耐盐高吸水树脂P(AMPS/AM/MA)合成和评价

以N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂、过硫酸氨(APS)为引发剂,采用丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和马来酸(MA)为单体,在水溶液中合成AMPS-MA-AM三元共聚物。探讨单体比例、温度和反应时间等对共聚物的吸水性能的影响;结果表明:聚2-丙烯酰胺基-2-甲基丙磺酸/马来酸/丙烯酰胺P(AMPS/MA/AM)具有优良的吸水、耐盐性能;在去离子水、生理盐水中吸水倍率可以达到358、135g/g。     

香豆素标记AA-AMPS共聚物的制备与性能

以3-氨基酚和乙酰乙酸乙酯为原料,合成一种新型香豆素荧光单体N-(4-甲基-1,2-苯并吡喃酮-7-基)丙烯酰胺(FM)。采用自由基溶液共聚合法,将FM、丙烯酸(AA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)共聚得到新型荧光示踪型共聚物FM-AA-AMPS。通过红外光谱和热重分析对共聚物进行了分析和表征。FM-AA-AMPS的荧光性质和阻垢性能研究结果表明,其荧光强度与质量浓度呈良好线性关系,线性相关系数为0.98783,检测下限为1.0×10-2mg/L;采用静态法,当用药剂量为20 mg/L时,对碳酸钙阻垢率可达86.9%,且具有优良的分散氧化铁性能;扫描电镜和X射线衍射分析表明,共聚物能很好地抑制碳酸钙垢的生长,所形成的是方解石、球霰石和文石的混合物。     

离子液体中的AM/AMPS/ST三元共聚反应

采用1-丁基-3-甲基咪唑氟硼酸盐([bmim]BF4)离子液体作为聚合反应介质,以过氧化苯甲酰(BPO)/N,N-二甲基苯胺(DMA)为引发剂,以丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为亲水单体,苯乙烯(ST)为疏水单体,合成了AM/AMPS/ST三元共聚物。考察了反应温度、时间、引发剂用量、单体的摩尔比对聚合反应的影响。用IR谱和1H-NMR1、3C-NMR谱表征了共聚物结构。测定了共聚物水溶液的表观黏度,表明其有良好的耐温性和抗剪切性。     

AMPS/AA/MA/St共聚吸附剂的合成及性能研究

在交联剂N,N′-亚甲基双丙烯酰胺(NMBA)的作用下,单体2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)、顺丁烯二酸酐(MA)和淀粉(St)以溶液热聚合的方式合成四元共聚吸附剂。采用单因素法探究了反应条件对树脂吸附亚甲基蓝染料性能的影响,得到最佳的树脂合成工艺条件。实验结果表明:n(AMPS)∶n(AA)∶n(MA)∶W(St)=1∶0.5∶0.1∶1.98(wt,质量分数,下同),pH=2,W(NMBA)=0.1%,固含量为31%时,该树脂的吸附量最大,为106.35mg/g。     

四元表面活性聚合物的制备与性能

制备了表面活性单体甲基丙烯酸二甲氨基乙酯-十六烷基溴(DMHB),进一步以DMHB、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(APMS)和甲氧基聚乙二醇丙烯酸酯(MPEGA)为原料,在偶氮/氧化还原双引发剂作用下合成了具有表面活性的AM/DMHB/AMPS/MPEGA四元共聚物。采用红外光谱和核磁共振氢谱对AM/DMHB/AMPS/MPEGA进行了表征,证明了四元聚合物的成功合成。对AM/DMHB/AMPS/MPEGA的合成条件进行单因素优化,并进行了抗温性、耐盐性和驱油实验等性能测试。结果表明,AM/DMHB/AMPS/MPEGA最佳合成条件为反应温度45℃、总单体浓度35%、DMHB浓度4%、AMPS浓度0.4%、MPEGA浓度15%、AM/DMHB/AMPS/MPEGA比相对分子质量为1420万的HPAM具有更好的抗温性、耐盐性、抗老化性和提高采收率能力,为油田提高采收率提供了新的研究方向。     

紫外辐射法制备AM/MA/AMPS/KF四元共聚吸附树脂及性能研究

以N,N,-亚甲基双丙烯酰胺(NMBA)为交联剂,在无氮气保护和不添加任何引发剂条件下,采用紫外辐照法合成魔芋粉(KF)/丙烯酰胺(AM)/马来酸酐(MA)/2-丙烯酰胺基-2-甲基丙磺酸(AMPS)共聚吸附树脂,研究了单体摩尔比、pH、交联剂用量、魔芋粉含量对树脂吸附亚甲基蓝的影响,并借助FT-IR、TG对树脂的结构、热稳定性进行了研究。实验表明:在优化条件下,n(AMPS)∶n(AM)∶n(MA)=2.5∶0.5∶0.4;w(KF)=2.5%,pH=3,w(NMBA)=0.35%,tcuring=5min时合成的树脂对亚甲基蓝的吸附量为104.14mg/g。     

静置法合成AMPS/AA/AM/MA四元共聚高吸水树脂

以N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,在没有引发剂和氮气保护的情况下,利用静置法制备以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)、丙烯酰胺(AM)、顺丁烯二酸酐(MA)为单体的四元共聚高吸水树脂,通过对反应条件优化,得到了最佳工艺条件:单体配比n(AMPS)∶n(AA)∶n(AM)∶n(MA)=1∶1∶1∶1,ω(NMBA)=0.03%,pH=2.2,在此条件下树脂吸蒸馏水倍率达到533倍。初步对树脂的吸液能力、耐热保水性、吸水速率、以及反复吸液性进行了研究,同时借助FT-IR、TG-DTG和显微镜对其结构、热稳定性及表面形态进行了表征。     

GG/AM/AMPS高吸水性树脂的合成及其性能分析

在没有任何保护气的环境下,用瓜尔胶(GG)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为反应原料,N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)为引发剂,使用水溶液热聚合法合成GG/AM/AMPS高吸水性树脂。采用正交实验法研究了反应条件对树脂吸水率的影响,在最优条件下对树脂的性能进行探究,并对其结构进行表征分析。实验结果表明,当单体摩尔比为n(AM)∶n(AMPS)=1∶1,pH=8,ω(NMBA)=0.08%,ω(KPS)=0.5%,ω(GG)=3.6%时,合成GG/AM/AMPS高吸水性树脂的吸水率达2752g/g。     

IA/AA/AMPS水煤浆分散剂的制备与表征

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)-丙烯酸(AA)-衣康酸(IA)三元共聚物为水煤浆分散剂,通过对水煤浆液体流变性能的研究得到了分散剂的最佳合成条件:单体配比为m(AMPS)∶m(AA)∶m(IA)=3.8∶1∶1,反应温度为85℃,引发剂的添加量为单体总质量的5%,次亚磷酸钠的最佳添加量为单体总质量的10%;并通过FT-IR、XRD、GPC等对聚合物分散剂的结构、分子量进行测定。结果表明,共聚物中成功引入了磺酸基和羧酸基,重均相对分子质量约为1.6×104,多分散系数为3.41。     

紫外光固化法合成St/AMPS/AM三元共聚高吸水性树脂

采用紫外固化法,以淀粉(St)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酰胺(AM)为单体,N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,在不加引发剂和任何气氛保护下,合成出St/AMPS/AM/共聚高吸水性树脂,考察了反应条件对树脂吸水倍率的影响,并借助红外、偏光显微镜对树脂的分子结构及表面形态进行了表征。结果表明,在优化条件下合成的高吸水性树脂吸蒸馏水倍率为2354g/g,吸盐率可达145g/g(0.1mol/L)。     

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.     

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.     

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 $\text{0.10 ?}\text{x}\text{? 0.14}$.     

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.     

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.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.