天然胶/杜仲胶共混硫化物结晶性对热致形变回复性能的影响

用XRD法分析天然胶/杜仲胶共混硫化胶的结晶性,研究其结晶性对天然胶/杜仲胶共混硫化胶的物理性能和热致形变性能的影响.实验结果表明:随着杜仲胶用量的增加,硫化胶在XRD图谱中的衍射峰强度增大,硫化胶的结晶性增大,硫化胶交联密度有明显减小.定伸应力和拉伸强度随杜仲胶用量的增加而增大,而拉断伸长率减小,热致回复温度降低,试样的最终形变率减小.     

异丁烯残留量对丁基橡胶溴化的影响

溶液法制备丁基橡胶可以直接得到丁基橡胶胶液,为溴化节省工艺步骤。但由于丁基橡胶优异的气密性,使得胶液中未反应的异丁烯单体很难彻底脱除。采用顶空气相色谱建立了测定胶液中异丁烯质量浓度的方法,将含有不同质量浓度异丁烯的胶液溴化,探究了异丁烯残留量对丁基橡胶溴化的影响。结果表明,随着胶液中异丁烯质量浓度的增加,溴化丁基橡胶的含溴质量分数不断降低,且溴代仲位烯丙基结构与溴代伯位烯丙基结构的相对摩尔比值逐渐增大。     

Liquid crystal polyarylates containing 2,6-naphthalene dicarbonyl group (I): Effects of kinky monomers on thermal and anisotropic behaviors

A series of copolyarylates primarily based upon 2,6-naphthalene dicarboxylic acid, hydroxybenzoic acid and 4,4-biphenol were prepared by slurry-melt polymerization with Santotherm 66 as a heat exchange medium. The frequently used kinky monomer, resorcinol or isophthalic acid, was introduced into these copolyarylates to modify the chemical strcture. The relationship of the thermal behavior and the crystalline structures for these copolymers was studied by means of DSC and wide angle X-rays diffraction. The amount of mcorporated kinky modifier was found to produce a significant effect on the liquid crystalline phase and the melting temperature of the copolyarylates. All of these liquid crystal polymers exhibited nematic textures; shreaded and/or Schlieren type, depending upon the incorporated kinky monomer. The liquid crystal polymers modified by isophthalic acid (up to 40 mole % of 2,6-naphthalene dicarboxylic acid replaced by isophthalic acid) possessed shreaded texture however high the temperatures of the polymer melts were. The liquid crystal polymers modified by resorcinol (60 to 100 mole % of 4, 4-biphenol replaced by resorcinol), however, would have two types of nematic textures: the shreaded texture occurred when the temperature of the polymer melt was between the melting temperature and the anisotropic transition temperature; the Schlieren texture existed when the temperature of the polymer melt was high above the anisotropic transition temperature. The Schlieren texture formed only when a liquid crystal polymer revealed good flowability and lower rigidity. The polydomain concepts could be utilized to explain the observed textures of these copolyarylates clearly.     

Critical Review of Fluorinated Electrolytes for High-Performance Lithium Metal Batteries

Lithium metal batteries (LMBs), due to their ultra-high energy density, are attracting tremendous attentions. However, their commercial application is severely impeded by poor safety and unsatisfactory cycling stability, which are induced by lithium dendrites, side reactions, and inferior anodic stability. Electrolytes, as the indispensable and necessary components in lithium metal batteries, play a crucial role in regulating the electrochemical performance of LMBs. Recently, the fluorinated electrolytes are widely investigated in high-performance LMBs. Thus, the design strategies of fluorinated electrolytes are thoroughly summarized, including fluorinated salts, fluorinated solvents, and fluorinated additives in LMBs, and insights of the fluorinated components in suppressing lithium dendrites, improving anodic stability and cycling stability. Finally, an outlook with several design strategies and challenges will be proposed for novel fluorinated electrolytes.     

A Dilute Fluorinated Phosphate Electrolyte Enables 4.9 V-Class Potassium Ion Full Batteries

Potassium ion batteries using graphite anode and high-voltage cathodes are considered to be optimizing candidates for large-scale energy storage. However, the lack of suitable electrolytes significantly hinders the development of high-voltage potassium ion batteries. Herein, a dilute (0.8 m ) fluorinated phosphate electrolyte is proposed, which exhibits extraordinary compatibility with both graphite anode and high-voltage cathodes. The phosphate solvent, tris(2,2,2-trifluoroethyl) phosphate (TFP), has weak solvating ability, which not only allows the formation of robust anion-derived solid electrolyte interphase on graphite anode but also effectively suppresses the corrosion of Al current collector at high voltage. Meanwhile, the high oxidative stability of fluorinated TFP solvent enables stable ultrahigh-voltage (4.95 V) cycling of a potassium vanadium fluorophosphate (KVPO₄F) cathode. Using TFP-based electrolyte, the 4.9 V-class potassium ion full cell based on graphite anode and KVPO₄F cathode shows rather remarkable cycling performance with a high capacity retention of 87.2% after 200 cycles. This study provides a route to develop dilute electrolytes for high-voltage potassium ion batteries, by utilizing solvents with both weak solvating ability and high oxidative stability.     

Electrochemical deposition of polypyrrole–carbon nanotube films using steroid dispersants

Polypyrrole (PPR)–carbon nanotube (CNT) films were prepared by an electrodeposition method, combining PPR electropolymerization and anaphoresis of CNT. PPR polymerization experiments showed advantages of a dopant from the catechol family for the deposition of PPR films at reduced electrode potentials. The method allowed the formation of adherent films on stainless steel substrates. The amphiphilic molecules with steroid-like structures, such as carbenoxolone disodium salt, glycyrrhizic acid, ammonium salt, and sodium taurodeoxycholate, were used for dispersion and charging of CNT. The new dispersing agents showed outstanding dispersion ability. In addition to dispersing properties, electrodeposition experiments revealed film-forming properties of carbenoxolone and ability to form pure carbenoxolone or carbenoxolone–CNT films. The PPR–CNT films formed using carbenoxolone disodium salt, glycyrrhizic acid ammonium salt, and sodium taurodeoxycholate showed diverse microstructural features. The dispersion and deposition mechanisms were discussed.     

Effect of end group of amorphous perfluoro-polymer electrets on electron trapping

Charge trap in amorphous perfluoro-polymer electret is studied, focusing on electron trap site and trap energy. Low-energy inverse photoelectron spectroscopy is adopted to measure solid-state electron affinity (EA) of cyclic transparent optical polymer (CYTOP). EA of CYTOP CTL-S is discovered by compensating the unwanted charge-up effect. Negatively-charged electret materials (polyethylene, ethylene-tetra-fluoro-ethylene, poly-tetra-fluoro-ethylene, and CYTOP) are analyzed by quantum mechanical calculation. Density functional theory with long-range correction is adopted to analyze orbital energies of single molecular systems. Intramolecular distribution of trapped electron and EA are investigated. Calculated electron affinities of CYTOP polymers with different end group are qualitatively in accordance with trapped charge stability measured with thermal stimulated discharge, signifying that electron affinities obtained with the present simulation can be used as an index of amorphous polymer electret.     

碳中和目标背景下包装行业发展的对策

目的 为了应对日益恶化的全球气候变化,并实现碳中和的目标,研究低碳化技术在包装行业的应用成为当下至关重要的任务。为了推动包装行业在碳中和背景下的低碳化转型,有必要对现有的低碳化技术进行分类和梳理。方法 从碳减排和碳移除两方面对包装行业已有的低碳化技术进行了研究。综述当前可降解生物塑料和聚合物单体化学循环技术在包装中的应用,介绍了几种清洁能源以及碳捕捉、碳利用和碳储存技术的发展现状。结论 对包装行业而言,实现碳中和的目标还面临着很多挑战。包装行业在推进碳中和目标时要选取与发展适合的低碳能源和碳中和技术。     

Single‐layered retardation films with negative wavelength dispersion birefringence made from liquid‐crystalline monomers

Organic light‐emitting diode displays have a cathode composed of a layer of highly reflective metal. Reflection of external light from this layer can be suppressed with a broadband quarter‐wave plate. Although various types of quarter‐wave plate retardation films have been prepared by copolymerizing, mixing, or laminating multiple polymers, ideal wavelength dispersion has not been achieved with thin retardation films because of their relatively low birefringence and the complexity of the procedure required manufacturing them. In this study, we developed (i) new liquid‐crystalline monomers with negative wavelength dispersion birefringence that we used to obtain thin, single‐layered retardation films suitable for coating and (ii) retardation films with different molecular alignments. We found that the monomers showed high solubility and high regularity of molecular alignment, with less damage to the substrate and alignment films. We also investigated the wavelength dispersion and thermal stability of the films. We succeeded in developing retardation films that had a homeotropic alignment or a hybrid alignment with negative wavelength dispersion. These alignments can be used to obtain antireflection films with an improved viewing angle for organic light‐emitting diode displays or next‐generation thin displays.