Combination of bifunctional aldehydes and poly(vinyl alcohol) as the crosslinking systems to improve paper wet strength

Abstract

Two bifunctional aldehydes (i.e., glyoxal and glutaraldehyde) are used as the crosslinking agents to improve paper wet strength in the presence of fully hydrolyzed poly(vinyl alcohol) (PVA) as a co-reactant. These bifunctional aldehydes alone improve paper wet strength but diminish its folding endurance. The use of PVA as a coreactant not only improves paper wet strength but also increases its dry strength and folding endurance. Glutaraldehyde is able to impart much higher levels of wet strength to the treated paper than glyoxal when a catalyst is present. The wet strength of the treated paper increases as the amount of PVA added is increased, and it also increases as the molecular weight (M w ) of the PVA increases. The data suggest that the reaction between glutaraldehyde and PVA promotes the formation of interfiber crosslinking, thus improving the wet strength without diminishing the flexibility of the treated paper. The use of a catalyst is critical to achieve high levels of durable wet strength of the treated paper. We studied the effects of different Lewis acids as the catalysts for crosslinking of pulp cellulose by glutaraldehyde and found that Zn(NO 3 ) 2 is the most effective one.

Immobilization of Modified Papain with Anhydride Groups on Activated Cotton Fabric

“…Several authors investigated the crosslinking potential of cellulose with glutaraldehyde. Xu et al [12] reported the use of glutaraldehyde and glyoxal to impart higher levels of wet strength to paper, comparing their different reactivities with cellulose. Choi et al [13] tested the use of these two aldehydes for replacement of formaldehyde in durable press finishing of cotton, reporting higher efficiency of glutaradehyde in the crosslinking with cellulose.…”

Combination of Glyoxal and Chitosan as the Crosslinking System to Improve Paper Wet Strength

“…Dipping the sheets in different solutions improved the wet strength of the handsheets, but the treated handsheets became more brittle, especially when the crosslinking system combining glyoxal and chitosan was employed. The reduction of folding endurance is possibly a result of crosslinking between pulp fibers, which limits the mobility of cellulose molecules and thus reduces the flexibility of paper sheets (Xu et al 2004). The dry strength indices of all the treated handsheets were lower than that of the control sample (96.1 Nmg -1 ).…”

“…Glyoxal is reported as a crosslinking agent to improve the wet strength of paper in a dipping process that can provide temporary wet strength to paper without the aid of a catalyst and improve the permanent wet strength to some extent when catalysts such as Zn(NO 3 ) 2 are used (Xu et al 2002). Compared with glyoxal alone, the combination of glyoxal and polyvinyl alcohol (PVA) as a crosslinking system can achieve higher folding endurance when the wet strength of paper is improved (Xu et al 2004).…”

UV Radiation of Cellulose Fibers and Acrylic Acid Modified Cellulose Fibers for Improved Stiffness in Paper

“…1 compare to no. 2), since fines and small fiber fragments in between the long fibers cause more fiber joints in the network, which increased the strength properties (Xu et al 2004;Horvath et al 2010). At higher magnification, the fiber joints of the UV-radiated reference sample (Fig.…”

“…Crosslinking of cellulose has been shown to increase the wet strength properties of paper because of stronger fiber-fiber joints in the fiber network (Xu et al 2004;Horvath et al 2010). Crosslinking or grafting of cellulose can be performed in different conditions, such as plasma treatment (Zubaidi and Hirotsu 1996), irradiation Chen and Wang 2006;Kumar et al 2006), ionic grafting (Ikeda et al 1988;Tsubokawa et al 2000), and ring-opening reactions (Toledano-Thompson et al 2005).…”