The effects of clay dispersion on the mechanical,physical, and flame‐retarding properties of wood fiber/polyethylene/clay nanocomposites

In this study, nanosized clay particles were introduced into wood fiber/plastic composites (WPCs) to improve their mechanical properties and flame retardancy, which are especially important in various automotive and construction applications. A high degree of exfoliation for nanoclay in the wood fiber/high density polyethylene (HDPE) composites was successfully achieved with the aid of maleated HDPE (PE‐g‐MAn), through a melt blending masterbatch process. The structures and morphologies of the composites were determined using X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. This article presents the effects of clay content and degree of clay dispersion on the mechanical and physical properties and flame retardancy of wood fiber/HDPE composites that contained a small amount of clay, in the range of 3–5 wt %. We concluded that achieving a higher degree of dispersion for the nanosized clay particles is critical to enhance the mechanical properties and the flame retardancy of WPCs when small amounts of clay are used. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of submicron-sized porous titanium oxide particles by the swelling process

A method to prepare submicron-sized porous titanium oxide (TiO₂) particles is studied in this work. Polystyrene (PS) template particles were prepared by emulsifier-free emulsion polymerization. The polymer templates dispersed in the aqueous solution have been used for entrapping titanium(IV) isopropoxide (TTIP), by the swelling process in a suitable solvent mixture containing a swelling solvent (good solvent or poor solvent), a TiO₂ precursor (TTIP), and a chelating agent (AcAc), within the polymer templates, followed by hydrolysis/condensation reaction of TTIP confined in PS template particles by the addition of the chelating agent. The influence of various reaction parameters, such as mixtures of different weight ratios between the PS particles and desiccative TTIP, AcAc amounts, and the swelling solvent amounts and type, on the size, bulk, and composition of the particles was investigated. Porous TiO₂ particles have been prepared by thermal decomposition of the PS templates at 500 °C.     

Thermostable and flame retardant Mesua ferrea L. seed oil based non-halogenated epoxy resin/clay nanocomposites

Bio-based polymer nanocomposites have a unique niche of their own in the domain of green technology. A bio-based sulfone epoxy resin (BPSE) has been synthesized from the monoglyceride of Mesua ferrea L. seed oil, bis(4-hydroxyphenyl) sulfone, bisphenol-A and epichlorohydrin. The formation of resin was confirmed by the determination of viscosity, epoxy equivalent, etc. and the structure was elucidated from FTIR and ¹H NMR spectroscopies. This resin was used as the matrix for the preparation of epoxy/clay nanocomposites by ex situ technique using different doses of organo nano-clay (1, 2.5 and 5%, w/w). XRD, TEM, SEM, FTIR and rheological studies confirmed the formation of nanocomposites with partial exfoliated structure of the nano-clay. The study demonstrated that the tensile strength enhanced from 4 to 11.4 MPa, scratch hardness improved by two-fold, gloss value increased by 20 units, adhesive strength improved by two-fold and thermal stability improved by 19 °C on incorporation of 5 wt% of nano-clay with respect to the pristine polymer. The limiting oxygen index value and UL94 test indicated improvement of flame retardancy of the nanocomposites. The results exhibit the potentiality of these bio-based epoxy/clay nanocomposites for multifaceted advanced applications.     

聚环氧氯丙烷-二甲胺粘土稳定剂合成及其防膨性能评价

文章采用环氧氯丙烷和二甲胺为原料,采用交联聚合法进行聚合,合成了聚环氧氯丙烷-二甲胺粘土稳定剂,探讨了合成条件并评价了粘土稳定剂的防膨性能。确定聚环氧氯丙烷-二甲胺的最佳合成条件为:反应温度70℃,反应时间5h以上,n(环氧氯丙烷):n(二甲胺)=1.5:1,n(乙二胺):n(环氧氯丙烷+二甲胺)=3%。该粘土稳定剂防止粘土膨胀性能良好,防膨率达到90.3%。     

惰性粒子对水沸腾传热强化的实验研究

通过加入不同种类和体积分率的惰性粒子,在垂直管中进行了水的流动沸腾传热实验,研究了三相流沸腾传热特性。实验中预先对水加热,采用了沸点进料。实验发现,传热膜系数随热通量、液体流量的增加及粒子体积分率的增大而增加。对于不同粒子,这种变化趋势比较一致,但不同粒子对沸腾传热的强化效果不同。实验结果表明:由于固体粒子的存在,强化了沸腾传热,三相流沸腾传热系数是相同条件下汽液二相流沸腾传热系数的1.3—1.7倍。     

硅酸盐粘土矿物的晶体结构与陶瓷减水剂的解凝机理

从泥浆微粒表面的ζ电位、粘土矿物的晶体结构以及陶瓷减水剂的解凝机理出发,说明如何根据制浆中所用粘土矿物的类型选择不同类型的减水剂,从而提高减水剂的使用性能。说明了粘土矿物种类与减水剂选择之间的关系,从而为在生产中合理、正确地选择减水剂以及开发新型减水剂提供理论依据。     

浅谈高温泥绘在现代陶瓷装饰中的表现

现代陶瓷装饰在材料语言方面相对于传统的种种突破,体现了现代人的审美要求。高温泥绘,吸收了古人所留下的丰富视觉遗产,其艺术效果独特,表现形式丰富多彩,在陶瓷装饰领域独树一帜,并具有不可彰显的魅力。     

几种新粘土原料在高强度电瓷中的应用

通过对几种粘土原料的比较,确定新配方中采用介休洗泥和青草岭洗泥,并采用0.060 mm筛孔径（250目）的细矾土,使得新配方具有良好的工艺性能,瓷材料弯曲强度得到了提高。     

邯郸粉质粘土固结不排水试验归一化性状分析

为了得到土的强度和变形之间的有机统一关系,反映区域性土的本构关系实验参数,本文根据归一化幂因子理论,从围压和平均固结压力两个方面论述了土的归一化理论,通过对邯郸粉质粘土的固结不排水三轴试验,得到了土的应力应变关系曲线,在此基础上用两种归一化方法分析了邯郸粉质粘土的性状,得到了归一化参数,为邯郸粉质粘土的本构关系研究提出了基本参数,可用于岩土工程理论与应用分析。     

Impact of retention on trans‐column velocity biases in packed columns

The heights equivalent to a theoretical plate of a weakly and strongly retained compounds were measured on two packed columns having different average mesopore sizes. The measurements were carried out in two different cases, with access to the mesopores by the sample molecules blocked (filled with n‐nonane) or not. The experimental results demonstrate that the eddy dispersion terms of both columns are significantly smaller for porous than for nonporous particles. Two simultaneous phenomena explain this observation. First, packed columns are radially heterogeneous which causes significant trans‐column velocity biases warping the bands. Second, radial dispersion contributes to mass transfer across the column, relaxing the radial concentration gradients that are caused by these velocity biases. The impact of these biases is minimized when the pores of the particles are not blocked; it decreases with increasing residence time and radial dispersion coefficient of the solutes. © 2009 American Institute of Chemical Engineers AIChE J, 2009