VAC催化剂载体的孔结构特性和评价

醋酸乙烯(VAC)的生产需用活性炭做催化剂载体,往往依赖国外进口,如沸腾床反应器用日本椰壳炭,固定床反应器用美国BPL炭等。如能筛选出国产活性炭取而代之,则有重要的经济意义。本文拟从比表面、孔径分布等孔结构特性的角度,探讨选取代用品的可能性。     

第33届IUPAC国际高分子讨论会评述

第33届国际纯粹与应用化学学会高分子讨论会(33rd IUPAC International Symposium on Macromolecules)于1990年7月8日至7月13日在加拿大蒙特利尔举行。44个国家和地区近3000名学者参加了讨论会。中国代表10人,其中成都科技大学徐僖教授和广州中山大学李卓美教授是大会特邀报告人。此外,不少中国留学生参加了会议。会议交流论文1627篇,其中大会报告6篇,高分子材料48个专题组822篇,高分子物理和化学     

聚（丙烯酰胺—丙烯酸）／聚（丙烯酰胺—二甲基二烯丙然氯化铵）分…

通过Ｂｒｏｏｋｆｉｅｌｄ粘度测定及室内岩心驱油试验评定。研究了聚（丙烯酰胺－丙烯酸）／聚（丙烯酰胺－二甲基二烯丙基氯化法（Ｐ（ＡＭ－ＡＡ）／Ｐ（ＡＭ－ＤＭＤＡＡＣ）分子复合型聚合物驱油剂的增粘，抗温，抗盐性及其驱油效果，结果表明，聚合物组成一定时，其复合比影响溶液复合增粘效果，复合型聚合物溶液的抗盐性明显优于Ｐ（ＡＭ－ＡＡ）溶液的抗盐性，多价金属离子的加入是提高溶液抗盐性的有效途径，该驱油剂的最终     

基于电感耦合等离子体的InP基半导体材料干法刻蚀的研究

研究了基于电感耦合等离子体(ICP)刻蚀系统的InP基半导体材料的干法刻蚀.采用Cl2/Ar/H:混合刻蚀气体,分别研究了氯气体积分数和ICP功率与刻蚀速率之间的关系,及镍、二氧化硅和二者结合型掩膜版的适用范围.获得有效的刻蚀速率为450～1 200 nm/min,InP对金属镍的选择性刻蚀比值为175～190.掩膜版...     

芯棒与口模反向旋转挤出聚乙烯管结构与性能的研究

采用自行研制的新型旋转挤出装置,通过芯棒与口模同时反向旋转挤出制备聚乙烯(PE)管.结果表明,在口模与芯棒反向旋转挤出过程中,管道内外壁除受到轴向应力作用外,还受到芯棒和口模旋转所施加的环向应力,其合力方向不再是沿管道轴向而是与其有一定的角度.因此,分子链的取向方向和以此链为初级成核点形成的串晶偏离轴向,增强了管道抵抗...     

First-principles study of a new BP2 two-dimensional material

Two-dimensional materials have a wide range of applications in many aspects due to their unique properties. Here we carry out a detailed structural search and design of the BP₂ using the first principles method, and find a new PMM2 sheet. The analysis of the phonon dispersive curves shows that the 2D PMM2 is dynamic stable. The study of molecular dynamics shows that the 2D PMM2 can be stable under high temperature, even at 600 K. Most importantly, when a suitable strain is applied, the structure can exhibit other electronic properties such as direct band gap semiconductor. In addition, the small strain can tune the band gap value of the PMM2 structure to around 1.4 eV, which is very close to the ideal band gap of solar materials. Therefore, the 2D PMM2 may have potential applications in the field of photovoltaic materials.     

Low-voltage soft robots based on carbon nanotube/polymer electrothermal composites

Nowadays, soft robots have become a research hot spot due to high degree of freedom, adaptability to the environment and safer interaction with humans. The carbon nanotube (CNT)/polydimethylsiloxane (PDMS) electrothermal composites have attracted wide attention in the field of flexible actuations due to large deformation at low voltages. Here, the preparation process of CNT/PDMS composites was designed and optimized, and electrothermal actuators (ETAs) were fabricated by cutting the CNT/PDMS composite films into a "U" shape and coating conductive adhesive. The deformation performance of the ETAs with different thicknesses at different voltages was studied. At a low voltage of about 7 V, the ETA has a deformation rate of up to 93%. Finally, two kinds of electrothermal soft robots (ETSRs) with four-legged and three-legged structures were fabricated, and their inchworm-like motion characteristics were studied. The ETSR2 has the best motion performance due to the moderate thickness and three-legged electrode structure.     

线性超图的边染色

超图$H$的一个$k$-边染色是用$k$种颜色的边染色, 使得相交的边染不同的颜色. Erd\H{o}s-Faber-Lov\''asz猜想认为任一$n$个顶点的无环线性超图都有一个$n$-边染色. 2021年, Kang, Kelly, K\"uhn, Methuku和Osthus对充分大的$n$确认了该猜想成立. 在本文中, 我们证明该猜想对弱冲突的超图是成立的. 这严格拓展了Bretto, Faisant 和Hennecart在2020年的两个相关结果.