Microstructure Evolution of Immiscible PP-PVA Blends Tuned by Polymer Ratio and Silica Nanoparticles

Abstract

Composites of polypropylene (PP) and water soluble poly(vinyl alcohol) (PVA) can become an environmentally friendly precursor in preparing porous material, and their biphasic morphology needs to be manipulated. In this work, PP-PVA extrudates were prepared with a twin-screw extruder, and different PP/PVA ratios were employed to manipulate the morphology of the blends. Afterwards, different silicas were imbedded within the blends to further regulate the biphasic microstructure. PVA continuity, as a vital parameter in obtaining porous material, was determined by selective extraction measurement, and PP-PVA biphasic morphology was characterized by scanning microscopy analyses (SEM). Rheological measurement was also performed to correlate the microstructure evolution of the blends. First, it was found that with the increment of PVA proportion, PVA continuity is raised gradually, and the microstructure of blends containing 40–50 wt % of PVA is approaching co-continuous. Second, the localization of silicas was predicted based on the wettability of silica and polymers, and it was also confirmed by TEM that different silicas showed selective distribution. It is inspiring that R972 nanoparticles were found mainly distributed at the interface, which gives a possibility in preparing a surface-modified porous material. The shape distribution and average size of PVA nodules were examined by analyzing the SEM images. It is indicated that silicas with different wettabilities play disparate roles in tuning the biphasic microstructures, leading to heterogeneous PVA continuity.

Porous fibers surface decorated with nanofillers: From melt‐spun PP/PVA blend fibers with silica nanoparticles

“…30 It is of great interest to explore the fibrous morphology evolution and concomitant changes in mechanical properties in function of different silica nanoparticles. Dominantly at the interface, and a small amount in bulk polymers for Si R972 .…”

“…Based on the experience of the filler selections in the previous study, 30 the three silica nanoparticles are summarized in Table I, of which the related information is referred from their datasheets. These silica nanoparticles with different surface chemistries were introduced into the polymer blends.…”

“…30 It is essential to observe the evolution of PVA accessibility degree of the polymer blends from extrudates to multifilament yarns. It has been demonstrated that specific interface area of the biphasic fibers is maintained after the introduction of silica nanoparticles.…”

“…Li et al 29 used carbon black and nanotubes to enhance the electric conductivity of porous polypropylene (PP). In our previous work, 30 we have successfully controlled the microstructure of PP-PVA extrudates by selecting the different polymer ratios and silica nanoparticles with different wettability. These nanoparticles are dispersed in bulk phases rather than at the biphasic interface.…”

“…In this study, based on the strategy of thermodynamical migration and localization of silica nanoparticles, 30 the biphasic PP-PVA blends with 70:30 weight fractions were manufacutured into multifilament fibers again, but with the incorporation of fillers with different surface chemistries. In this study, based on the strategy of thermodynamical migration and localization of silica nanoparticles, 30 the biphasic PP-PVA blends with 70:30 weight fractions were manufacutured into multifilament fibers again, but with the incorporation of fillers with different surface chemistries.…”