戊二醛改性壳聚糖/ 纳米TiO2 复合膜的抗水性研究

采用戊二醛作为交联剂与壳聚糖进行交联,以提高壳聚糖/ 纳米TiO2 膜的抗水性。采用三元二次通用旋转组合设计实验方法,建立了力学性能、吸水率与戊二醛用量、交联时间、TiO2 溶胶添加量的二次回归数学模型,得出了制备戊二醛改性壳聚糖/ 纳米TiO2 膜的最佳工艺条件为交联剂用量0. 10 g/ (100 mL)乙酸溶液,交联时间4. 37 h,TiO2 溶胶添加量0. 08 mL/ (100 mL)的乙酸溶液。上述条件下得到的膜的拉伸强度为5. 69MPa,吸水率为133. 66%。与壳聚糖/ 纳米TiO2 膜相比,吸水率下降了72. 8%。     

低红外发射率TiO2/AgxCU1-x/Ti/TiO2纳米多层膜

利用磁控溅射制备了银含量在100％至80％之间的单层银铜合金薄膜和TiO2／AgxCu-1x／Ti／TiO2：纳米四层膜。利用x射线衍射、扫描电子显微镜、扫描俄歇微探针，分光光度计、红外发射率测量仪对样品进行表征，研究了单层金属膜和多层膜的光学、电学性质随着银含量的变化以及热处理前后薄膜性能的变化。结果表明：相同厚度的合金膜，随着Ag含量的降低，导电性能下降，Ag含量低于80％的合金已不适合作为多层膜的金属层；1500C大气下热处理30min，纯银薄膜性质发生明显变化，明视透过率下降10％，方块电阻由2．5W／口增加至18W／□，红外发射率由0．17增加到0．69。AgCu合金薄膜性质未发生明显变化。方块电阻相近的TiO2／AgxCu1-x／Ti／TiO2纳米多层膜，经250℃大气下热处理40min后，TiO2／Ag／Ti／TiO2和TiO2／Ag80Cu20／Ti／TiO2纳米多层膜的性质变化较小，热稳定性较好，其余的多层膜性质发生较大变化，红外发射率显著增加。     

胶原-壳聚糖二元膜材料的制备与性能表征

通过热脱氢交联（DHT）、戊二醛改性以及碳化二亚胺改性（EDC）等方法对胶原基膜材料进行改性，探讨其作为生物医用材料较为理想的改性方法。以胶原及壳聚糖为主要原料制备大孔径高孔率二元膜材料，通过单一或复合改性以后比较二元膜材料的各项性能。适当的DHT改性后获得的二元膜孔径为20～100μm，孔率90％左右，但膜材料机械性能较差，抗酶解能力提高不明显；0．02％的戊二醛．EDC复合改性交联程度较为合适，DHT改性可以一定程度减少戊二醛用量；DHT-EDC复合改性得到的二元膜孔径20～200μm，孔率95％左右，机械强度和耐酶稳定性较高，吸水率高且在水中不溶胀。DHT-EDC复合改性是较为理想的胶原基膜材料作为生物医用材料的改性方法。     

不同交联方式的明胶及明胶/蒙脱土纳米复合材料的力学性能

研究了戊二醛(GLA)蒸汽交联、溶液交联以及葡糖二醛溶液交联对明胶及明胶／蒙脱土(MMT)纳米复合材料力学性能的影响，并利用扫描电子显微镜(SEM)对材料的拉伸断口进行了观察。结果表明，与溶液交联相比，明胶蒸汽交联样品的交联度较大。溶液交联时，戊二醛比葡糖二醛交联效率高，相同浓度下试样的力学性能较好。明胶／MMT纳米复合材料无法通过GLA溶液交联方式制样，由于MMT片层的阻隔性，使蒸汽交联需要更长的时间才可达到一定的交联度。与MMT插层复合可大幅度提高明胶材料的力学性能，SEM表明韧性同时得到改善。     

剑麻纤维增强胶原基复合材料

用戊二醛作交联剂对皮革下脚料中提取的胶原水解物进行交联改性,采用溶胀度表征了材料的交联程度。探讨了戊二醛用量、胶原蛋白浓度和丙三醇含量对材料溶胀度的影响,并使用红外光谱对交联产物进行了表征。以改性胶原蛋白为基体、剑麻纤维为增强相,制备了剑麻纤维/胶原蛋白复合材料。用扫描电子显微镜对复合材料的形貌进行了表征,探讨了剑麻纤维的表面处理、纤维含量以及长度对复合材料力学性能的影响。结果表明,对剑麻纤维表面进行碱处理可以改善纤维的表面结构,增加纤维与基体的界面粘结,提高复合材料的力学性能。当剑麻纤维质量分数为15 %、纤维长度为 7～8 mm时,复合材料具有较好的力学性能。该复合材料可望在包装垫隔材料方面得以应用。      

聚酰亚胺/TiO2有机-无机纳米复合膜材料的合成与表征

以钛酸丁酯作前驱物，NMP为共溶剂，在可溶性聚酰亚胺PI(HQDPA．DMMDA)中通过溶胶．凝胶法制备出高TiO2含量的PI／TiO2有机-无机纳米复合膜材料。TiO2的实际含量高达35．5％时仍能成膜，低于27．2％时为透明浅黄色纳米复合膜。并通过XPS、WAXD、TG、DSC等手段对复合材料的结构和性能进行了表征。结果表明，在TiO2含量为27．2％时，PI／TiO2复合材料中TiO2的平均颗粒尺寸为35nm左右；热分解温度和玻璃化转变温度明显升高；复合材料力学性能良好。     

聚丙烯酸酯/纳米TiO2复合材料的制备与性能

通过无皂-原位乳液聚合法,以甲基丙烯酸甲酯、丙烯酸丁酯为原料,采用反应性乳化剂1-烯丙氧基-3-(4-壬基苯酚)-2-丙醇聚氧乙烯醚硫酸铵(DNS-86)制备聚丙烯酸酯/纳米TiO2复合材料。采用红外光谱(FT-IR)、动态激光光散射(DLS)、透射电镜(TEM)等检测手段对复合材料的结构进行了表征,通过力学性能、耐水性测试研究了纳米TiO2对复合材料性能的影响。FT-IR测试结果表明纳米TiO2与聚合物发生了相互作用,有少量的TiO2被接枝到聚合物分子中。DLS测试结果表明与纯聚丙烯酸酯相比,聚丙烯酸酯/纳米TiO2复合乳液乳胶粒的平均粒径和粒径分布都有所降低。TEM测试结果表明纳米TiO2分布在聚合物基体中。复合材料的性能测试结果表明,当纳米TiO2的加入量为0.5%时,聚丙烯酸酯/纳米TiO2复合材料的综合力学性能较好;纳米TiO2的加入可提高复合材料的耐水性。     

改性石蜡制备及低红外发射率研究

采用丙烯酸接枝石蜡与苯胺酰胺化的方法制备改性石蜡,以此为黏合剂,Al粉为填料,制备出发射率可调的复合相变材料,并对复合相变材料的结构、热性能、控温效果和红外发射率进行了表征。结果表明,改性石蜡的相变温度提高了16.3%,相变潜热提高近60%,控温效果提高了39.3%,添加40%Al粉的复合相变材料的红外发射率可降至最低。     

硅烷偶联剂对纳米二氧化钛表面改性的研究

利用硅烷偶联剂（KH-570）对表面包覆氧化硅的金红石相纳米TiO2进行了有机表面改性．采用红外光谱（IR）、X射线光电子能谱（XPS）、热分析（TG-DTA）、透射电镜（TEM）和润湿性实验等分析手段对表面改性前后的纳米TiO2进行了表征．红外光谱和X射线光电子能谱表明，KH-570以化学键合的方式结合在纳米TiO2的表面，并形成了有机包覆层．经测量，纳米TiO2表面包覆的KH-570的质量分数约为7．42％-8．59％．润湿性实验显示，经KH-570表面改性的纳米TiO2具有疏水性．力学性能实验表明，经KH-570表面改性的纳米TiO2能同时提高复合材料的强度和韧性．     

纳米TiO_2的表面改性及MF/纳米TiO_2复合树脂的制备

采用硅烷偶联剂KH550对纳米TiO2进行表面改性,将改性纳米TiO2与三聚氰胺甲醛树脂(MF)混合,制备MF/纳米TiO2复合树脂。红外分析表明偶联剂成功接枝于纳米TiO2表面;热失重分析得出表面改性的最佳工艺为:改性剂的添加量2%,改性温度70℃,改性时间120min;透射电镜分析表明纳米TiO2的表面改性提高了其在有机溶剂中的分散性;研究TiO2添加量对MF/纳米TiO2复合树脂的粘度、固化时间、固化温度和抗菌性的影响,结果表明TiO2的添加对树脂固化时间和固化温度影响很小,但能显著提高材料的粘度和抗菌性能。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.