Preparation and rheological studies on the solvent based acrylic pressure sensitive adhesives with different crosslinking density

On the basis of synthesis of a series of solvent based acrylic pressure sensitive adhesives (PSAs) with different crosslinking density, the thermal and rheological properties were characterized. T_g values were increased after crosslinked with MDI, and the thermal stability was also improved. Rheological studies were performed via frequency sweep, amplitude sweep, temperature sweep patterns, respectively. The creep recovery properties were also researched. In this way, it was proved that the linear viscoelastic (LVE) range was elongated as the feeding MDI increased, the elastic modulus (G′) of the acrylic PSAs was obviously increased after crosslinked with MDI whereas hardly making any change to the viscous modulus (G″). In the frequency sweep pattern, the PSAs samples behave as pseudoplastic non-Newtonian fluid; and zero shear viscosity increased as the feeding MDI mass ratio was increased, after discussing the cross-over frequency (?^?) and the relaxation time t_R, it can be concluded that the addition of MDI would make for the improvement of the elasticity of the PSAs; in the temperature sweep pattern, it could be seen that the cross-over temperatures (where G″=G′) were 34 and 70 °C for the samples crosslinked with 0 wt% and 0.1 wt% MDI, respectively. When the mass ratio of MDI fed was higher than 0.1 wt%, even though the temperature increased to 120 °C, the samples remained elastic (G′>G″). In the creep recovery test, it was noteworthy that as the feeding ratio of MDI was increased, the creep recovery properties of the acrylic PSAs were substantially improved. And for the same sample, as the applied constant stress increased from 200 to 1000 Pa, the recoverable proportion of the materials was principally not changed in that all the experiments were carried out within the linear viscoelastic range of the samples. And the sample crosslinked with 0.5 wt% MDI shows the highest 180° peel stress.     

活性无烟煤过滤去除有机物的性能研究

通过小试试验研究了活性无烟煤过滤对水中有机物的去除效果.试验结果表明,活性无烟煤过滤能有效去除浊度,出水浊度小于0.5NTU,与传统滤料石英砂和无烟煤的过滤效果相当;反冲洗周期为6 d时,活性无烟煤过滤对TOC和UV<,254>均能稳定去除,平均去除率分别为33.4%和43.6%;反冲洗周期为28 h的长期运行过程中,...     

PAN/PPG纤维预氧化及碳纤维结构和性能研究

采用聚丙二醇(PPG)与聚丙烯腈(PAN)共混制备的PAN/PPG原丝进行预氧化和碳化,利用SEM、FTIR、元素分析仪、力学性能测试等仪器和手段,研究了PPG的加入对预氧丝和碳丝的结构和性能的影响.研究发现:PPG的加入使PAN预氧丝的表面结构更加均匀,减少了碳纤维中的孔洞;同时还促进了纤维在预氧化和碳化过程中的氧化...     

PA6/POE-g-MAH/纳米BaSO4三元复合体系增韧研究

采用纳米BaSO4及马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)对聚酰胺(PA)6进行增韧改性,研究了PA6/POE-g-MAH共混体系的脆韧转变,讨论了纳米BaSO4的用量对PA6/POE-g-MAH脆韧转变体系的增韧作用.结果显示,当POE-g-MAH质量分数为10%～20%时,PA6/POE-g-MAH共混...     

Genetic Diversity and Phylogeny of Antagonistic Bacteria against Phytophthora nicotianae Isolated from Tobacco Rhizosphere

The genetic diversity of antagonistic bacteria from the tobacco rhizosphere was examined by BOXAIR-PCR, 16S-RFLP, 16S rRNA sequence homology and phylogenetic analysis methods. These studies revealed that 4.01% of the 6652 tested had some inhibitory activity against Phytophthora nicotianae. BOXAIR-PCR analysis revealed 35 distinct amplimers aligning at a 91% similarity level, reflecting a high degree of genotypic diversity among the antagonistic bacteria. A total of 25 16S-RFLP patterns were identified representing over 33 species from 17 different genera. Our results also found a significant amount of bacterial diversity among the antagonistic bacteria compared to other published reports. For the first time; Delftia tsuruhatensis, Stenotrophomonas maltophilia, Advenella incenata, Bacillus altitudinis, Kocuria palustris, Bacillus licheniformis, Agrobacterium tumefaciens and Myroides odoratimimus are reported to display antagonistic activity towards Phytophthora nicotianae. Furthermore, the majority (75%) of the isolates assayed for antagonistic activity were Gram-positives compared to only 25% that were Gram-negative bacteria.     

粉煤灰提取氧化物研究进展

粉煤灰是目前世界上排放量最大的固体废弃物之一。研究表明,中国部分地区粉煤灰具有极高的利用价值。近年来,关于粉煤灰中硅、铝的提取和应用方面的研究逐渐升温。介绍了粉煤灰提取氧化物的4种主要方法：赤泥法、烧结法、酸法、碱法,详细介绍了烧结法、酸法、碱法并给出了其典型工艺路线。综述了目前中国粉煤灰提取氧化物的最新研究进展。总结了几种方法各自的优缺点,展望了中国粉煤灰提取氧化硅、氧化铝的前景。粉煤灰提硅提铝工艺的研究和开发,有良好的社会效益和经济价值。     

Preparation and visible light photocatalytic activity of Ag/TiO₂/graphene nanocomposite

Great efforts have been made to develop efficient visible light-activated photocatalysts in recent years. In this work, a new nanocomposite consisting of anatase TiO(2), Ag, and graphene was prepared for use as a visible light-activated photocatalyst, which exhibited significantly increased visible light absorption and improved photocatalytic activity, compared with Ag/TiO(2) and TiO(2)/graphene nanocomposites. The increased absorption in visible light region is originated from the strong interaction between TiO(2) nanoparticles and graphene, as well as the surface plasmon resonance effect of Ag nanoparticles that are mainly adsorbed on the surface of TiO(2) nanoparticles. The highly efficient photocatalytic activity is associated with the strong adsorption ability of graphene for aromatic dye molecules, fast photogenerated charge separation due to the formation of Schottky junction between TiO(2) and Ag nanoparticles and the high electron mobility of graphene sheets, as well as the broad absorption in the visible light region. This work suggests that the combination of the excellent electrical properties of graphene and the surface plasmon resonance effect of noble metallic nanoparticles provides a versatile strategy for the synthesis of novel and efficient visible light-activated photocatalysts.     

Encapsulation of gold nanoparticles by simian virus 40 capsids

Viral capsid-nanoparticle hybrid structures constitute a new type of nanoarchitecture that can be used for various applications. We previously constructed a hybrid structure comprising quantum dots encapsulated by simian virus 40 (SV40) capsids for imaging viral infection pathways. Here, gold nanoparticles (AuNPs) are encapsulated into SV40 capsids and the effect of particle size and surface ligands (i.e. mPEG and DNA) on AuNP encapsulation is studied. Particle size and surface decoration play complex roles in AuNP encapsulation by SV40 capsids. AuNPs ≥15 nm (when coated with mPEG750 rather than mPEG2000), or ≥10 nm (when coated with 10T or 50T DNA) can be encapsulated. Encapsulation efficiency increased as the size of the AuNPs increased from 10 to 30 nm. In addition, the electrostatic interactions derived from negatively charged DNA ligands on the AuNP surfaces promote encapsulation when the AuNPs have a small diameter (i.e. 10 nm and 15 nm). Moreover, the SV40 capsid is able to carry mPEG750-modified 15-nm AuNPs into living Vero cells, whereas the mPEG750-modified 15-nm AuNPs alone cannot enter cells. These results will improve our understanding of the mechanisms underlying nanoparticle encapsulation in SV40 capsids and enable the construction of new functional hybrid nanostructures for cargo delivery.     

SnO₂ nanosheet hollow spheres with improved lithium storage capabilities

In this work, we employ new chemistry to grow tin oxide nanosheets in the gel matrix of sulfonated polystyrene hollow spheres. After calcination in air, hierarchical hollow spheres assembled from SnO(2) nanosheets can be obtained. In virtue of the porous shell structure and internal voids, these SnO(2) hierarchical nanosheet hollow spheres exhibit improved lithium storage capability.     

应用GT-Styrene~苯乙烯回收技术对裂解汽油的改质分析

通过采用GT-Styrene苯乙烯回收技术对传统的裂解汽油处理工艺进行改进,汽油的产品性能可以得到有效的改善,并回收有价值的苯乙烯产品和得到高质量的混合二甲苯产品。