聚对苯二甲酸-共-丁二酸丁二醇酯的研究及产业化现状

介绍了生物可降解材料脂肪族/芳香族共聚酯聚对苯二甲酸-共-丁二酸丁二醇酯(PBST)的合成工艺技术及基本性能,综述了近年来国内外PBST的研究现状和产业化现状。PBST的合成工艺主要是酯交换法和直接酯化法,酯交换法原料成本高、副产物分离较难、合成的PBST相对分子质量低;直接酯化法可以得到纯度较高的PBST,副产物只有四氢呋喃,现已成为合成PBST的主流工艺。PBST具有良好的生物可降解性,与聚对苯二甲酸-己二酸丁二醇酯(PBAT)的性能相近,在耐热性、拉伸强度、透水率方面性能更优。国外PBST没有批量化商业产品,国内PBST工程化技术开发和产业化推广方面拥有了自主知识产权,可以利用PBAT生产装置通过工艺调整进行生产。国内PBST产业化主要受原料丁二酸(SA)的制约,今后的研发重点是加强PBST合成、应用技术的开发,开发高效环保的SA生产方法。     

碱减量工艺对微孔型聚酯纤维强力的影响研究

使用氢氧化钠对微孔型聚酯纤维织物进行碱减量处理,重点研究了碱减量工艺中氢氧化钠浓度、碱处理时间和温度对微孔聚酯纤维织物减量率以及断裂强力的影响。此外还考察了减量率与处理织物吸湿性和抗起毛起球性之间的关系。结果表明,增大氢氧化钠浓度、延长碱处理时间以及升高碱处理温度都有利于减量率的提高,但是会导致织物断裂强力降低,当使用0．8％wt氢氧化钠溶液、在100℃处理60min时,减量率可控制在10％左右,纤维断裂强力下降是可以接受的。     

棉织物等离子体预处理后的前处理工艺研究

文章对常压空气等离子体预处理后的棉织物进行碱氧一浴前处理工艺研究,通过研究得知,经常压等离子体预处理的织物碱氧一浴前处理即节约了化学助剂的用量,又节省了水、电、汽的用量,而且达到了传统前处理的效果.     

液晶纤维

液晶高分子是在一定条件下能以液晶相态存在的高分子,它兼有液晶和高分子两类物质的特性。根据液晶形成的条件,可分为溶致液晶高分子和热致液晶高分子两大类。溶致液晶高分子已有不少种类开发成高性能纤维。对现有液晶纤维进行了归纳总结,以期对中国液晶纤维的发展具有一定的借鉴作用。     

Reduced mass transport resistance in polymer electrolyte membrane fuel cell by polyethylene glycol addition to catalyst ink

Effects of Polyethylene glycol (PEG) addition to cathode catalyst ink were investigated by changing the addition amount of PEG. Performance of the polymer electrolyte membrane fuel cells (PEMFCs) increased and then decreased at the higher current density than 1.5 A/cm² as the amount of PEG addition increased. However, durability was not changed by the addition of PEG to the catalyst ink. Three different molecular weights of PEG were compared for PEG additives to cathode catalyst ink. Performance at high current density region increased and then decreased as PEG molecular weight increases from 200 to 10000. Increased performance by addition of PEG was attributed from reduced mass transport resistance. However, addition of large molecular weight PEG to catalyst ink reduced the performance because it lowered ionomer conductivity in the catalyst layer and then reduced proton transport resistance. Increased pore size in the catalyst layer and increased hydrophilicity on the electrode were also analyzed by addition of PEG to catalyst ink.     

Preparation and characterization of Ni catalysts supported on pillared nanoporous bentonite powders for dry reforming reaction

The Ni/pillared-bentonite catalysts with high BET area were synthesized and used in dry reforming reaction. The effects of different parameters such as calcination temperature, OH⁻/Al³⁺ ratio, temperature and time of pillaring process and the content of nickel on the textural and catalytic properties of the synthesized catalysts were studied. The results indicated that the 15 wt% Ni catalyst supported on pillared bentonite prepared under specified conditions (OH⁻/Al³⁺ = 2.2, pillaring temperature of 40 °C and pillaring time of 3 h) possessed the highest BET area (90.80 m²/g). Also, this catalyst possessed higher catalytic activity and stability with lower amount of deposited carbon in comparison to other prepared catalysts in methane reforming with CO₂.     

The effect of acid mixture on the structure of sol–gel PZT fibers

Author's previous studies [J. Am. Ceram. Soc., in press] showed that the acidification of the precursor solution controls the strength and length of sol–gel PZT fibers. Two acids, acetic acid (CH₃COOH) and methacrylic acid (C₄H₆O₂), were studied. C₄H₆O₂ produced longer fibers with small cracks, while CH₃COOH produced shorter and denser fibers. In order to take advantage of the opposite effect of each of these acids, mixtures of acetic and methacrylic acid are used in this work to obtain longer and dense fibers. The effect of the ratio of CH₃COOH/C₄H₆O₂ mixture on the precursors' chemical structure, crystalline phase formation and microstructure of PZT fibers is investigated and discussed. Long and almost crack-free PZT fibers are obtained for a 1/2 ratio of CH₃COOH/C₄H₆O₂.     

Shielding behaviour of conducting polymer-coated fabrics in X-band,W-band and radio frequency range

Electromagnetic interference response of conducting polyaniline-coated fabrics in the microwave range, W-band, RFI range as well as in UV–Vis–NIR range has been studied. In the radio frequency range from 100 to 1000 MHz, conducting polyaniline-coated fabrics shows a shielding effectiveness in the range 30–40 dB. Shielding effectiveness of the conducting fabrics in W-band region at 101 GHz shows an attenuation of 35.61 dB. The microwave reflectance studies of the coated fabrics in 8–12 GHz range shows that conducting fabrics gives shielding effectiveness value of −3 to −11 dB. The reflectance studies of conducting polyaniline-coated fabric shows that 98% of the energy is absorbed in the UV–Vis–NIR range and 2% is reflected back. In polypyrrole-coated fabric 96% of energy is absorbed and 4% is reflected back, whereas in substituted polythiophene-coated fabric, 82% of the energy is absorbed and 18% is reflected back.     

Properties of containing Sn nanoparticles activated carbon fiber for a negative electrode in lithium batteries

Activated carbon fiber (ACF) containing Sn nanoparticles were prepared by impregnation and were investigated as a negative electrode material in lithium batteries. The tin particle size was controlled by selecting an ACF with an adequate surface structure. This Sn/ACF composite cycled versus Li metal showed a first discharge capacity as high as 200 mAh g⁻¹ compared to the pristine ACF which showed only 87 mAh g⁻¹. Excellent cyclability with these composites was obtained with ACF BET SSA as large as 2000 m² g⁻¹ and 30 wt.% Sn.     

Hollow graphene spheres coated separator as an efficient trap for soluble polysulfides in LiS battery

Hollow graphene spheres are successfully prepared and employed as the separator coating materials for lithium-sulfur batteries. The hollow graphene spheres coated separator has been proven an efficient trap to adsorb and block polysulfide, greatly alleviating the shuttle effect. In the case of using elemental sulfur as cathode active material and the weight of the diaphragm is only increased by 10.3%, the lithium-sulfur battery with hollow graphene spheres coated separator delivers a high initial specific capacity of 1172.3 mAh g⁻¹ at the current density of 0.2 C, and the discharge capacity remains at 829.6 mAh g⁻¹ after 200 cycles with a capacity decay of 0.146% per cycle, showing excellent electrochemical performance.