中空纤维亲和膜吸附蛋白质的动力学模型

通过对蛋白质溶液在中空纤维亲和膜中流动状况和吸附反应的分析,建立了中空纤维亲和膜蛋白质吸附的动力学表达式．以人γ─免疫球蛋白在A蛋白为配基的亲和膜上的吸附为例,分析了所有亲和吸附位点的反应速度常数都一致的均一吸附和存在两种亲和吸附位点、反应常数不同的非均一吸附两种情况并建立了相应的模型．用有限差分法获得了吸附透过曲线并与实验结果进行了对照．结果表明非均一吸附模型的预测与实验值更为接近．     

Cu2+-IDA金属螯合尼龙-壳聚糖复合膜的制备及其亲和分离性能研究

为获得既具有良好机械强度和化学稳定性又具有大量活性官能团的金属螯合亲和膜介质,以尼龙膜为基膜,采用环氧氯丙烷活化共价偶联壳聚糖,制备尼龙-壳聚糖复合膜,膜上偶联壳聚糖的含量达98.2 mg·(g膜)-1,为配基的固载提供了大量活性位点.再次采用环氧氯丙烷活化复合膜,进而偶联亚氨二乙酸(IDA)、固定化Cu2+,获得金属螯合尼龙-壳聚糖复合型亲和膜,配基Cu2+固载量为5.4μmo1·cm-2.以牛血清白蛋白为目标蛋白,考察亲和膜的分离性能.研究结果表明:牛血清白蛋白在膜上的吸附行为符合Langmuir吸附等温方程,膜对牛血清白蛋白具有较好的亲和吸附效果,吸附容量达1.09 mg·cm-2.该膜具有较长的使用寿命并且容易再生.     

PAC-UF处理含蛋白质类溶液过程中的膜污染研究

使用粉末活性炭(PAC)-超滤(UF)组合工艺处理牛血清白蛋白(BSA)溶液,研究了不同PAC投量下组合工艺的膜污染情况。结果表明,PAC本身对膜污染无明显贡献,PAC吸附BSA后使得膜通量急剧下降;PAC对改善BSA溶液通过超滤的膜通量和膜污染阻力均有一个最佳投加值;PAC在膜表面形成的滤饼层对膜通量改善作用明显;PAC滤饼层主要形成可逆污染,而水中BSA则是不可逆膜污染。     

无菌原料药头孢噻肟钠细菌内毒素的控制

细菌内毒素是热原的一种,当噻肟钠注射剂中含有过量的内毒素时会引起一系列的不良反应,所以在噻肟钠原料药中要严格控制内毒素的量。从内毒素的危害着手,验证了用0.06 EU/mL的鲎试剂凝胶法检验头孢噻肟钠中内毒素残留时,不干扰检测的浓度范围为1.25～5.0 mg/mL,确定了日常检测头孢噻肟钠溶液浓度为1.5 mg/mL。并根据内毒素的特性,结合生产实际,研究在生产过程中应从工艺用水,原辅料和日常的容器,工具清洗,工艺操作等方面控制细菌内毒素的产生。     

膜与蛋白质溶液的相互作用及膜污染机制的能谱研究

引　言蛋白质溶液的浓缩和分离广泛地存在于食品、医药、水处理以及生物技术等领域 ,膜过滤以其无相变、能耗低、设备简单、占地少等优点而成为浓缩与分离蛋白质物系的重要手段之一 .但由于蛋白质对膜的污染比较严重 ,膜过滤的效率和使用范围受到限制 .为了解决这一问题 ,首先需要深入认识蛋白质污染膜的机理 ,对此 ,人们已进行了一些探讨 .Ｔｒａｃｅｙ[1] 认为蛋白质超滤过程初始的通量下降与孔缩小或孔堵塞模型一致 ,而后长时间的通量下降则可用滤饼形成模型来描述 ;Ｍｅｉｒｅｌｅｓ[2 ] 和Ｋｉｍ[3] 提出 ,是膜面高剪切力引起蛋白质变…     

黄麻纳米原纤增强壳聚糖膜的制备及表征

以黄麻为原料,先用化学处理得到黄麻纤维素,再用超微粉碎机处理,分离出黄麻纳米原纤,用黄麻纳米原纤增强壳聚糖膜得到复合膜。通过扫描电镜(SEM)、傅里叶变换红外吸收光谱(FTIR)、X射线衍射(XRD)、拉伸强度测试、紫外吸收光谱(UV)进行了表征及分析。结果表明,黄麻原纤在壳聚糖膜中具有良好的分散性与光透性,含黄麻原纤20%的壳聚糖复合膜具有较高的抗拉强度和模量,其分别为152.31 MPa和2.20 GPa,较纯壳聚糖膜提高了175.87%和168.29%。     

黄麻纳米原纤增强壳聚糖膜的制备及表征

以黄麻为原料,先用化学处理得到黄麻纤维素,再用超微粉碎机处理,分离出黄麻纳米原纤,用黄麻纳米原纤增强壳聚糖膜得到复合膜。通过扫描电镜(SEM)、傅里叶变换红外吸收光谱(FTIR)、X射线衍射(XRD)、拉伸强度测试、紫外吸收光谱(UV)进行了表征及分析。结果表明,黄麻原纤在壳聚糖膜中具有良好的分散性与光透性,含黄麻原纤20%的壳聚糖复合膜具有较高的抗拉强度和模量,其分别为152.31 MPa和2.20 GPa,较纯壳聚糖膜提高了175.87%和168.29%。     

对壳聚糖/聚乙烯醇共混膜在织物化学镀中的应用探讨

壳聚糖属于天然高分子,其与聚乙烯醇混合后发生一系列化学反应能够促使两者融合;而两者在强烈的氢键作用下形成网络结构的二元共混膜。利用傅里叶红外光谱表征以及薄膜拉伸强力测试对比分析了共混膜的结构以及性能;利用壳聚糖与聚乙烯醇预制共混液于涤纶织物的表层,并对其进行化学镀镍研究;通过扫描电子显微镜、热重分析等检测其综合性能。实验表明,经壳聚糖/聚乙烯醇共混液处理后的涤纶织物,其镀层表面均匀细密、具备优良导电性、能与织物紧密结合。     

壳聚糖膜的改性及在废水处理中的应用进展

着重从提高壳聚糖膜吸附性能的角度出发,结合水处理机理,从表面改性、共混改性、纳米复合改性、离子印迹改性、接枝改性及其他改性方法六个方面综述了近年来改性壳聚糖膜的方向及其在处理染料废水、重金属离子废水及其他水生污染物中的应用进展。介绍了壳聚糖膜的成膜机理和制备方法,并探讨了膜的重复使用性。总结改性壳聚糖膜的优缺点,展望了壳聚糖膜的改性新方向。     

膜蒸馏用PDMS/PVDF/PTFE三元共混微孔膜制备

采用浸没沉淀相转化法制备了聚二甲基硅氧烷/聚偏氟乙烯/聚四氟乙烯（PDMS/PVDF/PTFE）三元共混微孔膜,并用于20 g/L NaCl水溶液的膜蒸馏脱盐实验。通过扫描电子显微镜观察以及接触角、膜孔隙率和膜平均孔径分析,研究了PTFE含量对膜结构与性能的影响。结果表明,随着PTFE含量的增加,共混微孔膜断面的指状孔逐渐被海绵状取代,平均孔半径由0.234 μm增加到0.354 μm,膜孔隙率由53.4 %增加到81.3 %;膜下表面与水接触角从118.52 °增加到131.11 °;膜蒸馏过程中通量逐渐增加,截留率先稳定后降低,PTFE含量为40 %（质量分数,下同） 时达最大,为99.99 %,此时膜蒸馏通量达16.60 kg/(m2·h)。     

Solution‐derived ferroelectric vinylidene fluoride oligomer thin films with large polarization

Dense and uniform vinylidene fluoride (VDF) oligomer thin films with a highly polar β phase were prepared for the first time by a low‐cost and scalable solution casting approach, after treatments of substrate surface functionalization and hot‐pressing. Introducing hydrated salt in the precursor solution effectively promoted the ferroelectric β phase. The VDF oligomer thin films obtained with short molecular chains exhibited high crystallinity and high remnant polarization (91 mC m^?2), which is larger than both the polymer and copolymer counterpart films. The reasons for the observed low dielectric constant at low electric field, despite its larger polarization at high field, and the relatively high coercive field are discussed on the basis of the distinct structural characteristics of VDF oligomers. The low polar bulky end‐groups and difficulties in kink formation and propagation may result in the observed low dielectric constant at low electric field and the high coercive field. Copyright © 2011 Society of Chemical Industry     

Modified silicone–PVDF composite hollow‐fiber membrane preparation and its application in VOC separation

Polydimethylsiloxane^vi–poly(vinylidene fluoride) (PDMS^vi–PVDF) composite membranes were prepared using asymmetric PVDF hollow‐fiber membranes as the substrate where a very thin layer of silicone‐based coating material was deposited via a developed dip coating method. The preparation of the composite membranes under various conditions were investigated. In the optimal coating procedure, homogenous and stable oligo‐PDMS^vi coating layers as thin as 1–2 μm were successfully deposited on the surface of PVDF membranes. The developed PDMS^vi–PVDF composite membranes were applied for separation of a wide variety of volatile organic compounds (benzene, chloroform, acetone, ethyl acetate, and toluene). The results showed that the PDMS^vi–PVDF hollow‐fiber composite membranes that had been developed exhibited very high removal efficiency (>96%) for all the VOCs examined under favorable operating conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Structure,properties, and phase transitions of melt‐spun poly(vinylidene fluoride) fibers

Three different experimental techniques were used to study structural phase transitions in melt‐spun poly(vinylidene fluoride) fibers, which were produced with different process parameters and processed in the draw‐winding process at different temperatures and draw ratios. The fibers are examined with the help of wide‐angle X‐ray diffraction at elevated temperatures, differential scanning calorimetry with stochastic temperature modulation, and dynamic mechanical analysis. An oriented mesophase and deformed crystal structures can be observed in all fibers and assigned to the mechanical stress occurring in the processes. Furthermore, several phase transitions during melting and two mechanical relaxation processes could be detected. The observed transitions affect the crystal geometry, the orientation distribution, anisotropic thermal expansion, and the mechanic response of the fiber samples. The relaxation processes can be related with an increasing amount of crystalline β‐phase in fibers drawn at different temperatures. The detailed information about phase transitions and the related temperatures are used to produce fibers with an extended amount of β‐phase crystallites, which are responsible for piezoelectric properties of the material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PEG含量对PVDF/PEG共混膜性能的影响

以聚乙二醇(PEG)为添加剂,利用非溶剂致相分离法制备了聚偏氟乙烯(PVDF)/PEG共混膜,使用傅里叶变换红外光谱、X射线衍射、扫描电子显微镜、接触角测量等表征测试方法,研究了PEG含量对PVDF/PEG共混膜性能的影响。结果发现,PEG的加入使PVDF的结晶性能下降,同时也使其结构发生了变化。但是由于PEG的亲水性,当PEG的质量分数小于5%时,PVDF/PEG共混膜的亲水性随着PEG含量的增大而逐渐得到改善。     

“Smart” membrane materials: Preparation and characterization of PVDF‐g‐PNIPAAm graft copolymer

In this research, a smart membrane material of graft copolymer of poly(vinylidene fluoride) with poly(N‐isopropylacrylamide) (PVDF‐g‐PNIPAAm) was synthesized by atom transfer radical polymerization (ATRP) using poly(vinylidene fluoride) (PVDF) as a macroinitiator and direct initiation of the secondary fluorinated site PVDF facilitates grafting the N‐isopropylacrylamide comonomer. The copolymers were characterized by Fourier transform infrared (FTIR), ¹H NMR, gel‐permeation chromatography (GPC), and X‐ray photoelectron spectroscopy (XPS). The temperature‐sensitive membrane was prepared from the PVDF‐g‐PNIPAAm graft copolymers by the phase inversion method. The effects of temperature on the flux of pure water of membrane was investigated. The results showed that alkyl fluorides were successfully applied as ATRP initiators in the synthetic condition and the flux of pure water through the PVDF‐g‐PNIPAAm membrane depended on the temperature change. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1482–1486, 2007     

CH4在PVDF中渗透行为及机理的分子模拟研究

采用巨正则蒙特卡洛法(GCMC)和分子动力学法(MD)相结合的方法模拟研究了典型气体CH4在聚偏氟乙烯(PVDF)中的吸附扩散行为,探讨了温度及压力对气体吸附扩散能力的影响,分析了CH4在PVDF中的吸附位点及扩散轨迹.模拟结果表明,CH4在PVDF中的溶解系数、渗透系数随温度的升高先增大后减小,随压力的升高而增大;扩...     

强疏水性PDMS/PVDF微孔膜的制备及其性能研究

利用非溶剂相转化法（NIPS）,通过在聚偏氟乙烯(PVDF)铸膜液中加入聚二甲基硅氧烷(PDMS),制备了PDMS/PVDF共混疏水微孔膜,并研究了凝胶浴组成（水/乙醇）对铸膜液凝胶动力学、膜形貌、疏水性及力学性能的影响。结果表明,随着凝胶浴中乙醇百分含量由零增加至100 %时,PDMS/PVDF共混膜的断面上指状孔基本消失,海绵状孔结构贯穿断面;当凝胶浴中乙醇含量为100 %时,PDMS与PVDF发生分相;膜表面疏水性能增加,水接触角达到139.68 °;弹性模量、拉伸强度、断裂伸长率分别由（48.06±4.20）、（2.82±0.15） MPa、（92.90±2.53） %下降至（15.70±2.83）、（0.72±0.13） MPa、（15.47±1.63） %。     

Temperature‐dependent transition of crystal phases in the electrospinning process of poly(vinylidene fluoride‐co‐hexafluoropropylene)

The temperature‐dependent transition of the crystal phases of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) was investigated in the electrospinning process. A solution of PVDF‐HFP in N,N‐dimethyl acetamide (DMAc) produced only the β‐phase‐dominant crystal up to 70 °C, irrespective of the spinneret temperature. In a mixed solvent of DMAc and acetone, however, the crystal phase of the electrospun fibers was dependent on temperature: β‐phase‐dominant at 30 and 50 °C and α‐phase‐dominant at 70 °C. The transition was related to a change of the coagulation rate during electrospinning, because the less perfect α phase is preferable to the β phase at a higher coagulation rate. The temperature‐dependent increase of the coagulation rate was more drastic in the presence of acetone, so the transition took place only in the mixed solvent. At elevated temperature, acetone not only raised the evaporation rate of the solvent but promoted the phase separation of the polymer resulting from the lower critical solution temperature behavior, which was rheologically traced. © 2019 Society of Chemical Industry     

Thermal behaviour and annealing of poly(vinylidene fluoride)

In this study, we report the melting behavior of poly(vinylidene fluoride) (PVF₂) annealed in a differential scanning calorimeter. PVF₂ annealed under isothermal conditions often shows double or triple melting endotherms depending on the annealing temperature (T_a) and the heating rate. The lower melting peak temperature increases as T_a increases. When the annealing time is varied, there is a systematic increase in the size of the lower endotherms. This suggests that a portion of the main endothermic response is due to reorganization during the scan. Annealing PVF₂ not only increases the degree of crystallinity, but also improves the crystal perfection. The ability of an annealing sample to reorganize decreases as the annealing time increases. However, an additional third melting peak appears when PVF₂ is annealed at 140°C for a sufficiently long time. The existence of this peak suggests that more than one kind of distribution of crystal perfection may occur when PVF₂ is quenched from the melt into liquid nitrogen and subsequently annealed.