FP-g-P(AA-co-AM)高吸水树脂的制备

研究了鱼蛋白(FP)接枝聚合丙烯酸(AA)和丙烯酰胺(AM)制备蛋白改性高吸水性树脂的方法.通过对产品吸(盐)水性能的测试,得到合成产品的合适条件为:鱼蛋白、引发剂和交联剂相对单体的量分别约为7.5%、1.0%和0.025%,丙烯酸与丙烯酰胺的质量比为9:1,丙烯酸中和度为90%,单体质量分数为18%.在此条件下制备的高吸水性树脂,其吸水倍率达1061g/g,吸盐水倍率达136g/g.并用红外光谱对产物进行了表征.     

利用竹屑制备可降解纤维素基高吸水树脂

竹屑(BS)经过H_2O_2/H_2SO_4体系预处理得到改性竹屑(MBS),以丙烯酸(AA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,添加聚乙烯醇(PVA),通过水溶液聚合法制备出MBS-Co-P(AA-AMPS)/PVA半互穿高吸水树脂。探究反应物配比对树脂吸液性能的影响,得到较优的聚合条件为m(MBS):m(AA):m(AMPS):m(PVA):m(KPS):m(MBA)=1.5:6:3:0.1:0.033:0.012,AA中和度65%,此条件下制得树脂的吸去离子水倍率为1870 g/g,吸生理盐水倍率为92 g/g。利用红外光谱、扫描电镜、X射线衍射和热重分析对树脂的形态结构进行了表征;并考察了树脂的溶胀动力学、pH敏感性和自然降解率。结果表明,树脂在去离子水中的溶胀过程符合二级动力学模型,对外界pH刺激具有敏感性,45 d自然降解率为28%。     

高吸水尿素-聚乙烯醇-丙烯酸树脂的合成及性能研究

通过水溶液聚合法,采用尿素、丙烯酸、聚乙烯醇为原料,过硫酸钾为引发剂、N,N-亚甲基双丙烯酰胺为交联剂合成高吸水尿素-聚乙烯醇-丙烯酸树脂。从吸液率、吸液速率、保水率等几方面对合成树脂进行了性能测定。研究通过单因素试验设计考察了影响树脂吸液率的因素,并得到了最佳条件:尿素质量用量0.8%,丙烯酸与聚乙烯醇质量比90/10,引发剂用量0.5%,交联剂用量0.04%,丙烯酸中和度70%,水用量300mL。在最佳合成条件下合成树脂的吸水倍率可达1635g/g、合成树脂的吸盐水倍率可达161g/g。通过红外光谱分析对产物结构进行了表征。     

淀粉基接枝丙烯酸钠复合高吸水树脂材料的制备及性能测试

以丙烯酸和可溶性淀粉为主要原料,过硫酸铵为引发剂,N-N'-亚甲基双丙烯酰胺为交联剂,丙烯酰胺为单体,采用水溶液聚合法合成高吸水树脂(SAR).通过设计L25(55)正交试验,确定SAR制备条件,并分别添加适量高岭土、蒙脱土、锂皂石制备复合高吸水性树脂.利用FT-lR和SEM-EDS、TG等对复合高吸水性树脂进行表征.考察复合高吸水性树脂的吸液性能与保水性.SAR实验条件为:丙烯酰胺与淀粉质量比5:4、合成温度45℃、引发剂0.13 g、交联剂0.01 g、氢氧化钠9 g.结果表明:此条件下的SAR吸水倍率最大为179.5 g/g,吸盐倍率为70.75 g/g.FT-lR和SEM-EDS结果显示树脂已成功制备.无机物高岭土、蒙脱土、锂皂石的加入提高了SAR的吸液性能及热稳定性,其中含高岭土SAR的吸水倍率和吸盐倍率均达到最大,吸水倍率为245.0 g/g,吸盐倍率为83.3 g/g.     

有机/无机复合高吸水树脂耐盐性和防潮性能研究

以过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,丙烯酸、2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,聚乙烯醇为有机合成聚合物,硅藻土为无机黏土,采用水溶液聚合法合成有机/无机复合高吸水树脂。采用傅里叶变换红外光谱仪、扫描电子显微镜和热重分析仪对有机/无机复合高吸水树脂进行了表征,考察了引发剂用量、交联剂用量、AMPS用量及硅藻土用量对复合吸水树脂吸液性能的影响。在最佳反应条件下,有机/无机复合高吸水树脂吸蒸馏水倍率、吸0.9%生理盐水倍率分别为1574g/g和101g/g;纯有机高吸水树脂暴露在空气中的吸湿性是复合高吸水树脂的20～30倍,说明有机/无机复合高吸水树脂具有优异的防潮性能,在不同阳离子盐溶液中(Na~+、Ca~(2+)和Fe~(3+))其吸液性能明显优于纯有机高吸水树脂。     

鱼蛋白接枝聚合丙烯酸高吸水树脂的制备

用溶液聚合法制备了鱼蛋白基丙烯酸(FP-g-AA)高吸水性树脂。采用单因素法改变组分配比分别进行合成试验。并通过对产品的吸(盐)水性能的测试,优化合成配方及用红外光谱仪对产物进行表征。结果表明,当过硫酸钾、N,N′-亚甲基双丙烯酰胺、鱼蛋白用量分别为丙烯酸的1.0%、0.07%、10.0%,丙烯酸的中和度和在溶液中的质量分数分别为80%和18%时,该高吸水性树脂的吸水倍率达981g/g,吸生理盐水(0.9%NaCl)倍率达127g/g。红外光谱也显示,产品为鱼蛋白接枝聚合丙烯酸树脂。     

PVA/CTS/P(AA-AMPS)互穿网络结构高吸水树脂耐盐性和防潮性能研究

以过硫酸钾(KPS)为引发剂,N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,丙烯酸(AA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,壳聚糖(CTS)为天然聚合物,聚乙烯醇(PVA)为合成聚合物,采用水溶液聚合法合成了互穿网络结构高吸水性树脂[PVA/CTS/P(AA-AMPS)],并对其进行了表征。考察了引发剂用量、交联剂用量、CTS用量和PVA用量对树脂吸液性能的影响。在最佳反应条件下,PVA/CTS/P(AA-AMPS对蒸馏水和0.9%(wt,质量分数)的氯化钠溶液的吸附量分别为1800g/g和110g/g。暴露在空气中8d条件下的吸湿性低于单层网络的87.5%,在不同阳离子盐溶液中(Na~+、Ca~(2+)和Fe~(3+))的吸液性能也明显优于单层网络。     

机械活化淀粉接枝丙烯酸高吸水树脂的制备与性能研究

以机械活化木薯淀粉、丙烯酸为主要原料,过硫酸铵为引发剂,采用反相乳液聚合法制备了机械活化淀粉接枝丙烯酸高吸水树脂,考察了引发剂用量、交联剂用量、丙烯酸(AA)中和度和单体淀粉质量比等因素对吸液性能的影响。结果表明:制备机械活化淀粉接枝丙烯酸高吸水树脂的最适宜工艺条件为引发剂用量为0.6%,交联剂用量为0.12%,丙烯酸中和度为80%,单体淀粉质量比为10∶1。在此条件下,树脂吸去离子水倍率为930.67g/g,吸生理盐水倍率为90.57g/g。对产物进行红外分析的结果表明活化木薯淀粉与丙烯酸发生了接枝共聚反应。     

新型两步水溶液聚合法制备PAA/PAMPS复合材料及其吸液性能研究

以N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂、过硫酸铵-焦亚硫酸钠氧化-还原体系为引发剂,采用新型水溶液聚合法制备了PAA/PAMPS水凝胶.考察了单体浓度、丙烯酸中和度时凝胶吸液性能的影响,并与传统共混水溶液聚合法制备的凝胶的吸液性能进行了对比.实验结果表明,AMPS用量为40%、中和度为75%的水凝胶的吸液性能较好,吸水倍率达976g/g,吸盐水倍率为75g/g,而采用传统方法制备的凝胶的吸水倍率为380g/g,吸盐水倍率为52g/g.采用FTIR及SEM对样品的结构及形貌进行了表征.     

聚丙烯酰胺/丙烯酸钾互穿网络多孔水凝胶的制备和性能

以丙烯酸、丙烯酰胺为单体,过硫酸钾为引发剂,N,N′-亚甲基双丙烯酰胺为交联剂,利用水溶液聚合法和乙醇致孔法制备了聚丙烯酰胺/丙烯酸钾互穿网络多孔水凝胶.采用红外光谱(FTIR)和扫描电镜(SEM)等分析技术对水凝胶进行了表征,研究了水凝胶的溶胀行为和吸0.9％NaCl(质量分数,下同)盐水的能力.实验结果表明,该多孔水凝胶具有较快的吸水速率,其最高吸水倍率可达3600g/g,吸0.9％NaCl盐水倍率最大可达120g/g,凝胶粉末能在8min内达到溶胀平衡.     

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.     

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.     

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.     

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.     

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.     

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.     

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.