【作者】 孙辉；

【导师】 杨贤金； 盛京；

【作者基本信息】 天津大学 ， 材料学， 2007， 博士

【摘要】 本文用熔融共混法制备了不同共混比和不同加工条件下的等规聚丙烯/顺丁橡胶(iPP/PcBR)共混物,并对它们的相容性、结构及其性能进行了详细研究。用DMA测试了iPP/PcBR共混物的相容性。结果显示,共混物两组分之间有部分相容性。当共混时间增加、共混温度升高或共混转速加快时,两组分间的部分相容性没有进一步改善。通过计算平衡熔点值法,证实了DMA的测试结果。应用SEM观察了共混物的相形态。分散相呈不规则颗粒状分散在连续相中,当PcBR含量为40-50vol%时,出现了双连续相结构。对SEM图像、SALS的Vv谱图和BSALS图像进行计算机处理发现,分散相含量增加,则分散相尺寸增大,粒径分布变宽;在共混前期,分散相粒径减小,体系分布不均匀,到了中后期,分散相粒径基本不变,体系分布均匀;相结构的改善不随共混温度的升高或者转速的加快呈正比例变化。分别采用POM、SALS的Hv谱图和WAXD、SAXS对共混物结晶形态和结构进行了分析。研究发现,PcBR的加入破坏了球晶的完整程度,使球晶边界模糊化,球晶尺寸减小;当加入的PcBR含量小于40vol%时,会诱导PPβ晶产生;另外,共混时间的延长、共混温度或转速的增加,都有利于改善球晶的结晶形态结构。用DSC测试了不同共混比的iPP/PcBR共混物的等温和非等温结晶过程。结果显示,添加PcBR,增大了共混物的结晶速率,缩短了结晶诱导时间, PcBR对iPP的结晶起到了异相成核的作用;找到了适合描述我们共混物的等温和非等温结晶过程的模型;添加较高含量的PcBR,使共混物的结晶活化能有所下降。力学性能测试显示,添加PcBR相会使共混物拉伸性能下降、冲击性能上升;延长共混时间使共混物的力学性能逐渐改善;降低共混温度或加快共混转速,使得共混物的冲击性能上升;存在最佳的共混温度和转速区间,使得共混物拉伸性能最优。经过流变测试,共混物均表现为非牛顿流体性质;PcBR含量或共混时间增加,共混物的表观粘度增加;共混温度或转速增加,表观粘度减小。用一种新的流变的方法表征了共混物的结晶诱导时间,结果与DSC的测试结果吻合。更多还原

【Abstract】 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.更多还原