Penetrant diffusion in polyethylene spherulites assessed by a novel off-lattice Monte-Carlo technique

• Semi-crystalline polymers have a complex hierarchical structure. The purpose of this study was to mimic the real structure of polyethylene spherulites by computer simulation using an off-lattice method in order to predict their diffusion properties. The principles used to build the spherulites were based on established findings obtained by electron microscopy. Spherulites in the crystallinity range of 0-55 vol% were built. Diffusion of small-molecule penetrants assuming no interfacial trapping at the amorphous-crystal boundary was studied using a Monte-Carlo technique. The main findings were: (i) diffusion was isotropic; (ii) diffusion was independent of the aspect ratio of the crystal building bricks, clearly in disagreement with the Fricke model: (iii) the geometrical impedance factor showed a dependence on the average free path length of the penetrant molecules in the amorphous phase: and (iv) data for the geometrical impedance factor obtained by simulation compared favourably with experimental data obtained for several penetrants showing limited interfacial trapping.

Ämnesord

NATURVETENSKAP  -- Kemi -- Polymerkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Polymer Chemistry (hsv//eng)

Nyckelord

Polyethylene spherulite

Off-lattice mesoscale simulation

Diffusion

Monte-Carlo model

molecular-dynamics simulation

melt-crystallized polyethylene

lamellar

morphology

isotactic polypropylene

transport-properties

free-volume

n-alkanes

organization

polymers

gases

Polymer chemistry

Polymerkemi

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)