溶胶－凝胶二氧化硅驻极体薄膜的物理化学改性

实验研究了由溶胶－凝胶法制备二氧化硅驻极体薄膜的工艺。用红外透射谱、扫描电子显微镜以及驻极体等温表面电位测量和热刺激放电等实验考察了热处理和化学表面修正两个关键工艺对溶胶－凝胶二氧化硅样品驻极体性能的影响。结果表明经过高温条件下一定时间的热处理和化学表面修正，可以制备出性能优良的驻极体薄膜     

Ultrasonic study of molecular association of poly(vinyl chloride) solution in tetrahydrofuran

Ultrasonic absorption, velocity, adiabatic compressibility, relaxation time and relaxation amplitude measurements are reported on poly(vinyl chloride) (PVC) solution in tetrahydrofuran (THF) using pulsed ultrasonic apparatus operating at 2 MHz and 313 K. Results show a linear increase of velocity. density, viscosity, absorption coefficient, relaxation time and relaxation amplitude values with the increase of PVC concentration in THF. In contrast the compressibility decreases with increasing PVC concentration. This suggests interaction between PVC and THF molecules.     

溶胶-凝胶法制备(Sr,Pb)TiO3纳米晶粉及表征

采用溶胶－凝胶法成功地合成了（Sr,Pb)TiO3纳米晶粉，并利用FTIR技术对凝胶的形成过程及350℃，1．5h煅烧获得的粉体材料进行了表征。实验以TG－DSC分析作为拟定煅烧温度的依据，以XRD作为煅烧产物的分析手段，最佳煅烧温度为600℃，所合成的（Sr,Pb)TiO3纳米晶粉的平均晶粒尺寸约为21nm，属钙钛矿型立方顺电相结构。     

凝胶燃烧法合成LiCoO2超细粉体的研究

以LiNO3和Co(NO3)2@6H2O为原料,柠檬酸为燃料.采用凝胶低温燃烧技术合成了LiCoO2超细粉体.并利用各种分析技术对柠檬酸和硝酸盐形成的凝胶及凝胶燃烧合成的粉体进行了研究柠檬酸硝酸盐凝胶在350-400℃之间发生燃烧反应,得到黑色疏松粉体X射线衍射分析表明.适当提高柠檬酸在凝胶中的含量.燃烧后得到的粉体晶粒尺寸显著减小未经燃烧的粉体中除含有LiCoO2外.还有CoO,Li2CO3等杂质相.但在450℃下经短时间煅烧后.杂质相消失,其晶相为层状岩盐结构的高温LiCoO2相扫描电镜和透射电镜观察发现.随着煅烧温度的提高.LiCoO2粉体的粒径有所增大.但远小于在相同煅烧条件下用固相反应法制备的LiCoO2粉体.这表明采用燃烧法更适于合成具有单一相结构的,可在低温条件下烧结的超细LiCoO2粉体.     

纳米C—S—H/PCE对硅酸盐-硫铝酸盐复合水泥凝结硬化的影响

研究了纳米C—S—H/PCE对硅酸盐-硫铝酸盐复合水泥凝结时间、早期水化历程及抗压强度的影响,采用XRD、TG、pH计和SEM等分析测试手段对早龄期水化产物和液相碱度等进行表征,探讨了纳米C—S—H/PCE对硅酸盐-硫铝酸盐复合水泥的增强机理。结果表明：掺加纳米C—S—H/PCE能有效缩短硅酸盐-硫铝酸盐复合水泥浆体初凝及终凝时间,当C—S—H掺量≥1.0%时,硅酸盐-硫铝酸盐复合水泥的初、终凝时间差明显缩短。纳米C—S—H/PCE加快了硅酸盐-硫铝酸盐复合水泥水化放热速率,提高了总的水化放热量,早期水化产物生成数量多,但对水泥水化产物类型没有影响,硅酸盐-硫铝酸盐复合水泥体系8、12、16 h的抗压强度显著提高。     

Toward Largely Enhanced Toughness and Balanced Strength in PA1012/EPDM Blends via Synergistic Effect of Sacrificial Bonds and Network Structure

Here, zinc-neutralized ethylene propylene diene monomer (EPDM) ionomers with different neutralization levels are prepared through melt blending, and are then incorporated with polyamide 1012 (PA1012) to fabricate PA1012/EPDM ionomer blends. Interestingly, complex crosslinking networks are formed in the blends due to the construction of sacrificial bonds (Zn²⁺-carboxyl, Zn²⁺-amide). The as-formed network structure and sacrificial bond endow the PA/EPDM blends with largely enhanced toughness (16 times higher than that of neat PA), as well as balanced strength and stiffness. Meanwhile, the rheological behaviors of PA1012/EPDM ionomer blends indicate their relative low melting viscosity, which can avoid the processing shortcomings of plastics toughened with rubber. Moreover, PA1012/EPDM ionomer blends show obvious gelation behavior, and a maximum notched Izod impact strength exhibited at the gel point, in which unique double network structure can be observed obviously, indicating that there is a corresponding correlation between the rheological and mechanical parameters. Furthermore, the supper-toughening mechanism of PA1012/EPDM ionomer blends at gel point is explored, which origins from the large deformation and cavitation of rubber particles and the destruction of special double network morphologies. This study provides a novel and effective strategy to fabricate PA materials with outstanding toughness and excellent strength simultaneously.     

Yb2O3／TiO2纳米颗粒的制备及表征

采用溶胶-凝胶法制备了微量 Yb2O3掺杂纳米 TiO2颗粒,采用 XRD, TG-DTA, TEM等手段对试样经不同温度热处理后的结构相变、表面形貌、颗粒大小等特性进行了表征.实验表明温度不高于 400℃时,试样的颗粒粒径较小,粒径在 15 nm以下,比表面积大于 107.22 m2@ g-1, TiO2呈锐钛型;在 400℃以上, TiO2粒径迅速增大,微粒出现锐钛相与金红石相混晶结构;800℃时 TiO2微粒完全转化成金红石相.     

2—甲基—1，4—萘醌对DNA光敏损伤的诱导作用

选择波长337nm的激光作为激励光源，借助凝胶电泳研究了2－甲基－1，4－萘醌诱导的DNA光敏损伤。结果表明：在氧气饱和、脱氧条件下光敏损伤显著，DNA损伤主要与光子剂量、核酸与萘醌浓度比及DNA存在形式有关。     

Ionic liquid mediated nano-composite polymer gel electrolyte for rechargeable battery application

ABSTRACT

Nano-composite polymer gel electrolytes (NPGEs) based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP, ionic liquid, 1-butyl-3- methylimidazolium bis(trifluoromethanesulfonyl)imide BMIMTFSI, Li-salt along with the addition of SiO₂ nanoparticles have been synthesized and characterized by various techniques. Prepared NPGEs show high room temperature ionic conductivity (~10^?3 S/cm) and have a wide electrochemical window (ECW) (~3.3–3.5 V). The galvanostatic charge/discharge profile was studied by sandwiching best performing NPGEs between a LiFePO₄ cathode and lithium metal anode. The specific discharge capacity of the cell (Li/NPGE/LiFePO₄) room temperature at 0.1C rate is found to be 138 mAh/g.     

Modification of phenol–formaldehyde resol resins by lignin,starch, and urea

Lignin‐based chemicals, starch, and urea were used as modifiers for phenol–formaldehyde resol resins. The effects of the addition stage of the modifiers used in the synthesis of the resins and the type of modification reagent on the structures of the resins and their molar masses and reactivities were investigated. The modifications with corn starch and lignin promoted condensation; this was verified by increased molar masses and high ratios of methylene bridges to the sum of free ortho and para aromatic groups with respect to the corresponding reference resin without a modification reagent. The later the modifier was added to the resin condensation mixture, the more methylene bridges were formed with respect to the amounts of free ortho and para aromatic groups. In addition, when urea or wheat starch was added in the later condensation stage, the final condensation also reached high stages. The modifications with lignosulfonate and starch, as well as the early addition of urea, enhanced p–p′ bridge structures. The lowest condensation stage and, therefore, the highest reactivity were found when wheat starch was added with the starting reagents. The curing heat of the wheat‐starch‐modified resins decreased according to the deferred addition point of starch. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 582–588, 2003