Study On Evolution's Fractal Of Phase Structure And On Relation Between Structure And Mechanical Properties Of Polypropylene/Ethylene-1-octene Copolymer Blends

By applying scanning electronic microscope (SEM) and phase contrast microscope (PCM) to samples obtained online during blending from the interim mixer, and by using character length and statistic theory, the corresponding scaling function is introduced and the dynamic self-similarity of formation and evolution of phase structures in PP/POE blends during blending can be confirmed from that. Therefore, the fractal behavior of formation and evolution of phase structures in PP/POE blends during blending can be proved and the fractal dimension can be calculated. The fractal is meaningful only in the dimensionless region which the fractal exists. In the specific melting blending, changes in POE phase dimension are the independent dynamic self-similarity which can be described by scaling functions inferred from the character length. At this result, SEM analysis accords with PCM analysis. The whole melting mixing should consist of three stages, that is, initial, middle, and later stage. Thus, the temporal periods in which changes in POE phase dimension are the dynamic self-similarity should contain three ones. The first is from the start of initial mixing to the interim of that. The second is from the end of initial mixing to the start of later mixing. The third is from the interim of later mixing to the end of that. These periods which are the dynamic self-similarity maybe overlap because of the different speed of rotor. Average character length is an effective structure parameter which can describe POE phase dimension appearing in phase morphology like both"sea-island"and co-continuous structure.By applying small angle x-ray scattering (SAXS) and SEM to the extrusive samples which obtained from Haake rheometer, the corresponding scaling function is introduced with light scattering theory inferred by Stein and Debye-Bueche and the formulae inferred by Schaefer, and the self-similarity can be conformed from it. Therefore, the fractal behavior exists in PP/POE blends and the fractal dimension can be calculated. This fractal dimension doesn't change with the weight ratio of PP phase to POE phase. This fractal dimension is the mass fractal one and different with SEM analysis and PCM analysis. Meanwhile, the correlative structure parameters which are important to characterize PP/POE blends, such as Porod exponent which can describe the shape of dispersed phase, radius of gyration Rg and average chord lengths L , can be easily acquired.By applying SEM, mechanical testing and differential scanning calorimetry (DSC) to samples obtained from interim and extrusive mixer, the prediction of modulus and extreme disable strength of the material are researched with some theoretical models which predict the modulus and with the simplified model which analyzes the extreme disable strength of composite. The relations between structures (such as the ratio of uneven lengths, uniform aspect ratio which is supposed to be oriented in one direction, and the degree of crystalline) and mechanical properties (such as Young's modulus, tensile strength and yield strength) are also studied and some results have been acquired.