Multi Functional High-Wet-Strength Paper Enabled By Fiber Hydrolysis/Dissolution

With the rapid development of modern society,people's requirements for everyday materials are ever-increasing,and various polymer materials have been developed.Petroleum-based polymer materials are widely used in various fields,however,synthetic plastics are difficult to degrade and harm the environment.Therefore,sustainable,green and environmentally friendly strategies for designing renewable biomaterials have become increasingly popular.The use of biomass to develop renewable and biodegradable polymer materials that can eventually be cycled in nature holds great potential to replace traditional plastics.Under the background of "Plastic ban",multifunctional paper-based composite materials would usher in new opportunities.This work,which builds on previous published findings,involves the structural disassembly fibers(on the basis of fiber hydrolysis or non-derivatizing dissolution)for designing high-wet-strength paper with multifuncitonalities.Key research activities associated the current work are as follows:(a)Pulp fibers(softwood-derived bleached kraft pulp)were treated with a sulfuric acid solution.The resulting aqueous system containing disassembled fibers were neutralized,freeze-dried,redispersed in water,and subsequently used for the treatment of cellulosic paper via a simple vacuum filtration process.Such a treatment was assessed and analyzed in terms of structural chacteristics and critical properties(e.g.,wet strength)of cellulosic paper.(b)Non-derivatizing aqueous solvent systems containing divalent metal salt and a minor amount of trivalent metal salt were used to dissolve pulp fibers into a "cellulosic solution".The possibities of using the "cellulosic solution" as additives for surface engineering of cellulosic paper were explored.(c)The possibilities of treating cellulosic paper with the above-mentioned solvent systems,which involve partial dissolution of fibers,regeneration of dissolved polysaccharides,etc.,were explored.The disassembly of pulp fibers into miscellaneously distributed structures,catalyzed by sulfuric acid,shows an interesting role in designing cellulosic toward new capabilities.In particular,the simple filtration process can result in significant enhancement of the ratio of wet strength to dry strength(i.e.,around 300%).This simple treatment can also lead to the densification densification of cellulosic paper.Most encouragingly,non-derivatizing solvent systems containing mixed metal salts(i.e.,a divalent metal salt and a trivalent metal salt)can be efficiently used to deliver high mechanical strength(e.g.,ratio of wet tensile strength to dry tensile strength can be increased by 30 times)as well as liquid barrier,flame retaradant,and antibacterial properties to cellulosic paper.In particular,the flame retardancy tests of the functionalized cellulosic paper show an LOI value of above 39%.The combination of zinc chloride with ferric chloride or aluminum chloride to formulate aqueous solvent systems has found to be very effective in designing the multifunctionalities of cellulsosic paper.Overall,the facile concept of delivering functionalities to cellulosic paper by manipulating the processes of non-derivatizing dissolution of fibers is very encouraging,and such technologies holds great potential in terms of commercial applications.Paper-based products with multifunctionalities enabled by fiber dissolution would find use as the substitutes for synthetic plastics,possibly in cases where flame retardancy,antibacterial activity,and high wet strength are necessities.In the context of global efforts toward sustainability,the findings of this work may provide new possibilities for the paper industry.