Research Article pubs.acs.journal/ascecg
High-Bulk Water Dispersible Paper-Based Composites Ved Naithani,†,‡ Lucian Lucia,*,†,‡ and Sujit Banerjee*,§ †
North Carolina State University, Departments of Wood & Paper Science and Chemistry, Raleigh, North Carolina 27695, United States ‡ Qilu University of Technology, Key Laboratory of Pulp & Paper Science and Technology, Jinan, China 250353 § Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, Georgia 30332, United States
ABSTRACT: Paper sheets having a lignin content of ∼12% by mass (kappa = 78) containing 50% fines prepared from slurries, soy lecithin, and β-cyclodextrin display an unusually low density (i.e., high bulk) and rapid water dispersibility. It is postulated that lecithin adsorbs to fiber lignin and the cyclodextrin associates with the lecithin. The cyclodextrin subsequently expands the sheet in the z-direction because it has a hydrophilic periphery embedded within a hydrophobic matrix. The sheet is water dispersible owing to its high bulk and disintegrates at nearly the same rate as toilet tissue. Potential applications include packaging or thermal insulation products such as coffee sleeves that can be safely flushed away in water after use. KEYWORDS: Soy, Lecithin, Cyclodextrin, Fines, Water-dispersible
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pids.8 It can increase paper strength by binding to both cellulose and lignin9 and improves formation by deaggregating fiber clumps. Thus, soy components can interact with fibers through both bonding and debonding mechanisms. It was serendipitously found that these effects can be further modulated by adding a small amount of β-cyclodextrin (CD), a cyclic oligosaccharide made from the enzymatic hydrolysis and cyclization of starch. CD is best known for its application in odor control through commercial products such as Febreze; it can also be used for sludge dewatering10 and stickies control.11 Because CDs can bind to both hydrophobic and hydrophilic groups,12 it is known to interact with lecithin which contain both types of groups, as shown in Figure 1. In the current report, an unusual interaction of fiber, lecithin, and CD that leads to high-bulk water-dispersible sheets is demonstrated. The potential application of these sheets in packaging for consumer products or for insulating materials such as coffee cup sleeves is discussed. The benefit is that the sheets can be flushed away in water after use, thereby reducing solid waste.
INTRODUCTION The practice of using plant-based materials to design and develop useful societal items has become increasingly significant within today’s environmentally conscious populace. A commodity item that is seeing a renaissance in its utility for high end applications is lignocellulosics or paper fibers. Paper is a sustainable material because it is nearly carbon neutral in its footprint and possesses no toxicity. It and its sundry forms no longer strictly serve only as commodity items as personified by writing or packaging grades, but have been endowed with additional functionality for biomedical, electronic, sensing, and similar advanced applications.1−3 One highly functional grade of paper that has significant utility is water dispersible paper. It has seen utility within pressure-sensitive adhesives, coatings, and hygiene industries among others as a specialty form of paper for one-time applications followed by immediate disintegration and disposal.4−6 Its value lies in its ability to rapidly disintegrate to provide a level of secrecy to documents, environmental benefit to landfills, and facility of disposal (no need to collect other than discarding down sink or toilet). We have recently shown that addition of soy flour to a commercial-scale repulper increases the strength of recycled paper.7 This finding prompted further investigation to whether other surface-active components of soy could potentially contribute to such phenomena. The soy lecithin component, for example, is a mixture of various surface-active phospholi© 2017 American Chemical Society
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METHODS AND MATERIALS
Performix E, a soy lecithin preparation (SLP) was provided by Archer Daniel Midland. The CD was a gift from Wacker. Kraft pulps were Received: July 12, 2017 Revised: August 8, 2017 Published: October 24, 2017 11334
DOI: 10.1021/acssuschemeng.7b02337 ACS Sustainable Chem. Eng. 2017, 5, 11334−11338
Research Article
ACS Sustainable Chemistry & Engineering
Figure 1. An example of a phosphatidylcholine fraction of lecithin. The red residue is a zwitterionic choline and phosphate group, the black backbone is glycerol, the green moiety is an unsaturated fatty acid, and the blue region is a saturated fatty acid. prepared from pulping pine chips; the bleached pulp was made with a DEpD sequence. Fines (
