What is known about the solvent permeability of low density polyethylene
?Polyethylene film and sheeting, used for making carrier bags with reinforced handles for example, is generally considered to be relatively impermeable. There are, however, some notable differences because the permeation rate is related to the molecule diameter d and depends on the particular solvent. Accordingly, the activation energy for solvent permeability can be taken to be proportional to d’. This enables one to estimate the barrier effect towards the series of homologous ketones and alcohols which are the solvents under consideration.
The temperature at which solvent diffusion occurs is also important, especially compared with the glass transition temperature Tg. Below Tg for example, the activation energy is about 25 % lower, other conditions being the same. The molecular structure is also important, being affected by the degree of semi-crystallinity. Solvent permeability can be determined using the apparatus marketed by G. Lyssy, Zurich, Switzerland.
