3.1. Separation of PE–Al composites using organic solvents
In the initial studies, organic non-polar solvents were used at
room temperature, and we found that after 48 h, PE films were
separated in low yields. Therefore, the contact treatment time
was increased (Table 1). Although superior yields were obtained,
they still remain low. However, an important increasing in the PE
yield was observed using higher temperatures in shorter times.
These experiments showed that the temperature plays an important
role in the separation process.
In the next step, several solvents were tested and the results are
summarized in Table 2. Diverse effects were noted by the treatment
of PE–Al composites with the studied solvents at reflux temperature.
First, we confirmed that the best yields were obtained
when solvents with high boiling points are used. According to
Igwe (2007), xylene showed the best ability for dissolving PE and
afforded the best yields. Moreover, the recovery yield is also
dependent of the solvent polarity. For example, PE separation in
hexane resulted more efficient than using THF even though these
solvents have similar boiling points, a similar situation occurred
with ethyl acetate (b.p. 77 C) and ethanol (b.p. 78 C). These facts
suggest that non-polar solvents with higher boiling points are the
best for this kind of processes.