Effects of polymeric dispersants and surfactants on the dispersing stability and high‐speed‐jetting properties of aqueous‐pigment‐based ink‐jet inks

Good jetting performance and pigment‐dispersing stability are necessary for pigment‐based ink‐jet inks. This study investigates how the chemical structures of the polymeric dispersants affect the pigment‐dispersing stability and jetting performance of ink‐jet inks. A series of polymeric dispersants containing styrene (hydrophobic unit) and acrylic acid (hydrophilic unit) with different ratios have been synthesized and used to disperse different pigments. Because 3000–12,000 ink drops can be expelled from the nozzle of a thermal bubble‐type ink‐jet printer within 1 s, the jetting behavior is related to the rheology variation of a dilute solution under a high shear. An in situ drop formation system has been used to study the high‐shear‐rate rheology (dynamic surface tension and dynamic viscosity) of a solution with a viscosity lower than 3 cps, which no commercial rheometer can measure. Excellent ink‐jet inks can only be produced by the combination of pigments, dispersants, and surfactants with appropriate hydrophilicity. Moreover, the correlation of the pigment surface properties, the chemical structures of the polymeric dispersants, and ink formulation is discussed. The effects of the surfactants and firing conditions on the jetting behavior of the ink‐jet ink are also examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1909–1920, 2003     

Historical iron gall ink containing documents — Properties affecting their condition

Iron gall ink, also referred to as iron gallotannate ink, is one of the most important inks in the history of western civilisation, and was in widespread use from the middle ages until the 20th century. Unfortunately, iron ions and acids present in these inks induce enhanced degradation of paper, thus severely damaging numerous historical artefacts. Yet, when examining documents, it is frequently observed that not all materials containing iron gall ink are suffering from ink corrosion. While some are completely destroyed, others may be in excellent condition even centuries after their creation. In order to establish the main properties of materials, common to severely degraded documents, the effects of the type and quantity of metal ions in the ink, as determined by in-air PIXE method, pH of the ink on paper, grammage of paper, its absorptivity and the width of ink lines were evaluated against the extent of corrosion. Using multiple linear regression analysis, a correlation has been obtained between the width of the applied ink lines, pH, grammage of paper and the extent of ink corrosion. Based on these factors, which can be acquired non-destructively from most historical documents, it is therefore possible to predict the stability of historical iron gall ink containing paper.     

核磁共振氢谱法鉴定油性圆珠笔文书的书写时间

油性圆珠笔文书书写时间的鉴定是司法鉴定工作中的热点.该文采用核磁共振氢谱法(~1H NMR)对所购6种不同型号油性圆珠笔的油墨进行了表征,研究了圆珠笔油墨中的溶剂——苯氧基乙醇在文书老化过程中的变化,并建立了MG-115书写文书的自然老化标准曲线.该标准曲线能够准确鉴定MG-115圆珠笔4个月内的文书书写时间,重现性良好;同时,该文探究了人工老化与自然老化的关系,为文书书写时间的鉴定提供了依据.     

Does power ultrasound affect Nafion® dispersions?

The effect of low frequency power ultrasound on Nafion® ionomer used for fabricating proton exchange membrane fuel cell (PEMFC) and water electrolyzer (PEMWE) catalyst inks was investigated. In this study, a series of Nafion® dispersions having three concentrations (10, 5, and 2.5% w/v) were studied under various irradiation durations (t_us), at fixed ultrasonic frequency (f = 42 kHz) and ultrasonic power (P > 2 W), under either controlled or unregulated bulk solution temperature conditions using a laboratory ultrasonic cleaning bath. Viscosity (η), thermal degradation, and glass transition temperature (T_g) for all Nafion® dispersion samples was measured and compared to untreated Nafion® samples. In our conditions, it was found that power ultrasound lowered the viscosity of all tested Nafion® dispersion samples; whilst thermogravimetric and differential scanning calorimetry analyses showed that for all ultrasonically irradiated samples, a negligible overall polymer degradation and no obvious change in T_g was observed under controlled and unregulated bulk temperature conditions. It was found that it is possible that acoustic cavitation causes depolymerisation followed by a polymerisation initiation step during ultrasonication. By comparing the ultrasonically treated and high-shear mixed samples, it was also observed that acoustic and hydrodynamic cavitation played an important role in the reduction of dispersion viscosity.     

高效液相色谱法鉴定蓝色圆珠笔油墨字迹的书写时间

由圆珠笔油墨形成的契约、合同、收据和借条等可疑文件的真伪及形成时间的鉴定是目前法庭科学实验室经常遇到的问题, 因此建立一种简便、灵敏和准确的检验圆珠笔油墨字迹色痕的异同及形成时间的方法是十分必要的。文章介绍了一种可以检验圆珠笔油墨的种类及形成时间的方法。这种方法是依据高效液相色谱法分析圆珠笔油墨中染料的种类及染料随时间的变化关系来确定圆珠笔油墨字迹的异同及书写时间,染料随时间的变化可以通过相应的色谱峰的峰面积比计算而得。     

Micro-spectrochemical analysis of document paper and gel inks by laser ablation inductively coupled plasma mass spectrometry and laser induced breakdown spectroscopy

Current methods used in document examinations are not suitable to associate or discriminate between sources of paper and gel inks with a high degree of certainty. Nearly non-destructive, laser-based methods using laser induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to improve the forensic comparisons of gel inks, ballpoint inks and document papers based on similarities in elemental composition. Some of the advantages of these laser-based methods include minimum sample consumption/destruction, high sensitivity, high selectivity and excellent discrimination between samples from different origins. Figures of merit are reported including limits of detection, precision, homogeneity at a micro-scale and linear dynamic range. The variation of the elemental composition in paper was studied within a single sheet, between pages from the same ream, between papers produced by the same plant at different time intervals and between seventeen paper sources produced by ten different plants. The results show that elemental analysis of paper by LIBS and LA-ICP-MS provides excellent discrimination (> 98%) between different sources. Batches manufactured at weekly and monthly intervals in the same mill were also differentiated. The ink of more than 200 black pens was analyzed to determine the variation of the chemical composition of the ink within a single pen, between pens from the same package and between brands of gel inks and ballpoint inks. Homogeneity studies show smaller variation of elemental compositions within a single source than between different sources (i.e. brands and types). It was possible to discriminate between pen markings from different brands and between pen markings from the same brand but different model. Discrimination of ~ 96–99% was achieved for sets that otherwise would remain inseparable by conventional methods. The results show that elemental analysis, using either LA-ICP-MS or LIBS, provides an effective, practical and robust technique for the discrimination of document paper and gel inks with minimum mass removal (9–15 μg) and minimum damage to the document's substrate.     

Stainless steel cloth modified by carbon nanoparticles of Chinese ink as scalable and high-performance anode in microbial fuel cell

Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel cloth(SC) modified with carbon nanoparticles of Chinese ink(Cl) using polypyrrole(PPy)as a building block(PPy/Cl/SC).After modification,PPy/Cl/SC showed a 30% shorten in start-up time(36.4 ± 3.3 h vs.52.3± 1.8 h),33% increase in the maximum current(12.4 ± 1.4 mA vs.9.3± 0.95 mA),and2.3 times higher in the maximum power density of MFC(61.9 mW/m~2 vs.27.3 mW/m~2),compared to Ppy/SC.Experimental results revealed that carbon nanoparticles were able to cover SC uniformly,owing to excellent dispersibility of carbon nanoparticles in Cl.The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm2.This enhanced electron transfer between the electrode and bacteria.Further,embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents,which were bene ficial to bacteria adhesion on electrodes.Taking adva ntage of high mechanical strength and good conductivity,a large-size PPy/Cl/SC was successfully prepared(50×60 cm~2)demonstrating a promising potential in practical applications.This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.     

Laser crystallization of amorphous silicon films investigated by Raman spectroscopy and atomic force microscopy

The intrinsic and phosphorous (P)-doped hydrogenated amorphous silicon thin films were crystallized by laser annealing. The structural properties during crystallization process can be investigated. Observed redshifts of the Si Raman transverse optical phonon peak indicate tensile stress present in the films and become intense with the effect of doping, which can be relieved in P-doped films by introducing buffer layer structures. Based on experimental results, the established correlation between the stress and crystalline fraction (X_C) suggests that the relatively high stress can limit the increase in X_C and the highest crystalline fraction is obtained by a considerable stress release. At high laser energy density of 1250 mJ/cm², the poorer crystalline quality and disordered structure of the film originating from the irradiation damage and defects lead to the low electron mobility.     

A promising approach to conductive patterns with high efficiency for flexible electronics

A promising approach for conductive patterns with high efficiency for flexible electronics was developed by direct-writing, silver(I) solution (silver nitrate, acetate silver, etc.) with no solid particles as a conductive ink, conductive pen as a writing implement, and polyimide (PI) film as a substrate. The physical properties of the conductive ink were investigated by a dynamic contact angle system, ubbelohde viscometer and surface tension instrument. Conductive properties of silver ink film were investigated by 4-point probe, scanning electron microscope (SEM) and surface profilometer. It is demonstrated how the design of solvent composition in conductive ink affects surface morphology, and conductivity of silver ink films. It can be obtained that conductive patterns drawn on PI substrate not only have good mechanical/electrical fatigue properties, but also have low resistivity. Especially, when the sintering condition is 200 °C for 60 min, the resistivity can be down to 6.6 μΩ cm, 4.25 times the silver bulk resistivity.     

基于原位体积加成制备导电线路的研究

本文提出一种制备导电电路的方法。以纳米铜为导电填料，以光固化树脂为连接剂，制备含铜光固化油墨，利用丝网印刷方法获得含有纳米铜的图案，利用铜与银盐间的置换反应，将铜纳米粒子图案通过原位体积加成转化为导电银图案。研究结果表明，铜图案不具有导电性，而置换反应生成的银图案具有导电性，且导电能力受铜含量、银盐浓度、光照时间、浸泡反应时间等因素影响，本实验中获得的最高电导率为1.25×10⁵ S/m，导电线路具有良好的耐弯曲、耐疲劳性能，同时兼具优异的可修复性能，为导电线路的制备提供了常温下简单有效、成本低廉的实现方法，具有重要的参考价值。