Study On The Phase Behavior Of Binary Polymer Blends And Ternary Mixtures Containing Fillers By Dynamic Rheological Technique

The commonly used polymer materials are usually manufactured not only by mixing several macromolecular fluids, but also by incorporating solid "filler" particles. The final properties of the multicomponent polymer systems depend on their final morphology and structure whose formation and development is largely dependent on their phase behavior on the investigation of which, therefore, a great value is placed from the academic and commercial viewpoint. The common research techniques used in this area, such as differential scan calorimetry (DSC), dynamic mechanical analysis (DMA), fluorescence spectrum, Fourier-transform infrared ray (FTIR), small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and small angle laser sacattering (SALS) and so forth, have intrinsic drawbacks. To eliminate the drawbacks from those techniques, here a comparatively new technique based on dynamic rheology, was adopted, which is theoretically on the basis of the fact that the dynamic rheological behavior of multicomponent polymer systems is countless tied to both the interactions between the blending components and their phase morphology and structure, and in return their dynamic rheological behavior is able to precisely probe the formation and evolution of their phase morphology and structure. Thus, the phase behavior of PMMA/SAN blends was first investigated by dynamic rheological measurements; such investigations were then extended to PMMA/SAN/SiO₂ systems to explore the influence of active fillers on the phase behavior of binary polymer blends. Hereafter, an innovative way to examine the phase behavior of the multicomponent polymer blends, especially the ternary mixtures containing fillers, has successfully been sought out in this thesis. The main work and conclusions are as follows.1. The relationship between the linear dynamic viscoelastic response of PMMA/SAN blends and their corresponding phase behavior were systematically explored in Chapter 3. The following statements can be made: (1) In the homogeneous regime of binary polymer blends, the principle of time-temperature superposition (TTS) holds for both G' and G". However, in the pretransitional regime, the thermorheological complexities set in, which are shown as the breakdown of TTS for both G' and G" , enhanced elasticity and prolongedrelaxation time; and G are more sensitive than G" to phase separation. (2) A single dynamic temperature ramp test is adequate in determining both the binodal and spinodal phase separation temperatures. (3) The critical composition and temperature of PMMA/SAN is 56/44 and 184#, respectively. The thermodynamic interaction parameter, %h, between PMMA and SAN segments, is correlated with temperature as x_b(T) =0.017-6.442/T . It was extrapolated, according to this equation, to obtain x_b at the room temperature, equal to -0.0046, which is near to the value, X> 0.01, which was determined using SANS by other researchers.2. By incorporating the nucleation and growth phase separation process into the simplified Palierne emulsion model, the binodal phase separation kinetics of PMMA/SAN(80/20) blend and the effect of linear dynamic rheological measurement on the spinodal phase separation process of PMMA/SAN(56/44) were examined in Chapter 4. It has been found that: (1) The delay time of binodal phase separation, similar to that of spinodal phase separation, also exists in binary polymer blends. (2) In theG'- Time curves at a series of low frequencies, the dependence ofG'on time becomes weaker with increasing frequencies; and G'increases rapidly in the initial stage of phase separation, then increases slowly with time. (3) The linear dynamic rheological measurements can influence the evolution of the co-continuous morphology that is formed by spinodal phase separation. Therefore, the dynamic rheological measurements may be not suitable for the examination of spinodal phase separation kinetics. (4) The growth index of the dispersed domains in PMMA/SAN(80/20) mixture is 0.366 which is slightly larger than 1/3 correspo...