Synthesis and photovoltaic properties of dithienyl benzotriazole based poly(phenylene vinylene)s

Two new alternating copolymers based on dithienyl benzotriazole segment and phenylene vinyl unit were synthesized by Heck cross coupling method. The polymers exhibited broad absorption bands (from 300 nm to 752 nm for P1 , and from 300 nm to 654 nm for P2 ) in the UV‐visible region with optical bandgap ranging between 1.6 and 1.9 eV and proper electronic energy levels measured by cyclic voltammetry. The photovoltaic properties of the polymers as electron donors with 6.6‐phenyl C61‐butyric acid methyl ester as the electron acceptor in a bulk heterojunction structures were reported. Preliminary results showed moderate power conversion efficiency of 0.36% and 0.4%, respectively, under the illumination of AM 1.5, 100 mW/cm² with a device structure of ITO/PEDOT : PSS/polymer : PC₆₀BM (1 : 3)/Ca/Al. Furthermore, the side chain effect on properties has also been investigated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of rice straw fiber morphology and content on the mechanical and thermal properties of rice straw fiber‐high density polyethylene composites

Rice straw fiber‐high density polyethylene (HDPE) composites were prepared to investigate the effects of rice straw fiber morphology (rice straw refined fiber, rice straw pellet, rice straw strand), fiber content (20 and 40 wt %), and maleic anhydride polyethylene (MAPE) concentration (5 wt %) on the mechanical and thermal properties of the rice straw fiber‐HDPE composites in this study. Rice straw refined fiber exhibited more variability in length and width, and have a higher aspect ratio of 16.3. Compared to the composites filled of rice straw pellet, the composites made of the refined fiber and strand had a slightly higher tensile strength and lower tensile elongation at break. The tensile and flexural strength of the composites increased slightly with increasing rice straw fiber content up to 40 wt %, while the tensile elongation at break decreased. With addition MAPE, the composites filled with 20 wt % rice straw fiber showed an increase in tensile, flexural and impact strength and a decrease in tensile elongation at break. Differential scanning calorimetry showed that the fiber addition and morphology had no appreciable effect on the crystallization temperature of the composites but decreased the crystallinity. The scanning electron microscopy observation on the fracture surface of the composites indicated that introduction of MAPE to the system resulted in promotion in fiber dispersion, and an increase in interfacial bonding strength. Fiber breakage occurred significantly in the composites filled with refined fiber and strand after extruding and injection processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study of stability of high‐temperature polyimides using TG/MS technique

The oxidative stability of the carbon fiber‐reinforced composite of polyimide was examined, in real time, using the evolved gas analysis techniques. Off‐gas degradation products suggested the onset temperature for chain scissions to be fairly low at about 190–220°C. Based on the off‐gas products present and the trend of their release, the composite degradation mechanism appeared to be similar between 190 and 371°C, thereby marking 371°C to be the highest accelerated aging temperature for its long‐term lifetime prediction. Beyond 371°C, different degradation mechanisms would apply. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1219–1227, 2002     

Preparation and characterization of porous carbon beads and their application in dispersing small metal crystallites

Porous carbon beads were prepared by the pyrolysis of poly(vinylidene chloride) beads that were synthesized by suspension polymerization. After prolysis treatment at 180–300 °C under argon stream, the polymeric beads were further carbonized at 1000 °C for 3 h under argon stream to acquire porous carbon beads, of which the specific surface area was about 1000 m²/g, and pore size was mainly in the width range of 0.8–1.2 nm. The carbon structure and surface chemical composition characterized by X-ray diffraction and X-ray photoelectron spectroscopy, depended on the preparation temperature and the relations between them were examined. The characterization of the carbon beads by scanning electron microscopy, atomic force microscopy presented the morphological structure of the carbon beads surface and a global view of pores. The dispersion of nickel crystallites on the carbon beads surface was characterized by electron microprobe analysis. This study reveals that uniform surface morphological structure leads to the fine dispersion of metal crystallites.     

纳米TiO2颗粒的表面改性研究进展

较全面概述了在纳米TiO2颗粒改性中表面活性剂的作用机理与应用。对应于不同目的采用不同的改性剂甚至进行改性剂的复配方法及工艺，即为了改善纳米二氧化钛颗粒表面的润湿性和分散性，采用有机物改性方法；为了提高经伙二氧化钛颗粒的耐久性和化学稳定性目的时，采用无机物包裹的方法等。文中重点介绍了多种主要的改性剂和改性工艺，对于其它纳米颗粒的改性也有参考意义。     

有限元方法在玻璃成形工艺研究的应用

分析了玻璃在熔融状态下的力学性质、弹粘塑性和刚粘塑性本构方程以及玻璃成形的力学特性等,并结合玻璃成形的热力学公式,介绍了对玻璃成形的热力耦合分析的基本原理,还介绍了在玻璃成形过程中玻璃和模具之间的非线性接触、摩擦问题的求解,自动网格重划分技术.为了说明玻璃成形有限元分析的过程,最后介绍了利用三维大变形有限元方法来模拟电视显像管管屏的压制成形过程和饮料瓶吹制成形过程.     

Aging-Induced Metal Redistribution in Bimetallic Catalysts

Alloy particles were detected by XRD in bimetallic catalysts, made from physical mixtures of powders comprising distinct metal-support combinations (e.g., Pd on alumina and Rh on ceria-zirconia), following high-temperature redox aging. The morphology of the catalysts was examined by TEM, and the compositional structure of some of the alloy particles was determined. Two different effects of the redistribution of metals on oxygen-storage capacity were identified, one due to Pd enrichment of the surface of Pd-Rh alloy particles and the other due to loss of contact between metal and ceria-zirconia.     

环境监测报告格式规范的探讨

按照GB/T15481-2000《检测和校准实验室能力的通用要求》标准的要求,以环境监测废水监测报告为例,来探讨监测报告设计的格式要求。     

L-肉碱的酶法生产

要L-肉碱是与动物体内脂肪酸代谢有关的化合物,主要功能是作为载体将长链脂肪酸从线粒体膜外输送到膜内促进脂肪酸的β-氧化,将脂肪代谢转变为能量。L-肉碱广泛用于医药、保健食品及饲料等行业。江苏省微生物研究所在成功解决了高转化率微生物酶的选育、肉碱与巴豆甜菜碱的分离技术和巴豆甜菜碱的回收问题后,开发了L-肉碱的微生物酶法生产技术,并与常茂生物化学工程有限公司合作进行了日产1kg规模的中试,用300L发酵罐发酵产酶,150L酶反应器进行酶转化,L-肉碱的发酵水平达15g/L以上,用401L有机玻璃层析柱系统提取精制,提取收率达70％以上,产品质量符合USP23版标准。     

发酵法生产多价不饱和脂肪酸的研究

γ-亚麻酸在医药、食品、化妆品和饲料领域拥有广阔的应用前景,研究发现采用小于16％糖浓度的流加工艺进行发酵时,γ-亚麻酸产量为2.4g/L,生产周期短,生产消耗低,适合实际生产应用,适宜的产物提取方法是乙醇-正己烷两步法;DHA、EPA等不饱和脂肪酸主要结合在甘油的2-位,利用脂肪酶对油脂选择性水解的特点对鱼油进行水解反应可以达到富集多价不饱和脂肪酸的目的,筛选了两种目标酶并研究了其固定化方法;用被孢霉属菌株在100L发酵罐中生产花生四烯酸,菌干重可达36g/L,花生四烯酸达4.9g/L。