Zhaoqing Lu

Contrasting liquid imbibition into uncoated versus pigment coated paper enables a description of imbibition into new-generation surface-filled paper

Abstract.The transport of print fluids into paper is directly dependent on the imbibition characteristic of the paper including both the z-, x- and y-directions. As the measurement of free liquid imbibition into the paper thickness (z-direction) is difficult experimentally, due to the thin nature of paper, in this paper we resort to imbibition along the y-direction of paper to analyse and explore the possibility of understanding the mechanistic differences between wicking into uncoated unfilled paper versus that of controllable pigment-filled paper and paper coating. Considering the classical imbibition dynamic, the measured imbibition was characterised firstly with respect to

Largely enhanced mechanical and dielectric properties of paper-based composites via in situ modification of polyimide fibers with SiO2 nanoparticles

\surd{} t

Highly improved mechanical and dielectric properties of paper-based composites with polyimide chopped fiber functionalized by ethylenediamine

√t and secondly with respect to linear t. It is shown that the wicking behaviour of uncoated unfilled paper follows neither the classical viscous drag balance model of Lucas-Washburn (

The fractal characteristic of porous coatings prepared with ground calcium carbonate

\surd{} t

From Poly(p-phenylene terephthalamide) Broken Paper: High-Performance Aramid Nanofibers and Their Application in Electrical Insulating Nanomaterials with Enhanced Properties

√t) nor the more comprehensive inertia-included imbibition described by Bosanquet. However, by increasing the filler load into the surface layer of the paper, the imbibition dynamic is seen to revert to the Bosanquet model. Thus, when using highly filled papers, the imbibition dynamic for printing liquid shows a fast imbibition at the initial stages dominated by inertial plug flow, and then transits to the Lucas-Washburn viscosity-dominated imbibition component over longer time.Graphical abstract

Structural evidence for the timescale separated liquid imbibition phenomenon in porous media

AbstractIn this study, SiO2 nanoparticles were in situ grown onto the surfaces of polyimide fibers via sol–gel synthesis and the corresponding paper-based composites were fabricated by wet-forming process using the as-obtained fibers as the starting materials. A simultaneous enhancement of the tensile and tearing index as well as the interlayer bonding strength of paper-based composites could be achieved with an increment of 17.7%, 17.2% and 50%, respectively. What is more, the dielectric strength of the resultant composites increased by 127% compared with the pristine paper-based composites. The results indicated that the SiO2 nanoparticles could be used as an excellent interfacial linker between the fibers and polymer matrix, and a smart cushion to release interior and exterior applied forces. Besides, satisfactory results on thermal stability of paper-based composites were attained after coated with SiO2 nanoparticles. In this graphical abstract, carboxylated PI@SiO2 fibers were successfully fabricated via a facile approach that SiO2 nanoparticles were in-situ grown onto the surfaces of carboxylated PI fibers via sol-gel synthesis. Moreover, the modified paper-based composites consisting of carboxylated PI@SiO2 fibers possess more excellent dielectric strength compared with the pristine paper.HighlightsA dense and uniform SiO2 nanoparticles layer can be in situ synthesized onto the PI fibers via sol–gel synthesis after activating the surface of PI fibers.SiO2 nanoparticles could be used as an excellent interfacial linker between the fibers, and the interlayer bonding strength and dielectric strength of modified PI paper-based composites was significantly enhanced with an increment of 50 and 127%, respectively.

Argon low-temperature plasma modification of chopped aramid fiber and its effect on paper performance of aramid sheets

In this study, polyimide (PI) chopped fibers were modified by ethylenediamine, and PI paper-based composites were fabricated using the as-modified PI chopped fibers and para-aramid fibrids which served as raw materials through the wet-forming process. The influence of different alkali treatment durations on the properties of PI fibers and composites was investigated. In sharp contrast with the pristine PI fibers, there was a satisfying difference in modified PI fibers including rougher surfaces and improved wettability due to the introduction of hydrophilic groups as confirmed by scanning electron microscope and Fourier transform infrared spectrometer. With increase in the modification time, the tensile index, the tearing index, and the internal bond strength of the composites were improved by 40.6, 27.0, and 103.57%, respectively, due to the hydrogen bonds. Meanwhile, the dielectric strength of the composites increased by 77.2% compared with the unmodified ones. These remarkable changes were mainly attributed to the enhanced interfacial bonding of the composites and decreased porosity in the three-dimensional network structure of the paper. Moreover, thermal stability was kept preferably within a certain range in spite of slight decrease.

A ductile and highly fibrillating PPTA‐pulp and its reinforcement and filling effects of PPTA‐pulp on properties of paper‐based materials

To enhance the print quality of coated paper, the methodology of adjusting the porous structure of the coating is frequently employed to obtain particular imbibition characteristics for print liquids. Due to the complex and random pore structure of coating materials, it is not plausible to use Euclidean geometry to describe the stochastic morphology of the pore surface. Therefore, we use the non-Euclidean fractal geometry to characterise the irregular internal pore surface and offer some evidences for the fractal nature of coating materials. To exemplify, we adopt an extensively used mineral coating pigment, ground calcium carbonate (GCC), to analyse the structural characteristics based on the fractal method. The fractal dimensions of these materials accordingly are calculated by the classical fractal Frenkel-Halsey-Hill (FHH) model on the basis of isothermal nitrogen sorption measurement. The fractal feature of GCC coatings is represented by the fractal dimensions, showing excellent correlation with the observed structure data (R 2 = 0.900~0.993). In addition, the relationship between spontaneous liquid imbibition into GCC coatings and their fractal dimensions is also discussed to support this model further. Thus, in principle, it is possible to adjust the porous structural parameters and internal surface morphology via fractal dimension to perform specific functions.