聚丙烯酸接枝型聚偏氟乙烯多孔膜的pH值感应开关特性

A series of pH-responsive gating membranes, with a wide range of grafting yields, were prepared by grafting poly (acrylic acid) (PAAC) onto porous polyvinylidene fluoride (PVDF) membrane substrates with a plasma-induced pore-filling polymerization method. The effect of grafting yields on gating characteristics of pH-responsive gating membranes was investigated systematically. The results showed that the grafting yield heavily affected water flux, pH-responsiveness coefficient and pH-responsive gating factor of membrane pore size. When the grafting yield was smaller than 1.01%, both flux responsiveness coefficient and pH-responsive gating factor of pore size increased with increasing grafting yield. When the grafting yield was in the range from 1.01% to 6.44%, both flux responsiveness coefficient and pH-responsive gating factor of pore size decreased with increasing grafting yield; however, when the grafting yield was higher than 6.44%, both flux responsiveness coefficient and pH-responsive gating factor of membrane pore size approached to 1, i.e. , little gating characteristics existed. In order to obtain a satisfactory pH-responsive gating property of the membrane, the grafting yield must be kept in a proper range.     

PH值与温度感应型智能开关膜的研究

利用等离子体诱导填孔接技聚合法将聚异而基丙烯酰胺(PNIPAM)或聚丙烯酸(PAAC)接枝聚合在聚偏氟乙烯(PVDF)微孔膜上,制备了一系列具有较宽接枝率范围的温度感应型开关膜(接枝PNIPAM)和pH值感应型开关膜(接技PAAC),研究了接枝率对膜的温度感应以及pH值感应开关特性的影响。研究结果表明,开关膜的接枝率对膜的开关特性有十分重要的影响。对于温度感应型开关膜,当接枝率等于2.81％时,可以获得最好的膜孔开关特性;而且发现在溶质扩散时,低接枝率膜与高接技率膜呈现两种完全相反的开关特性。对于pH值感应型开关膜,当接枝率为1.01％时膜孔开关特性最好。因此,为了获得预期的开关特性,必须将接枝率控制在合适的范围内。     

接枝量对等离子体接枝聚异丙基丙烯酰胺开关的多孔膜的温度感应透过性的影响

The effect of graft yield on both the thermo-responsive hydraulic permeability and the thermo-respousive diffusional permeability through porous membranes with plasma-grafted poly(N-isopropylacrylamide) (PNIPAM)gates was investigated. Both thermo-respousive flat membranes and core-shell microcapsule membranes with a wide range of graft yield of PNIPAM were prepared using a plasma-graft pore-filling polymerization method. The grafted PNIPAM was formed homogeneously throughout the entire thickness of both the fiat polyethylene membranes andthe microcapsule polyamide membranes. Both the hydraulic permeability and the diffusional permeability were heavily dependent on the PNIPAM graft yield. With increasing the graft yield, the hydraulic permeability (water flux) decreases rapidly at 25℃ because of the decrease of the pore size; however, the water flux at 40℃ increases firstly to a peak because of the increase of hydrophobicity of the pore surface, and then decreases and finally tends to zero because of the pore size becoming smaller and smaller. For the diffusional permeability, the temperature shows different effects on the diffusional permeability coefficients of solutes across the membranes. When the graft yield was low, the diffusional coefficient of solute across the membrane was higher at temperature above the lower critical solution temperature (LCST) than that below the LCST; however, when the graft yield was high, the diffusional coefficient was lower at temperature above the LCST than that below the LCST. It is very important to choose or design a proper graft yield of PNIPAM for obtaining a desired thermo-respousive “on/off“ hydraulic or ditfusional permeability.     

多孔膜基材对等离子体接枝膜微观结构的影响

采用等离子体诱导接枝聚合法,在有机聚偏氟乙烯(PVDF)膜、尼龙(N6)膜和无机多孔阳极氧化铝(PAA)膜上接枝甲基丙烯酸(MAA),系统地研究了多孔膜基材及接枝工艺条件对接枝开关膜微观结构的影响。结果发现,对于PVDF基材膜,单体溶液脱气次数越多接枝率越大。对于不同类别的多孔膜基材,采用相同工艺条件接枝时,N6膜的接枝率高于PVDF膜,PAA膜接枝率最低。在接枝率相近的时候,接枝层在PVDF膜整个断面孔内和表面均存在,而N6膜则主要集中在表层。在PAA膜上接枝时发现,等离子体照射功率的强弱对基材膜的影响很大,当功率超过50W时,PAA膜表层就会被刻蚀而导致膜的质量减轻。     

聚烯烃弹性体接枝率对其增韧PA1010的影响

通过接枝马来酸酐（ＭＡＨ）,实现了聚烯烃性体（乙烯／α－烯烃）共聚物（ＥＯＣＰ）的官能化。与未接枝的ＥＯＣＰ相比,接枝的ＥＯＣＰ显著增强了它与ＰＡ１０１０共混物的界面粘合,改善了两者的相容性。接枝率为０．３￣０．５１％的接枝弹性体能有效提高共混物的冲击性能,接枝弹性体明显降低了共混物的熔体汉动速度。扫描电镜显示,接枝率在０．１３￣０．９２％,弹性体粒子的粒径随接枝率的增大而减小。     

聚N-异丙基丙烯酰胺接枝核孔膜微观结构及温敏响应特性

采用等离子体诱导填孔接枝聚合法在聚碳酸酯核孔（PCTE）膜上成功地接枝了聚N-异丙基丙烯酰胺（PNIPAM）,采用X射线光电子能谱（XPS）、傅里叶变换红外光谱仪（FT-IR）、扫描电镜（SEM）、原子力显微镜（AFM）、接触角测量仪和水通量实验,系统地研究了PNIPAM-g-PCTE膜的化学成分、微观结构和温敏特性,以期为环境感应型开关膜的设计和制备提供指导.结果表明,PNIPAM被均匀地接枝在PCTE膜表面和膜孔中;当填孔率F<44.2%时,PNIPAM-g-PCTE膜的膜孔由于孔内接枝物的体积变化而表现出温敏开关特性,并且膜孔径随着F的增大而减小;当F>44.2%以后,水溶液中膜的膜孔被溶胀的PNIPAM接枝链堵塞,此时PNIPAM-g-PCTE膜不再具有温度开关特性;40 ℃时膜孔被完全堵塞的临界填孔率范围在30%～40%之间;随着温度从25 ℃增加到40 ℃,PNIPAM-g-PCTE膜表面的接触角也从58.5°增加到87.9°;PNIPAM-g-PCTE膜水通量的温敏开关特性主要取决于膜孔径的变化,而不是膜表面亲水性的改变.     

氨基聚硅氧烷接枝改性纤维素膜对其结构和性能的影响

采用氢氧化锂/尿素/水溶液作为溶剂,通过冷冻-解冻配置稳定的纤维素溶液并制备纤维素膜.利用高碘酸钠选择性氧化纤维素葡萄糖单元临近的两个羟基制备出二醛纤维素,然后用氨基聚硅氧烷对其进行改性制备出憎水性复合纤维素膜.通过傅立叶红外光谱仪、扫描电镜、热重分析、接触角测定和溶胀率测定等表征氧化纤维素和憎水性复合纤维素的结构和性能.研究了不同质量分数的高碘酸溶液对纤维素的氧化程度以及对纤维素膜的结构的影响,通过改变氨基聚硅氧烷的摩尔浓度来制备不同接枝度的憎水性复合纤维素.结果表明,二醛纤维素具有很强的反应活性,改性纤维素膜的憎水性得到明显提高.在纤维素改性及功能化材料制备的研究中,较强的反应活性使其可以应用在更多的领域.     

ABS乳液接枝聚合反应中影响接枝率的因素

采用乳液聚合法合成ABS接枝聚合物,通过改变反应过程中聚丁二烯、引发剂和分子量调节剂的用量,改变反应温度及增量反应时间,考察ABS接枝聚合物接枝率的变化。结果表明：在实验范围内,接枝率随着聚丁二烯或分子量调节剂用量的增加迅速减小;随着引发剂用量的增加或增量反应时间的增长而增大;随着反应温度的升高而增大,但变化不大。     

接枝率对ABS产品性能的影响

介绍了高速离心分离法测试ABS接枝率的过程,通过分析ABS接枝率与力学性能的关系,总结出ABS接枝粉料接枝率低时融流指数有增大的可能,过低接枝率的ABS冲击强度也低.同时冲击强度与接枝率之间并不是绝对关系,还有其它因素影响产品冲击强度.运用电子扫描显微镜分析冲击断面,证明接枝率对相容性的影响.     

聚合物接枝改性及接枝率的表征

综述了聚合物接枝改性的几种常见方法。如溶液接枝聚合、悬浮接枝聚合、超声波引发接枝聚合、超临界流体技术引发接枝聚合等,介绍了接枝聚合原理、研究和应用,并总结了接枝改性聚合物接枝率的表征方法,包括酸碱滴定法、傅里叶红外光谱（FTIR）、X射线衍射图谱分析（XRD）和元素分析法等。     

炭化条件对多孔炭膜性能的影响

以石油沥青为原料,采用无粘结剂成型制备多孔炭膜,考察了炭化条件对炭膜的Ｈ２和Ｎ２气体渗透率和理想分离系数的影响,并用压汞法表征了炭膜的孔径分布,结果表明：炭化温度是影响炭膜性能的关键因素,制备的炭膜具有均匀性孔径分布,平均孔径为１５３ｎｍ。     

等离子体引发炭黑 接枝聚合的溶剂效应

用等离子体处理炭黑发现,这些等离子体黑颗粒经辉发放电后会产生不同种类的活性种,如高能电子、光子、自由基等,这些活性能引发乙烯基单体进行接枝聚合反应。等离子体炭黑对不同的乙烯基单体具有较强的选择性,当选用不同的溶剂时会产生明显的溶剂效应,产生溶剂效应的原因与等离子体引发聚合的机理有关。等离子体的位阻排斥引发机理会对乙烯基单体的接枝聚合产生较强的选择性。等离子体的溶剂化活性引发机理会对乙烯基单体的接枝聚合产生较强的溶剂效应。当等离子体炭黑与甲基丙烯酸甲脂、甲基丙烯酸丁酯接枝聚合时,溶剂采用二甲基甲酰胺,可得到较高的树枝率。同时讨论了接枝反应的的影响因素。在炭黑颗粒上接枝不同的乙烯基单体会对炭黑体系的分散稳定性产生不同的影响。     

辐照接枝丙烯酸改性聚砜超滤膜

采用液相共辐照技术在聚砜超滤膜上接枝丙烯膜，通过改变辐照剂量和丙烯酸单体浓度可以获得具有不同接枝率的改性聚砜膜。实验结果表明，随着接枝率的提高，改性聚砜抗蛋白质吸附污染的能力显著增强，并且认为接枝膜的亲水性提高是膜污染减轻的主要原因。     

注塑模浇注系统工程设计

以聚合物熔体流变学为基础,根据动量方程建立了数学模型,提供了较实用的注塑模浇注系统工程设计方法,并用实例验证了其可行性效果。     

PB-g-SAN接枝粉料的含胶量对ABS性能的影响

通过种子乳液聚合合成了一系列含胶量不同的聚丁二烯接枝(苯乙烯／丙烯腈)共聚物(PB-g-SAN)接枝粉料。考察了PB—g-SAN接枝粉料的含肢量对其接枝率的影响。将PB-g-SAN接枝粉料与SAN共混制备ABS,控制二者比例使每批ABS含胶量相同,均为15％。研究了PB—g—SAN接枝粉料的含胶量对ABS性能的影响。发现PB—g-SAN接枝粉料的含胶量在60％时,ABS的力学性能最好。     

甲醇/正己烷的渗透汽化分离的研究 Ⅰ.渗透汽化膜的研制

本文研制了从甲醇／正己烷体系中分离甲醇的渗透汽化复合膜ＣＡ／ＰＡＮ（ＰＥＳ）、ＰＶＡ／ＰＡＮ（ＰＥＳ）。实验证明膜对该体系有较高的选择分离性和良好的渗透性，当进料甲醇浓度为３％时，渗透通量Ｊ≈０．６００ｋｇ／ｈ·ｍ２，分离因子α→∝。本文还考察了不同操作条件对膜分离性能的影响及膜的稳定性和均匀性。     

EFFECT OF SODA CONCENTRATION ON THE MORPHOLOGY OF MFI-TYPE ZEOLITE MEMBRANES

MFI-type zeolite membranes were hydrothermally synthesized as a thin layer on macroporous α-alumina discs coated with 1µm MFI-type seed crystals as seed. The effect of soda (Na₂O) concentration on the morphology of the membranes was investigated. Soda concentration, and thus the hydroxyl ion concentration, was changed between 0.25 and 6.5 mol/mol gel. At low soda concentrations the crystals forming the layer exhibited mostly (h0h)/c-axis orientation, but at high soda concentrations a membrane layer formed from randomly oriented crystals. The membranes showed high H₂/n-butane ideal selectivity of 476 and 36 at 25°C and 150°C, respectively.