Enhancement of barrier properties regarding contaminants from recycled paperboard by coating packaging materials with starch and sodium alginate blends

Novel composite packaging materials based on „clever paper“ (CP) (a mixture of polyethylene with calcium carbonate in a mass ratio of ∼1:1) with a coating layer of biodegradable polymers – corn starch (St) and sodium alginate (Alg) with and without activated carbon – were tested to determine their barrier properties against several substances (undecane, heptadecane, dodecane, triethylcitrate, dipropylphthalate, 4-methylbenzophenone, cholestane) that simulate the migratable contaminants from recycled paperboard. Industrial samples of synthetic films (LDPE, BOPP, BOPET, EVA, PLA, PVA), as well as films based on starch/alginate (St/Alg) blends (St/Alg 90/10 and St/Alg 50/50) have been tested as well. Good barrier properties against the penetration of mineral oils (less than 5% undecane has permeated after 10 days at 40 °C) were demonstrated by the film based on St/Alg 90/10. The coating of CP by a layer consisting of St/Alg 90/10 and activated carbon (AC) yielded the composite material CP/St/Alg 90/10/AC with very low permeability (close to aluminum foil). To further showcase the effectiveness of starch/alginate coatings against penetration of contaminants, additional tests were performed with purchased recycled paper coated by films based on St/Alg 70/30.