As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-hel...As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear resistance.In this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the modifier.In addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear resistance.The optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink standard.With this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified one.It is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical stress.The new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.展开更多
Identification of altered documents written in black gel ink is widely recognized as problematic,especially if both the original and alteredstrokes contain carbon.In this work,we used a black handwriting resistance me...Identification of altered documents written in black gel ink is widely recognized as problematic,especially if both the original and alteredstrokes contain carbon.In this work,we used a black handwriting resistance measurement instrument to measure the resistance values ofink strokes.Because black gel inks are made with different types of pigments,their resistance values could be used to differentiate betweendifferent pen models from the same brand and among brands.In this study,30 black gel inks were classified by their resistance values.In apair‑wise comparison analysis of the results,there were 435 possible pairs and 347(i.e.,79.8%of the total)of these were able to be effectivelydistinguished.This is a nondestructive,convenient,and effective method to identify altered documents.展开更多
Ink-jet printing of ceramic thick films is one of low cost on-site ceramic pattern fabrication methods.It is necessary to investigate the rheological behaviour of ceramic inks and drying behaviour of droplets.Two kind...Ink-jet printing of ceramic thick films is one of low cost on-site ceramic pattern fabrication methods.It is necessary to investigate the rheological behaviour of ceramic inks and drying behaviour of droplets.Two kinds of BaTiO3 ceramic inks were prepared by mechanical mixing and sol-gel methods,respectively.The effect of preparation parameters,such as quantity of polyacrylic acid(PAA)and solid content,on physicochemical and rheologic properties of the ceramic inks was investigated.The results show that they satisfy the requirements of continuous ink-jet printing.The appearances of printed dots and single printed layers were observed by SEM.The SEM images indicate that dots printed with mixing method ink are in ring shape,and dots printed with sol-gel method ink are in pancake shape,so the printed layer surface with the latter ink is smoother.The causes of these phenomena were discussed.展开更多
基金supported by Shanxi Provincial Science and Technology Achievement Transformation Guidance Special Program of China(202104021301052)Shanxi Provincial Patent Transformation Special Plan Project(202202054,202306013).
文摘As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear resistance.In this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the modifier.In addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear resistance.The optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink standard.With this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified one.It is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical stress.The new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.
基金This study was supported by the Program of the Major Research and Development Projects of Shandong Province(Grant No.2017GSF20110)This study was supported by the Program of the Major Research and Development Projects of Shandong Province(2017GSF20110)This article was accepted by the 3rd International Symposium on Sino Swiss Evidence Science(3rd ISSSES),held by China University of Political Science and Law.
文摘Identification of altered documents written in black gel ink is widely recognized as problematic,especially if both the original and alteredstrokes contain carbon.In this work,we used a black handwriting resistance measurement instrument to measure the resistance values ofink strokes.Because black gel inks are made with different types of pigments,their resistance values could be used to differentiate betweendifferent pen models from the same brand and among brands.In this study,30 black gel inks were classified by their resistance values.In apair‑wise comparison analysis of the results,there were 435 possible pairs and 347(i.e.,79.8%of the total)of these were able to be effectivelydistinguished.This is a nondestructive,convenient,and effective method to identify altered documents.
基金Project(106151)supported by the Major Program of the Ministry of Education of ChinaProject(59842001)supported by the National Natural Science Foundation of China
文摘Ink-jet printing of ceramic thick films is one of low cost on-site ceramic pattern fabrication methods.It is necessary to investigate the rheological behaviour of ceramic inks and drying behaviour of droplets.Two kinds of BaTiO3 ceramic inks were prepared by mechanical mixing and sol-gel methods,respectively.The effect of preparation parameters,such as quantity of polyacrylic acid(PAA)and solid content,on physicochemical and rheologic properties of the ceramic inks was investigated.The results show that they satisfy the requirements of continuous ink-jet printing.The appearances of printed dots and single printed layers were observed by SEM.The SEM images indicate that dots printed with mixing method ink are in ring shape,and dots printed with sol-gel method ink are in pancake shape,so the printed layer surface with the latter ink is smoother.The causes of these phenomena were discussed.
