SKIN AND LAYER FORMATION IN FILMS PREPARED FROM CARBOHYDRATES, POLY(ETHYLENE-CO-ACRYLIC ACID), AND POLYETHYLENE

Cornstarch, a canary dextrin, and a maltodextrin were compared in film s blown from carbohydrates compounded with poly (ethylene-co-acrylic a cid) (EAA), low-density polyethylene (LDPE), and aqueous ammonium hydr oxide plasticizer. Dextrins or maltodextrins having dextrose equivalen t values of one and greater caused dark-colored films with caramel odo rs, probably due to Maillard reactions. Blown films with hydrophobic s kins and water-sensitive cores were produced with the dextrinized carb ohydrates, but not from natural cornstarch. Water sensitivity of films containing the dextrinized carbohydrate was reduced by recycling the films through.the blown film die. A mechanism for development of the s kins is proposed, as is a method for preparing thin semipermeable memb ranes. (C) 1993 John Wiley & Sons, Inc.