Catalytic characteristics of various rubber-reinforcing carbon blacks in decomposition of methane for hydrogen production

Carbon black has recently been reported to act as an effective catalyst for methane decomposition and to exhibit stable catalytic behavior despite carbon deposition, and thus it can be used for CO₂-free production of hydrogen from natural gas. In this work, various carbon blacks with different primary particle size were investigated with respect to methane decomposition under atmospheric pressure from 1123 to 1223 K. Catalytic characteristics, such as activity, activation energy and reaction order, were investigated and compared. It was observed that with decreasing primary particle size (or increasing specific surface area), the specific activity increased and the activation energy decreased. The reaction orders for various pelletized, rubber-reinforcing carbon blacks were 0.6–0.7, about the same regardless of the primary particle size, while they were near 1 for fluffy carbon blacks. Fluffy carbon black showed higher activity and activation energy than the pelletized carbon black of the same primary particle size. Changes of the surface morphology during carbon deposition were observed by TEM. Variations of the number of active sites were discussed in regard of the primary particle size, carbon deposition and binder. The presence of different types of active sites was also suggested.     

模具对振动注射成型制件作用效应的初步研究

采用自制的振动试验台，分别安装两个不同的试样模具，使用了不同的聚合物材料，在不同的温度，压力下变化不同的振动频率和振幅进行实验，研究了聚合物熔体在振动场中注射成型时，成型模具对聚合物振动成型效应的作用。结果表明，模具浇口及型腔尺寸不同。振动注射制件的强度不同；模具型腔尺寸大振动产生的效应弱。型腔小振动产生的效应强。     

反式 -1,4-聚异戊二烯相对分子质量的调节

采用负载钛本体沉淀聚合法,以氢气作链转移剂,制备了不同相对分子质量的反式-1,4-聚异戊二烯(TPI),讨论了老化、氢气调节及塑炼对其相对分子质量的影响,以及不同相对分子质量TPI的结构与性能。结果表明,本体系合成TPI的数均相对分子质量为(5～15)×104,相对分子质量分布为2.00～3.00;门尼粘度为20～120时,随着TPI相对分子质量的降低,其结晶速度提高,结晶度无明显变化,拉伸强度明显降低,扯断伸长率、屈服强度和邵尔A型硬度无明显变化。     

聚甲醛/共聚酰胺共混物的结晶形态及力学性能

研究了共聚酰胺含量对聚甲醛/共聚酰胺(POM/COPA)共混物结晶形态及力学性能的影响。结果表明:POM/COPA共混物中存在氢键相互作用;结晶温度对POM的结晶形态有较大影响,温度较高时POM结晶较完善,球晶尺寸较大;同时,COPA的加入使共混物的球晶细化,极大地改善了POM的韧性。当COPA含量为4%时,共混物缺口冲击强度达到最大值,拉伸强度几乎不变,POM/COPA具有较理想的综合力学性能。     

Hydrothermal synthesis of flaky crystallized La2Ti2O7 for producing hydrogen from photocatalytic water splitting

Flaky monoclinic La₂Ti₂O₇ was prepared via a hydrothermal method based on the reaction of Ti(SO₄)₂ and La(NO₃)₃. Relative to the solid-state reaction sample, the flaky La₂Ti₂O₇ showed higher surface areas, much smaller crystal size and more efficient light absorption. All these factors led to the higher photoactivity to produce H₂ from water splitting under UV irradiation.     

闪蒸法聚乙烯无纺布的研究进展

介绍了无纺布的发展历程以及我国无纺布的现状，着重讨论了开展闪蒸法聚乙烯纺粘型无纺布研究的意义、方法、生产工艺。     

Lipase-catalyzed transesterification of phosphatidylcholine at controlled water activity

The incorporation of a free fatty acid into thesn-1 position of phosphatidylcholine by lipase-catalyzed transesterification was investigated. The thermodynamic water activity of both the enzyme preparation and the substrate solution was adjusted to the same value prior to the reaction. The reaction rate increased with increasing water activity but the yield of modified phosphatidylcholine decreased due to hydrolysis. By using a large excess of the free fatty acid (heptadecanoic acid), the hydrolysis reaction was slowed down, so a higher yield was obtained at a given degree of incorporation. The best results were obtained withRhizopus arrhizus lipase immobilized by adsorption on a polypropylene support. With this preparation, a yield of 60% and nearly 50% incorporation of heptadecanoic acid (100% incorporation in thesn-1 position) was obtained at a water activity of 0.064. The enzyme preparation had good operational stability and position specificity. Little incorporation (<1%) was observed in thesn-2 position, when almost all the fatty acid in thesn-1 position was exchanged.     

玻璃含硫气泡与配合料的关系

借助拉曼光谱、原料C当量数测定及SC-132定硫仪分析等方法对玻璃气泡、配合料Redox数及硫溶解度之间的关系进行了研究.     

二种双邻位甲基取代的聚芳醚酮类树脂的合成与性能

合成二种双邻位甲基取代的聚芳醚酮类聚合物,聚芳醚酮醚酮酮(DM-PEKEKK)和聚芳醚酮酮醚酮酮(DM-PEKKEKK),用FT-IR、1H NMR、DSC、WAXD、TG等技术对其进行表征,研究表明:较之于未取代的PEKEKK和PEKKEKK玻璃化转变温度和溶解性能大幅度提高,热分解温度有所下降,但均在450℃以上.     

楔形环管片纵向接头对施工荷载力学响应研究

楔形环管片是盾构隧道曲线段的重要组成部分。以珠海-澳门轻轨某急弯隧道为例,利用ANSYS有限元软件计算了楔形环管片在不同管片幅宽、楔形量、隧道曲率半径、千斤顶压力等条件下管片纵向接头的受力情况,重点分析了管片环间接头的最大正负弯矩。研究结果表明:随着盾构隧道曲线半径减小,正负最大弯矩均增大,不同隧道转弯半径下,管片最大正负弯矩均随接头抗弯刚度的增大而增大;不论正负弯矩,均有管片幅宽越小最大弯矩越大的现象。不同管片幅宽下,管片最大正负弯矩均随接头抗弯刚度的增大而增大;曲线半径为150 m时,最大正弯矩基本随着千斤顶压力呈线性增大的趋势,最大约为1 180 k N·m。研究结果对今后的急弯盾构隧道管片设计有一定的指导意义。