γ-BL/TEP混合溶剂对PVDF膜结构和性能的影响

通过溶解度参数预测,膜渗透性能检测,及扫描电镜(SEM)对膜形貌观察,考察了聚偏氟乙烯(PVDF)在γ-丁内酯(γ-BL)、磷酸三乙酯(TEP)为混合溶剂,乙二醇(EG)、N,N-二甲基乙酰胺(DMAc)及其混合物为凝固浴时,相转化条件及溶剂配比对PVDF膜在孔隙率、纯水通量、BSA截留率,以及拉伸强度等性能方面的影响行为。结果表明,随混合溶剂中TEP质量分数的增加,凝胶浴中溶剂DMAc质量分数增大,PVDF膜皮层逐渐变薄,PVDF结晶球粒粒径变小,孔隙率增加,拉伸强度下降。当混合溶剂中TEP的质量分数为60%,凝胶浴DMAc含量30%时,膜纯水通量达2 100 L/(m2·h),BSA截留率仍保持58.7%,具有良好的超滤性能,可作为制备高通量、较高截留PVDF超滤膜的最佳条件。     

新型聚芳醚腈酮中空纤维超滤膜的研究

以含二氮杂萘酮结构聚芳醚腈酮(PPENK)为膜材料,N-甲基-2-吡咯烷酮(NMP)为溶剂,采用干-湿相转化法制备了中空纤维超滤膜.考察了聚合物浓度、添加剂含量以及纺丝过程中空气间隙、凝胶浴温度和纤维壁厚对膜结构及性能的影响.结果表明,当聚合物浓度为13%,添加剂EgOH含量α=0.9时,膜通量可达770 L·m-2·h-1,对BSA的截留率在90%以上;增大空气间隙可使膜的截留性能提高,但膜通量有所下降,最佳空气间隙为5～8cm;凝胶浴温度的升高增大了膜的通量,截留率下降幅度不大,凝胶浴温度宜控制在21～25℃范围内;纤维壁厚在0.15～0.18 mm时膜性能最佳.     

凝固浴组成对SMA/CPVC共混超滤膜的结构与性能影响

通过非溶剂致相分离（NIPS）法制备了苯乙烯-马来酸酐共聚物（SMA）/氯化聚氯乙烯（CPVC）共混超滤膜,探讨了凝固浴中不同溶剂（DMAc）含量对其超滤膜表面酸酐基团偏析程度、微观结构、亲水性、水通量、截留率和抗污染的影响。结果表明：凝固浴中溶剂含量的增加抑制了酸酐基团向膜表面的偏析,导致亲水性减弱;同时,铸膜液中溶剂与水分子之间扩散速率的变小引起延迟分相,使得膜表面孔径变小和分布变窄。当溶剂质量分数为3%时,超滤膜对牛血清白蛋白（BSA）截留率提升至98.10%、通量恢复率为96.82%,且不可逆污染率降为3.77%,表明凝固浴中适量的溶剂可进一步提高超滤膜抗污染性能。     

DMI增塑二醋酸纤维素超滤膜的制备与性能研究

以绿色环保的1,3-二甲基-2-咪唑啉酮(DMI)为增塑剂,采用复合热致相分离法制备了二醋酸纤维素(CDA)超滤膜。通过扫描电子显微镜(SEM)观察以及纯水通量、牛血清白蛋白(BSA)截留率、孔隙率和拉伸强度等测试,研究了CDA固含量对超滤膜结构和性能的影响。同时,通过综合比较不同固含量CDA膜的纯水通量和蛋白截留率,确定了最佳铸膜液配方。结果表明:提高CDA的固含量可以消除膜截面中的大孔结构,但同时降低了膜的孔隙率。其中,当铸膜液中CDA固含量为20%时,所制备平板膜的拉伸强度高达6.10 MPa,对0.1 g/L BSA水溶液的渗透通量为47.7 L/(m~2·h),截留率达到96.4%。     

杂萘联苯共聚醚砜中空纤维超滤膜的制备

以杂萘联苯共聚醚砜为膜材料、N,N-二甲基乙酰胺为溶剂、乙二醇甲醚(EGME)为添加剂,采用干-湿纺丝工艺制备新型中空纤维非对称超滤膜,考察了EGME含量、干纺程长度以及凝胶浴温度对杂萘联苯共聚醚砜中空纤维膜结构和性能的影响。结果表明,随着EGME含量的增加超滤膜的水通量增大,而对聚乙二醇10000的截留率基本不变,干纺程长度和凝胶浴温度对超滤膜的性能有较大影响,所制备的中空纤维超滤膜对聚乙二醇10000的截留率高于95%,水通量达到258 L/(m2.h)。     

聚偏氟乙烯-溶剂-非溶剂-添加剂体系膜制备及其性能

以聚偏氟乙烯(PVDF)为膜材料,测定了不同温度下PVDF/DMAc、PVDF/DMF和PVDF/NMP溶液的混合参数,得出非溶剂沉淀能力大小为:甘油>DEG>PEG200>PEG400,并与Hansen溶解度的理论计算值进行了比较。此外,讨论了不同PEG400在混合溶剂中的比例以及不同添加剂对膜性能的影响;PEG400的加入,使膜的纯水通量、机械性能均有所提高,截留率保持不变;VAH、Tween80、PEG20000和成核剂使膜的纯水通量提高到100 L/(m2.h)以上,LiCl的加入对通量影响不大。     

聚偏氟乙烯/纳米纤维素复合超滤膜的研究

以聚偏氟乙烯为原材料,聚乙烯吡咯烷酮( PVP K30)为添加剂,并向聚偏氟乙烯铸膜液中混入纳米纤维素,采用相转化工艺制备了复合超滤膜.通过正交试验分析了各因素对产品性能的影响,并得出了制备复合超滤膜的最优条件:聚偏氟乙烯质量分数为14％,添加剂PVP K30质量分数为0.5％,纳米纤维素加入量为0.7％,空气中溶剂蒸发时间为10s,凝胶浴为水.测定复合超滤膜的水通量、截留率、平均孔径、孔隙率、力学强度等一系列性能,膜的水通量为40.7 L/(m2·h),对牛血清蛋白的截留率为91.8％,孔隙率为52.3％,平均孔径为15.3 nm.     

金属-聚乙烯醇-二醋酸纤维素共混复合亲水超滤膜的制备

在大孔径金属纤维毡上制备了金属-聚乙烯醇-二醋酸纤维素(金属-PVA-CA)共混复合超滤膜及金属-NaCl改性PVA-CA共混复合超滤膜。该复合超滤膜在操作压力为0.25-0.45 MPa,处理质量浓度为1000 mg/L的含油乳化液,可获得40-70 L／(m2·h)的透液通量,COD截留在90％以上。研究还表明金属-NaCl改性PVA-CA共混复合超滤膜的综合性能略优于金属-PVA-CA共混复合超滤膜。     

聚砜中空纤维膜的亲水改性研究

将吐温80或磺化聚砜(SPSF)加入聚砜-聚乙二醇400-二甲基乙酰胺(PSF–PEG400–DMAc)体系,共混制成均一铸膜液,采用浸入沉淀相转化法制备聚砜中空纤维超滤膜,考察吐温80或SPSF对聚砜中空纤维膜的亲水改性效果。对膜结构、铸膜液黏度、纯水通量、截留率、拉伸强度等进行了表征。研究结果表明,SPSF相比吐温80对膜的亲水性改善更明显。当SPSF质量分数为1.5%时,就可将PSF中空纤维膜的纯水通量提高一倍以上,膜纯水通量达到302 L/(m~2·h),对牛血清白蛋白(BSA)的截留率达到93%。     

PEO改性PVDF/SMA膜结构和性能

将聚氧化乙烯(PEO)添加到聚偏氟乙烯/苯乙烯马来酸酐树脂(PVDF/SMA)膜体系中,通过非溶剂致相分离法(NIPS)制备了添加不同PEO含量的PVDF/SMA共混膜。其中PEO质量分数为2%的共混超滤膜性能最好,水通量为531.1L/(m²·h),牛血清蛋白(BSA)截留率为65.8%,水接触角为63.6°,膜剥离强度为0.2756kN/m。接着以PVDF/SMA膜为主要研究对象测试了凝固浴温度对共混超滤膜的纯水通量以及BSA截留率的影响,该实验的结果表明凝固浴温度的改变对膜性能没有产生明显的影响。因此,选择在常温凝固浴温度下测试不同凝固浴成分对共混膜性能的影响。探究了膜在凝固浴成分分别为N,N-二甲基乙酰胺(DMAc)(质量分数为3%、6%、9%)、氯化钠(NaCl)(0.05mol/L、0.1mol/L、0.2mol/L)和乙醇(质量分数为3%、6%、9%)时的膜性能变化,以及对各个组分得到的膜样本进行扫描电子显微镜(SEM)表征。结果表明,随着DMAc含量增加,膜表面的孔在减少,且膜皮层的厚度增加,使得膜的水通量减少而BSA截留率提高。而随着NaCl浓度...     

Photopyroelectric Spectroscopic Studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) Ceramics

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.     

Biological Properties of IRIM, the Iridium(III) Analogue of (Imidazolium (Bisimidazole) Tetrachlororuthenate) (ICR)

Some biological aspects of the new complex imidazolium bisimidazole tetrachloro iridate(III)-IRIM- the iridium(III) analogue of ICR, were considered. More in detail the conformational effects produced by IRIM on DNA and the cytotoxic properties of IRIM on some selected human cell lines were measured. Dialysis experiments and DNA thermal denaturation studies are suggestive of poor binding of IRIM to DNA; formation of interstrand crosslinks is not observed. In any case CD measurements suggest that addition of increasing amounts of IRIM to calf thymus DNA results into significant spectral changes, that are diagnostic of a direct interaction with DNA. A number of experiments carried out on the A2780 human ovarian carcinoma, B16 murine melanoma, MCF7 and TS mammary adenocarcinoma tumor cell lines strongly point out that IRIM does not exhibit significant growth inhibition effects within the concentration range 10(-4)-10(-6) M. It is suggested that the lower biological effects of IRIM compared to ICR are a consequence of the larger kinetic inertness of the iridium(III) center with respect to ruthenium(III).     

Thermal studies of blends of poly(phenylene sulfide) (PPS) with poly(phenylene sulfide sulfone) (PPSS) and with poly(phenylene sulfide ether) (PPSE)

The miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures T_g of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control T_g and melting temperature T_m of PPS by varying amounts of PPSE in blends. The melt crystallization temperature T_mc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE. The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ?2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t_1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases.     

Rheological behavior of blends of poly(methyl methacrylate) (PMMA) and poly(acrylonitrile-stat-styrene)-graft-polybutadiene (ABS)

The rheological behavior of blends of poly(methyl methacrylate) (PMMA) and poly(acrylonitrile-stat-styrene)-graft-polybutadiene (ABS) was investigated using a cone-and-plate rheometer. The rheological properties measured were shear stress (σ₁₂), viscosity (η), and first normal stress difference (N₁) as functions of shear rate (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma$ \end{document}) in steady shearing flow, and storage modulus (G′) and loss modulus (G″) as functions of frequency (ω) in oscillatory shearing flow. It has been found that the rheological behavior of blends of ABS and PMMA was very similar to that of blends of poly(styrene-stat-acrylonitrile) (SAN) and PMMA, in that N₁ in logarithmic plots of N₁ versus σ₁₂, and G′ in logarithmic plots of G′ versus G″, vary regularly with blend composition. This has led us to conclude that the rubber particles that are grafted on an SAN resinous matrix in ABS resin plays only a minor role in influencing the compatibility of ABS/PMMA blends, and that the SAN chains attached to the surface of rubber particles, and the SAN matrix phase, play a major role in compatibilizing ABS resin with PMMA.     

以( )-脱氢枞胺为原料合成( )-弥罗松酚

报道了以(+)-脱氢枞胺为起始原料,通过两条路线合成生物活性的二萜化合物(+)-弥罗松酚。路线(1):(+)-脱氢枞胺在羟氨-O-磺酸和氢氧化钠作用下还原脱氨生成脱氢松香烷,再经Friedele-Crafts乙酰化、BaeyerVilliger氧化、水解生成(+)-弥罗松酚,总产率29.5%。路线(2):(+)-脱氢枞胺还原脱氨,然后与过氧化邻苯二甲酰反应得到(+)-弥罗松酚,总产率31.9%。     

Photooxidative stability of substituted poly(phenylene vinylene) (PPV) and poly(phenylene acetylene) (PPA)

The addition of side groups to improve the photooxidative stability of polymers used in polymer-based light-emitting diodes (LEDs) is explored. Infrared spectroscopy and computational chemistry techniques are used to study the effects of chemical substitution of the reactive vinylene moiety in poly(phenylene vinylene) (PPV). The bond order of the vinylene group in small oligomers is calculated using semiempirical techniques to assess the improvement in stability toward oxidants such as singlet oxygen. We find that PPV dimers allow relative comparisons across a range of possible substitutions. Experimental results correlate well with these calculations. The addition of electron-withdrawing substituents, such as nitrile groups, to the vinylene moiety is found to be particularly effective in reducing the reactivity of alkoxy-substituted PPV toward singlet oxygen. The photooxidative stability of a poly(phenylene acetylene) (PPA) derivative is also studied. It appears that this family of polymers is more stable toward photooxidation than are its PPV analogs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2451–2458, 1998     

Victrex® poly(ethersulfone) (PES) and Victrex® poly(etheretherketone) (PEEK)

Properties of two high performance engineering thermoplastics, amorphous polyethersulfone (PES) and semicrystalline polyetheretherketone (PEEK), are discussed. Both resins can be processed by conventional techniques, compounded with high performance fibers, and have high service temperature (up to 300°C). Due to the amorphous character PES can be dissolved and spray coated into metals.     

Finite strain behavior of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG)

Uniaxial and plane strain compression experiments are conducted on amorphous poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG) over a wide range of temperatures (25-110 °C) and strain rates (.005-1.0 s⁻¹). The stress-strain behavior of each material is presented and the results for the two materials are found to be remarkably similar over the investigated range of rates, temperatures, and strain levels. Below the glass transition temperature (θ_g=80 °C), the materials exhibit a distinct yield stress, followed by strain softening then moderate strain hardening at moderate strain levels and dramatic strain hardening at large strains. Above the glass transition temperature, the stress-strain curves exhibit the classic trends of a rubbery material during loading, albeit with a strong temperature and time dependence. Instead of a distinct yield stress, the curve transitions gradually, or rolls over, to flow. As in the sub-θ_g range, this is followed by moderate strain hardening and stiffening, and subsequent dramatic hardening. The exhibition of dramatic hardening in PETG, a copolymer of PET which does not undergo strain-induced crystallization, indicates that crystallization may not be the source of the dramatic hardening and stiffening in PET and, instead molecular orientation is the primary hardening and stiffening mechanism in both PET and PETG. Indeed, it is only in cases of deformation which result in highly uniaxial network orientation that the stress-strain behavior of PET differs significantly from that of PETG, suggesting the influence of a meso-ordered structure or crystallization in these instances. During unloading, PETG exhibits extensive elastic recovery, whereas PET exhibits relatively little recovery, suggesting that crystallization occurs (or continues to develop) after active loading ceases and unloading has commenced, locking in much of the deformation in PET.     

Photo-Initiated Lamination of Polyethylene (PE) and Poly(ethylene terephthalate) (PET)

Besides plasma-based processes, photo-initiated surface modifications have an interesting potential for adhesion promotion. This is of special interest with applications ranging from classical finishing to composites. Photo-chemical processes using continuous UV sources — monochromatic as well as broad band — are based on radical activation and ensuing reaction with the atmosphere. Achievable effects are addition of atoms — e.g., introduction of oxygen (photo-oxidation) resulting in increased surface energy — or grafting of functional groups. Both have certain potentials for adhesion promotion in a physico-chemical way. Based on the fundamental scheme of these processes — i.e., a photon-initiated radical reaction at the substrate-atmosphere interface — a direct 'inter-linking' of coating polymer and substrate is presented in this paper. The principal idea is to apply a thin layer of coating polymer on the substrate and irradiate this composite system at certain UV wavelengths. Given a low absorption of the radiation by the thin coating and — at the same time — a high absorption by the substrate, the radiation will penetrate the coating layer and generate radicals at the interface, which will induce cross-linking between the coating polymer and substrate. It is shown that for the example of laminates of polyethylene (PE) film on fabrics made of poly(ethylene terephthalate) (PET), extremely high adhesion strenghths are achieved without any use of additional adhesion promoters.