Preparation of a new anion exchanger by pre-irradiation grafting technique and its adsorptive removal of rhenium(Ⅶ) as analogue to ^(99)Tc

A new anion exchanger with pyridine groups was prepared by grafting of 2-vinyl pyridine onto polypropylene(PP) nonwoven fabrics by pre-irradiation grafting technique, followed by quaternization of pyridine rings in grafted chains in reaction with bromoethane. The results showed that the grafting yield increased with the monomer concentration and conversion ratio of quaternization increased with the time. The grafted and quaternized fabrics were characterized by FT-IR, DSC, SEM and ICP. The possibility of adsorption of perrhenate(ReO–4), a nonradioactive analogue to pertechnetate(99TcO–4), from aqueous solution by anion exchanger was investigated. The experiments performed at pH= 0.1–6 showed that p H = 2.2 was the optimal acidity for ReO–4adsorption, and an adsorption equilibrium was achieved in 30 min. The reaction enthalpy was-12.55 k J/mol,indicating that the adsorption process is exothermic. XPS tests indicated that the Re O–4uptake was a typical ion exchange between Cl–on anion exchanger and ReO–4.

Graft co-polymerization of maleic acid and vinyl acetate onto poly(vinylidene fluoride) powder by pre-irradiation technique

Binary monomers of maleic acid and vinyl acetate are grafted onto poly(vinylidene fluoride) (PVDF) powder by pre-irradiation induced graft polymerization technique in emulsion solution. The co-grafting of binary monomers is successfully proved by FT-IR spectroscopy analysis. The influences of the absorbed dose, reaction temperature, reaction time, total concentration of monomers, and feed ratio of binary monomers on the degree of grafting are investigated. The thermal property of grafted PVDF powder was characterized by differential scanning calorimetry (DSC) and thermo-gravimetry analysis (TGA).

Humidity Sensing Properties of Pre-irradiation Grafted HDPE Membranes

Grafted high density polyethylene (HDPE) films have been prepared by grafting sodium styrene sulfonate (SSS) and acrylic acid (AA) onto HDPE using preirradiation method.The structure and surface morphology of both grafted and ungrafted HDPE films were observed by FTIR spectroscopy and scanning electron microscope (SEM),respectively.The humidity sensing properties of grafted HDPE films were investigated.The results show that the impedance of the film decreases with increasing of relative humidity (RH).The films display high sensitivity with nearly three orders of magnitude change in the resistance during the relative humidity variation from 5% to 98%.Grafted HDPE films exhibit excellent properties as humidity sensors.

Grafting Copolymerization of Styrene and Acrylic Acid onto Pre-irradiated Polypropylene Fabric

Grafting copolymerization of styrene and acrylic acid onto polypropylene fabric had been studied by using a pre-irradiation technique. The polypropylene fabric Samples were irradiated by Y-ray and electron beam under the conditions of air and nitrogen gas, respectively. The effect of absorbed dose, monomer concentration in solvent, reaction temperature and reaction time on the degree of grafting were determined. The effects of metallic salts and sulphuric acid on the grafting yield of acrylic acid were also examined. The samples irradiated by electron beam give a much higher degree of grafting than those by Y -ray when styrene was grafted to polypropylene fabric. However, the grafting yield of acrylic acid on polypropylene fabric in the presence of metallic salts and sultric acid showed the opposite results from the case of styrene. This effect is reasonably interpreted by assuming that the grafting is dominated by trapped radicals and peroxides in pre-irradiated polypropylene.

Determining the degree of grafting for poly(vinylidene fluoride) graft-copolymers using fluorine elemental analysis

Acrylic acid (AAc) and styrene (St) were grafted onto poly(vinylidene fluoride) (PVDF) powder or membrane samples by pre-irradiation graft copolymerization.The grafted chains were proved by FT-IR spectroscopy analysis.The degree of grafting (DG) of the grafted PVDF was determined by fluorine elemental analysis (FEA) method,and was compared with the DGs determined by weighing method,acid-base back titration method and quantitative FT-IR method.The results show that the FEA method is accurate,convenient and universal,especially for the grafted polymer powders.

Synthesis of Amine-type Adsorbents with Emulsion Graft Polymerization of 4-hydroxybutyl Acrylate Glycidylether

Radiation induced graft polymerization on polymeric matrix followed by functionalization is widely accepted for the preparation of metal adsorbents. In this paper, a pre-irradiation method was used for emulsion graft polymerization of 4-hydroxybutyl acrylate glycidylether (4-HB) onto polyethylene/polypropylene (PE/PP) nonwoven fabric. The degree of grafting (Dg) which can be calculated by weight increment was determined as a function of reaction time, irradiation dose, and monomer concentration. After 30 kGy irradiation, with 4-HB concentration of 5%, surfactant Span 20 of 0.5% at 40°C for 2 h, the trunk polymer was made grafted at a Dg of 135%. 4-HB-grafted PE/PP nonwoven fabric was modified by ethylenediamine (EDA) in isopropyl alcohol (IPA) as a solvent at 60°C. With a Dg of 135%, the amine group density of the adsorbent is 2.8 mmol/g. The adsorption test was carried out by batch experiment in several metal ion solutions, and the removal ratio from the EDA modified adsorbent of the metal ions is in the order of Cu2+ > Pb2+ > Zn2+ > Ni2+ > Li+. Compared with glycidyl methacrylate (GMA) which is a typical functional monomer for graft polymerization, 4-HB-grafted adsorbent exhibited not only better mechanical property but also higher adsorption capacity of Cu2+ and Pb2+.

Preparation and characterization of proton exchange membranes from polystyrene grafted poly(vinylidene fluoride) powder

Proton exchange membranes(PEMs)were prepared in three steps:grafting of polystyrene onto PVDF powder using pre-irradiation graft polymerization technique,processing the grafted PVDF powder into membranes of around 50-μm thickness,and sulfonating them with cholorosulfonic acid to form poly(vinylidene fluoride)-g-poly(styrene sulfonic acid)membranes.Kinetics of the graft polymerization was studied.The existing of polystyrene side-chains in the grafted PVDF powders,and PSSA groups in PEMs,were proved by FT-IR.Properties of the PEMs,i.e.the ion exchange capacity,water uptake,proton conductivity,thermal property and oxidative stability, were characterized.Dependence of properties on the degree of grafting was investigated,too.

^(60)Coγ射线预辐照制备淀粉-丙烯酰胺接枝物

采用预辐照的方法研究了淀粉与丙烯酰胺的接枝反应，制备出了淀粉与丙烯酰胺的接枝物；采用元素分析法测量了接枝率。对预辐照接枝反应的一些影响因素，如吸收剂量、反应温度、反应时间、阻聚剂及辐照后效应也进行了研究，并获得了相关结果。淀粉预辐照的吸收剂量约１０ｋＧｙ，辐照后 １０ｍｉｎ内在 ２５～３０℃下进行接枝可以获得 ８０％以上的接枝率。

预辐射接枝四氟乙烯-乙烯共聚物湿敏膜的制备及特性研究

利用2 MeV电子加速器,在常温下采用预辐照引发接枝的方法,在四氟乙烯-乙烯共聚物(ETFE)上接枝丙烯酸(AA)和对苯乙烯磺酸钠(SSS),制备了一种含羧酸基团和磺酸基团的接枝膜.傅里叶变换红外光谱(FTIR)分析结果证明了磺酸基团和羧酸基团的成功引入,并对接枝膜的热力学和化学特性进行了研究.结果表明,随着接枝率的增加,接枝膜的结晶度逐渐降低,接触角逐渐减小,接枝膜的亲水性逐渐增强.利用制备的接枝膜构建了电阻型湿度传感器,并测定了传感器的电学特性.在相对湿度(RH)从5%变化到98%时,传感器电阻线性变化范围接近4个数量级,具有响应速度快(吸附<1 min,解吸<2 min),湿滞小(<2%RH)的特点.

预辐射引发气相接枝法制备PE-g-PAN材料

氰基是一类化学活性较高的基团,可以制备各种配位基团。接枝聚丙烯腈是引入氰基的主要方法之一。本文利用γ射线预辐射气相接枝的方法将丙烯腈接枝聚合到聚乙烯(PE)无纺布上,系统地研究了接枝率在不同温度、时间和吸收剂量时的变化规律。通过傅里叶变换红外光谱仪(Fourier transform infrared spectroscopy,FTIR)、拉力、扫描电子显微镜(Scanning electron microscope,SEM)、接触角等表征了样品的理化性能。结果证明,通过预辐射气相接枝方法可以成功的将丙烯腈接枝聚合到聚乙烯无纺布上;接枝聚丙烯腈后,无纺布的接触角会略有提高;无纺布受辐照后,机械性能下降,而接枝聚丙烯腈对无纺布的机械性能影响较小。

交联聚苯乙烯-二乙烯基苯与丙烯腈的辐照接枝

聚苯乙烯系列的树脂颗粒有很强的耐辐照性，采用预辐照法所需剂量很大。苯环有共轭π结构，它的π电子是非定域的，辐射时苯基吸收的能量虽然足以使键断裂，但由于能量很快在整个分子重新分布，把能量集中于某一键使其断裂几率是很低的，所以采用预辐照接枝法所需的吸收剂量很大，相关的研究报道很少。本工作主要就共辐照和预辐照接枝聚合丙烯腈的方法进行了讨论。

修饰性产物SDB-g-MMA与丙烯腈单体的辐射接枝

以共辐照接枝共聚物SDB-g-MMA为基材,利用γ射线在空气中对SDB-g-MMA进行预辐照,然后在场外接枝丙烯腈单体,获得了SDB-g-MMA-AN材料。通过FT-IR分析和接枝率测定,确认了预辐照接枝反应的进行。XRD和SEM分析结果表明,丙烯腈侧链的引入对材料的整体结构有序度具有显著影响。探讨了SDB-g-MMA二次辐照过程中的降解与氧化反应机理,获得了预辐照接枝产物SDB-g-MMA-AN的结构模型。

聚乙烯膜表面辐射接枝甲基丙烯酸-4,5-二甲氧基-2-硝基苯甲酯实现光敏化

通过预辐射接枝方法将光敏性单体甲基丙烯酸-4,5-二甲氧基-2-硝基苯甲酯(DMNBMA)以共价键方式接枝到聚乙烯(PE)表面。系统地研究了辐射接枝动力学,考察了吸收剂量、反应温度、反应时间、单体浓度等因素对接枝率的影响。通过红外光谱(FT-IR)对接枝后材料的化学结构进行了表征,结果表明DMNBMA成功接枝到PE上。用紫外光对接枝后样品PE-g-PDMNBMA进行照射,使接枝链上的光敏基团4,5-二甲氧基-2-硝基苯甲酯发生光解反应而转化为羧基,红外表征证明了光解反应成功进行,同时接触角测试证明材料经紫外光照后由疏水变成了亲水。辐射接枝DMNBMA可以成功实现对材料表面的光敏化修饰。

乙烯-醋酸乙烯共聚物接枝聚苯乙烯的制备及性能

采用预辐照与悬浮接枝聚合技术制备了乙烯-醋酸乙烯共聚物(EVA)接枝聚苯乙烯共聚物(EVA-g-PS)。利用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、差示扫描量热和透射电子显微镜、力学性能测试、高温老化试验等对EVA和EVA-g-PS的结构、性能进行了研究。结果表明,在EVA-g-PS的FT-IR谱图中,700cm^-1、755cm^-1、1480cm^-1、1602cm^-1及3060cm^-1处都出现了吸收峰,而且在EVA-g-PS的1H-NMR谱图的化学位移δ6~8之间有5组峰出现,均可证明聚苯乙烯(PS)与EVA接枝成功;随着接枝率提高,接枝物结晶能力及高温稳定性降低;当接枝率为76.7%时,接枝物中双键明显增多,粒径分布一致,说明PS分布均匀;相比于EVA,接枝物的抗老化性及加工性能均得到提高。

蚕丝绸的γ-预辐照接枝整理研究

用N-羟甲基丙烯酸胺(NMA)研究了蚕丝绸的γ-预辐照接枝规律及其影响因素,完成了γ-预辐照接枝的应用实验.考察了γ-预辐照接枝NMA对蚕丝绸抗皱性能的改善情况,同γ-共辐照接枝效果作了一定的比较。

PP预辐射接枝丙烯酸酯的研究

用预辐射方法在 Ｐ Ｐ上接枝丙烯酸乙酯，详细研究了辐射总剂量、单体浓度、溶剂、反应时间、反应温度等因素对接枝率的影响规律，并用红外光谱（ Ｆ Ｔ Ｉ Ｒ）对产物进行表征。实验表明，随着辐射总剂量的增加， Ｐ Ｐ的接枝率持续增加，在９ Ｍｒａｄ 时达到最高点，然后，随着辐射总剂量的进一步增加，接枝率缓慢下降。当反应温度为１１０ ℃时， Ｐ Ｐ的接枝率最高。 Ｄ Ｓ Ｃ表明 Ｐ Ｖ Ｃ／ Ｐ Ｐｇ Ｐ Ｅ Ａ 的相容性好于 Ｐ Ｖ Ｃ／ Ｐ Ｐ的。

预辐照聚丙烯接枝研究状况

综述了预辐照聚丙烯(Polypropylene,PP)接枝法,介绍了预辐照接枝方法的性质、反应机理、特点、应用及辐射降解的防止;PP预辐照接枝带有功能基团的单体,能改变其染色性﹑粘接性﹑抗静电性﹑亲水性等,使PP得到更广泛的应用。

电子束预辐照聚丙烯与丙烯酸的接枝共聚合

应用电子束预辐照的方法对丙烯酸与等规聚丙烯粉末的接枝共聚合进行了研究．讨论了辐照剂量、储藏时间、反应温度、Ｍｏｈｒ’ｓ 盐浓度及单体浓度等因素对接枝率的影响（ 所有的实验，辐照及接枝聚合等都是在有氧的条件下进行的） ．同时对接枝材料对金属离子的吸附性能作了初步的探讨．结果表明，接枝聚合可以在有氧的条件下顺利进行．接枝材料在离子吸附方面有较大的应用前景．

预辐照聚丙烯悬浮接枝聚苯乙烯的制备及结构性能

通过预辐照和悬浮接枝技术制备聚丙烯接枝聚苯乙烯(PP-g-PS)。利用红外光谱、核磁共振、X射线衍射、差示扫描量热分析、旋转流变仪及高压击穿实验对PP-g-PS的结构和性能进行了表征。结果表明,PP-g-PS的FT-IR在1493cm^(-1),1601 cm^(-1)和3027 cm^(-1)处出现了新的吸收峰,其中1601 cm^(-1)和3027 cm^(-1)分别为PS苯环上C=C和C-H的特征吸收峰;1H-NMR在1.2,1.4和2.0位置处出现新的化学位移峰,在δ7.1和7.2处出现2组峰,这是PS苯环上氢的化学位移,证明PS已接枝到PP的大分子链上。与PP相比,PP-g-PS的熔融温度和结晶度降低,结晶温度升高;随接枝率增大,PP-g-PS的结晶温度升高;PP-g-PS的耐电压击穿性能好,其击穿场强可达PP的1.4倍。

硅橡胶膜上NIPAAm预辐射接枝机理研究

采 用预辐射 方式将 Ｎ Ｉ Ｐ Ａ Ａｍ 接枝到 硅橡胶上 ，结果表 明：接枝反 应 是由 样品 在空 气中辐照生 成的过 氧化物（ 主 要是氢 过氧化物） 引发的 ，并且仅 在较 高温 度下 接枝 才能 进行。 研究 了过氧化物 的产生 和分解，计 算出过 氧化物分 解的活 化能为２７ ２ｋ Ｊ／ ｍ ｏｌ 。 通过 对接 枝反 应动 力学 的研究表明 ，接枝反 应的活化 能较低 ，约５４７ ｋ Ｊ／ ｍ ｏｌ 。讨 论了接枝 反应机理 。