abstract
In paper manufacture, many colloidal particles are added to improve with a pulp suspension on paper. Under the right conditions, these various colloids flocculate and interact. Examples of colloids papermaking fillers and internal sizing agents, opacity and hydrophobicity to improve the paper, respectively. Internal sizing agents (added in the wet end of a paper machine) together emulsion droplets stabilized by cationic starch and other stabilizers solidified. We studied the interaction of a common internal sizing agent, alkyl ketene dimer (AKD), with calcium carbonate fillers. AKD is a liquid over 50-65 ° C (depending on the alkyl chain length) which can be emulsified above its melting point in the presence of a stabilizer, which include, after cooling in the solid colloidal particles to 1 micron in size. We have investigated the interaction of AKD particles stabilized by cationic starch, with precipitated calcium carbonate (PCC) particles. Pure PCC particles are positively charged, but they are in the process water is negative. Flocculation experiments with positively charged and negatively charged AKD were PCC with a photometric dispersion analyzer. Instead of the expected heteroflocculation between AKD and PCC, we observed homoflocculation PCC and AKD homoflocculation, results confirmed by SEM. The results from the transfer of starch from AKD to PCC explains what to PCC flocculation by starch and AKD destabilization due to depletion of the stabilizer.
abstract
α-alumina-g-polyacrylamide (α-Al2O3-g-PAM) composite abrasive filaments prepared by surface graft polymerization. Composition, structure and morphology of the product were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy and scanning electron microscopy, is in each case. Then, the chemical mechanical polishing performance of the composite abrasive body were studied on glass substrates. Atomic force microscopy images show that the average roughness of the polished glass substrate surface can be reduced from 0.74 nm for pure α-Al2O3 abrasive to 0.45 nm for α-Al2O3-g-PAM abrasive.
abstract
Hybrid thin films with nano-sized inorganic domain were synthesized from poly (acrylic) and monodispersed colloidalsilica with adhesion promoter. The 3 - (trimethoxysilyl) propyl methacrylate (MSMA) was treated with colloidalsilica first, is bound and then polymerized with acrylic monomer to form a precursor. Then, the precursor was spin-coated and cured to form the hybrid films. The silica content in the hybrid thin films was varied from 0 to 50 wt%. The experimental results showed that the coverage area of the silica particles from the MSMA decreased with increasing silica content and resulted in the aggregation of silica particles in the hybrid films. In this way the silica in the hybrid films from 20 to 35 nm was varied by varying molar ratios MSMA to silica. The results of scanning electron microscopy, transmission electron microscope, and elemental analysis support the above results. The prepared hybrid films from the crosslinked acrylic polymer moiety showed much better film uniformity, thermal stability and mechanical properties than the poly (methyl methacrylate) (PMMA) hybrid materials. Large needle holes were in the PMMA-silica hybrid films found probably due to the significant difference in the thermal properties between the two groups or the evaporation of solvent. The refractive index increases linearly with increasing proportion of silica in the hybrid films. Excellent optical clarity was obtained in the prepared hybrid films. These results show that the hybrid thin films have potential applications as passive films for optical devices.
abstract
Previous research has shown that the laccase-catalyzed oxidation of lignin fibers containing wood can improve the strength of fibreboard Medium density. In the present study it was examined whether laccase treatment had no effect on the tensile strength of unbleached kraft pulp yield high. Treatment with laccase alone had only a very small effect on the wetstrength pulp, that the addition of lignin rich extractives increased the wetstrength after enzyme treatment significantly. Mediated oxidation gave a similar improvement of the wet tensile strength, although no lignin was added to the fiber suspension. Furthermore, it was found that heat treatment combined with a mediated oxidation resulted in greater improvement in wet tensile strength that could be addressed by individual care. No change in the dry tensile strength of laccase treatment was observed. It is suggested that the observed improvement wet tensile strength is related to the polymerization of the lignin on the fibers in the sheet of hands and / or the coupling of phenoxy radicals on the lignin associated with adjacent fibers. For different mediators studied, a correlation was found between oxygen consumption during oxidation and mediated generation wetstrength in the pulp.
Various hydrophilic polyelectrolytes, including cationic starch products are used by papermakers to promote inter-fiber bonding and increase the paper dry strength. Thus, papermakers customer requirements with a lower net cost of materials, more recycled fibers, or higher content of minerals to meet. In the absence of polymeric additives, key bond include mechanisms for the development of cellulose fibers capillary three-dimensional mixing of macromolecules on facing surfaces, and formability of the materials, and hydrogen bonding. Dry-strength additives adsorb efficiently onto fibers have a hydrophilic character and a sufficiently high molecular mass. Although it is possible to achieve significant strength gains through optimal use of each polyelectrolyte, a greater strength gains oppositely charged polyelectrolytes by sequential addition can be achieved. Superior strength can be achieved, followed by in situ formation of polyelectrolyte complexes, these complexes by deposition on fiber surfaces. Polyampholytes promise as an efficient chemical additives strength. Opportunities for further increases the performance of dry-strength agent can be, for fiber surface modification, self-assembled layers, and the optimization of the dry film properties of dry-strength polymers or polymers.
Flow experiments with the polyacrylamide-chromium-gel system have shown that a structure of the resistor in a localized area occurs at some distance from the front of the injected gel solution. The age of the solution at the time of development of resistance is less than the beaker gel time. This resistance has been described as in the filtration of pre-gel aggregates, and a linear model on the basis of this mechanism was shown to show that experimental data suggest.
This document describes the extension of the filtration model for the polyacrylamide gel chromium on the simulation of changes in permeability treatments in a wellbore penetrating a stratified reservoir in which there were examined polyacrylamide crossflow The impact on the treatment viability more parameters. The parameters include the permeability case of vertical permeability and thickness, injection pressure, gel-solution viscosity and zonal isolation.
The injection behavior in three successive flow regimes can be divided, is the last of which by relatively longer flow into the zone of low permeability embossed and should be avoided. The treatment is improved by a high permeability contrast, low viscosity gel solution and zonal isolation. Filtration of pre-gel aggregates, polyacrylamide under the right conditions, cross-flow is reduced in the zone with low permeability and thus works to improve gel placement.
Flow experiments with the polyacrylamide-chromium system for a construction of the resistor in a localized area at some distance from the front of the gelant. Several pore volumes of flow through this region occurs gelant to complete blockage of the sand pack. The age of the solution obtainedpolyacrylamide by the zone of the flow resistance substantially lower than the "gel time" of the in a beaker. These trends suggest cause the structure of the flow resistance during in situ gelation not in front of a simple bulk gelation during the displacement. When increasing the flow velocity, penetrates further into the sand gelant packs, but also the male sand packs at a faster rate.
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Carbon / carbon Surface Sizing Agent composites were prepared with thermosetting resin-derived carbon matrix, and two groups of carbon fibers (ie, surface-treated and non-surface treated) with and without treatment dimensioning. These composites were treated with heat at 1000 ° C and 3000 ° C flexural strength and fracture behavior of the composites were investigated at room temperature. Surface treatment of carbon fibers played an important role in fracture behavior and strength of the composites. Composite with surface-treated carbon fibers heat treated at 1000 ° C, showed a low strength and a catastrophic fracture pattern, while the heat treated at 3000 ° C showed aSurface Sizing Agent pseudo-plastic fracture pattern. However, the exact opposite behavior in combination with non-surface-treated carbon fibers.
Graphitization of composites with two rows of carbon fibers exhibited a very different matrix microstructure. Composites with surfaceSurface Sizing Agent treated fibers showed a columnarlike carbon matrix while those with non-surface-treated fibers have a lamellar type carbon matrix well oriented on carbon fibers.
