Effect of coating paper using chitosan and modified polylactic acid

This study was carried out to determine the effect coating with polylactic acid-chitosan complex on the packaging paper by two methods of mixing and grafting. For this purpose, handsheet (80 g/m2) was made using long fibers collected from Mazandaran Wood and Paper Factory. Poly lactic acid, chitosan and nanocytosis with the concentration of 1 wt. %, were prepared by dissolving in chloroform and 1% acetic acid, respectively. In both methods, three layers coating was applied. Then, coated samples were dried in oven. In the mixing method, polylactic acid and chitosan were mixed and then applied on base paper. In the grafting method, by chemical modification of chitosan and polylactic acid, 0.01 g of EDC (N-(3-dimethy laminopropyl)-N/-ethylcarbodiimide hydrochloride), 0.1 g of Span 80 and 0.047 g of HOBT ( 1- Hydoxy benzotriazole) homogeneous solution were prepared and applied on a paper surface. Finally, barrier and mechanical properties including contact angle, water absorption, air permeability and burst strength were measured respectively. The results showed that papers which were coated with grafting method, using three layers of coating (P3nCs3) had the highest air permeability resistance compared to the mixing method. Control sample showed minimum air permeability resistance. Water absorption decreased in coated samples by mixing method compared to grafting method and grafting method further reduced water absorption. Contact angle increased in coated samples by the grafting method compared to the mixing method.