Application of modified cellulose nanofibrils as coating suspension on recycled paper using size press

Cellulose based nanomaterials have the great potential to be applied to paper as bulk additive or coating material to improve overall final properties, especially in secondary fiber. In the present work, the effect of applying different kinds of cellulose nanofibrils (CNF) to papers obtained from recycled fibers using size press on physical, mechanical and barrier properties was investigated and compared with the sole use of starch as coating material. The coating process of CNF was carried out by the addition of size press grade starch to coating suspension. As a cellulose source, wheat straw was evaluated and CNF was obtained through oxidative and enzymatic pretreatments. Results indicate that starch/CNF suspension improves the overall paper properties. As a result of the deposition of coating suspension contains of 4 % wt. periodate-oxidized CNF onto paper surface, tensile and burst indices of papersheets increased as 52.2 % and 194.4 %. Significant decreases were observed in air permeability as 69.8 %. Compression tests also have been conducted to evaluate papersheets end-use properties. In comparison to the other pretreated CNF, due to is lower viscosity, applying periodate-oxidized CNF as size press significantly increased the mechanical properties of the papers fabricated from the recycled pulps.

Effect of Process Variables on Efficiency and Particle Growth of Spilanthes oleracea Seeds Coating

The coating of vegetable seeds is a very common technique, mainly for the species which have small seeds. One of its functions is to increase the seed size to direct sowing. In the present study the coating of Spilanthes oleracea L. seeds with a polymeric suspension in fluidized bed was analyzed. The effects of process variables on the coating efficiency of top-spray fluidized bed coating were evaluated. The independent variables studied were the flow rate of coating suspension and the air mass flow. The quantification for the entrance variables influence on the coating efficiency and granule growth, as well as the identification of optimal conditions were made by means of an experiment factorial design technique. Polynomial models for the responses: efficiency and relative growth of the particles were deduced. The highest coating efficiency was achieved at a high flow rate of coating suspension.