Abstract
BackgroundAlthough polypropylene (PP) has been widely used, its brittleness restricts even further applications.MethodsIn this study, we have used a melt blending process to synthesize styrene acrylonitrile (SAN)/PP blends containing 0, 5, 10, 15 and 20 wt% SAN. The effects of adding various amount of SAN on the blends characteristics, mechanical properties, thermal behavior and morphology were investigated.ResultsThe results demonstrated that SAN had no obviously effect on crystal form but reduced the crystallinity of PP and increased the viscosity. The heat deflection temperature and Vicat softening temperature were enhanced for all SAN/PP blends, in particular for blends with low SAN content (5 and 10 wt%). The morphology of SAN/PP blends with 10 wt% SAN revealed the presence of nanoparticles dispersed on the surface, while SAN/PP blends with 20 wt% SAN exhibited the presence of spherical droplets and dark holes. All SAN/PP blends showed higher impact strength compared to pure PP, especially for SAN/PP blend containing 10 wt% SAN for which the impact strength was 2.3 times higher than that of pure PP.ConclusionsThe reason for significant increase in impact properties seemed to have a strong correlation with nanoparticles morphology and the decrease of PP crystallinity.
Highlights
Polypropylene (PP) has been widely used, its brittleness restricts even further applications
XRD studies of styrene acrylonitrile (SAN)/PP blends It is known that PP is a polymorphous crystal, showing three crystalline forms designated as α-phase, β-phase, and γ-phase. α-phase is the dominanting; β-phase and γ-phase are induced when nucleating agents are added into the PP matrix [23,24,25]
Our results showed that SAN/PP blends exhibited higher impact strength than pure PP, but the properties varied according to the amount of SAN
Summary
Some extrudate was immediately molded in an injection molding machine (TC-150-P, Tiancheng Machinery Co. Ltd, China) at 180, 195, and 205 °C in sequential zones from hopper to mold to obtain dog-bone shaped sheets of 150 mm × 10 mm × 4 mm and rectangular samples of 80 mm × 10 mm × 4 mm for mechanical (tensile, impact tests), thermal (heat deflection and Vicat softening temperatures, melt flow index test and morphological examination (scanning electron microscopy). Thermal deformation behavior and viscosity analysis The melt flow indexes (MFI) of PP and SAN/PP blends were determined using a flow rate meter Rectangular samples (80 mm × 10 mm × 4 mm) were scanned from 25 °C to deformation temperature at a heating rate of 120 °C/h under a perpendicular loading weight of 75 g (bending normal stress: 0.45 MPa) in line with GB/T1634.2-2004. The Vicat softening temperatures of the specimens were measured under a loading weight of 1000 g, heating from 25 °C to Vicat softening temperature at a rate of 50 °C/h in terms of GB/T 1633-2000
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