改性罗布麻纤维的吸附功能研究

以Ce~(4+)引发丙烯腈与罗布麻纤维接枝共聚反应,用红外光谱表征了接枝纤维的结构。并探讨了接枝纤维皂化物时汞离子的吸附性能。C_(AN)为1.2×10~(-1)mol/L、C_(Ce)~(4+)为10×10~(-3)mol/L时接枝率较高,该接枝共聚物经皂化后能有效地吸附汞离子,pH值在10～11时吸附率最高,达0.583mg Hg~(2+)/g。     

含季铵基离子交换纤维的制备研究

以辐射接枝丙烯酸(AA)后的聚丙烯(PP)无纺布(PP-g-AA)为基材,采用紫外引发的方法接枝甲基丙烯酰氧乙基三甲基氯化铵(DMC),建立了一种制备阴离子交换纤维的新方法,得到了PP-g-AA-DMC纤维.研究了丙烯酸接枝率、DMC浓度、溶剂种类、光照时间,浸泡时间等因素对DMC接枝率的影响,结果表明,DMC的接枝率随着丙烯酸接枝率、DMC浓度、光照时间和纤维浸泡时间的增加而增大.接枝前后纤维的红外光谱分析表明,DMC被成功接枝在PP-g-AA基材上.吸附性能测定结果表明,纤维对水中以阴阳离子存在的金属铬均具有较好的吸附性能.     

聚四氟乙烯强酸性阳离子交换纤维的制备研究

采用共辐射引发将苯乙烯接枝到聚四氟乙烯(PTFE)纤维上,然后磺化制备出强酸性和超强酸性离子交换纤维,接枝率随苯乙烯单体浓度和辐射剂量增加而提高,随辐射剂量率的增加而降低,当接枝率为20%左右时,PTFE-co-St-SO3H离子交换纤维的Hammett酸度函数低于-11.99,呈现出超强酸性。     

纤维素纳米纤维接枝聚(N-异丙基丙烯酰胺)水凝胶的制备与表征

将具有温度响应的聚N-异丙基丙烯酰胺(PNIPAm)接枝到电纺纤维素纳米纤维膜上,制备温度响应型纤维素接枝聚N-异丙基丙烯酰胺(PNIPAm-g-Cell)纳米纤维水凝胶。 研究接枝单体(N)与纤维素(c)的质量比、反应温度、反应时间和引发剂浓度对产物接枝率、溶胀性和形貌的影响。 结果表明,最佳聚合反应条件为m(N):m(c)=15:1、反应温度40 ℃、反应时间3 h、引发剂浓度为10 mmol/L,得到PNIPAm-g-Cell接枝率和溶胀率分别为35%和31%。 与PNIPAm相比,PNIPAm-g-Cell水凝胶的低临界相转变温度(LCST)显著升高,说明亲水性纤维素的引入改变了体系的亲疏水平衡。 去溶胀动力学测试表明,0.5 min内接枝率为25%和35%的水凝胶保水率分别降低至93%和61%。 说明接枝率越高PNIPAm-g-Cell水凝胶对温度的响应速度越快,对温度越敏感。     

一缩二乙二醇二甲基丙烯酸酯接枝真丝的结构

通过电子扫描电镜 (SEM)、红外光谱 (IR)、双折射、X 射线衍射及氨基酸分析等手段 ,研究了真丝用一缩二乙二醇二甲基丙烯酸酯 (P 2 )接枝后其结构与接枝率之间的关系 .氨基酸分析结果表明P 2接枝主要在真丝大分子中酪氨酸、丝氨酸、组氨酸和精氨酸的NH2 、OH和—NH—活性基团上 .通过X 射线衍射分析 ,P 2接枝并不直接影响结晶区 ,但引起分子取向的下降 ,接枝后真丝双折射下降说明接枝后因大分子取向度下降 ,接枝真丝的红外光谱显示出真丝具有 β折迭结构和P 2高聚物的结构特征峰 ,从而说明P 2接枝在纤维的无定型区内部进行 .当接枝率大于 35 %时 ,纤维的表面覆盖了一层高聚物 (P 2 ) ,并且纤维的横截面表现出明显的分纤现象 ,接枝真丝的红外光谱表明了纤维与P 2重叠吸收峰 ,说明了P 2在丝纤维内部接枝聚合 .     

辐射接枝苯乙烯和磺化对聚四氟乙烯强酸性纤维力学性能的影响

采用共辐射引发将苯乙烯接枝到聚四氟乙烯(PTFE)纤维上后,然后磺化可以制备出强酸性离子交换纤维PTFE-g-St-SO3H.辐射、磺化和氧气可以使纤维力学性能大幅度下降,当接枝率较低时,断裂强度高于原纤维,随着接枝率的增大,断裂强度呈下降趋势.轻度交联能够改善纤维的力学性能,但是对纤维力学性能的影响比接枝率小.断裂强度与磺化率关系不大,主要受磺化反应温度影响,反应温度越高,断裂强度越低,断裂伸长率也相应较低.磺化后模量大幅度降低,断裂伸长率和屈服伸长率显著增大,断裂强度明显降低,纤维韧性提高.采用氮气保护,控制适当接枝率和较低磺化反应温度可以得到力学性能较好的PTFE基强酸性离子交换纤维.     

聚烯烃纤维表面光接枝的ESCA表征

以320—440nmUV为光源,二苯甲酮(BP)为光引发剂,丙烯酸(AA)和丙烯酰胺(AM)为单体,在高强度聚乙烯(HSPE)纤维上进行光引发接枝反应。由于纤维,表面接枝仅发生在小于50A的极薄层内,这样的表面接枝率不可能用通常的称重法测定,因而无法用通常意义的重量接枝率来表征。本文对表面接枝纤维用X射线光电子能谱(ESCA)进行分析测试,以谱中氮(或氧)原子1s内壳层电子和碳原子1s内壳层电子谱线的积分强度相对比值来表征接枝程度。傅里叶红外(FTIR)内反射光谱的测试结果,以及对接枝纤维进行的染色性和粘接性测试表明,用ESCA的上述积分强度相对比值(RI％)来半定量表征接枝程度是合宜的。     

丙烯酸酯类与亚麻纤维接枝共聚反应的研究

Abou-Zeid等人曾报道以Fe(~2+)-H_2O_2体系引发丙烯腈等单体与黄麻纤维的接枝共聚反应,Misra等人报道了以S_2O_8_2-TU为引发体系,甲基丙烯酸甲酯与黄麻纤维的接枝共聚,最近,我们报道了以Ce(Ⅳ)引发甲基丙烯酸甲酯、丙烯酸乙酯(EA)分别与苧麻及亚麻纤维的接枝共聚。亚麻纤维与丙烯酸酯类单体接枝改性后,仲长率有所提高,加强了结合力,改善了成纱品质,因此引起人们的重视。本文以过硫酸钾-硫脲(KPS-TU)为引发体系,研究丙烯酸甲酯(MA)、EA及丙烯酸丁酯(BA)与亚麻纤维的接枝共聚反应规律,用IR、SEM、X射     

高分散性SiO2/PMMA复合材料的制备与表征——SiO2在纤维内的分散

将复杂接枝(接枝率为1540.3％)、简单接枝(接枝率为484.4％)和未接枝3种具有不同接枝交联结构的SiO2/聚甲基丙烯酸甲酯(PMMA)复合材料作为无机预分散母料,通过与PMMA树脂的溶液共混,制得一系列PMMA/SiO2/N,N-二甲基甲酰胺(DMF)高分子溶液,再将其应用于静电纺丝制备相应的电纺复合纤维.发现,只有简单接枝复合材料所制共混高分子溶液具有较好的可纺性,且通过纺丝工艺和配方的改变,即可较方便地调控电纺纤维的尺寸和SiO2含量.进一步通过粒度分析(DLS)、扫描电镜(SEM)和透射电镜(TEM)考察SiO2在高分子溶液和电纺复合纤维内的分散状态;通过超声水洗、氢氟酸刻蚀并结合马弗炉锻烧实验,定量评估SiO2在电纺复合纤维体系各部分中的分布情况.结果表明,通过上述简单过程,即可较方便地实现绝大部分简单接枝SiO2在PMMA/DMF高分子溶液和PMMA电纺纤维内初级粒子形式的高度均匀稳定分散.     

羊毛纤维接枝季铵盐的化学改性及其抗菌性能研究

通过化学引发接枝的方法,以含季铵基的烯类单体接枝羊毛纤维,制备了一类抗菌羊毛纤维。探讨了反应体系pH值、引发剂浓度、反应时间、温度、单体浓度和浴比等因素对羊毛纤维接枝率的影响,并优化了接枝工艺。其中,单体浓度、化学引发剂过氧化氢与抗坏血酸的浓度是影响羊毛纤维接枝率的关键因素。高单体浓度在增大接枝率的同时,还形成了大量的均聚物;而高过氧化氢浓度在促进接枝的同时,会造成了羊毛纤维的降解。接枝羊毛纤维的抗菌性能及耐洗涤性能测试表明,接枝率大于4%的羊毛纤维具有良好的抗菌性能,对大肠杆菌、金黄色葡萄球菌、白色念珠菌的抗菌率均大于99.9%;抗菌羊毛纤维经20次洗涤后,仍能保持良好的抗菌性能。     

Surface treatment of PET fiber by EB-irradiation-induced graft polymerization and its effect on adhesion in natural rubber matrix

Aiming to develop a high performance fiber-reinforced natural rubber (NR) without using resorcinol formaldehyde latex (RFL) adhesives of environmental load substances, a special technique using electron beam (EB) irradiation-induced graft polymerization was applied to high-modulus polyethylene terephthalate (PET) fibers. Although PET is chemically inert, acrylate functional silane could be graft-polymerized onto the PET fiber surface by this special technique. The composite of NR and grafted PET fibers indicated a linear increase in the initial modulus with the fiber content. The fiber reinforced rubber with a good performance was obtained in the system of NR and grafted PET fibers.     

高强聚乙烯纤维的冷等离子体改进

高强聚乙烯纤维的冷等离子体改进金士九，倪亦斌，张佐光（中国科学院化学研究所北京１０００８０）（北京航空航天大学北京）关键词　高强聚乙烯纤维，等离子体，表面改性，界面性能由高强聚乙烯纤维制成的复合材料抗高速撞击（抗弹）性能远远优于芳纶纤维，广泛用作各种...     

MODIFICATION OF SILK FIBER via EMULSION GRAFT COPOLYMERIZATION WITH FLUOROACRYLATE

2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed by FTIR and WAXD,and the results revealed that the fluoroacrylate was successfully grafted onto silk fiber and the crystalline structure of silk fibroin withβ-sheet structure was not changed after graft copolymerization.The FT-IR corrected method was used to simulate the grafting yield onto ...     

Atom transfer radical polymerization from cellulose fibers at ambient temperature

Cellulose fibers have been successfully grafted with poly(methyl acrylate) using atom transfer radical polymerization, mediated by Me6-TREN and Cu(I)Br at ambient temperature. The initially hydrophilic cellulose was first modified by reacting the hydrozyl groups with 2-bromoisobutyryl bromide whereupon methyl acrylate was grafted from the surface. The resulting polymer-grafted papers were extremely hydrophobic, thetaa = 133 degrees . FT-IR analysis indicates that the amount of grafted polymer can be controlled by adding sacrificial initiator to the polymerizing system. Size exclusion chromatography of the bulk polymer revealed narrow polydispersities and a molecular weight corresponding to the ratio [M]:[I].     

Poly(meth)acrylate grafted EPDM via reverse atom transfer radical polymerization: A single pot process

This investigation reports a one pot preparation of poly(meth)acrylate grafted EPDM via reverse ATRP and evaluation of their physical and mechanical properties. The graft copolymerization of 2-ethylhexyl acrylate and methyl methacrylate was carried out from EPDM using reverse ATRP in toluene at 90 °C using CuBr₂ as catalyst in combination with PMDETA as ligand and AIBN as thermal initiator. The grafted EPDMs were separated from the reaction mixture, purified and then characterized by FT-IR, ¹H NMR, DMA and TGA analyses. Surface energies and tensile properties were evaluated by Goniometer and UTM respectively. Acrylate grafted EPDMs showed better thermal stability, better tensile property, whereas methacrylate grafted EPDMs showed higher surface energy and better oil resistance property than the pristine EPDM. Surface morphologies of grafted EPDMs were analyzed by AFM and SEM analyses. This one pot grafting approach led to very high grafting percentage without undesirable homopolymerization and gelation.     

Surface modification of polymers. III. Grafting of stabilizers onto polymer films

Polypropylene, polystyrene, and polyethylene have been grafted with glycidyl acrylate and glycidyl methacrylate. After 5 min of grafting with UV irradiation, polystyrene was extensively grafted to 91% coverage of glycidyl acrylate according to ESCA, while polypropylene was grafted to only 50% coverage. With glycidyl acrylate the grafting depth is estimated to be 0.1 μm for PP and 0.23 μm for PS. Glycidyl methacrylate is grafted in a thinner layer than glycidyl acrylate. The stabilizers 2,4-dihydroxybenzophenone, phenyl 4-aminosalicylate, and 4-amino-2,2,6,6-tetramethylpiperidine were attached to LDPE surfaces containing grafted glycidyl acrylate by opening of the epoxide bond. The reaction between epoxide and stabilizer is diffusion controlled at high concentrations of stabilizer. UV spectroscopy on an LDPE film grafted and reacted with 2,4-dihydroxybenzophenone showed that 227 nmol stabilizer/cm² was bound to the surface.     

Enhanced mechanical properties of carbon fiber composites by grafting different structural poly(amido amine) onto fiber surface

The mechanical properties of carbon fiber composites depend on the interfacial strength between fiber and epoxy matrix. Different poly (amido amine) (PAMAM) dendrimers were grafted onto carbon fiber to improve the interfacial strength of the resulting composites. Functional groups on the carbon fiber surface were examined by X-ray photoelectron spectroscopy. The surface morphology of the resulting materials was characterized by scanning electron microscopy and atomic force microscope. The characterization results revealed that PAMAM dendrimers were chemically grafted onto the surface of carbon fiber. More importantly, the mechanical properties of the resulting composites were enhanced owing to the presence of sufficient functional groups on the carbon fiber surface. In addition, after PAMAM containing chair conformations were grafted, the interlaminar shear strength had the highest increase of 53.13%, higher than that of the fiber grafted with PAMAM containing terminated linear amine. This work provides an alternative approach to enhance the mechanical properties of fiber composites by controlling the interface between fiber and epoxy matrix.     

Control of the electrical conductivity of composites of antimony doped tin oxide (ATO) nanoparticles and acrylate by grafting of 3-methacryloxypropyltrimethoxysilane (MPS)

The effect of the addition of antimony doped tin oxide (ATO) nanoparticles on the electrical conductivity of acrylate films is described. To enable dispersing of ATO in acrylate matrices, 3-methacryloxypropyltrimethoxysilane (MPS) was grafted on the surface of the filler. The amount of MPS used for this surface modification was found to strongly affect the electrical conductivity. Surface modification with a large amount of MPS resulted in colloidally stable dispersions of ATO, leading to a homogeneous distribution. Surface modification with small amounts of MPS led to instable ATO dispersions and aggregation of ATO into a fractal type network, which gives a much higher conductivity especially at low-volume fractions. For composites with a fractal type ATO network a second effect was found. Decreasing the amount of on ATO grafted MPS resulted in an increase of the electrical conduction between the ATO particles.     

Generation of radical species on polypropylene by alkylborane‐oxygen system and its application to graft polymerization

Graft polymerization of ethyl acrylate and n‐butyl acrylate onto surface of polypropylene (PP) beads (diameter: 3.2 mm) were carried out by using a redox system composed of triethylborane (Et₃B) and molecular oxygen in air. The amounts of the grafted polymers increased by prolonging a period of soaking PP beads in a solution of Et₃B in hexane, a less polar solvent of which affinity with PP would be higher than that of tetrahydrofuran, a highly polar solvent. These results implied that the present graft polymerization involved: (1) interpenetration of Et₃B into the surface area with the aid of hexane as a solvent, (2) its aerobic oxidation to generate a radical species, (3) abstraction of proton from PP by the radical species, and (4) initiation of polymerization from the resulting radical on the PP surface. Besides the acrylates, acrylic acid, and glycidyl methacrylate were also grafted onto the surface of PP to endow it with carboxyl and epoxy moieties, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6163–6167, 2009     

Direct Polymerization of Polyacrylic Acid on Mica Substrates using ATRP – A Preliminary Study

Summary: Unprecedented direct polymerization of sodium acrylate (NaA) on mica and silica substrates was undertaken using standard ATRP polymerization conditions at room temperature. The resulting thickness of the poly(sodium acrylate) (PNaA) grafted layer was determined using ellipsometry and AFM.