聚偏氟乙烯的辐射效应及其温度影响

利用ＳＰＳ，红外光谱，凝胶含量测试及辐照失重等方法，研究了聚偏氟乙烯（ＰＶＤＦ）的辐射效应及其温度的影响。结果表明，在低剂量范围内，提高辐照温度，明显地有得辐交联反应。在高温下，ＰＶＤＦ中不饱和双键的形成主要是通过交或支化结构的进一步脱ＨＦ反应实现。而室温条件下，含氟自由基脱ＨＦ形成稳定的共轭多烯，也是导致双键形成的重要原因。     

粉体PVDF辐射接枝苯乙烯

以聚偏氟乙烯（PVDF）粉体为基材,采用预辐射接枝方法,在PVDF粉体上接枝聚合苯乙烯单体。并通过红外光谱、元素分析、差示扫描量热分析、热重分析对接枝后粉体进行了表征。红外光谱证明苯乙烯被成功接枝到PVDF粉体上,DSC图谱反映出结晶度随接枝率的增大而减小,接枝苯乙烯后粉体的热重图与接枝前的粉体比较也有明显的变化,进一步佐证了苯乙烯的成功接枝。     

动态测量强脉冲离子束辐照产生的冲击波

当强脉冲离子束(Intense pulsedion beam,IPIB)辐照材料表面时,在靶材料表面引发快速升温、熔融、气化、烧蚀以及随后的快速固化,并产生热应力与冲击波.本文通过构建并改进以聚偏二氟乙烯(Polyvinylidenefluoride,PVDF)膜为核心的测量系统,成功地对强脉冲离子束辐照所产生的冲击波进行了动态的探测,实验测量与我们自行开发的理论模拟计算相比较,获得较好的吻合.     

辐射PVDF／PEA共混物的熔融与结晶行为研究

ＰＶＤＦ／ＰＥＡ共混物熔融后在冰水中淬火或自然冷却，制得两种没结晶度的试样，经电子束辐照后，用示差热分析等方法研究它们熔融与结晶行为。结果表明，自然冷却试样的熔点Ｔｍ和结晶温度ＴＣ随辐照剂量的增加而降低，而熔融热焓ΔＨｆ，结晶度ＸＣ和结晶热焓ΔＨＣ随辐照剂量的增加先增加后降低。     

预辐射接枝丙烯酰胺改性PVDF粉体及其亲水性滤膜的制备

通过γ射线预辐射接枝方法将丙烯酰胺(Acryl amide,AAm)单体接枝到聚偏氟乙烯Poly(vinylidene fluoride),PVDF]粉体上,通过测定粉体接枝前后氟元素含量的变化来计算接枝率.研究了同一单体浓度下,接枝率随反应时间的变化规律,并将具有不同接枝率的改性粉体溶解在N-甲基吡咯烷酮(N-met...     

辐射接枝制备有机-无机纳米杂化粒子及其分散性能

本文采用共辐射接枝技术,在室温真空氛围中利用γ射线引发一步制备聚偏氟乙烯(PVDF)接枝改性的钛酸钡(BT)有机-无机纳米杂化粒子.通过傅里叶变换红外光谱(FTIR)、热失重分析仪(TGA)以及透射电子显微镜(TEM)对产物进行分析,证明了PVDF成功接枝在钛酸钡纳米粒子表面.利用差示扫描量热仪(DSC)与X射线衍射仪...     

γ射线共辐照接枝聚偏氟乙烯超滤膜表面亲水性研究

采用γ射线液相共辐照法对聚偏氟乙烯(Poly(vinylidene fluoride),PVDF)超滤膜进行接枝改性,研究了单体浓度、辐照剂量、链转移剂异丙醇(Isopropanol,IPA)、盐酸(Hydrochloric acid,HCl)、阻聚剂CuSO4浓度对接枝率及膜表面亲水性的影响.结果表明,在所涉实验条件下,接枝率随辐照剂量和接枝体系中单体浓度的增大,随CuSO4及IPA含量的增大而减小,改性膜表面接触角表现出相反的趋势;接枝体系中HCl的添加可以显著提高接枝率,有效降低改性膜表面接触角;改性后PVDF超滤膜表面亲水性显著提高,表面接触角由改性前的83.3°可降低至改性后的39.2°.     

预辐照聚偏氟乙烯粉体接枝甲基丙烯酸缩水甘油酯

用<'60>Co γ射线预辐照接枝法,在聚偏氟乙烯(PVDF)粉体上接枝甲基丙烯酸缩水甘油酯(GMA),制备了含有高活环氧基团的PVDF-g-PGMA粉体.结果表明,接枝率随反应时间增大,5 h后基本不变;接枝率随辐照剂量增大;单体浓度较低时接枝率随单体浓度增大,单体浓度>15%后接枝率减小;温度较低时并无接枝反应发生,温度高于30℃,接枝率随着温度增加,50℃时达最大值,温度继续升高接枝率又有所降低.傅里叶红外光谱测试表明接枝物为PVDF-g-PGMA共聚物;差热扫描量热仪分析表明,接枝粉体的熔融温度Tm以及熔融焓△Hf均随接枝率的增大而降低.对接枝粉体进行化学改性得到了多胺基吸附材料.实验证明,改性粉体材料对Cu2+有较好的吸附作用.     

偕胺肟基聚偏氟乙烯粉体对铀酰离子的吸附研究

通过批量吸附实验研究了辐射接枝技术制备的偕胺肟基聚偏氟乙烯(PVDF-g-PAO)粉体对低浓度铀酰离子的吸附行为,考察铀酰离子初始浓度、温度、pH值对吸附行为的影响。结果表明,PVDF-g-PAO粉体对低浓度铀酰离子的吸附较快,约180 min达动态平衡,吸附过程符合准二级动力学模型和Freundlich等温吸附模型,吸附反应是熵增加的吸热反应。体系pH值对铀酰离子吸附率影响表明,pH值在5?8范围内时,吸附率变化不大,偕胺肟基材料比较适合海水环境下的吸附,同时发现对材料上已吸附铀酰离子可用酸或碱溶液脱附。     

γ射线辐照聚偏氟乙烯接枝苯乙烯磺酸乙酯

以聚偏氟乙烯(Polyvinylidene fluoride,PVDF)树脂为基材,采用γ射线预辐射接枝法在PVDF树脂上接枝苯乙烯磺酸乙酯(Ethyl styrenesulfonate,ETSS),探讨吸收剂量、接枝温度、接枝反应时间及单体浓度对接枝率的影响。之后在95℃水解PVDF-g-PETSS聚合物得到PVDF接枝苯乙烯磺酸(PVDF-g-PSSA)离子交换树脂。红外光谱、X射线光电子能谱、热重分析证明PVDF-g-PETSS及PVDF-g-PSSA被成功制备。当接枝率为120%时,PVDF-g-PSSA的离子交换容量达到2.05 mmol/g。这种将带有磺酸基团的单体通过辐照接枝引入PVDF基材然后水解的方法简单、高效、污染小,有望在离子交换树脂及离子交换膜的制备中得到应用。     

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).     

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.     

PVDF粉体预辐照接枝甲基丙烯酸缩水甘油酯制备锂离子二次电池隔膜研究

以聚偏氟乙烯（PVDF）粉体为基材,采用预辐照接枝方法,在PVDF粉体上用乳液聚合接枝甲基丙烯酸缩水甘油酯（GMA）,并采用溶液铸膜的方法制备了PVDF-g-PGMA膜。利用红外光谱（FTIR）,扫描电子显微镜（SEM）,压汞仪,电导率测试等分析表征手段对制备的PVDF—g-PGMA膜进行了表征。在氩气手套箱中组装成扣式电池,在电池测试系统上测试扣式电池的充放电循环性能。测试结果表明,在相同制备条件下,以PVDF-g-PGMA作为隔膜的锂离子电池性能优于以PVDF作为隔膜的锂离子电池性能。     

Plasma Induced Grafting of PMMA onto Titanium Dioxide Powder

Grafting of polymer of methyl methacrylate （PMMA） onto titanium dioxide powder is investigated in this paper. The graft polymerization reaction is induced by dielectric-barrier- discharge produced N2 plasma treatment of titanium dioxide surfaces. IR, XPS and TGA results show that PMMA is grafted onto the surfaces of titanium dioxide powder. And crystal structure of the titanium dioxide powder observed with XRD spectra is unchanged after plasma graft polymerization.     

Radiation-chemical synthesis of polypropylene fabrics with sulfonic acid functional groups

A sorption-active material carrying sulfonic acid groups was synthesized by the radiation-induced graft polymerization of styrene monomer onto the surface of non-woven polypropylene fabric, followed by sulfonation of the grafted polystyrene chains. The effect of the main experimental parameters (absorbed dose, monomer concentration, reaction time) on the styrene degree of grafting was investigated. The sulfonation process with 5% chlorosulfonic acid at room temperature was investigated in detail and the optimal sulfonation conditions for the samples with a medium degree of grafting (70-140%) were determined. Densities of 3.5-5 meq/g were obtained by applying those sorption-active PP fabrics with a sulfonic acid group.     

Development of sulfonated FEP-Nafion hybrid proton exchange membranes for PEFC

The performance of polymer electrolyte fuel cell (PEFC) is affected by an interfacial property between a proton exchange membrane (PEM) and electrodes. Thus, to develop a well-laminated membrane electrode assembly (MEA), a hybrid PEM (FN) was fabricated by mixing a radiation grafted membrane (sulfonated FEP) with ionomer (Nafion^® dispersion) which is applied to coat the interface of the PEM and electrodes.The obtained FN, sulfonated FEP and Nafion^®112 were characterized in terms of water uptake, ion exchange capacity (IEC), polarization performance and electrochemical impedance. FN showed high IEC and water uptake, which would induce the highest ionic conductivity (IC) among tested PEMs. In terms of FN, the interface between the PEM and electrodes should have been improved because FN showed the lowest charge transfer resistance than other tested PEMs. The high IC and improved interface between the PEM and electrodes resulted in the best cell performance of FN in tested PEMs.     

Proton exchange membranes prepared by radiation-induced graft copolymerization from binary monomer mixtures onto poly(tetrafluoroethylene-co-hexafluoropropylene) film

Sulfonic acid proton exchange membranes based on a poly(tetrafluoroethylene-co-hexafluoropropylene) film were synthesized through the single-step graft copolymerization of sodium styrenesulfonate and acrylic acid monomers from binary monomer aqueous solutions using the electron beam pre-irradiation method in air. The effects of the various polymerization parameters (absorbed dose, reaction time, and monomer ratio) on the degree of grafting were studied.A correlation between the degree of grafting and some of the physical-chemical properties (water uptake and ion-exchange capacity) of the synthesized copolymers was established. The distribution of the sulfonic acid groups was investigated across the thickness of several membranes in order to gain a better understanding of the graft copolymerization process from binary monomer aqueous solutions onto the fluorinated film and to synthesize membranes with optimal physical-chemical properties.