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.

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.

SYNTHESIS AND CHARACTERIZATION OF POLYPROPYLENE/MONTMORILLONITE NANOCOMPOSITES VIA AN in-situ POLYMERIZATION APPROACH

Polypropylene/montmorillonite (PP/MMT)nanocomposites were prepared by in-situ polymerization using aMMT/MgCl_2/TiCl_4-EB Ziegler-Natta catalyst activated by triethylaluminum(TEA). The enlarged layer spacing of MMT wasconfirmed by X-ray wide angle diffraction (WAXD), demonstrating that MMT were intercalated by the catalyst components.X-ray photoelectron spectrometry (XPS) analysis proved that TiCl_4 was mainly supported on MgCl_2 instead of on the surfaceof MMT The exfoliated structure of MMT layers in the PP matrix of PP/MMT composites was demonstrated by WAXDpatterns and transmission electron microscopy (TEM) observation. The higher glass transition temperature and higher storage modulus of the PP/MMT composites in comparison with pure PP were revealed by dynamic mechanical analysis (DMA).

Influences of Polypropylene Fiber and SBR Polymer Latex on Abrasion Resistance of Cement Mortar

Influences of polypropylene （PP） fiber and styrene-butadiene rubber （SBR） polymer latex on the strength performance, abrasion resistance of cement mortar were studied. The experimental results show that the flexural strength, brittleness index （σF/σC） and abrasion resistance can be improved significantly by the addition of PP fiber and SBR polymer latex. The relationship between the flexural strength and abrasion resistance was analyzed, showing a good linear relationship between them. The reinforced mechanism of PP fiber and SBR polymer latex on cement mortar was analyzed by some microscopic tests. The test results show that the addition of SBR polymer latex has no significant influence on the cement hydration after 7 d curing. Adding SBR polymer latex into cement mortar can form a polymer transition layer in the interfaces of PP fiber and cement hydrates, which improves the bonding properties between the PP fiber and cement mortar matrix effectively.

High Efficieney Synthesis of Isotaetie Polypropylene and Linear Polyethylene Using a New C_2-symmetric Carbon-bridged Zirconocene Catalyst

Ansa-Cyclohexyl-bis（4,5,6,7-tertrahydro-l-indenyl） zirconium dichloride （5） was used as catalyst for propylene and ethylene polymerization together with methyl aluminoxane （MAO） as the cocatalyst. Isotactic polypropylene （PP） was obtained with the highest activity of 6.37× 107g PP （molZr）^-1h^-1. The mesomeso （mmmmm） pentads sequence content of PP was determined by 13C NMR spectroscopy. The dependence of the microstructure on the reaction temperature and the AI/Zr molar ratio was examined and the catalytic activity of complex 5 was compared with that of the similar ansa-zirconocene 3. The high activity of the new zirconocene 5 for propylene isospectic polymerization at high temperature （60℃） is the result of its unique bridged-group structure. Complex 5/MAO displays also high catalytic activity of 0.46× 10^6 to 9.87× 10^6g PE（molZr）^-h^-in the homo-polymerization of ethylene, The visometric molecular weight of PE ranges from 0.97×10^4 to 11.16×10^4 g.mol^- under the given conditions.^13C NMR spectroscopy analysis proves the PE to be linear polyethylene （LPE）.

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.

INTERACTION BETWEEN THE SURFACE GLYCOSYLATED POLYPROPYLENE MEMBRANE AND LECTIN

A glycopolymer bearing glucose residues was tethered onto the surface of polypropylene microporous membrane by UV-induced graft polymerization ofα-allyl glucoside.Concanavalin A (Con A),a glucose recognizing lectin,could be specifically adsorbed to the membrane surface.On the other hand,the membrane surface showed no recognition ability to another lectin peanut agglutinin.Moreover,the recognition complex between the glycosylated membrane surface and Con A could be inhibited by glucose and mannose solution.T...

Synthesis and characterization of novel polypropylene paper releasing anion

Polypropylene synthetic paper releasing anion was prepared from polypropylene resin, anion additives, titanium dioxide, etc., by calendar forming method. The synthetic paper was tested by anion detector, SEM, AFM, etc. Tensile strength, elongation at break, fight angle tear strength of the polypropylene synthetic paper reached the GB 13022 or QB/T1130 Standard. The synthetic paper was water and oil resistance, and released anions 10,530 cm^-3. It was environment-friendly, and a kind of good material for human＇s health.

Effect of Graphene Nanoplatelets Presence on the Thermal and Mechanical Properties of Polypropylene Fibers Produced by Melt Spinning

In aiming to obtain fibers with enhanced thermal and mechanical properties,graphene based textile fibers with 144 filaments were developed using an approach in which the PP/GnP(polypropylene/graphene nanoplatelets)nanocomposite was employed as conductive material in a fiber with circular cross-section geometry.The kinetics of thermal degradation was evaluated by the Broido method using thermogravimetric analysis(TGA).Activation energy was enhanced from 260.6 kJ·mol^-1 to 337.4 kJ·mol^-1 compared to the neat PP.GnP increased the thermal stability of the PP,slowing its degradation by thermal depolymerization.Furthermore,the degree of crystallization declined as the GnP content increased,reducing the tenacity of the yarn,but improving its elastic modulus from 91.9 to 95.9 cN/tex,being a promising alternative to produce smart textiles.In conclusion,it has been confirmed that GnP loading up to 1%(w/w)can be incorporated into polypropylene by melt spinning and that the resulting nanocomposite fibers are suitable for several applications in the textile industry.

Study on Property of Polypropylene Catalyst with New Internal Donor

A P-substituted sulfonyl-containing compound was synthesized in the lab. The structure of the compound was demonstrated by 1H and 31P NMR. The propylene polymerization catalysts were prepared by incorporating an internal donor, and the content of Ti, H and C in the catalysts was also checked by elemental analysis. The effect of dosage of the donor, the Al/Ti ratio and the polymerization temperature on the catalyst activity were studied, the results suggested that the dosage of donor, the Al/Ti ratio and the polymerization temperature could affect not only the activity of catalyst but also the isotacticity index of the polymer. A catalyst with high activity was selected, and the polypropylene formed in the presence of this catalyst had high isotacticity index.

THE INFLUENCE OF SUBSTITUENTS IN METALLOCENE ON PROPYLENE POLYMERIZATION

Two new unbridged zirconocenes, bis(2.4,7-trimethyl indenyl)zirconium dichloride (Met-I) and bis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-II) were prepared in order to investigate the steric effects of substituents on the nature of the catalysts for the: polymerization of propylene. A mixture of methyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)(3)] was used as cocatalyst to activate these catalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted in an increase of both activity and molecular weight as well as the isotacticity.

STEREOCHEMICAL CONTROL IN PROPYLENE POLYMERIZATION CATALYZED BY UNBRIDGED METALLOCENE CATALYSTS

Two unbridged metallocene catalysts, bis(2,4,7-trimethylindenyl)zirconium dichloride (met-I) and bis(2,4,6-trimethylindenyl)zirconium dichloride (met-II), which are different in the position of substituents on the six-membered ring of the indenyl ligands were synthesized. The effect of substituents in the two metallocenes on the propylene polymerization was studied in the presence of methylaluminoxane (MAO) and triisobutylaluminium (TIBA). From the analysis of microstructure determined by C-13-NMR, it was demonstrated that the polymers produced by met-II have higher [mmmm] isotactic sequences than that of met-I. Using a mechanism based on model statistical analysis, it was found that chain-end model was dominant for met-I. However, met-II obeys the concurrent two-sites model during polymerization, which can be attributed to the existence of 'racemic-like' conformer in its system.

INTERFACE REACTION BETWEEN γ-AMINOPROPYLTRIMETHOXYSILANE AND ULTRAVIOLET IRRADIATED POLYPROPYLENE

The interface reaction between ultraviolet irradiated polypropylene (UV-PP) and an amino silane coupling agent, γ-aminopropyltrimethoxysilane (γ-APS) adsorbed on glass fibers has been investigated by means of the combining use of solvent extraction and FTIR as well as XPS. First, polypropylene (PP) physisorbed on the glass fibers surface was removed by the solvent extraction in order to minimize the effect of the PP siginal in FTIR and XPS analyses. Second, the remaining glass fibers after solvent extraction were analyzed by FTIR and XPS. The results show that the absorption bands of PP still exist in the FTIR spectrum and two new bands of N1s at 399. 1eV and 401.6eV appear in the XPS spectrum for the composite with UV-PP and γ-APS treated glass fibers. Thus, the interface reaction between the UV-PP and γ-APS has been monitored directly. In addition, it may be concluded that OH and COOH groups of UV-PP form chemical bonds with NH2 group of γ-APS , respectively.

Influence of Spinning Technology on Dye Uptake of Modified Polypropylene Fiber

By adding small amount of olefin polymer additive, the dyeability of polypropylene fiber can be improved.Research results show that the improvement of dyeing performance of modified PP fiber is mainly due to the formation of looser structure of PP matrix and the microchannels among additive particles in blended fiber. The dye uptake of drawn fibers decreases with drawing ratios obviously and changes with temperature of heat plate and heat roller a little.

Propylene Polymerization Catalysts with Sulfonyl Amines as Internal Electron Donors

Three sulfonyl aliphatic amines [(R2SO2)2NR1 , viz.: compound 1, in which R1 =Me, and R2 =Ph; compound 2, in which R1=n-Bu, and R2 =CF3 ; and compound 3, in which R1 =C8H17 , and R2 =CF3], have been synthesized and employed as internal electron donors (IED) for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the Al/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.

丙烯液相本体聚合过程Polymers Plus建模与分析

依据聚合反应机理,采用ASPEN公司的PolymersPlus为软件平台,对Hypol工艺的丙烯液相本体聚合过程进行建模与流程模拟。聚合体系的物性以及相平衡采用含链扰动的统计流体理论(PC-SAFT)方法计算,参考文献值并结合工业装置的操作数据对丙烯聚合反应机理及其动力学参数进行修正。模拟分析表明,催化剂的氢活化速率常数、催化剂自失活速率常数以及链增长速率常数对单体转化率影响较大;氢气的链转移常数、活性中心向单体的链转移常数以及链增长速率常数对聚合度影响较大;催化体系的多活性中心导致相对分子质量分布加宽,对相对分子质量分布曲线进行解耦得到催化剂的活性位个数为6;反应器温度的变化不仅影响产量,同时也影响产品的相对分子质量。

多孔有机聚合物中试制备及其在聚烯烃催化剂中的应用

多孔有机聚合物广泛应用在吸附、分离、催化等领域。本文采用分散聚合工艺,中试制备得到形貌及流动性良好的POP3120T和POP3100载体,POP3120T载体堆密度为0.29g/cm^(3),比表面积为282m^(2)/g,与无机硅胶载体相当,颗粒粒径23.4μm,粒径分布1.00;POP3100载体堆密度为0.34g/cm3,比表面积约503m^(2)/g,均高于无机硅胶载体,颗粒粒径36.0μm,粒径分布0.93。负载的POP型Z-N聚丙烯催化剂具有良好的丙烯聚合活性,其活性可达到1.0×10^(7)g/(mol·h)以上。得到的聚合物堆密度可以达到0.36g/cm^(3),聚合物细粉含量小于1%,达到商业催化剂的水平,此外负载的POP型Z-N聚丙烯催化剂具有高的立构规整选择性及宽的分子量分布,采用DIBP作为内给电子体制备的催化剂,丙烯聚合制备的聚合物等规度可达97.5%以上,分子量分布可达11以上。

丙烯等规配位聚合催化剂及电容器膜基材iPP的制备技术研究进展

生产包括电容器膜基材iPP在内高端聚丙烯的关键技术是丙烯高等规聚合的高活性催化剂和先进聚合工艺。本文详细介绍了丙烯聚合催化剂的发展历程,包括高效Ziegler-Natta催化剂、茂金属催化剂和非茂金属催化剂,指出了在合成电容器基材iPP方面此三类催化剂的优缺点。阐述了烯烃聚合催化剂的近期发展动态:产生了在催化剂结构/组成中引入强吸电子基团有利于提高催化剂活性和聚烯烃分子量的新理论,发展了新一代烯烃聚合催化剂包括内外给电子体于同一分子的丙烯聚合催化剂和全杂环金属有机催化剂,提出了制备嵌端共聚烯烃的可逆“络合-断开”配位聚合新方法。基于丙烯聚合先进工艺,结合高端电容器膜基材iPP技术指标的严苛要求,分析了聚丙烯粉料和粒料中灰分产生的主要因素,建立了在聚丙烯粉料灭活之前进入复合有机溶剂洗涤工序的生产方法,制备合格的高端电容器膜基材i PP。

两种丙烯聚合用球形Ziegler-Natta催化剂的性能研究

采用扫描电子显微镜、激光粒度仪、密度仪和熔体流动速率仪(MFR)等研究了2种丙烯聚合用球形齐格勒-纳塔(Ziegler-Natta)催化剂(记为1#和2#)的性能。结果表明:与2#相比,1#的平均粒径更小,粒径分布更宽,活性更高,对氢气更敏感,且所得聚丙烯(PP)堆积密度更高,但PP颗粒粒径较小。不同外给电子体对丙烯聚合的影响不同。采用二环戊基二甲氧基硅烷为外给电子体时,2种催化剂活性均最高,所得PP的MFR均最小。