A Novel Cellulose Nanocrystals-Based Approach To Improve the Mechanical Properties of Recycled Paper

The ability to introduce cellulose nanocrystals (CNs) into any of a number of single-component or composite applications is currently limited because they are difficult to efficiently isolate and in certain cases difficult to maintain homogeneously disperse. The current research introduces a novel purification technique and composite application for modified cellulose nanocrystal derivatives by using them as an additive for dry strength in recycled paper OCG (old corrugated containerboard). More specifically, the present work illustrates a way to easily isolate CNs by extracting them through a traditional mineral acid hydrolysis followed up by washing them several times with ethanol. The extracted cellulose nanocrystals did not flocculate and were completely homogeneously dispersed in water. Additionally, it was found that the incorporation of carboxylic acid functionalities onto the CNs by reaction with diethylenetriamine pentaacetic acid (DTPA) followed by cross-linking with chitosan and introduction into the OCC greatly improved its tensile and other mechanical properties. The tensile and burst strength of the modified OCC pulp sheet increased 40.3% and 46%, respectively, with significantly increased gloss and decreased roughness and tear strength as compared to the control sample. Spectral characterization of the CNs and their derivatives was accomplished using TGA, DSC, FT-IR, and SEM.