Bei Hai He

Effect of Electrical Characteristics Modification on Viscosity of Kaolin Suspension

Modifications of the interfacial electrical characteristics of kaolin were investigated through reversing particles surface charges induced by organic cationic polyelectrolyte and natural anionic organic substance. Zeta potential and rheology tests indicated that polymeric OH-Al reversed the edge charges and reached a saturation adsorption on kaolin surface at dosage of 45μmol/g, corresponding to a lower viscosity of kaolin suspension, as a result of the combined action of OH-Al modified positive particle surface and negative charges from sodium hexametaphosphate dispersant. A significant reduction in viscosity of kaolin modified by gallic acid was also observed in either dilute or concentrated suspension. The strong interaction of OH-Al ions with clay greatly increased the gallic acid adsorption, and resulted in the lowest viscosity for modified kaolin, indicating the bound of gallic acid to the reactive surface sites induced by OH-Al. It can be concluded in this experiments that the highly charged organic coating play a role in the dispersion of kaolin particles.

Preparation, Characterization of Cellulose Fibers Grafting by β-Cyclodextrin and their Application for Antibacterial Products

Cyclodextrins (CDs) can form inclusion complexes with a variety of molecules making them very attractive in different areas, such as pharmaceutics, biochemistry, food chemistry and papermaking. In this communication the preparation of β-cyclodextrin-grafted cellulose fibers was carried out by reacting β-cyclodextrin with cellulose fiber via citric acid (CA). Both fourier transform infrared (FTIR) and cross polarization magic angle spinning solid state nuclear magnetic resonance (CP-MAS NMR) indicated that β-CDs had been chemically attached to cellulose backbone through the formation of ester bonds. Furthermore, the β-CD-grafted cellulose fibers formed inclusion complexes with ciprofloxacin hydrochloride (CipHCl). And the β-CD-grafted cellulose fibers loaded with CipHCl showed excellent antibacterial activity against E.coli and S.aureus.

A Study of Coating Surface Microstructure and Characteristics of Coated Paper Related to Binder

The surface topography and properties of coating layer have an important influence on penetration and distribution of the print ink. In this research, the main objective was to investigate the effect of binder on the coating surface topography and characteristics. The surface microstructure was explored in the method of numerical and visual analysis using mercury porosimetry measurment and atomic force microscopy (AFM). The findings indicated that the binder content on the coating surface affected the pore size, depth and distribution of the coated paper surface. The conclusions were drawn that more amount of binder on the coating surface could contribute to improve the coating surface topography and the formation of even pore size and distribution, which was good to the paper surface characteristics and resulted in low roughness, high paper gloss, low ink absorption and high paper surface efficiency.

Synergetic Performance of Retention Aids on Reconstituted Tobacco by Papermaking Process

In this work, the effects of four kinds of additives including polyethyleneimine, carboxymethylcellulose, guar gum, and chitosan on the retention performance of reconstituted tobacco pulp and strength character of final base sheet were discussed. The results showed that the filler retention efficiency and first pass retention efficiency increased by 17.7% and by 5.8% at chitosan dosage of 0.2%, respectively. Moreover, the tensile index showed a distinct increase in chitosan retention system. The largest strength index was found to be in carboxymethylcellulose retention system, the tensile index was increased from 6.5 N•m/g to 8.67 N•m/g, and the wet tensile index was increased from 0.37 N•m/g to 0.51 N•m/g.

Investigation into the Coating Surface Topography and Properties of Paper Related to Drying Condition

The physical structure and chemical properties of coating layer have an important influence on transferring and setting of the printing ink. The typical objective of coating is to improve the appearance and printing properties of paper. In this study, the effect of drying condition on coating layer structure, surface properties, and print quality was investigated. The relationship between surface topography and drying condition was explored using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The conclusions were drawn that high and low drying temperature were not good to the paper properties, which resulted in high roughness, low paper gloss, high ink absorption, low print gloss and paper surface efficiency. The findings indicated that the coating drying temperature affected the pore size, depth and distribution of the coated paper surface. Moderate temperature was benefit to pigment particles and binder arranging orderly, which made the coating surface had high smoothness, gloss, paper surface efficiency, and modest ink absorption.

Effect of Dispersants Pre-Adsorption and Grinding on Dispersion Performance of Kaolin Pigment

The solid content of kaolin pigment suspension used in paper coatings must be as high as possible in order to minimize the drying cost. X-ray photoelectron spectroscopy (XPS) analysis on elemental compositions showed that, the kaolin combined less dispersants possessed worse dispersion capacity. Therefore, the effect of pre-adsorption of organic or inorganic negatively charged polymers sodium polyacrylate (PAA) and sodium hexametaphosphate (HMP) on the dispersing performance of concentrated kaolin suspensions was investigated, moreover, the effect of pre-adsorbing with or without grinding processing was evaluated. It was found that the viscosity of PAA pre-adsorbed kaolin decreased considerably, probably due to the stronger electrostatic repulsion. And grinding treatment had a dramatical influence on the dispersing behavior of kaolin with PAA pre-adsorbed on, resulting in low relative viscosity at high solid content.

Study on the Effect of Coating Solid on Ink Penetration of Coated Paper

The objective of this experiment was to investigate the influence of coating solid on surface properties and ink penetration and to characterize the penetration depth through quantitative analysis by laser scanning confocal microscope (LSCM). Fluorescent ink was used to observe and characterize ink penetration and distribution by LSCM. The results implied that the surface properties of coated paper could be adjusted and improved by increasing the coating solid. With the increasing of coating solid, ink penetration depth declined and ink penetration uniformity increased. It could be concluded that the coated paper with high coating solid compared with low coating solid resulted in lower ink usage and better printability on the condition of same print density.

Relationship between Binder Content and Ink Absorption of Coated Paper

The ink penetration behavior depends on the coating surface structure and surface properties of the coating layer in the papermaking process, which include coating recipes and coating conditions, etc. The objective of this experiment was to investigate the relationship between binder content and ink absorption using laser scanning confocal microscope (LSCM). Fluorescent ink was used to observe and characterize ink penetration and distribution in coated paper by LSCM. The results indicated that higher binder content could result in higher amount ink absorption. With the increasing of binder content, ink penetration depth in coated paper increased. Sample G2 with 20 parts binder produced the most unevenness ink distribution. It could be concluded that the coated paper with 25 parts binder compared with the other samples resulted in higher ink usage and better printing quality.

Dissolution of Absorbent Cotton in Ionic Liquid and Characterization of the Regenerated Cellulose

Dissolution of absorbent cotton (DP above 4000) using ionic liquids as solvent and regeneration was investigated. The results show that 1-ally-3-methylimidazolium chloride (AMIMCl) was a good solvent to dissolve absorbent cotton and a solution of 3 wt% can be reached in 18 min at 120°C. Besides, as the dissolving temperature increased the time needed for the cotton linters to dissolve decreased. The physic-chemical properties of the regenerated cellulose films were also characterized by XRD, FTIR and TGA analysis.

Study on Coating Surface Topography and Properties of Coated Paper Related to Pigment

The physical structure and chemical properties of coating layer have an important influence on transferring and setting of the printing ink. In this study, the effect of pigment on coating layer structure and surface properties was investigated. The surface topography was explored using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The findings indicated that the pigment affected the pore size, depth and distribution of the coated paper surface. The conclusions were drawn that coating could improve coating surface topography and calcium carbonate pigment compared with kaolin pigment was not good to the paper surface properties, which resulted in high roughness, low paper gloss, high ink absorption and low paper surface efficiency.