Gas permeability modification of polyolefin films induced by D-limonene swelling

Gas permeability (H-2, O-2, N-2, CO2, C2H4, and C3H6) and permselectivity a gainst nitrogen in the polyolefin films (LDPE, HDPE, Metallocene PE, EVA5, PP, and PMP) strongly influenced by the swelling of D-limonene (DL) absorpt ion, were studied, All the gas permeability obtained in these films were co mmonly increased by increasing the amount of D-limonene absorbed in the fil ms (C-DL: cm(3) STP/cm(3)), which indicated an especially drastic enhanceme nt of CO2 permeability in low density polyethylene (LDPE) from 15.2 to 67.8 Barrer (1 Barrer = (x10(-10)) cm(3) STPc m/cm(2) cmHg s) at C-DL = 2.3. Ba sed on experimental evidences that bras permeability was proportionally inc reased with increasing C-DL, whereas the film crystallinity of LDPE evaluat ed with method of a wide-angle XRD decreased, it was concluded that the gas permeability enhancement was caused by the film crystallinity decay due to D-limonene sorption. On the permselectivity against, nitrogen obtained for all the gases, CO2, C3H6 and C2H4 were characterized by a positive enhance ment, and H-2 and O-2 a slight negative enhancement. The effect of D-limone ne absorption into the polyolefin films on the CO2 permeation was interesti ngly characterized by a simultaneous enhancement of permeability (P) and CO 2/N-2 permselectivity (alpha (co2)), typically indicating from P = 15.2 to 67.8 Barrer and from alpha (co2) = 19 to 26.1 for LDPE. (C) 2001 Elsevier S cience B.V. All rights reserved.