مقاله خارجی بررسی خواص مکانیکی و خواص نفوذ پذیری آلیاژ پلی اتیلن ترفتالات و پلی پروپیلن
Mechanical Properties and Permeability of Polypropylene and Poly(ethy1ene terephthalate) Mixtures
The synthetic membranes currently used for soil stabilization
and road construction are mainly made of polypropylene
and of polyesters. They are used separately for each
application. The polymer used has an effect on the wettability
and the permeability of the membrane. The polypropylene
membranes, for instance, have a zero wettability,
whereas it is high for polyester membranes. This paper
reports on the mechanical properties and the permeability
of mixtures of polypropylene (PP) and poly(ethy1ene terephthalate)
(PET). The elastic modulus of the mixture was at
a minimum for a 50/50 mixture. For the other compositions,
the moduli gave a positive deviation as compared
with the additivity equation results. This is probably due
to the fact that pure PET has a fragile behavior at the
temperature at which the mechanical tests were run. This
50/50 composition corresponds to the domain where a
phase inversion occurs. The permeability to water vapor
gave an S-shape curve that is typical of a “mixture” of
immiscible polymers. The diffusion of the water molecules
is controlled by the continuous phase. To compatibilize the
two homopolymers, a 94/6 copolymer of PP and of polyacrylic
acid was added, at various levels, to a 60/40 mixture
of PET and PP: This did not affect markedly the elastic
modulus. The yield stress increased, however, indicating
that we had a better adhesion and that the copolymer
seems to have a certain emulsifier effect, increasing the
.quality of the dispersion.