-g-PLLAs is illuminated. For this purpose, the PLLA chains are covalently grafted from the sidewall of aminated MWCNTs. Then, the MWCNT-g-PLLAs/PLLA composite films are prepared by solution casting using chloroform as solvent. It is found that the MWCNT-g-PLLAs well dispersed in PLLA matrix. The mechanical properties of PLLA enhanced gradually with the increasing concentrations of MWCNT-g-PLLAs up to 2 wt%. The MWCNT-g-PLLAs increase the glass transition temperature (T _g) and melting point of PLLA as revealed by the curves from differential scanning calorimeter (DSC). In addition, the dynamic mechanical analysis (DMA) results show that the T _g and Young modulus of PLLA increase with the increment in the concentrations of MWCNT-g-PLLAs. Due to the homogenous dispersion of MWCNT-g-PLLAs and the van der Walls force between grafted PLLA chains on the sidewall of MWCNTs and the PLLA matrix chains, the chain stiffness in amorphous phase of PLLA increases. In addition, the MWCNT-g-PLLAs as heterogeneous nucleation agents increase the crystallinity of PLLA.     

关于正项几何规划的对偶规则

本文利用著名的 Lagrange 函数理论直接地建立了正项几何规划的对偶规划,而没有利用算术——几何不等式及(h一Φ))凸函数理论。     

Effects of ultraviolet absorbers on the ultraviolet degradation of rice‐hull/high‐density polyethylene composites

In China, rice‐hull powder is widely used as a fiber component to reinforce polymers because of its ready availability and lower cost compared to wood fibers. However, an issue concerning these composites is their weathering durability. In this study, the effects of two ultraviolet absorbers (UVAs), UV‐326 and UV‐531, on the durability of rice‐hull/high‐density polyethylene (HDPE) composites were evaluated after the samples were exposed to UV‐accelerated weathering tests for up to 2000 h. All of the samples showed significant fading and color changes in exposed areas. X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to detect surface chemical changes. The results indicate that surface oxidation commenced immediately within the first 500 h of exposure for all of the samples. However, the control rice‐hull/HDPE composites underwent a greater degree of oxidation than those with the UVAs. Scanning electron microscopy revealed that the rice‐hull/HDPE composites degraded significantly upon accelerated UV aging, with dense cracking on the exposed surface. The UVAs provided effective protection for the rice‐hull/HDPE composites, and UV‐326 had a more positive effect on the color stability than UV‐531. The results reported herein serve to enhance our understanding of the efficiency of UV stabilizers in the protection of rice‐hull/HDPE composites against UV radiation, with a view toward improving their formulation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012