suggests that the crystalline phase can be attributed to the increase in gas diffusivity
in crystalline and liquid crystalline polymers.
Figure 8 presents the relationship between gas diffusivity and solubility in crystalline
and liquid crystalline polymers, with the amorphous data for comparison (Kanehashi
and Nagai 2005). Gas permeability is a product of the solubility and diffusivity, as
shown in Eq. 1. Compared with solubility, the gas diffusivities in crystalline, liquid
crystalline, and glassy amorphous polymers are widely distributed. For example, O 2
diffusivity varies from 3.90 Â 10
À9 to 6.70 Â 10
À7 for glassy amorphous polymers,
1.10 Â 10
À9 to 1.37 Â 10
À6 for crystalline polymers, and 6.20 Â 10
À11 to
7.65 Â 10
À7 cm
2 s
À1 for liquid crystalline polymers. Oxygen solubility varies from
0.15 to 1.44 for amorphous polymers, 0.00680 to 0.190 for crystalline polymers, and
0.00480 to 0.177 cm
3 (STP) (cm
3 atm)
À1 for liquid crystalline polymers. These results
suggest that the permeability of non-condensable gases, such as O 2 and N 2 , in
crystalline, liquid crystalline, and glassy amorphous polymers depend more on diffusivity rather than on solubility. Gas solubility in crystalline and liquid crystalline
polymers shows lower values, and diffusivity shows higher values than that in glassy
amorphous polymers at the same gas permeability (Fig. 8). Thus, the gas transport
behavior in crystalline and liquid crystalline polymers can be different from glassy
amorphous polymers. This difference is attributed to the presence of crystal structures
assuming they follow similar solution/diffusion mechanisms. Therefore, gas transport
properties in crystalline and liquid crystalline polymers could be strongly affected by
the crystal structure parameters, such as crystal size and distribution.
References
Alter H (1962) Critical investigation of polyethylene gas permeability. J Polym Sci 57:925–935
Ash R, Barrer RM, Palmer DG (1970) Solubility and transport of gases in nylon and polyethylene.
Polymer 11:421–435
Auras RA, Harte B, Selke S, Hernandez R (2003) Mechanical, physical, and barrier properties of
poly(lactide) films. J Plast Film Sheeting 19:123–135
Bao L, Dorgan JR, Knauss D, Hait S, Oliveira NS, Maruccho IM (2006) Gas permeation properties
of poly(lactic acid) revisited. J Membr Sci 285:166–172
Bernal-Lara TE, Liu RYF, Hiltner A, Baer E (2005) Structure and thermal stability of polyethylene
nanolayers. Polymer 46:3043–3055
Bixler HJ, Michaels AS, Salame M (1963) Gas transmission in irradiated polyethylene. J Polym Sci
Part A: General Papers 1:895–919
Budzien JL, McCoy JD, Weinkauf DH, LaViolette RA, Peterson ES (1998) Solubility of gases in
amorphous polyethylene. Macromolecules 31:3368–3371
Buquet CL, Doudou BB, Chappey C, Dargent E, Marais S (2009) Permeation properties of poly(mxylene adipamide) membranes. J Phys Chem B 113:3445–3452
Chen DS, Hsiue GH (1993) Gas transport properties of linear and crosslinked side-chain liquidcrystalline polymers with variable spacer lengths. Makromol Chem 194:2025–2033
Chen DS, Hsiue GH, Hsu CS (1991) Gas permeation through a side-chain liquid-crystalline
polysiloxane-based membrane. Makromol Chem 192:2021–2029
Chen DS, Hsiue GH, Hsu CS (1992) Gas permeation through two side-chain liquid-crystalline
polyacrylate-based membranes containing 4-methoxyphenyl 4-hexyloxybenzoate or
4-cyanophenyl 4-hexyloxybenzoate mesogenic side groups. Makromol Chem 193:1469–1479
19 Gas Permeation and Barrier Properties of Liquid Crystalline Polymers
543
in crystalline and liquid crystalline polymers.
Figure 8 presents the relationship between gas diffusivity and solubility in crystalline
and liquid crystalline polymers, with the amorphous data for comparison (Kanehashi
and Nagai 2005). Gas permeability is a product of the solubility and diffusivity, as
shown in Eq. 1. Compared with solubility, the gas diffusivities in crystalline, liquid
crystalline, and glassy amorphous polymers are widely distributed. For example, O 2
diffusivity varies from 3.90 Â 10
À9 to 6.70 Â 10
À7 for glassy amorphous polymers,
1.10 Â 10
À9 to 1.37 Â 10
À6 for crystalline polymers, and 6.20 Â 10
À11 to
7.65 Â 10
À7 cm
2 s
À1 for liquid crystalline polymers. Oxygen solubility varies from
0.15 to 1.44 for amorphous polymers, 0.00680 to 0.190 for crystalline polymers, and
0.00480 to 0.177 cm
3 (STP) (cm
3 atm)
À1 for liquid crystalline polymers. These results
suggest that the permeability of non-condensable gases, such as O 2 and N 2 , in
crystalline, liquid crystalline, and glassy amorphous polymers depend more on diffusivity rather than on solubility. Gas solubility in crystalline and liquid crystalline
polymers shows lower values, and diffusivity shows higher values than that in glassy
amorphous polymers at the same gas permeability (Fig. 8). Thus, the gas transport
behavior in crystalline and liquid crystalline polymers can be different from glassy
amorphous polymers. This difference is attributed to the presence of crystal structures
assuming they follow similar solution/diffusion mechanisms. Therefore, gas transport
properties in crystalline and liquid crystalline polymers could be strongly affected by
the crystal structure parameters, such as crystal size and distribution.
References
Alter H (1962) Critical investigation of polyethylene gas permeability. J Polym Sci 57:925–935
Ash R, Barrer RM, Palmer DG (1970) Solubility and transport of gases in nylon and polyethylene.
Polymer 11:421–435
Auras RA, Harte B, Selke S, Hernandez R (2003) Mechanical, physical, and barrier properties of
poly(lactide) films. J Plast Film Sheeting 19:123–135
Bao L, Dorgan JR, Knauss D, Hait S, Oliveira NS, Maruccho IM (2006) Gas permeation properties
of poly(lactic acid) revisited. J Membr Sci 285:166–172
Bernal-Lara TE, Liu RYF, Hiltner A, Baer E (2005) Structure and thermal stability of polyethylene
nanolayers. Polymer 46:3043–3055
Bixler HJ, Michaels AS, Salame M (1963) Gas transmission in irradiated polyethylene. J Polym Sci
Part A: General Papers 1:895–919
Budzien JL, McCoy JD, Weinkauf DH, LaViolette RA, Peterson ES (1998) Solubility of gases in
amorphous polyethylene. Macromolecules 31:3368–3371
Buquet CL, Doudou BB, Chappey C, Dargent E, Marais S (2009) Permeation properties of poly(mxylene adipamide) membranes. J Phys Chem B 113:3445–3452
Chen DS, Hsiue GH (1993) Gas transport properties of linear and crosslinked side-chain liquidcrystalline polymers with variable spacer lengths. Makromol Chem 194:2025–2033
Chen DS, Hsiue GH, Hsu CS (1991) Gas permeation through a side-chain liquid-crystalline
polysiloxane-based membrane. Makromol Chem 192:2021–2029
Chen DS, Hsiue GH, Hsu CS (1992) Gas permeation through two side-chain liquid-crystalline
polyacrylate-based membranes containing 4-methoxyphenyl 4-hexyloxybenzoate or
4-cyanophenyl 4-hexyloxybenzoate mesogenic side groups. Makromol Chem 193:1469–1479
19 Gas Permeation and Barrier Properties of Liquid Crystalline Polymers
543