硅橡胶膜辐射接枝中酸效应的研究——Ⅰ.与丙烯酸共辐射接枝反应

本文以硅橡胶为基材深入研究了与丙烯酸共辐射接校中的酸效应。结果表明,甲醇-丙烯酸与硅橡胶共辐射接枝体系中酸效应在不同吸收剂量范围是不同的。<5kGy时酸有敏化作用,在5—13kGy范围酸有相反的效果。在所有剂量范围内单体浓度、剂量率等因素对辐射接枝反应的酸效应无明显影响。除吸收剂量外,酸效应还与基材组成、单体与溶剂类型以及接枝方法等多种因素有关。     

A study on the distribution of polystyrene sulfonic acid grafts over the cross-section of a PFA film

In this study, the distribution behaviors of polystyrene sulfonic acid (PSSA) grafts over the cross-section of grafted PFA membranes (PFA-g-PSSA) were investigated by using SEM-EDX analysis. Membranes with various degrees of grafting (DOG) and thicknesses were prepared by a simultaneous radiation grafting of styrene and a subsequent sulfonation with chlorosulfonic acid. A SEM-EDX instrument was utilized to directly observe that the distribution behaviors of the PSSA grafts over the cross-section of grafted PFA membranes and the results showed that the distribution behaviors were largely affected by the grafting conditions such as the degree of grafting, monomer concentration, and film thickness.     

聚四氟乙烯膜辐射接枝反应条件的研究

采用了共辐射接枝技术，在室温下将苯乙烯接枝到聚四氟乙烯薄膜上，合成了辐射接枝膜。研究了溶剂种类、单体浓度、辐射剂量以及剂量率等因素对接枝反应的影响。结果表明，单体浓度和辐射剂量率是反应的主要影响因素，两者对接枝反应速率的影响指数分别为1．2和0．4。     

聚乙烯辐照接枝体系改变pH对接枝率的影响

采用γ射线辐照引发接枝的方法，在高密度聚乙烯（HDPE）上接枝丙烯酸（AA）和对接枝苯乙烯磺酸钠（SSS），制备了一种含羧酸基团和磺酸基团的阳离子交换膜，详细研究了反应体系在不同pH值下的接枝率变化规律。实验表明，在共辐照接枝方法中，当AA与SSS一步法接枝HDPE或接枝上AA的HDPE膜再共辐照接枝SSS时，总接枝率（Gt）及对苯乙烯磺酸钠的接枝率（Gs）随体系的pH的降低而升高，在预辐照一步法接枝中，Gt与Gs随体系pH的降低先升高后又有所降低，综合分析认为，改变pH值使体系粘度发生变化，从而影响了单体向基体的扩散速率。     

过氟化聚合物的苯乙烯接枝研究--辐照条件与反应条件的影响

Fuel cell is in focus as a very low exhaust new dynamo system. Especially polymer electrolyte fuel cells (PEFC) using proton exchange membranes (PEM) have attracted much attention for the electrical vehicle and other mobile applications such as cellar phone and personal computer. Conventional perfluoro-sulfonic acid membranes such as Nation() (DuPont de Nemours LTD.) have been the popular PEM used in PFEC. However, there are still several problems such as insufficient gas barrier properties, low thermal resistance, and their high costs.In this study, hawse have studied the partially fluorinated PEM for PEFC by radiation grafting onto per-fluorinated polymers such as PFA, FEP and ETFE with reactive styrene monomers using pre-irradiation grafting method in gas and in liquid phase, respectively, and successive sulfonation. Characteristic properties of the grafted and sulfonated materials have been discussed and optimized fabricating conditions were determined.Characteristic properties of the obtained materials have been measured by differential scanning calorimetry,thermogravimetric analysis and FT-IR spectroscopy, etc.In the case of irradiation in air, glass transition temperatures (Tg) of the grafted materials depend on the yields of styrene grafting onto the materials. That is higher yields of grafting give lower thermal stability. On the other hand, when the peroxy radicals were converted trapped radicals by exposure in air after irradiation under oxygen-free atmosphere, Tg of the grafted materials hardly depends on the grafting yields.Moreover, the yields of grafting in gas phase were higher than that of liquid phase. However, the sample form of grafting in gas phase has been greatly changed, whereas the sample form of grafting in liquid phase has kept its original feature.Therefore, it is suggested that the fabricating conditions for PEFC membranes were preferred to irradiation under oxygen-free atmosphere and grafting in liquid phase.Ion exchange capacities of the sulfonated-materials could be 3.0meq/g. Other properties of the obtained membranes such as chemical structure were also discussed.     

电子束引发双功能基阳离子交换膜的制备研究

在所有的离子交换膜中,最引人注目的当数20世纪70年代已商品化的Nation系列膜。具有磺酸功能基的Nation膜电阻低,但用在氯碱工业时电流效率低。1974年Seko发明了全氟羧酸阳离子交换膜,使电流效率有实质性提高,并推动了复合膜的发展。复合膜具有磺酸膜的低电阻性能和羧酸膜的高电流效率。本工作采用辐射接枝法制备含羧酸基团和磺酸基团的双功能基阳离子交换膜,目的主要是以低成本且简单可行的辐射接枝法代替共聚法,制备稳定性好、低电阻、高电流效率的阳离子交换膜。     

羟基磷灰石辐射接枝甲基丙烯酸甲酯反应的研究

研究了羟基磷灰石在空气中预辐照法接枝甲基丙烯酸甲酯（ＭＭＡ）反应的接枝剂量、单体浓试、接枝温度及无机酸对接枝体系的影响。结果表明，接枝率是由动力学条件控制的，经过恰当的条件选择，可以获得较高的接枝率。对接枝物进行重量法、灼烧法、扫描电镜及红外光谱研究，从不同的侧面证实ＭＭＡ已通过化学键接枝在羟基磷灰石上。表明用辐射引发无机材料接枝有机单体，改善无机－有机复合材料界面，制备生物医学材料的方法是可行的     

Study of radiation-induced grafting of acrylic acid-sodium styrene sulfonate onto poly （tetrafluoroethylene-cohexafluoropropylene） film

Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were immersed in aqueous solution of acrylic acid (AA) and sodium styrene sulfonate (SSS), then irradiated by ^60Co γ-rays at 25℃. The effects o| reaction time, absorbed dose, dose-rate, inhibitor and monomer concentration on the grafting yield were studied. Grafting yields of both AA and SSS onto FEP, respectively, increase with irradiation dose, but some saturation will appear at high dose and monomer concentration. The grafting yield increases with reaction time and then levels off. The grafting of SSS onto FEP is more difficult than the grafting of AA. The analysis of grafted membranes using DSC and FT-IR have been done.     

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.     

HDPE预辐照接枝SSS与AA体系的反应动力学研究

采用电子束引发预辐照接枝方法在高密度聚乙烯(HDPE)上接枝丙烯酸(AA)与对苯乙烯磺酸钠(SSS)两种单体,以制备含磺酸和羧酸基团的双功能基阳离子交换膜。研究发现,接枝速率与辐照剂量、单体总浓度及反应温度密切相关。接枝反应的活化能为22．2kJ／mol。傅立叶变换红外光谱(FTIR)测试表明,接枝膜上引入了磺酸基团和羧酸基团。