Effects of aging and moisture on the dynamic viscoelastic properties of oriental lacquer (urushi) film

The effects of aging and moisture on the dynamic viscoelastic properties of three oriental lacquer films were investigated. With aging over 1000 days at room temperature, the glass‐transition temperature of the lacquer films (T_α) shifted to higher temperatures, the maximum loss tangent (tanδ_α) decreased, and the storage modulus at 20°C (E) increased. These changes were analogous irrespective of lacquers. With increasing moisture content, E decreased and tanδ increased at room temperature. Although the equilibrium moisture content of the virgin lacquer (sap) film was higher than that of the clear lacquer film, its E and tanδ were more stable with an increase of moisture content. It was speculated that the polysaccharides aggregated in the sap film did not effectively contribute to the mechanical properties of the film, while their hygroscopicity resulted in higher moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2288–2294, 2002     

生漆改性研究及漆酚金属高聚物

本文综述了生漆改性研究的概况 ,总结了漆酚金属高聚物的合成方法、结构特征及其主要性能 ,提出了今后生漆改性研究的发展方向和重点内容     

生漆的光氧化降解特性

本文综述了生漆的光氧化降解特性、光氧化降解机理的研究情况,以及提高生漆抗光氧化性能的改性方法和改性机理,并提出了改进生漆耐候性能的发展方向。     

Viscoelastic properties of suspensions with weakly interacting particles

Rheological characterization of a model suspension containing hydroxyl-terminated polybutadiene and glass beads with filler concentration up to 30% by volume was performed by using a Haake parallel disk rheometer. The rheological tests conducted were the measurement of the storage modulus, G′, loss modulus, G′, and complex viscosity, η*, as functions of the frequency and the steady shear viscosity as a function of the shear rate. The linear viscoelastic region was determined to extend up to 50% strain by measuring G′, G′, and η* as functions of strain amplitude. By using multiple gap separations between the disks, it was found that the suspension did not exhibit slip at the walls of the rheometer. G′ and G′ were used to determine the relaxation times distribution, G_i(λ_i, ⊘) as functions of the relaxation time, λ_i, and the filler content, ⊘. The relaxation moduli, G_i(λ_i, ⊘), decreased with the relaxation time, but increased with the filler content. The Cox–Merz rule was also observed to be valid for these suspensions. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 507–514, 1998     

中国生漆文明的起源

漆器和生漆技术是中国独特的发明,有着7000年不间断的文明史,是"地地道道从中国传过去的整个化学最重要的根源之一。生漆是从漆树皮层采集的天然树脂,具有神奇的变色现象和惊人的黏结力,自然固化后又能形成光亮的黑色物质。远古的人类在同大自然的抗争中,学会了生存技巧,增长了智力,发展了谋生手段,掌握了生漆的特性,积淀了生漆的知识,并利用生漆用于制器、装饰和记事表意,美化生活,记录文字,成为贵族阶层财富和地位的象征物。随着技术进步,生漆技术逐渐演化成为一种成熟的、高级的营造工艺和极致的艺术形态,孕育出了髹漆工艺体系和生漆文明,成为人类永远的财富。探究人类对髹漆器物的最初需求以及与之相应的髹漆工艺的发生和进化轨迹,能使我们更加深刻地理解生漆与人类源远流长的文化关系以及人类与环境的关系。     

Viscoelastic properties of lupin proteins produced by ultrafiltration-diafiltration

The linear and nonlinear rheological properties of defatted lupin proteins produced by ultrafiltration-diafiltration were investigated. Five concentrations ranging from 10 to 30% of the defatted ultrafiltered-diafiltered (DUD) lupin proteins were prepared. The viscoelastic properties strongly depended on concentrations. Below 12%, the DUD lupin proteins exhibited more fluid-like behavior. At 15%, lupin proteins became more viscoelastic, and above 20%, the viscoelastic solid-like properties became stronger. Below 12%, the high-frequency behaviors of moduli were proportional to ω^1/2, as expected for a semiflexible coil. Above 20%, the high-frequency behaviors of moduli were proportional to ω^1/2, indicating a flexible coil. The nonlinear steady shear rheological properties were also concentration-dependent and showed shear-thinning behavior, which could be described by a power law constitutive model. The trend of the power law exponent shift is very consistent with the linear viscoelastic behavior change with the lupin protein concentration. These results suggest DUD lupin proteins undergo a structural change between 12 and 20%.     

四氯化钛在天然生漆膜表面的化学修饰

通过四氯化钛和生漆膜的化学反应,在天然生漆膜表面形成一层修饰层。用红外光谱、X-射线能量色散光谱和扫描电子显微镜等,对该修饰层进行测试表征。结果表明漆膜易与四氯化钛发生化学反应并生成漆酚钛聚合物,反应后金属氧化物含量达10.76%,X-射线能量色散光谱(EDS)分析证明,反应主要在漆膜表面进行。     

氢氧化钠对生漆膜腐蚀行为的研究

本文用氢氧化钠水溶液对天然生漆漆膜进行腐蚀,并用红外分析、元素分析、热重分析和扫描电镜分析等手段来研究漆膜的腐蚀机理。结果表明,漆膜在氢氧化钠水溶液腐蚀下,漆膜的酚羟基氧化生成醌、侧链不饱和键生成醛或酮,醚键上发生断裂,漆膜中的部分多糖和糖蛋白发生降解而流失,漆膜出现多而大的孔洞,吸水率升高,光泽度和耐热性降低。     

良渚文化的髹漆艺术

良渚文化是中国长江三角洲平原范畴内的新石器时代晚期文化,以其精湛的琢玉技术闻名于世,其实,良渚文化的髹漆工艺也很精彩,反山、瑶山、卞加山、梅堰等遗址都出土了为数不少的髹漆器物,器形多样,胎骨主要有木胎、陶胎和石胎等,以生活用器为主。髹漆彩绘和髹漆嵌玉技术是这一时期的重大创新,代表了良渚文化漆器装饰艺术的最高成就,是器物实用与审美相结合的完美体现,也是等级分化的标志之一。髹漆工艺的发展是人类审美发展、欲求膨胀、技术进步、财富增长的结果,是为贵族服务的产物,富裕的环境促使人去注意生活装饰,愉悦自己。     

Viscoelastic properties of polyelectrolyte solutions in non-entangled concentrated regions

Viscoelastic properties of non-entangled concentrated aqueous solutions of three sodium polystyrenesulfonates with low molecular weights were measured in oscillation flows. Master curves of dynamic moduli were obtained by shifting the moduli data measured at different concentrations along the frequency (ω) axis for each molecular weight. The concentration shift factor used in making the master curves composes a single line irrespective of molecular weight. Storage and loss moduli are proportional to ω² and ω, respectively, in the terminal region, while they are proportional to ω^1/2 in the transition region. All the master curves can be well represented by the modified Rouse theory using the experimental values of concentration, molecular weight and viscosity in a reference state.     

A potential biodegradable rubber—Viscoelastic properties of a soybean oil-based composite

Scientists are more and more interested in biodegradable materials owing to their environmental advantage. We investigated viscoelastic properties of a newly developed biomaterial made from epoxidized soybean oil (ESO). ESO cross-linked by triethylene glycol diamine exhibited viscoelastic solid properties. The storage modulus (G′) was 2×10⁴ Pa over four frequency decades. The phase angles were 14–18°. Stress relaxation measurements showed that there was no relaxation up to 500 s. From the plateau modulus we estimated that the M.W. of this cross-linked soybean oil was on the order of 10⁵. The composites of cross-linked ESO with three different fibers had 50 times higher elasticity (G′) than those without fiber. Phase shifts were the same as those of cross-linked oil without fibers, but the linear range of rheological properties was much narrower than that of the material without fibers. All these results indicated that this new biopolymer made from soybean oil exhibited strong viscoelastic solid properties similar to synthetic rubbers. These rheological properties implied that this biomaterial has high potential to replace some of the synthetic rubber and/or plastics.     

Dielectric characterization of relaxation and curing behavior of oriental lacquer

Dielectric analysis was used to investigate the effects of temperature and humidity on the curing behavior of oriental lacquer and to characterize the dielectric properties of the lacquer film. It was found that the oriental lacquer could not cure to its hardened state at relative humidity less than 50% in ambient temperature and that the cure time could be shortened tremendously by increasing the curing temperature. In order to study the dielectric properties of oriental lacquer film, two films were prepared at different curing temperatures. The glass transition and secondary relaxation temperatures of ordinary oriental lacquer film, room temperature cured purified lacquer, were observed at 45 and −40°C, respectively. The high temperature cured purified lacquer film showed a secondary relaxation at around −50°C. The relationship between thermodynamic properties and chemical structures was explored based on the analysis of the dielectric relaxation behavior using Cole–Cole plots and the dielectric relaxation intensity Δϵ. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1804–1810, 2000     

中国大漆的故事

数千年来,大漆是中国人生产生活的重要组成部分,在中国文化中打下深深的烙印。本文拟从漆字的演变过程,与漆有关的姓氏、成语、地域及河流,中国大漆的特性等方面,全方位的讲述中国大漆的故事。     

黏弹性表面活性剂压裂液室内研究

优选了VES压裂液体系,最优配比为黏弹性表面活性剂VES 4%,助剂1.0%,还研究了体系的耐温、抗剪切、抗盐、破胶性能。结果显示,随着温度的升高,VES压裂液的黏度有明显的变化。不同的无机盐对VES压裂液有完全不同的影响,NH4C l具有明显的增黏作用,而KC l则有降黏作用;煤油、柴油都可使VES压裂液破胶,而且破胶后无残渣。     

Effects of Time and Temperature on the Viscoelastic Properties of Chinese Fir Wood

The effects of time and temperature on dynamic viscoelastic properties of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) were investigated using dynamic mechanical analysis in this study. The isothermal tests were applied to the small clear specimens with a moisture content of about 0.6% at constant temperatures ranging from 25 to 200°C for 550 min at atmospheric pressure. Changes in storage modulus and loss tangent with heating time were examined. The results indicated that heating time mainly resulted in thermal softening, thermal degradation of wood, and the reduction of wood stiffness. At more than 60°C, the reduction in storage modulus was accelerated generally as the wood was subjected to a higher temperature or longer heating time. At constant temperatures of 140 and 160°C, a relaxation phenomenon was observed with a slight change in weight, which could be attributed to the relocation of lignin molecules. At the temperature range of 140 to 180°C, the higher the heating temperatures, the earlier the tanδ peak appeared. It is suggested that the wood thermal softening occurs at higher temperatures with shorter heating times or at lower temperatures with longer heating times. At temperatures of 180 and 200°C, the loss of amorphous polysaccharides due to thermal degradation is considered to be the main factor affecting wood viscoelasticity.     

钯-炭催化生漆氢化制备饱和漆酚

研究了不同用量的钯 炭催化剂对生漆催化氢化的影响。实验结果表明,钯 炭催化剂比ＲａｎｅｙＮｉ催化剂更好     

Development of an eco-friendly hybrid lacquer based on kurome lacquer sap

An eco-friendly hybrid lacquer that dries quickly in a low relative humidity environment was synthesized using kurome lacquer (KL) and volatile organic compound-free hydrolyzed amine-functionalized silane (HAS). The HAS structure was characterized by nuclear magnetic resonance (NMR), and the results showed that the ethoxysilyl group in N-(2-aminoethyl)-3-aminopropyltriethoxysilane was completely hydrolyzed. After hybridization with the kurome lacquer, the properties of the hybrid lacquer were measured in detail including viscosity, molecular weight, drying behaviors, and film hardness. Viscosity measurements confirmed the mechanism of hydrolysis and the condensation reaction of silane.     

“张成造”剔红栀子花盘的启示

漆艺是中国传统文化的重要组成部分。雕漆在中国漆工艺发展史上占据十分重要的地位,雕漆是漆材质运用的巅峰样式。在雕漆的发展过程中,以"张成造"剔红栀子花盘为代表的元末雕漆起到承上启下的作用。同时,从漆材质语言角度,以"张成造"剔红栀子花盘为代表的雕漆潜含了漆材质自身发展的规律,漆艺的历史线索是伴随着漆材质的本体特性不断展开的过程。     

Viscoelastic characterization of rubber compounds

The viscoelastic properties of gum rubbers and the properties of corresponding compounds are discussed. Representative examples are given to illustrate the important influence of gum rubber on the compound properties. A method for evaluating strain amplification and strain-rate amplification is proposed. Examples are given to show the characterization of compounds with respect to the variation in gum rubbers and carbon black grades. The unique characteristics of compounds which are not observed in gum rubbers are also discussed.     

生漆改性及其应用进展

综述了生漆改性的几种途径及改性生漆在高性能防腐涂料、催化剂、吸附材料及传感器等应用方面的国内外研究进展,为生漆的高值化利用提供了参考。