SURFACE MODIFICATION OF MICROPOROUS POLYPROPYLENE MEMBRANES BY GRAFT POLYMERIZATION OF N,N-DIMETHYLAMINOETHYL METHACRYLATE

Surface modification of microporous polypropylene hollow fiber membranes was performed by radical-induced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA). The influences of temperature, monomer concentration and pre-adsorbed amount of benzoyl peroxide on grafting degree were studied respectively. It was found that the appropriate graft temperature was 75 'C, at which the grafting degree was the highest and the hydrolytic decomposition of DMAEMA the lowest. Scanning electron photomicrography and the average pore diameters of the modified membranes demonstrated that part of the micropores on the membrane surface was plugged by the grafted polyDMAEMA chains, especially at high grafting degree. Contact angle and water swelling experiments showed that a moderate grafting degree could improve the hydrophilicity of the membranes. In the range of 11.3%-12.0% grafting degree, the water swelling percentage reached its maximum (51.1%) and the contact angle reached its minimum (74 degrees). The bovine serum albumin (BSA) adsorption experiment indicated that the grafted polyDMAEMA had a dual effect on protein adsorption. At the first stage, the BSA adsorption decreased with increasing of DMAEMA grafting degree. As the interaction between BSA and polyDMAEMA on membrane surface increased, the BSA adsorption increased with increasing of DMAEMA grafting degree.

SURFACE MODIFICATION OF POLYPROPYLENE MICROPOROUS MEMBRANE BY TETHERING POLYPEPTIDES

Two kinds of polypeptides were tethered onto the surface of polypropylene microporous membrane （PPMM） through a ring opening polymerization of L-glutamate N-carboxyanhydride initiated by amino groups which were introduced by ammonia plasma and y-aminopropyl triethanoxysilane treatments. X-ray photoelectron spectroscopy （XPS）, attenuated total reflectance Fourier transform infrared spectroscopy （FT-IR/ATR）, scanning electron microscopy （SEM）, together with water contact angle measurements were used to characterize the modified membranes. XPS analyses and FT-IR/ATR spectra demonstrated that polypeptides are actually grafted onto the membrane surface. The wettability of the membrane surface increases at first and then decreases with the increase in grafting degrees of polypeptide. Platelet adhesion and murine macrophage attachment experiments reveal an enhanced hemocompatibility for the polypeptide modified PPMMs. All these results give evidence that polypeptide grafting can simultaneously improve the hemocompatibility as well as reserve the hydrophobicity for the membrane, which will provide a potential approach to improve the performance of polypropylene hollow fiber microporous membrane used in artificial oxygenator.

Photo-Grafting Copolymerization of PP Nonwoven Fabric and Its Application for Acidic Dye Adsorption and Filtration

The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and adsorptive filtration performance of the resulted PP fabrics were investigated.The results showed that the grafting copolymerization preferred to happen in the inner layer of the fabrics. The water flux of the grafted fabrics decreases with the increase of grafting yield. The collapse of the grafted polymer chains causes the flux increase in acidic condition,or vice versa at alkaline version. The coiling of the polyelectrolyte chains upon the dye adsorption seems to violate the routine assumption of the rigid substrate, and this gets the adsorption energy constant negative. The static adsorption process follows the Lagergren's pseudo-second order kinetic equation. The removals of circa( ca.) 100% of the total permeation volume3 500 mL simulated dye wastewater was reached during permeation.The dye adsorbed fabrics were regenerated by the mixed media of the cationic surfactant / ethanol /water. The grafted fabric assumes stable fabric integrity and stability during permeation,and presents excellent dye adsorption capacity,easy desorption, and repeatable utilization.

Surface Photografting of Novel Sulfobetaine Copolymers on Silica

A couple of novel sulfobetaine copolymer is developed via Michael-type addition reaction. The comonomers, diamines and maleimide react via Michael reaction through UV irradiation using AIBN as photoinitiator producing polyamine chain. Further, sulfobetaine copolymers were obtained on treatment of the polyamine with sulfopropylating agent, 1,3-propane sultone. These novel sulfobetaine polymers were grafted on silica surface to produce responsive biocompatible surface. This easy straightforward, catalyst free facile protocol for synthesis of polymer grafted surface is useful for developing biomedical devices. Additionally, both the copolymers show fluorescence characteristics.

Ultravilolet-radiation-induced graft polymerization of acrylamide onto the melt-blown polypropylene filter element by dynamic method

By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.

PLASMA MODIFICATION OF POLYPROPYLENE SURFACES AND GRAFTING COPOLYMERIZATION OF STYRENE ONTO POLYPROPYLENE

The surface of polypropylene （iPP） is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy （SEM） show the surface etching pattern of iPP films. The chemical structures of iPP films are confirmed by X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared （FTIR） spectroscopy. The wetting properties of modified surfaces of iPP films are characterized by contact angle, and the free energy of surfaces is calculated. The free radical of modification surfaces of iPP is measured by chemical method. The surfaces of iPP are achieved with Ar plasma treatment followed by grafting copolymerization with styrene （St） in St. The grafting polymer of St onto iPP is characterized by FTIR. The grafting rate is dependent on plasma exposure time and discharge voltage. The studies show that homopolymerization of St is undergone at the sane time during the graftingcopolymerization of St onto/PP.

Studies on the Crystallization Behavior of Polypropylene Solid Phase Grafted Maleic Anhydride

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CHARACTERIZATION OF AMPHIPHILIC AND MICROPHASE SEPARATED GRAFT COPOLYMERS Ⅱ SURFACE CHARACTERIZATION AND IN VITRO BLOOD-COMPATIBILITY ASSESSMENT OF POLYSTYRENE-GRAFT-ω-STEARYLPOLY (ETHYLENE OXIDE)

This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed.

An Approach to the Flame Retardancy of EVA Copolymer by Plasma Treatmentc2

An attempt was made in the paper aiming at imparting flame retardancy to polymers by plasma grafting technique Based on EVA copolymers with different VA contents the author tried to use the Ar plasma followed by grafting with/without subsequent saponification and metal ion exchange expediting the charring of polymers upon heationg Characterization of the flammability of the plasma treated EVA copolymers grafted with acrylic monomers(MAA,AA and AAm)indicates that this approach turns out to be a promising way and worthy doing whatever in research and/or applications

Synthesis and characterization of macromolecular surface modifier PP-g-PEG for polypropylene

A novel macromolecular surface modifier,polypropylene-grafted-poly(ethylene glycol)copolymer(PP-g-PEG),was synthesized by coupling polypropylene containing maleic anhydride with monohydroxyl-termi-nated poly(ethylene glycol).The effects of the reaction condition on the graft reactions were studied.The copo-lymers were characterized by IR,1 H NMR,thermogravi-metry(TG)and differential scanning calorimetry(DSC).The results indicated that the graft reactions were hin-dered by increasing the molecular weight of PP or PEG.The graft copolymer was found to have a higher initial thermal degradation temperature and lower crystalliza-tion capacity as compared with pure PP,and the side chain of PEG hindered the PP chain from forming a per-fect b crystal.The thermal stability of PP-g-PEG decreased with the increasing content or molecular weight of PEG.The copolymers were blended with polypropy-lene to modify the surface hydrophilicity of the products.The results of attenuated total reflectance FTIR spectro-scopy(ATR-FTIR)showed that PP-g-PEG could diffuse preferably onto the surface of the blends and be suitableas an effectual macromolecular surface modifier for PP.

Grafting of PEG400 onto the surface of LLDPE/SMA film

Linear low-density polyethylene(LLDPE)was melt and blended with styrene-maleic anhydride copolymer(SMA).The blending films were then immersed in poly(ethylene glycol)400(PEG400)at room temperature.The surface composition of the blend films was determined by Fourier transform infra-red spectroscopy coupled with a variable incidence angle attenuated total reflection accessory(ATR-FTIR).Results show that PEG400 can be grafted onto the surface of the films via esterification with SMA.The immersion of PEG promotes the enrichment of SMA onto the surface of the films.The water contact angle data show that grafting of PEG400 onto PE can greatly improve the hydro-philicity of the PE surface.These experiments show that sur-face functionalization of polyethylene films by blending SMA and then surface grafting of PEG is feasible,which suggest an effective and simple route for PE surface modification via blending and grafting.

纳米SiO_2/聚丙烯复合材料的反应性增容

利用反应性增容技术制备了纳米二氧化硅/聚丙烯复合材料.首先探讨了将甲基丙烯酸缩水甘油酯-丙烯酸丁酯共聚物接枝到纳米二氧化硅粒子表面进行改性的各种影响因素,然后将接枝改性纳米二氧化硅与聚丙烯以及作为反应性增容剂的氨基化聚丙烯共混.结果表明,改性粒子上的环氧基与氨基化聚丙烯上的氨基之间的化学反应大大增强了复合材料的界面作用,从而在粒子含量很低时明显提高了聚丙烯的拉伸强度、模量和冲击强度.

悬浮法合成聚丙烯接枝丙烯酸

用过氧化二苯甲酰作引发剂以水相悬浮法合成聚丙烯接枝丙烯酸。通过反应条件、组分等因素对PP的接枝率和接枝效率的影响研究 ,确定较佳配比工艺条件 :溶胀时间 80min;反应温度 90℃ ;反应时间90min ;在氮气气氛中 ,丙烯酸 7% ;过氧化二苯甲酰 3 .3 % ;二甲苯 2 5% ;水和聚丙烯的重量比为 3∶1 ;若加入适量催化剂 ( 1 -1 .7% )异氰尿酸三烯丙酯能显著提高接枝率。用此PP -g-AA作PP/CaCO3 、PP/PA6复合物的相容剂 ,材料的力学性能有很大的提高。

聚丙烯熔融接枝马来酸酐反应机理的研究

改变聚丙烯 ( PP)熔融接枝马来酸酐 ( MAH)反应中的单体和引发剂的浓度以及添加适当助剂 ,考察了接枝产物的接枝率和在恒定剪切应力 ( 60 0 k Pa)及温度 ( 2 1 0℃ )下的剪切粘度 ,验证了作者先前所提出的PP熔融接枝 MAH的反应机理 .即 :在 PP熔融接枝 MAH的过程中 ,过氧化物自由基在熔融接枝过程中直接引发 MAH单体及 MAH单体在聚丙烯的大分子链段发生 β断裂前直接被其引发而产生的接枝反应是影响产物的接枝率和分子量的关键 .在不改变单体和引发剂浓度的情况下 ,降低过氧化物自由基在熔融接枝过程中直接引发 MAH单体反应的程度而提高聚丙烯的大分子自由基直接引发 MAH单体的反应趋势 。

反应挤出条件对PP-g-GMA接枝率、接枝效率和熔体流动速率的影响

用反应挤出法在聚丙烯 (PP)分子链上接枝甲基丙烯酸环氧丙酯 (GMA) ,制备功能化聚丙烯 .重点讨论了单体浓度、引发剂浓度、反应温度及物料在螺杆中的停留时间等对接枝产物 PP-g-GMA的接枝率、接枝效率和熔体流动速率的影响 .结果表明 ,PP-g-GMA接枝率与加入的单体浓度成正比 ,与引发剂浓度无关 ,反应挤出的适宜温度窗口在 1 95～ 2 3 0℃之间 ,停留时间超过 1 min后接枝率与停留时间无关 ;PP-g-GMA的熔体流动速率与单体浓度成反比 ,与引发剂的用量成正比 ,在反应温度窗口内与反应挤出温度和物料停留时间关系不大 ;单体和引发剂的浓度、反应挤出温度及物料停留时间对 PP-g-GMA的接枝效率无显著影响 .

聚丙烯纤维与丙烯酸辐射接枝共聚反应的研究

采用６０Ｃｏ－γ射线预辐照接枝法，研究了聚丙烯（ＰＰ）纤维与丙烯酸（ＡＡｃ）在苯中的接枝共聚反应。讨论了预辐照剂量、单体浓度、反应时间以及反应温度对接枝共聚反应的影响。实验结果表明，接枝率随预辐照剂量和反应温度的增加而增加。实验获得的接枝共聚物，其亲水性有明显的改善，但当预辐照剂量超过２Ｍｒａｄ时，机械强度有所下降。

丙烯腈-聚丙烯接枝共聚物的制备

以二甲苯为溶剂,过氧化二异丙苯(DCP)为引发剂,采用高压溶液法制备了丙烯腈-聚丙烯接枝共聚物(APG)。讨论了反应时间、反应温度、引发剂浓度、单体浓度等条件对接枝率的影响,并对接枝物的结构进行了表征。

聚丙烯纤维与丙烯酸接枝共聚反应的研究

用高锰酸钾 /硫酸作为引发体系 ,聚丙烯纤维与丙烯酸进行接枝共聚反应。研究聚丙烯纤维接枝率与硫酸浓度、丙烯酸浓度、高锰酸钾浓度、高锰酸钾预处理纤维时间、预引发时间、聚合温度和反应时间的关系。结果表明 :硫酸浓度为 0 .2 mol/ L,高锰酸钾浓度为 5× 10 - 3mol/ L,丙烯酸浓度为 0 .8mol/ L,高锰酸钾预处理时间为 30 min,预引发时间为 32 min,反应温度为 80℃ ,反应时间为 3.5h时 ,接枝率较高。

聚丙烯固相接枝聚合及接枝机理研究进展

综述了近年来有关聚丙烯固相接枝机理的文献报道,讨论了引发剂、催化剂、接枝单体、界面剂等反应物的种类与用量以及反应温度、搅拌转速等影响因素对接枝反应的影响,对聚丙烯固相接枝反应今后的研究方向提出建议。

木素磺酸盐和丙烯酸电化学接枝共聚反应的研究

木素磷酸盐与丙烯酸溶液在以二氧化铅为阳极、不锈钢为阴极的无隔膜电解槽中电解，可以发生电化学接校共聚反应。接技产物的红外话留在1724cm－1处出现强的谈基吸收峰；接技产物中羧基的含量明显增大；接技产物的表面活性明显改善，1％的接技产物水溶液与大庆原油的界面张力达到10-1mN／m，表面张力也明显降低；接技产物具有很好的分散性能。