高熔体强度聚丙烯中长支链结构的分析与表征方法新进展

高熔体强度聚丙烯(high melt strength polypropylene,HMSPP)是具有较高熔体强度和弹性、在熔融拉伸时存在应变硬化现象的一种新型聚丙烯材料。近年来,对长支链(LCB)型HMSPP (LCB-HMSPP)的研发引起了学术界和工业界的广泛关注。在利用各种方法和工艺制备LCB-HMSPP之后,所得聚合物是否具有长支链结构,长支链的化学组成、密度及链长度等拓扑结构信息,都需要通过各种仪器分析与表征方法对其进行定性或定量验证。本文着重对傅里叶变换红外光谱(FTIR)法、核磁共振碳谱(¹³C NMR)法、凝胶渗透色谱(GPC)及其联用方法、流变学表征法和结晶行为表征法在LCB-HMSPP中LCB链结构分析与表征中的研究新进展进行总结和评述,介绍了这些方法各自的优缺点和适用性并对这些方法进行了对比,最后对用于LCB-HMSPP中LCB链结构的分析与表征方法研究的未来发展及应用前景进行了展望。     

聚酯分子量分布对可纺性的影响

根据不同聚酯切片在常规指标相同的情况下可纺性往往不同，重点介绍用凝胶渗透色谱法和筛析色谱法对聚酯的低分子成分及分子量分布的检测研究，以及分子量分布对可纺性具有的重要意义。     

Study of tritium transport characteristics in a transportable fluoride‐salt‐cooled high‐temperature reactor

Tritium management is one of the most critical issues that limit the development of fluoride‐salt‐cooled high‐temperature reactor (FHR); therefore, it is important to figure out the tritium transport characteristics in FHRs. In this paper, 3 works concerning about tritium in FHR are conducted: first, the tritium transport characteristics in the primary loop of FHRs are introduced, including tritium production and speciation, the absorption and desorption by graphite, dissolution and diffusion in molten salt, and permeation through structural materials. Second, the physical and mathematical models are established for tritium transport characteristic analysis in a transportable FHR (TFHR). The tritium transport characteristic analysis code (TAPAS) for TFHR is developed and benchmarked. The results prove the fidelity and accuracy of TAPAS. Finally, the tritium transport characteristics in the TFHR are analyzed systematically by TAPAS. Three conclusions are obtained: (1) tritium in the primary coolant loop is mainly in the form of T₂; (2) when TFHR operates at steady state, the permeation rate of T₂ can be regarded as a constant (9.03 × 10⁹ Bq ? EFPD^?1 ); and (3) ⁷Li enrichment and redox potential of molten salt have great influence on the tritium distribution. This work might provide contribution to the tritium control in FHRs.     

Hydrogen permeation behaviour of X56 steel in simulated atmospheric environment under loading

Abstract

The hydrogen permeation behaviour of X56 steel under loading in a simulated atmospheric environment was investigated. The results show that the hydrogen permeation current increases as the elastic deformation of the steel increases. In addition, the hydrogen permeation current decreases with an increase in plastic deformation. Cracking of the passive film and the reduced specimen thickness after deformation are proposed as reasons for the decrease in permeation. Thus, during plastic deformation, there is a competition between dislocation trapping and dislocation transport of hydrogen, which affects the overall hydrogen permeation current.     

Synthesis,spectral, thermal,and chelation potentials of polymeric hydrazone based on 2,4‐dihydroxy benzophenone

A chelating polymer, poly(2,4‐dihydroxy benzophenone hydrazone–formaldehyde) [poly(DHBPH–F)], was synthesized by the polycondensation of 2,4‐dihydroxy benzophenone hydrazone with formaldehyde in the presence of oxalic acid as a catalyst. Poly(DHBPH–F) was characterized by Fourier transform infrared and ¹H‐NMR spectral data. The molecular weight of the polymer was determined by gel permeation chromatography. Polychelates were obtained when the dimethylformamide solution of the polymer containing a few drops of ammonia was treated with an aqueous solution of metal ions. Elemental analysis of the polychelates indicated that the metal–ligand ratio was 1 : 2. The IR spectra of the polymer–metal complexes suggested that the metals were coordinated through the oxygen of the phenolic? OH group and the nitrogen of the azomethine group. The electron paramagnetic resonance and magnetic moment data indicated a square planar configuration for Cu(II) chelate and an octahedral structure for Ni(II) chelate. The thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction data indicated that the incorporation of the metal ions significantly enhanced the degree of crystallinity. The polymerization initiation, electrical conductivity, and catalytic activity of the polychelates are discussed. Heavy‐metal ions [viz., Cu(II) and Ni(II)] were removed with this formaldehyde resin, and the metal‐ion uptake efficiency at different pH's, the nature and concentration of the electrolyte, and the reusability of the resin were also studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of surface activation on the hydrogen permeation properties of PdAg cathode membrane

The influence of surface oxidation and hydrogen upload into the Pd_0.79Ag_0.21 membrane on hydrogen permeation was examined by measuring the permeation of: 1) gas-phase H₂ sent from the electrode back-side and 2) electrolytic H₂ produced on electrolyte side. It was verified that hydrogen upload into PdAg lattice has positive effect i.e. increases hydrogen permeation, while surface oxides formed during and after electrolysis cycles are the main factors acting on decrease of hydrogen permeation. Particularly, silver oxides are identified as permeation-blocking species. Consequently, several treatments were proposed aiming to reduce electrode deactivation; beside wet chemistry treatments applicable after electrolysis, the in situ electrode reactivation by ultrasonic pulses was presented.     

Lightweight Concrete Using Local Industrial By-product

Construction is one of the largest users of energy, material resources and water and it is a formidable polluter. One of the major materials used in construction is concrete and ordinary concrete contains about 12% cement which is a major producer of greenhouse gas in the world. The use of waste materials as partial replacement of cement in concrete reduces greenhouse gases, frees up land fill space, and reduces raw materials consumption. This contributes towards sustainable development, as in a sustainable society, nature is not subject to systematically increasing concentrations of substances extracted from the earth＇s crust. This research work explores the possibility of replacing some percentage of cement in concrete with marble sludge powder to produce lightweight concrete. This was achieved by determining the compressive strength and some hardened properties of concrete like sorptivity and carbonation with marble sludge. The results so far have been able to prove that lightweight concrete can be produced when some percentage of cement is replaced with this waste.     

Orthogonal ligation to spherical polymeric microparticles: Modular approaches for surface tailoring

Modular ligation strategies for the functionalization of polymeric microspheres provide new perspectives for their applications in material science. In the current trend article we highlight variable synthetic procedures for generating functional microspheres via orthogonal modular conjugation chemistries. An overview of the different surface chemistries available is provided, followed by surface-sensitive characterization techniques relevant for the microparticles. Finally, we explore future trends in modular orthogonal modification approaches on microparticles and provide an outlook on the perspectives that the field of surface-modification of polymeric microparticles holds.     

Polyetherketones: Synthesis,Characterization and Antimicrobial Activity

ABSTRACT

Friedel-Crafts polyetherketones were prepared from o-chlorophenol, 1,4-phenylenedioxy diacetylchloride (1,4-PDC), chloroacetyl chloride (CAC), 1,2-dichloroethane (DCE), and dichloromethane (DCM) using anhydrous aluminium chloride (AlCl₃) as catalyst and carbon disulfide (CS₂) as solvent. These resins were characterized by IR spectroscopy and gel permeation chromatography. Carius method was employed to obtain the percentage of chlorine content in the resins. The kinetic parameters for the thermal behavior of the resins were evaluated from thermogravimetry (TG) using Broido method. Differential scanning calorimetry (DSC) thermograms of these resins were also obtained. All the polyetherketones were tested for their antimicrobial properties against bacteria, fungi, and yeast. It was observed that most of the polyetherketones synthesized could be used as antibacterial and antifungal agents.     

Chick Chorioallantoic Membrane as an In Situ Biological Membrane for Pharmaceutical Formulation Development: A Review

The use of animals in research has always been a debatable issue. Over the past few decades, efforts have been made to reduce, replace, and refine experiments for ethical use of experimental animals. The use of chick chorioallantoic membrane (CAM) was one of the proposed alternatives to the Draize rabbit ocular irritation test with several advantages including simplicity, rapidity, sensitivity, ease of performance, and cost-effectiveness. The recent use of CAM in the development of pharmaceuticals and testing models to mimic human tissue, including drug transport across CAM, will be discussed in this review.