Production of derivatives from wheat straw as reinforcement material for paper produced from secondary fibers.

Nowadays, a high percentage (> 50%) of the paper produced in Europe uses recovered paper (secondary fibers) as raw material. In order to improve the mechanical properties of the paper produced, different kinds of additives are usually incorporated into the paper. Emerging renewable materials based on agricultural or forest residues, such as cellulose nanomaterials, have recently proved good capacities as reinforcing agents for different applications. In this work, pulp from wheat straw with a content of cellulose nanomaterial has been produced and tested as a mechanical reinforcing agent for paper production. A soda semi-chemical process was applied for the delignification of straw, to produce pulp with high cellulose content. Posteriorly, pulps with cellulose nanofibers were obtained in a high-pressure homogenizer, applying three different pretreatments to the cellulose pulp (acid hydrolysis, enzymatic hydrolysis and thermal treatment with glycerol) in order to facilitate the obtention of cellulose nanomaterial. Handsheets of paper were prepared from two sources of secondary fiber (fluting paper and old corrugated containers), adding different percentages of wheat straw derivatives (0, 3.5, 5 and 7%). The fibers' morphology and the papers' mechanical properties were investigated. Noticeable improvement rates (up to 25%) were observed for some mechanical properties of paper containing nanocellulose produced after the enzymatic and acid pretreatments. The quality of the secondary fibers source also affected the improvement rates achieved, with higher percentage changes for the lower-quality recycled paper. [ABSTRACT FROM AUTHOR]