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RETENTION AID DEMANDS OF HIGHLY FILLED SHEETS -PILOT MACHINE STUDY
Wheeler,Clay 강원대학교 부설 창강제지 기술연구소 1998 제지기술 Vol.- No.12
This paper is about some of the demands we place on the wet end of a papermachine and some of the problems we face while making high ash sheets - mainly as they pertain to achieving first pass retention and first pass ash retention in Printing and Writing grades. Are there systems out there to handle not only where we are today, but also where we want to go tomorrow. This paper will discuss work recently completed on a high speed pilot former with ash levels approachting 35% - 40% in Printing and Writing grades. Under acid conditions where TiO_2 and clay were the primary fillers, financial incentive to raise ash levels were small and difficult to achieve because of the weaker sheet. With the conversion to alkaline papermaking for printing and writing grades in the 80's and early 90's, papermakers began to substitute low cost calcium carbonate for fiber provided papermakers with a good financial return and improvements in sheet quality. Today, 85% - 90% of printing and writing grades are made under alkaline conditions. Papermakers who made the conversion to alkaline a few years age are now raising ash levels to further capitalize on the cost savings and improved paper quality. It is estimated that by the end of 1997, the average filler content in printing and writing grades in North America will be 17% - 18%. By the year 2000, we expect average ash levels in printing and Writing grades to be greater than 20%. As ash levels increase today and increase to even higher levels tomorrow, what are some of the problems associated with high ash sheeets. Strength - As ash levels increase, we see reductions in most strength properties (stiffness, tensile, mullen). With eht introduction of improved fillers and improved application of existing fillers, these obstacles can be minimized. Paper Machine Runnability - Another problem associated with high ash sheets is machine runnability. The decrease in web strength can cause problems with holes and breaks. When breaks do occur, if the sheet does not have integrity to pass through the press section, then re-threading is difficult. Low Retentions - Low retentions caused by high levels of ash in the sheet can be a major problem related to papermaking.
Chemical and mechanical modulation of polymeric micelle assembly
Clay, N.,Whittenberg, J.,Leong, J.,Kumar, V.,Chen, J.,Choi, I.,Liamas, E.,Schieferstein, J.,Jeong, J.,Kim, D. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.16
<P>Recently, polymeric micelles self-assembled from amphiphilic polymers have been studied for various industrial and biomedical applications. This nanoparticle self-assembly typically occurs in a solventexchange process. In this process, the quality of the resulting particles is uncontrollably mediated by polymeric solubility and mixing conditions. Here, we hypothesized that improving the solubility of an amphiphilic polymer in an organic solvent via chemical modification while controlling the mixing rate of organic and aqueous phases would enhance control over particle morphology and size. We examined this hypothesis by synthesizing a poly(2-hydroxyethyl) aspartamide (PHEA) grafted with controlled numbers of octadecyl (C18) chains and oligovaline groups (termed 'oligovaline-PHEA-C-18'). The mixing rate of DMF and water was controlled either by microfluidic mixing of laminar DMF and water flows or through turbulent bulk mixing. Interestingly, oligovaline-PHEA-C18 exhibited an increased solubility in DMF compared with PHEA-C18, as demonstrated by an increase of mixing energy. In addition, increasing the mixing rate between water and DMF using the microfluidic mixer resulted in a decrease of the diameter of the resulting polymeric micelles, as compared with the particles formed from a bulk mixing process. Overall, these findings will expand the parameter space available to control particle self-assembly while also serving to improve existing nanoparticle processing techniques.</P>