环保型木器涂料

介绍水性和紫外光固化两类环保型木器涂料及其研究进展。水性木器涂料主要为丙烯酸酯与聚氨酯两大类，其研究进展集中表现为乳液改性，包括自交联、共混共聚、微乳液等；紫外光固化木器涂料包括其光固化树脂、活性稀释剂和光引发剂的功能及进展；指出研究新型乳液以提高水性木器涂料涂膜的表面性能，开发新型原材料以降低紫外光固化木器涂料的成本、扩大适应范围将成为今后环保型木器涂料的研究重点。     

Properties of poly(n‐butyl methacrylate) prepared by reverse atom transfer radical polymerization in an aqueous dispersed system

Reverse atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) in waterborne media using Cu(II) complexes with azo initiators (i.e., reverse ATRP) was conducted. The influence of several factors, such as surfactant, catalyst, and reaction time, on the stability of the emulsion, the particle size, the morphology of the emulsion particles, and the control of the polymerization was investigated. The results showed great differences between ATRP and conventional emulsion polymerization, especially the nucleation mechanism and the kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1542–1547, 2003     

激光诱导二甲基二乙氧基硅烷气相合成碳化硅超细粉

本工作首次采用有机硅试剂二甲基二乙氧基硅烷为反应物，进行了激光导气相反应，制备出平均粒径为４０ｎｍ的非晶ＳｉＣ粉末，粉末中Ｃ／Ｓｉ比随反应气流量的变化而变化。非晶ＳｉＣ粉末在１８７３Ｋ，氮气中退火１ｈ后转变为β－ＳｉＣ及α－ＳｉＣ，同时，粉末中部分氧杂质及自由碳脱出粉末。     

Perylene derivative sensitized multi-walled carbon nanotube thin film

Perylene-sensitized multi-walled carbon nanotubes (PV-MWNT) have been prepared by a π-stacking between nanotubes and perylene derivatives, N,N′-diphenyl glyoxaline-3,4,9,10-perylene tetracarboxylic acid diacidamide (PV). The resultant nanocomposites have been characterized by transmission electron microscope (TEM), UV-vis absorption, photoluminescence (PL) and photocurrent spectra. Long range ordering can be observed in the form of PV-MWNT via π-stacking by TEM. Red-shift in the optical spectra consisting of the UV-vis absorption and PL spectra with the attraction of PV on the surface of the MWNTs were observed. The evident quenching in PL spectra of PV-MWNT was ascribed to the absorption and transfer of recombination energy by MWNT. Photosensitivity spectra demonstrated an increasing photocurrent in the ultraviolet region and a broadening photosensitivity in the red spectral region for solar cells based on PV-MWNT.     

Effect of ethylene-propylene copolymer with residual PE crystallinity on mechanical properties and morphology of PP/HDPE blends

Morphology and mechanical properties of polypropylene (PP)/high density polyethylene (HDPE) blends modified by ethylene-propylene copolymers (EPC) with residual PE crystallinity were investigated. The EPC showed different interfacial behavior in PP/HDPE blends of different compositions. A 25/75 blend of PP/HDPE (weight ratio) showed improved tensile strength and elongation at break at low EPC content (5 wt %). For the PP/HDPE = 50/50 blend, the presence of the EPC component tended to make the PP dispresed phase structure transform into a cocontinuous one, probably caused by improved viscosity matching of the two components. Both tensile strength and elongation at break were improved at EPC content of 5 wt %. For PP/HDPE 75/25 blends, the much smaller dispersed HDPE phase and significantly improved elongation at break resulted from compatibilization by EPC copolymers. © 1995 John Wiley & Sons, Inc.     

碳化-冻融作用下钢筋混凝土梁承载力衰减分析

为了研究碳化-冻融环境对钢筋混凝土梁承载力的影响,对钢筋混凝土试验梁进行了多重循环碳化-冻融交替作用下的加速腐蚀试验,然后对完成腐蚀试验的钢筋混凝土梁进行抗弯荷载试验.通过荷载试验获得腐蚀梁的应变变化、裂缝发展及荷载位移曲线,分析碳化-冻融耦合作用对试验梁承载力衰减的影响.结果表明:荷载试验过程中腐蚀钢筋混凝土梁的跨中截面应变基本满足平截面假定,相同荷载下受腐蚀梁的跨中应变大于未腐蚀梁的应变值;与未腐蚀钢筋混凝土梁相比受腐蚀梁的裂缝出现的较早,裂缝较宽、数量较少;从试验梁的荷载-位移曲线可知同一级别荷载作用后梁体跨中位移值随碳化-冻融腐蚀周期的增加而增大,极限荷载随腐蚀周期的增加而降低.根据试验梁荷载试验的实测数据提出了钢筋混凝土梁在全寿命周期内承载力时变衰减系数的计算公式,并通过有限元模拟分析验证了其正确性,该系数可用于我国严寒区钢筋混凝土结构的承载力衰减模拟分析和评估,成果可为实际工程参考.     

Synthesis and Characterization of 2-(Dimethylamino)ethyl Methacrylate Homopolymers via aqueous RAFT Polymerization and Their Application in Miniemulsion Polymerization

Summary Homopolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) have been synthesized directly in aqueous media by reversible addition-fragmentation chain transfer polymerization (RAFT) using 4,4-azobis(4-cyanopentanoic acid) (V501) as a water-soluble azo initiator and 4-cyanopentanoic acid dithiobenzoate (CPADB) as a chain transfer agent. The resulting polymers were controlled in the range of narrow molecular weight distributions, with lower than 1.3. Using the produced dithioester-capped DMAEMA homopolymer as a macro chain transfer agent, miniemulsion RAFT polymerization of methyl methacrylate and styrene were carried out, respectively. ¹H NMR analysis showed that the diblock copolymer PDMAEMA-b-PMMA in the form of stable latices was obtained as expected. This revised version was published online at the end of November 2004. Unfortunately, the received date was incorrect due to a technical problem.     

A（B1／3′B2／3″）O3型复合钙钛矿微波介质陶瓷材料的发展

A（B1／3′B2／3″）O3型微波介质陶瓷是一种很有前途的信息功能材料，具有复合钙钛矿结构，高频率下Q值较高，可以很好的符合现代通信设备的要求。广泛应用在介质谐振器、滤波器、陶瓷电容器中。本文比较详细地介绍了A（B1／3′B2／3″）O3型微波介质陶瓷材料的结构、性能、制备工艺、发展历史以及研究前景。