| Isotactic polypropylene/poly(cis-butadiene) rubber (iPP/PcBR) blends with various blend ratios were prepared by melt mixing under different mixing conditions. The influence of PcBR content and various mixing conditions were investigated in details on structure and properties of iPP/PcBR blends.Miscibility of iPP/PcBR blends was studied by dynamic mechanical analysis (DMA). The result showed that iPP and PcBR were partly miscible, which was also validated by calculation of the equilibrium melting temperature of iPP and iPP/PcBR blends. The part miscibility could not improve by means of the increase in mixing time, mixing temperature or mixing rotation speed.Phase morphology of iPP/PcBR blends was observed by scanning electron microscope (SEM). The dispersed phase was distributed in the continuous phase in the shape of irregular particles. Co-continuous phase structure appeared as PcBR having 40-50vol% content was added. SEM images of iPP/PcBR blends were dealt with by our soft and some structure parameters were obtained. As the content of the dispersed phase increased, the average size of the dispersed phase increased and the distribution of this phase became broad. During the first 2-3min of mixing, the dispersed phase broke up into smaller particles and it almost didn't change with the increase of the rest mixing time. The improvement of phase structure wasn't proportional to the increasing of mixing temperature or rotation speed. Different structure parameters were gained from Vv images of small angle light scattering (SALS) and small angle light back scattering (BSALS), and the same conclusions were gotten by the analysis of change in these parameters.Crystalline morphology and structure of iPP/PcBR blends was investigated by polarized optical microscopy (POM), small angle light scattering (SALS), wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SALS), respectively. An increase of PcBR content led to less perfection of spherulites, vaguer boundaries between spherulites and smaller spherulite size. The presence of PcBR also remarkably affected the crystalline structure of iPP. An addition of PcBR with 10-40vol% content caused the form of PPβcrystal. The increase in the content of PcBR, mixing time, mixing temperature or rotation speed involved an improvement in crystalline structure of blends.Isothermal and nonisothermal crystallization of iPP/PcBR blends were carried out by differential scanning calorimetry (DSC). The introduction of PcBR resulted in a faster crystallization rate and a shorter crystallization onset time, meaning a heterogeneous nucleation effect of PcBR upon crystallization of iPP. The Avraim equation was suitable for describing the isothermal crystallization initial process of iPP/PcBR. The combined Avrami and Ozawa equation was more appropriate for the nonisothermal crystallization of our blends. Crystallization activation energy of iPP and blends was calculated by the Kissinger equation; the result showed that crystallization activation energy decreased as the content of PcBR was more than 20 vol%.Mechanical properties of iPP/PcBR blends were test. The incorporation of PcBR reduced tensile properties. The increase in mixing time or rotation speed and a decrease in mixing temperature were benefit for the enhancement of impact strength of iPP. There existed an optimal mixing temperature or rotation speeds to make tensile properties of iPP most excellent.Finally, rheological properties of blends were examined. Neat iPP and iPP/PcBR blends conformed to the law of Non-Newton behavior. For a given shear frequency, with the increase of PcBR content or mixing time, the apparent viscosity of blends increased. However, as mixing temperature or rotation speed increased, the apparent viscosity of blends decreased. The onset time of isothermal crystallization of iPP and iPP/PcBR blends was measured by a novel rheological method, which accords with the results from DSC.
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