响应面法优化PSSA/PVA共混膜催化酯化制备生物柴油

采用响应面法考察聚苯乙烯磺酸(PSSA)/聚乙烯醇(PVA)共混型催化膜催化酯化制备生物柴油工艺中催化膜用量、醇油质量比、反应时间和反应温度及其交互作用对酯化率的影响,结果发现,各因素对转化率影响顺序为:醇油比＞催化剂用量＞反应温度＞反应时间;同时,醇油比与催化剂量的交互作用对转化率的影响最强,而与反应时间相关的交互作...     

硫酸锆/聚乙烯醇杂化膜催化酯化制备生物柴油

采用溶液蒸发法制备了硫酸锆/聚乙烯醇[Zr(SO_4)_2/PVA]杂化催化膜,并将此催化膜用于催化酯化酸化油制备生物柴油.通过考察醇/油摩尔比、催化膜用量、反应时间、PVA与Zr(SO_4)_2质量比对酯化反应的影响.得到Zr(SO_4)_2/PVA催化膜制备生物柴油的最佳工艺条件,即保持反应温度65℃、反应时间120 min、催化膜用量为4%(质量分数)、PVA与Zr(SO_4)_2质量比1∶1,转化率可以达到94.5%.对比了交联与未交联Zr(SO_4)_2/PVA催化膜的重复使用性能,重复使用5次交联与未交联Zr(SO_4)_2/PVA催化膜转化率分别为64.3%和78.2%.     

纳米SiO_2有机杂化膜制备研究

采用共混法和溶胶-凝胶法制备了纳米SiO_2有机杂化膜,考察了制备方法和SiO_2的性质对杂化膜结构和性能的影响.结果表明:采用溶胶-凝胶技术制备的杂化膜同共混法得到的杂化膜及未杂化膜相比,机械性能明显提高,膜微观结构改善,并表现出良好的气体分离性能.此外,杂化膜中无机相的负载量也是一个影响杂化膜结构和性能的重要因素,当正硅酸乙酯的添加量为30%(wt)时,杂化膜的综合性能较为理想.     

原位乳液接枝法制备聚丁二烯/SiO_2杂化材料

在聚丁二烯(PB)胶乳中进行乳液自由基反应,将乙烯基三乙氧基硅烷(VTES)接枝到聚丁二烯分子链上,制备了聚丁二烯/SiO2杂化材料。运用硅含量、交联率、傅立叶变换红外光谱(FT-IR)、热失重分析(TGA)对产物结构进行了表征,考察了产物多种性能的变化情况,并探讨了杂化材料的形成机理。结果表明,VTES通过共价键合在PB链上,并与水解缩合形成的硅核连接,利用率达88.6%;接枝后产物凝胶率提高,分解速率降低,力学性能如门尼黏度、拉伸强度和断裂伸长率均显著改变。     

碱催化多孔SiO_2/PI杂化薄膜的制备与力学性能研究

采用碱催化正硅酸乙酯(TEOS)的溶胶-凝胶法与分子模板法相结合,通过旋转涂覆在硅衬底上制备掺杂聚酰亚胺(PI)的纳米多孔SiO2薄膜,并在其表面制备致密过渡膜。利用差热分析(DSC-TGA)、原子力显微镜(AFM)、台阶仪(Atomic-Profiler)、微纳力学性能测试仪(Universal Nano+Micro Mechanical Tester)等对薄膜的性能进行了分析表征。结果表明,所制备的SiO2/PI杂化多孔薄膜具有较好的力学性能和热稳定性;一层膜和两层膜的平均厚度分别为917和1288nm;镀有过渡膜的样品具有最为平整的表面形貌和最小的表面动摩擦系数。     

QCS/SiO_2有机/无机杂化膜的制备及其溶胀动力学研究

以季铵化壳聚糖(QCS)为主体膜材料,二氧化硅(SiO2)为无机前躯体通过溶胶-凝胶法制备QCS/SiO2有机/无机杂化膜,通过傅利叶变换红外光谱(FT-IR)、扫描电镜(SEM)和热失重分析(TGA)对制备得到的膜的结构、形貌以及热稳定性进行表征。同时,对QCS/SiO2杂化膜的溶胀机理、SiO2含量对该杂化膜溶胀度、溶胀速率和溶胀动力学的影响等因素进行了考察。结果表明:无机物质SiO2的含量对膜的溶胀过程有显著影响,随着SiO2含量的增加,溶胀速率常数呈现先增大而后减小的趋势。而且,该系列杂化膜在pH=7的水溶液中吸水溶胀时,溶胀过程遵循Schott’s二级溶胀动力学模型。另外,无机物质的引入优化了杂化膜的吸水溶胀过程,当杂化膜中无机物质SiO2含量为15%时(质量分数),初始溶胀速率(KsW2∞)为769.23,吸水速度较快。     

响应面法优化制备壳聚糖明胶活性膜

目的制备一种具有疏水功能的壳聚糖-明胶活性膜。方法通过研究不同质量浓度比的明胶-壳聚糖对膜性能的影响,确定两者的最佳质量浓度比,并研究柠檬酸三丁酯、甘油、吐温-20浓度对活性膜疏水性能的影响。根据Box-Benhnken试验设计原理,以膜的抗拉强度作为响应值,对活性疏水膜的制备工艺进行优化。探讨各因素交互作用,确定制备壳聚糖-明胶活性疏水膜的最佳条件。结果明胶-壳聚糖的最佳质量浓度比为1∶1,各因素对膜抗拉强度的显著性影响依次是柠檬酸三丁酯甘油吐温-20。经过验证,制备活性膜时,柠檬酸三丁酯、甘油、吐温-20的最佳质量浓度分别为0.9,0.3,0.1 g/mL,该条件下膜的抗拉强度为20.9 MPa,断裂伸长率为41.34%。结论该工艺条件下所制备的活性膜感官性能、物理性能和疏水性能均良好。     

SiO_2-PWA/PVDF杂化阳离子交换膜的制备及性能研究

膜法钴电积工艺中使用的阳离子交换膜需要有很高的氯离子阻挡性能和耐酸、耐氧化性能,针对这一问题,采用共混热压法制备出了二氧化硅固定磷钨酸的聚偏氟乙烯(SiO2-PWA/PVDF)杂化阳离子交换膜.以电解时膜的氯离子泄漏率为评价指标,研究了膜的氯离子阻挡性能和耐酸、耐氧化性能,并使用SEM,FTIR对膜的微观形貌和功能基团进行表征.结果表明,在TEOS与PWA的摩尔比为5∶1,SiO2-PWA添加质量分数为20%,热压温度为180℃的条件下,制备出的杂化阳离子交换膜性能最佳,氯离子泄漏率为7.5%,耐酸、耐氧化性能相对较好,具有应用于膜法钴电积工艺的潜力.     

PVA/SiO_2/TiO_2杂化纤维的制备与表征

采用溶胶-凝胶法以正硅酸乙酯(TEOS)和钛酸四丁酯(TBOT)为原料制备了SiO2/TiO2溶胶,并与PVA进行杂化,得到PVA/SiO2/TiO2杂化溶胶,陈化后用拉丝法制得PVA/SiO2/TiO2杂化纤维。研究了PVA和TBOT对杂化溶胶的黏度变化与成纤性能的影响,并对杂化纤维的性能进行了测试。用FT-IR、EDS、XRD和TG对制得的纤维进行了表征。结果表明,PVA有利于改善杂化溶胶的成纤性能,随钛含量增加杂化溶胶的黏度变化速度加快;杂化纤维中各组分分布较为均匀,通过杂化限制了PVA的结晶并改善了PVA的耐热性能。     

聚酰亚胺/SiO_2杂化膜的微观结构与力学性能

以聚酰亚胺(HQDDA-0DA)为基体,正硅酸乙酯(TEOS)为增强剂,在共溶DMF中,通过溶胶-凝胶法,制备出厚度约为20μm,不同含量SiO2的PI/SiO2杂化膜,用Fr-IR、SEM及万能拉力实验机对膜材料的微观结构和力学性能表征.结果表明,杂化膜中Si-OH和PI存在化学键;10%SiO2含量的杂化膜SiO2颗粒呈卵形镶嵌在PI基体中,取向与膜平行,随着SiO2含量的增加,颗粒尺寸增大,30%SiO2含量的杂化膜中,无机相形成部分的连续结构,并出现团聚;10%SiO2含量的杂化膜强度和模量均为最大,随着SiO2含量的进一步增加的膜的强度与模量均下降.     

自组装的壳聚糖/SiO2杂化膜

以硅溶胶为晶种,使硅酸钠在壳聚糖膜中自组装形成SiO2微粒和晶须,并得到壳聚糖/SiO2杂化膜(以下简称杂化膜).用电子扫描电镜观察了SiO2微粒和晶须的形貌,研究杂化膜在水中的溶胀率,杂化膜的拉伸强度、伸长率和弹性模量等力学性能,杂化膜的热稳定性能.结果表明:杂化膜内SiO2为长3.0～6.0 μm,宽150m的晶须,以及直径为3.0μm的微粒;当膜内SiO2质量分数为7.5%时,杂化膜的力学性能达到最佳,其拉伸强度、弹性模量和断裂伸长率分别为38.39MPa、2383.02MPa、19.82%;随着杂化膜内SiO2质量分数从2.5%增加到12.5%,其溶胀率从112.0%下降到83.7%;杂化膜在200～800 nm波长范围的吸光度也逐渐降低;杂化膜的分解温度为314℃,高于单纯壳聚糖膜的分解温度290℃,表明SiO2晶须与壳聚糖杂化可提高壳聚糖膜的热稳定性.     

基于热湿综合性能的棕榈醇-棕榈酸-月桂酸/SiO_2复合材料制备方案的响应面法优化

采用溶胶-凝胶法制备棕榈醇-棕榈酸-月桂酸/SiO_2复合材料。利用响应面法研究了无水乙醇用量、去离子水用量以及棕榈醇-棕榈酸-月桂酸用量对棕榈醇-棕榈酸-月桂酸/SiO_2复合材料热湿综合性能的影响,并对棕榈醇-棕榈酸-月桂酸/SiO_2复合材料的制备工艺参数进行了优化。结果表明,各因素对性能影响的主次顺序为:无水乙醇用量棕榈醇-棕榈酸-月桂酸用量去离子水用量;在本研究的各参数范围内,优化方案是无水乙醇用量(与正硅酸乙酯的物质的量比)为9.11、去离子水用量为5.21、棕榈醇-棕榈酸-月桂酸用量为0.52。优化棕榈醇-棕榈酸-月桂酸/SiO_2复合材料具有良好的热湿综合性能,即相对湿度50%时,平均平衡含湿量为0.102 0g/g,相变温度为26.81~28.52℃,相变焓为95.69J/g,属于微米级有机相变芯材/无机基体复合材料。     

Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology

We have optimized fabrication conditions of MgB₂/Fe superconducting monofilament tapes fabricated using ex-situ powder-in-tube method without any intermediate annealing. Influences of three effective parameters (annealing temperature, annealing time and argon (Ar) gas atmosphere pressure during the heat treatments) on the transport critical current densities (J_c) were investigated. The samples were characterized using X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrometer, optical microscope, critical transition temperature and J_c measurements. Response surface methodology was used to optimize the conditions for the maximum J_c of the samples and to understand the significance and interaction of the factors affecting J_c. 3-level-3-factor central composite design was employed to evaluate the effects of the fabrication conditions parameters such as annealing temperatures (850–950?°C), annealing times (30–120?min.) and Ar pressures (1–5 bars) on J_c of the samples. Based on the analysis of ridge max, the optimum fabrication conditions were as follows: annealing temperature 948?°C, annealing time 58?min. and Ar pressure 3 bars.     

响应面优化法研究蔗糖苯酚树脂胶粘剂的合成

以蔗糖代替甲醛,在碱性条件下合成了一种环保型蔗糖苯酚树脂胶粘剂.用响应面优化法对蔗糖苯酚树脂的合成条件进行了优化,以树脂黏度作为考察指标,根据中心复合的设计原理对实验进行设计并对结果进行分析.研究了温度、时间、糖酚比和催化剂用量对反应的影响,得到最佳工艺条件为:反应温度95.63℃,反应时间5.26h,糖酚比2.6,催...     

Optimization of enzymatic hydrolysis of wool fibers for nanoparticles production using response surface methodology

Optimization of enzymatic hydrolysis of wool fiber was carried out using a Central Composite Design (CCD) in order to produce wool nanoparticles. The effects of three important determinants, i.e. enzyme loading, substrate concentration and hydrolysis time on enzymatic efficiency were investigated. Polynomial regression model was fitted to the experimental data to generate predicted response such as particle size. The results were subjected to analysis of variance (ANOVA) to determine significant parameters used for optimization. Wool nanoparticles was produced under the attained optimal condition (enzyme loading: 3.3%, substrate concentration: 5 g/l and hydrolysis time: 214 h), followed by ultrasonic treatment. SEM micrographs indicated wool fiber degradation in which the outer cuticle layer was removed and the inner cortical cells were isolated. The results of particle size analysis indicated the positive effect of sonication on reducing particles size further. FTIR spectra denoted no evident changes in the composition of the chemical groups in the macromolecular structure of wool fiber. Besides, the enzymatic hydrolysis and ultrasonic treatment led to an increase in crystallinity, solubility in caustic solution and thermal stability of wool nanoparticles, but caused a decrease in moisture regain comparing to the raw wool fiber.     

Optimization of gas tungsten arc welding process by response surface methodology

Gas tungsten arc welding is widely used for connecting of boiler parts made of A516-Gr70 carbon steel. In this study important process parameters namely current, welding speed and shielding gas flow rate were optimized using response surface methodology (RSM). The simultaneous effects of these parameters on tensile strength and hardness were also evaluated. Applying RSM, simultaneous effects of welding parameters on tensile strength and hardness were obtained through two separate equations. Moreover, optimized values of welding process parameters to achieve desired mechanical properties were evaluated. Desired tensile strength and hardness were achieved at optimum current of 130 A, welding speed of 9.4 cm/min and gas flow rate of 15.1 l/min.     

聚醚砜对PES/SiO2杂化膜性能的影响

在PES/SiO2体系中添加PEG,采用相转化法制备了PES杂化膜,测定了PES杂化体系铸膜液的热力学相图、成膜动力学及膜性能.结果表明:与纯PES体系相比,PES/SiO2及在PES/SiO2中添加亲水性的PEG后,PES铸膜液杂化体系的分相曲线均不同程度的向聚合物/溶剂轴移动,分相时所需的凝固浴用量较少,PES体系的成膜速度有所提高.膜断面的SEM照片表明,PES/SiO2/PEG杂化膜具有更大的指状孔及表面微孔.该系列PES杂化膜的水通量和截留率均有不同程度的提高.     

Optimization of A-TIG process parameters using response surface methodology

In the present work, the influence of process parameters such as welding current (I), welding speed (S), and flux coating density (F) on different aspects of weld bead geometry for example depth of penetration (DOP), bead width (BW), depth to width ratio (D/W), and weld fusion zone area (WA) were investigated by using the central composite design (CCD). 9–12% Cr ferritic stainless steel (FSS) plates were welded using A-TIG welding. It was observed that all input variables have a direct influence on the DOP, BW, and D/W. However, flux coating density has no significant effect on WA. Mathematical models were generated from the obtained responses to predict the weld bead geometry. An optimized DOP, BW, D/W, and WA of 6.95?mm, 8.76?mm, 0.80, and 41.99?mm², respectively, were predicted at the welding current of 213.78 A, the welding speed of 96.22?mm/min, and the flux coating density of 1.99?mg/cm². Conformity test was done to check the practicability of the developed models. The conformity test results were in good agreement with the predicted values. Arc constriction and reversal in Marangoni convection were considered as major mechanisms for the deep and narrow weld bead during A-TIG welding.     

Optimization of electrochemical treatment of industrial paint wastewater with response surface methodology

The electrochemical oxidation of water-based paint wastewater was investigated batch-wise in the presence of NaCl electrolyte with carbon electrodes for the first time in literature. The electrochemical treatment conditions were optimized using response surface methodology where potential difference, reaction temperature and electrolyte concentration were to be minimized while chemical oxygen demand (COD), color and turbidity removal percents and initial COD removal rate were maximized at 100% pollution load. The optimum conditions were satisfied at 35 g/L external electrolyte concentration, 30 degrees C reaction temperature and 8 V potential difference (64.37 mA/cm(2) current density) realizing 51.8% COD and complete color and turbidity removals, and 3010.74 mg/Lh initial COD removal rate. According to these results, the electrochemical method could be a strong alterative to conventional physicochemical methods for the treatment of water-based paint wastewater.