Transport properties of organic vapors in nanocomposites of isotactic polypropylene

Abstract

Isotactic polypropylene nanocomposites were obtained by the melt blending of polypropylene-graft-maleic anhydride and organophilic layered silicate (OLS) consisting of synthetic fluorohectorite modified by cation exchange with protonated octadecylamine. The composition of the inorganic clay was varied between 2.5 and 10 wt %, and films of the composites were obtained via hot-press molding. X-ray analysis showed that nanocomposites in which silicate layers were either delaminated or ordered as in an intercalated structure were obtained. The elastic modulus of the samples was higher than that of the pure polymer over a wide temperature range and increased with increasing inorganic content. The transport properties, sorption and diffusion, were measured for two organic vapors, dichloromethane and n-pentane. For both vapors, the sorption was not very different from that of the pure polymer, whereas the zeroconcentration diffusion parameter strongly decreased with increasing OLS content. Therefore, the permeability, that is, the product of sorption and diffusion, decreased for both vapors as a result of the decreased value of the diffusion parameter. The decrease was higher for the less interacting n-pentane.

Investigation of water absorption in clay-reinforced polypropylene nanocomposites

“…In the literature, it has been shown [11,12] that the presence of clay particles in the polypropylene matrix decreases the permeability of the resulting nanocomposite materials with respect to certain solvents. This was attributed to the fact that the oriented clay platelets block the advancement of the solvent molecules and force them to follow a more tortuous path.…”

Oxygen barrier property of polypropylene-polyether treated clay nanocomposite

“…Nanocomposites are a multiphase system in which the coexistence of phases with different sorption and diffusion can cause complex transport phenomena [35]. Montmorillonite gives rise to superficial adsorption and specific interactions with some gases and solvents [10,40].…”

“…According to this theory, the impermeable inorganic filler in the relatively permeable polymer matrix will create a tortuous path for the diffusing molecules [3,10,31,35,36]. As a result, the filled polymer demonstrated reduced gas permeability, with the permeability being determined using the Equation (1): (1) where P f and P u are the permeability of the filled and unfilled polymer, φ p and φ f are the volume fraction of the polymer and filler, and L/W is the aspect ratio of the filler.…”

Infrared Spectroscopic Characterization of Polymer and Clay Platelet Orientation in Blown Films Based on Polypropylene‐Clay Nanocomposite

“…This orientation can influence the mechanical properties of the nanocomposite product, as has been demonstrated for polyethylene blown films, [2] syndiotactic polypropylene extruded tape, [3] and uniaxially drawn isotactic polypropylene. [4] In addition, the presence of ''nanoclay'' in polypropylenes has been shown to decrease the permeability with respect to certain solvents, [5,6] and it is usually considered that this is because the oriented clay platelets block the advancement of the solvent molecules and force them to follow a more tortuous path.…”