Surface Modification of Electrospun Poly(L-lactide)/Poly(ε-caprolactone)Fibrous Membranes by Plasma Treatment and Gelatin Immobilization

Biopolymer fibers have great potential for technical applications in biomaterials.The surface properties of fibers are of importance in these applications.In this study,electrospun poly(L-lactide)(PLLA)/poly(ε-caprolactone)(PCL)membranes were modified by cold plasma treatment and coating gelatin to improve the surface hydrophilic properties.The morphologies of the fibers were observed by scanning electron microscopy(SEM).Atomic force microscopy(AFM)was employed to show the surface characteristics of the fibers.The chemical feature of the fibrous membrane surfaces was examined by X-ray photoelectron spectroscopy(XPS).The surface wettability of the fibrous membrane was also characterized by water contact angle measurements.All these results show that plasma treatment can have profound effects on the surface properties of fibrous membranes by changing their surface physical and chemical features.Gelatin-PLLA/PCL membrane has great potential in applications of tissue engineering scaffolds.

Enhancement of the flux for polypropylene hollow fiber membrane in a submerged membrane-bioreactor by surface modification

To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor （SMBR） for wastewater treatment, polypropylene hollow fiber microporous membrane （PPHFMM） was surface-modified by the plasma-induced immobilization of poly （N-vinyl-2-pyrrolidone） （PVP） and the plasma treatment with different gases respectively. Attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscopy （XPS） and field emission scanning electron microscope （FE-SEM） were used to characterize the structural and morphological changes on the membrane surface. Water contact angle was measured by the sessile drop method. It was found that the water contact angle was 128.8, 72.3, 62.7, 74.4, 79.1, 86.3, and 71.3° for the nascent, PVP-immobilized, air, 02, Ar, CO2 and H2O plasma treated PPHFMM, respectively. The SMBR was operated at fixed transmembrane pressure to determine the limiting flux for the PPHFMM before and after surface modification. Results showed that the limiting flux appeared to be 103, 159, 117, 133, 136, 121 and 152 L/（m^2· h） for the nascent, PVP-immobilized, air, O2, At, CO2 and H2O plasma treated PPHFMM, respectively. After continuous operation for about 50 h in the SMBR, the antifouling characteristics were improved to some extent.

Plasma Modification of Activated Carbon Fibers for Adsorption of SO_2

Viscose-based activated carbon fibers （VACFs） were treated by a dielectric-barrier discharge plasma under the feed gas of N2. The surface functional groups of VACFs were modified to improve the adsorption and catalysis capacity for SO2. The surface properties of the untreated and plasma-treated VACFs were diagnosed by SEM, BET, FTIR, and XPS, and the adsorption capacities of VACFs for SO2 were also compared and discussed. The results show that after the plasma treatment, the external surface of VACFs was etched and became rougher, while the surface area and the total pore volume decreased. FTIR and XPS revealed that nitrogen atoms were introduced onto the VACFs surface and the distribution of functional groups on the VACFs surface was changed remarkably. The adsorption characteristic of SO2 indicates that the plasmatreated VACFs have better adsorption capacity than the original VACFs due to the nitrogen functional groups and new functional groups formed in modification, which is beneficial to the adsorption of SO2.

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.

STUDIES ON SURFACE CHARACTERIZATION AND ECOMATERIAL SHEET DEGRADATION OF BASALT FIBERS BY PLASMA TREATMENTS AND WOOD FIBERS

Plasma surface modification (Argon: Hydrogen =0.6: 0.4) of basalt fibers was investigated and the element contents of basalt and wood fibers were determined by X-ray energy dispersion spectroscope (EDS). Configuration of basalt fibers was described by means of confocal Laser Raman microRaman spectrometer and Fourier transform infrared spectroscopy. And the morphology of fiber surface was studied with scanning electron microscope (SEM). The modified samples were characterized by X-ray photoelectron spectra (XPS). The results showed that the roughness of basalt fibers was increased with the increase of exposure time of plasma. At the same time the wettability and surface characteristics such as active groups of NH2, OH were improved as well. Basalt fibers were of good chemical stability, better mechanism intension and thermo-stability etc. They mainly consist of 4-, 4-, 2- . Further experiments demostrated that they were degraded into edaphic matrix after use. Therefore, they were environmentally friendly.

BEHAVIOR OF CHO CELLS ON MODIFIED POLYPROPYLENE BY LOW TEMPERATURE AMMONIA PLASMA

The surface of polypropylene (PP) membrane was modified by low temperature plasma with ammonia. The effect of exposure time was investigated by means of contact angle measurement. The results show that low temperature ammonia plasma treatment can enhance its hydrophilicity. Chinese hamster ovary (CHO) cells attachment on the modified membrane was enhanced and the growth rate on the membrane was faster than unmodified one.

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.

Cu/ACF adsorbent modified by non-thermal plasma for simultaneous adsorption–oxidation of H_(2)S and PH_(3)

Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action time,simple process and no pollution.In this study,Cu/ACF(activated carbon fiber loaded with copper)adsorbent was modified with NTP to remove H_(2)S and PH_(3) simultaneously under low temperature and micro-oxygen condition.Meanwhile,the effects of different modified atmosphere(air,N_(2) and NH_(3)),specific energy input(0–13 J/mL)and modification time(0–30 min)on the removal of H_(2)S and PH_(3) were investigated.Performance test results indicated that under the same reaction conditions,the adsorbent modified by NH_(3) plasma with 5 J/mL for 10 min had the best removal effect on H_(2)S and PH_(3).CO_(2) temperature-programmed desorption and X-ray photoelectron spectroscopy(XPS)analyzes showed that NH_(3) plasma modification could introduce amino functional groups on the surface of the adsorbent,and increase the types and number of alkaline sites on the surface.Brunauer-Emmett-Teller and scanning electron microscopy showed that NH_(3) plasma modification did not significantly change the pore size structure of the adsorbent,but more active components were evenly exposed to the surface,thus improving the adsorption performance.In addition,X-ray diffraction and XPS analysis indicated that the consumption of active components(Cu and Cu_(2)O)and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.

Atomic layer deposition of Al_2O_3 on porous polypropylene hollow fibers for enhanced membrane performances

Porous polypropylene hollow fiber(PPHF) membranes are widely used in liquid purification. However, the hydrophobicity of polypropylene(PP) has limited its applications in water treatment. Herein, we demonstrate that, for the first time, atomic layer deposition(ALD) is an effective strategy to conveniently upgrade the filtration performances of PPHF membranes. The chemical and morphological changes of the deposited PPHF membranes are characterized by spectral, compositional, microscopic characterizations and protein adsorption measurements. Al_2O_3 is distributed along the cross section of the PP hollow fibers, with decreasing concentration from the outer surface to the inner surface. The pore size of the outer surface can be easily turned by altering the ALD cycles. Interestingly, the hollow fibers become much more ductile after deposition as their elongation at break is increased more than six times after deposition with 100 cycles. The deposited membranes show simultaneously enhanced water permeance and retention after deposition with moderate ALD cycle numbers.For instance, after 50 ALD cycles a 17% increase in water permeance and one-fold increase in BSA rejection are observed. Moreover, the PP membranes exhibit improved fouling-resistance after ALD deposition.

硅烷偶联剂改性聚丙烯纤维水泥基复合材料的性能研究

本文使用不同类型(KH550和KH560)和不同浓度(0.5%、1.0%、1.5%和2.0%,质量分数)的SCA对聚丙烯纤维(PPF)进行表面改性,通过无侧限抗压强度试验和抗折试验,研究了SCA改性聚丙烯纤维水泥基复合材料的承压能力,并使用扫描电子显微镜对改性后的聚丙烯纤维水泥基复合材料进行了微观表征。结果表明:KH560改性聚丙烯纤维对水泥基复合材料的流动度影响较大,KH550次之;整体上,SCA浓度越接近1.5%,对聚丙烯纤维水泥基复合材料流动度的影响越大;随着KH550浓度增大,水泥基复合材料孔隙率总体呈降低趋势,随着KH560浓度增大,水泥基复合材料孔隙率呈先下降后上升的趋势,并且浓度为1.5%时孔隙率最小;两种SCA均提高了PPF表面的粗糙度,并能在PPF-SCA-基体界面实现化学键连接;两种SCA对聚丙烯纤维水泥基复合材料抗折强度的影响较小,但能有效提高抗压强度。总体而言,KH550改性效果优于KH560。

聚丙烯纤维改性多孔生态混凝土的制备及性能研究

以玄武岩碎石为天然粗骨料,废弃混凝土为再生粗骨料,聚丙烯纤维为增强相,制备了不同聚丙烯纤维掺杂量的多孔生态混凝土,探究了聚丙烯纤维的掺杂量对多孔生态混凝土的物理性能、微观形貌、力学性能及抗冻性能的影响。结果表明,多孔生态混凝土的透水系数和孔隙率呈现出正向线性关系,随着聚丙烯纤维掺杂量的增大,混凝土的透水系数和孔隙率持续降低;适量聚丙烯纤维的掺杂能够在多孔生态混凝土中形成均匀致密的网格结构,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的致密度最高。随着聚丙烯纤维掺杂量的增大,混凝土的抗折强度先增大后降低,抗压强度先快速增大后缓慢增大。在28 d龄期下,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的抗折强度达到最大值4.68 MPa,对应的抗压强度为14.68 MPa。经历100次冻融循环后,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的质量损失率最低为2.17%,相对动弹性模量最高为84.81%,抗冻性能最佳。因此,聚丙烯纤维的最佳掺杂量为3%(体积分数)。

碳纤维表面改性技术研究进展及发展趋势

综述了近几年国内外碳纤维表面改性处理技术的研究进展,分别介绍了涂层改性、氧化改性、表面接枝改性、等离子体改性的改性原理及效果。现有碳纤维表面改性技术仅对表面产生物理或化学的改性,单独一种改性技术在连续化生产中难以实现有效控制,而多种改性技术的组合式应用技术可以相互融合各种改性技术的优点,适合在各个碳纤维生产流程中进行表面改性设计具有更高的研究价值。碳纤维组合式表面改性技术将是未来提升碳纤维连续化生产的发展趋势。

等离子体聚合改性在丙纶无纺布亲水整理中的应用

使用等离子体通过两步法对丙纶无纺布进行亲水整理。采用氮气等离子体处理丙纶无纺布,在纤维表面产生自由基;抽出氮气导入丙烯酸气体,利用自由基引发其聚合,并应用等离子体放电提高丙烯酸气体能量以加速聚合。采用红外吸收光谱(FTIR-ATR)、X射线光电子能谱(XPS)、扫描电镜(SEM)和接触角测试等方法对整理后静置3个月的丙纶织物进行测试。结果表明,整理后纤维在1700~1725 cm^(-1)处红外吸收略有增强,XPS发现整理后丙纶中存在羰基,说明丙烯酸对丙纶纤维实现了表面改性;整理对纤维形貌改变不大,仅表面出现少量鳞片状突起物;整理前丙纶无纺布的平均接触角为127°,整理后水滴于0.20 s内完全润湿,接触角为0°。

接枝偶联剂对F-12纤维/环氧复合材料界面改性的研究

采用一种大分子接枝偶联剂对 F- 1 2纤维表面进行等离子体接枝改性 ,并采用 ESCA对改性后的纤维表面进行分析 ,研究了接枝偶联剂的分子量和浓度对 F- 1 2 /环氧复合材料横向拉伸强度的影响 ,并结合横向拉伸的断口对改性机理进行了分析。实验结果表明 :接枝偶联剂接枝改性以后 ,能够有效地改善 F- 1 2 /环氧复合材料的界面结合状态 ,从而提高复合材料的横向拉伸强度。

聚丙烯(PP)纤维表面改性及其在混凝土中的应用

混凝土中加入纤维可以大大增强混凝土的强度,其中聚丙烯纤维增强混凝土复合材料以其优异的性能正得到越来越广泛的应用,研究发现聚丙烯纤维的表面微观结构及其与水泥界面之间粘接力的强弱是影响复合材料性能的重要因素。综述了近年来聚丙烯纤维的表面改性及其在混凝土中的应用。

接枝偶联剂对F-12纤维表面改性的影响

用一种大分子接枝偶联剂MGC对F -1 2进行等离子体接枝改性 ,研究了MGC的分子量和浓度对改性后的F -1 2 /环氧复合材料层间剪切强度 (ILSS)的影响 ,还通过ESCA对改性机理进行了分析 .实验结果表明 :一定分子量的MGC能够明显提高F -1 2 /环氧复合材料层间剪切强度 .

复合材料用碳纤维等离子体表面改性技术进展

近年来复合材料得到了广泛的应用,尤其在航空工业领域,已成为了世界强国竞相发展的核心技术。碳纤维树脂基复合材料作为复合材料中的优秀代表,由于其独特的性能优势,具有很大的发展潜力,但是界面结合强度是制约其应用的关键瓶颈。等离子体表面改性技术能提高碳纤维与树脂基的界面结合强度。总结了国内外学者工作,从等离子体处理装备发展和工艺参数影响两个角度对碳纤维等离子体表面改性技术的研究进展进行了阐述。在装备发展方面,重点介绍了在碳纤维表面处理研究中三类处理装置,包括射频等离子体处理装置、DBD等离子体处理装置和滑动弧射流等离子体处理装置,分析了各自的优缺点。在工艺参数方面,重点介绍了不同等离子体种类、等离子体处理时间、等离子体放电功率对碳纤维表面状态的影响规律。在此基础上,对碳纤维等离子体表面处理技术的未来发展方向进行了展望。

介质阻挡电晕放电用于聚丙烯薄膜的表面改性

聚丙烯薄膜浸渍特性是电力电容器的关键问题之一。为了改善聚丙烯薄膜的浸渍特性,采用低温等离子体技术对薄膜表面进行了改性研究。首先基于介质阻挡电晕放电原理制作了低温等离子体发生装置,研究了其放电的电学特性。然后利用该装置产生低温等离子体,应用于聚丙烯薄膜的材料表面改性处理。通过测量材料表面处理前后的表面化学元素、微观形貌和表面静态水接触角的变化,分析了等离子体处理对材料表面改性的影响。结果表明:聚丙烯薄膜经过等离子体改性处理后,表面的极性含氧基团数量增加到10%,静态接触角降低了30%,材料表面粗糙度和浸渍特性都有较大提高;其电学特性也发生了变化,处理之后聚丙烯薄膜的交流击穿电压提高了约12%。

表面处理对剑麻纤维增强聚丙烯复合材料力学性能的影响

为提高剑麻纤维和聚丙烯基体界面的粘合性,对剑麻纤维的几种表面改性方法进行了试验研究。用电镜、红外光谱仪和X射线衍射仪对剑麻纤维表面进行了表征,观察改性后纤维表面的变化,测定了复合材料的拉伸、弯曲和冲击等力学性能。结果表明:表面处理能有效提高剑麻纤维和聚丙烯基体界面的粘合性,从而提高复合材料的力学性能;但此复合材料性能还达不到实际使用要求。

硅烷偶联剂表面改性玄武岩纤维增强复合材料研究进展

表面改性是增强玄武岩纤维与基体材料之间结合性能的关键。综述了硅烷偶联剂表面改性以及酸、碱刻蚀,等离子处理辅助协同硅烷偶联剂表面改性玄武岩纤维的研究进展,介绍了硅烷偶联剂表面改性玄武岩纤维在聚合物基复合材料中的应用,并对发展趋势进行了展望,同时分析了硅烷偶联剂表面改性玄武岩纤维当前存在的问题。