Fiber surface saturation as a strategy to optimize dual-polymer dry strength treatment.Application: This study reveals a strategy to obtain the maximum strengthening effect of a dual-polymer dry-strength treatment, with benefits extending to the virgin and recycled paper made from the same pulp. Polymeric wet-end additives help meet customer requirements for the dry strength of paper, especially when recycled kraft fibers are used. This study showed how a dual-polymer dry-strength treatment can compensate for the drying-induced loss of inter-fiber bonding ability of unbleached kraft fibers. The treatment involved sequential addition of a highly cationic cationic having qualities dependent on having free cations available. cationic detergents are wetting agents that disrupt or damage cell membranes, denature proteins and inactivate enzymes. , linear polymer, poly-diallyldimethylammonium chloride (poly-DADMAC), followed by anionic an·i·on n. A negatively charged ion, especially the ion that migrates to an anode in electrolysis. [From Greek, neuter present participle of anienai, to go up : ana-, ana- carboxymethylcellulose carboxymethylcellulose /car·boxy·meth·yl·cel·lu·lose/ (-meth?il-sel´u-los) a substituted cellulose polymer of variable size, used as the sodium or calcium salt as a pharmaceutical suspending agent, tablet excipient, and (CMC (Common Messaging Calls) A programming interface specified by the XAPIA as the standard messaging API for X.400 and other messaging systems. CMC is intended to provide a common API for applications that want to become mail enabled. 1. ). Titration tests showed that at their level of saturation, the solid surfaces in the pulp slurry were able to adsorb adsorb /ad·sorb/ (ad-sorb´) to attract and retain other material on the surface; to conduct the process of adsorption. ad·sorb v. To take up by adsorption. 2-4 times as much poly-DADMAC, compared to the amount just sufficient to neutralize the negative charge at the surfaces of the fiber fines and fibers present in the pulp slurry. This same saturation level of poly-DADMAC also resulted in a maximum compression strength of the resulting unbleached kraft handsheets, when the second chemical additive, CMC, was applied at a constant level of 2% based on fiber mass. The same benefits were seen when the same fibers were redispersed and formed into a second generation of sheets without further chemical addition. Lower compression strength was observed both at lower and at higher levels of the cationic polymer. The saturation level of poly-DADMAC also coincided with a maximum in water retention value (WRV WRV White River Valley (High School) WRV Wave Riding Vehicles WRV Western Recreational Vehicles, Inc. WRV Wrong Return Value from Function (software fault) ) of the redispersed pulp and a minimum in the light scattering coefficient of the recycled paper. Martin A. Hubbe and Zhang are with North Carolina State University History
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