静电纺丝工艺参数对纤维直径影响的研究:实验及数值模拟

采用聚氧化乙烯(PEO)为原料对静电纺丝过程的实验参数进行研究,探讨了溶液质量分数、外加电压、接收距离和溶液流速4个参数对纤维直径和纤维网形态的影响.同时,通过数值模拟的方法对外加电压、接收距离及溶液弹性模量3个参数对纤维直径的影响进行研究,并和实验结果进行比较.     

聚氧化乙烯水溶液粘度行为的研究

测定了40 ℃时不同分子量的聚氧化乙烯(PEO)水溶液的粘度,发现在低浓度区PEO水溶液比浓粘度出现负偏离.用高分子溶液流过时间对浓度作图的外推值t*0进行校正,则PEO水溶液的比浓粘度与浓度之间满足线性关系.利用高分子溶液流过时间t之前和之后纯溶剂的流过时间t0和t0′的改变确定了40 ℃时PEO在毛细管管壁上吸附层的厚度.     

EFFECTS OF CRC SIMULACRUM MADE OF OLEIC ACID AND GLYCERIDE ON WET-END AND PAPER PROPERTIES OF NEWSPRONT

INTRODUCTIONMechanical pulp is the main furnish of newsprint. Unfortunately there are much more extractives in mechanical pulp than in other pulps such as Kraft. Extractives are often used to refer to the nonstructural components of wood and bark. Most extractives are organic solvents, including polyphenols, terpenoids, fats, waxes, organic acids, complex polysaccharides and nitrogenous compounds. The amount of extractives and their composition vary with respect to the botanical families…     

聚醚类减水剂的合成及性能

采用自由基共聚的方法将甲基烯丙基聚氧乙烯醚、 2-丙烯酰胺-2-甲基丙磺酸、 马来酸酐和丙烯酸4种单体合成一系列聚醚类高效减水剂, 并通过红外光谱、 核磁共振氢谱和凝胶渗透色谱(GPC)确认产物结构、 分子量及其分布, 探讨单体配比与合成工艺, 考察减水剂的掺量和温度对水泥净浆流动度及减水率的影响,
 比较该减水剂在不同水泥应用中的适应性. 实验结果表明： 该聚醚类高效减水剂分散性较高, 初始与1 h后净浆流动度分别为310,300 mm, 减水率为35%; 在3种水泥应用中均表现优异.     

RX/CuX/bpy催化体系中PEO大单体与PMMA接枝共聚物的合成与表征

本工作以正丁基溴为引发剂,卤化亚铜／联吡啶（bpy）为催化剂,研究了甲基丙烯酸甲酯（MMA）与末端为丙烯酰胺基的聚氧化乙烯（PEO）大单体的原子转移自由基聚合（ATRP）反应,得到了实测分子量与理论分子量相近,分子量分布较窄,有预期结构的接枝共聚物,用IR,1HNMR,VPO,GPC,DSC等进行了表征,并对共聚物的组成和分子量受单体总浓度、投料比、引发剂及反应时间的影响进行了讨论。     

聚氧乙烯(PEO)、丙烯酰胺与甲基丙烯酸甲酯三元共聚物的合成与表征

以THF为溶剂，磺胺嘧啶钠为引发剂，甲基丙烯酰氯为封端剂，阴离子聚合合成了一类含双键端基的聚氧乙烯(PEO)大单体；在此基础上，考察了此类大单体与丙烯酰胺、甲基丙烯酸甲酯的自由基共聚反应，合成了一类新型PMMA—PAM—PEO三元共聚物，此物在常温下易于成膜；大单体及共聚物经纯化后，用IR、^1H—NMR、VPO、GPC等进行了表征，证实了产物有预期结构。     

PEO/PVC,PEO/PS共混的研究

根据相容PEO/PVC,不相容PEO/PS共混体系的实验结果,提出分子界面模型,阐述了结晶/非晶高聚物共混体系相容性、分子间相互作用、结晶组分结晶性之间的关系。     

Studies on the Dielectric and Transport Properties of PEO/Chitosan Proton Conducting Polymer Electrolyte

1 Results The effect of ammonium nitrate (NH4NO3) content in 40 wt.% PEO and 60 wt.% chitosan blend has been analyzed in this study.The sample containing 40 wt.% NH4NO3 exhibited the highest room temperature conductivity.In order to ascertain that water does not influence the conductivity,the samples were dried in a dessicator and the conductivity determined daily until it shows a constant value.Results are as shown in Fig.1.Samples containing other salt concentrations were also kept in the dessicator f...     

聚氧化乙烯絮凝微细粒高岭石强化赤铁矿反浮选脱硅机理研究

通过矿物浮选试验并结合激光粒度测试、扫描电镜(SEM)、矿物Zeta电位及XPS等检测方法对赤铁矿反浮选过程中聚氧化乙烯絮凝细粒高岭石的行为及机理进行了研究.矿物絮凝浮选试验表明：添加聚氧化乙烯可以提高高岭石的单矿物回收率和人工混合矿分离效率,促进赤铁矿和高岭石反浮选分离.激光粒度测试和扫描电镜检测结果表明：聚氧化乙烯不絮凝赤铁矿,但絮凝高岭石颗粒,使其表观粒径增大.Zeta电位测试和XPS分析表明：聚氧化乙烯在高岭石颗粒表面发生化学吸附,并使其Zeta电位正移.因此,开展聚氧化乙烯对硅酸盐矿物絮凝的研究对赤铁矿和高岭石反浮选分离具有意义.     

Effects of Polyethylene Oxide Concentration on the Size of Beads in Electrospun Beaded Nanofibers

Embedding particle drugs in beaded nanofibers by electrospinning has been shown a potential approach to control drug release in tissue engineering. The bead size is one of the critical parameters in controlling the drug release rate. In this study,the relationship between polymer concentration and beads size was investigated. Aqueous polyethylene oxide（ PEO） solutions with different concentrations were prepared to obtain various beaded nanofibers by electrospnning. Optical microscope and scanning electron microscope（ SEM） were used to observe the variation tendency of bead size. With an increase in the polymer concentration,the diameter of fibers between beads became bigger,while the fiber uniformity improved. In addition, the polymer concentration influenced the distribution of bead diameter. Higher polymer concentration would reduce the possibility of small-sized beads formation and improve the uniformity of bead diameter. The study provides a possible way to control the size of beads,which is helpful for further research on the control of particle drug release.