Toughening of polypropylene with crystallizable poly(ethylene oxide)

Abstract

A crystallizable polymer, poly(ethylene oxide) (PEO), was used as new modifier to tailor the toughness of isotactic polypropylene (iPP). An optimum performance was achieved at a medium PEO content of 15 wt% where the toughness was enhanced by 300%, while the strength only decreased slightly. To elucidate the origin of toughening in the iPP/PEO blends, various crystallographic and morphological experiments including X-ray diffraction, electron microscopy and calorimetry were adopted to explore the dependences of polymorphic composition and crystallized morphology on PEO content. When the PEO content is less than 15 wt%, the dispersed PEO cannot crystallize, and these non-crystalline PEO microspheres are embedded in both α-and β-form iPP spherulites, which is mainly responsible for the toughening. In contrast, when the PEO content is higher than 15 wt%, the PEO phase becomes crystallizable, and significant phase segregation takes place, resulting in a marked deterioration in mechanical properties.

Synergistic effects of polyethylene glycol and ammonium polyphosphate on intumescent flame‐retardant polypropylene

“…As to the tensile properties, the tensile strength and the young's modulus change little with the addition of PEG. These results are in conformity with the conclusions of our previous work about toughening of iPP with PEO [ 30]. Therefore, PEG can improve not only the flame‐retardant properties but also the toughness of the blends.…”

“…In our previous work, a water‐soluble and crystallizable polymer, poly(ethylene oxide) (PEO) was added into iPP, and results showed the toughness of iPP was greatly improved [ 30]. This work suggests that the addition of appropriate and crystallizable PEO into iPP could be a new strategy for toughening iPP.…”

Thermal annealing-induced superior toughness in polypropylene/poly(ethylene glycol) blend and its structural origin

“…Two issues concerning the polymorphic composition of iPP/PEG blends are valuable to be noted. The first is that the adding 5 wt% PEG leads to a moderate content of β‐modification iPP, which is similar to the case of iPP/PEO blend . Compared with α‐modification crystals, β‐modification crystals possess higher ductility and deformability.…”

“…The holes in both α‐ and β‐form iPP spherulites (Fig. a–d) are noncrystalline PEG microspheres . After annealing, much more microvoids appear in the amorphous iPP region, as shown in Fig.…”

“…In our previous work, a water‐soluber, crystallizable polymer, poly(ethylene oxide) (PEO) was added into iPP, and a greatly improved toughness of iPP was observed . This work suggests that the incorporation of appropriate crystallizable polymer into iPP could be a new strategy for the toughening of iPP.…”