of the same composition showed similar properties when the blend
composition CA/WSP is around 50/50 (Table 3, Entries 5 and 12). At
high composition of the water soluble polymer (PVOH and HEC),
the CA/PVOH blend has better mechanical properties (Table 3,
Entries 7 and 14).
Blends morphology was studied by scanning electron microscopy
(SEM) with a view to further investigate their mechanical
performances. As representative examples, SEM microphotographs
of cryofractured surfaces of the uncompatibilized and compatibilized
CA/PVOH blends with 48 and 69 wt% pPVOH are shown in
Fig. 2. A morphological analysis of the fracture surface evidences an
increase of adhesion between blend components on the compatibilized
blend, which is more evident on the PVOH-enriched blends.
Indeed, small CA domains dispersed in the uncompatibilized blend
can be easy recognized while they are almost not present in the
compatibilized composition. Confirmation of the transition from a
dispersed to a co-continuous-like morphology after blend compatibilization
was obtained after selective PVOH etching of both
compositions in water. Actually, the immersion of the uncompatibilized
composition in water led to a complete fragmentation and
the recovery of CA nodules dispersed in water. In contrast, the
compatibilized sample remained monolithic after PVOH removal as
expected for a co-continuous-like blend morphology (Fig. 3).
Based on these results, we made a step forward on the melt
processing of these CA/water soluble polymer blends by attempting
to prepare monofilaments starting from selected compositions.
Indeed, it is expected that the compatibilization will improve the
capability of these blends for producing fibres from melt as
consequence of the better interfacial cohesion.