| The thesis dealt with the miscibility and the flame retardancy of PC/ABS alloys.The influence of AN, PB contents in the ABS resin on the miscibility between PCphase and SAN phase in the alloys was studied in details. The effects of the twocompatibilizing agents, ABS-g-MAH and SMA, on the miscibility of the PC/ABSalloys were also investigated. Differential scanning calorimetric (DSC) and scanningelectron microscopy (SEM) methods were used to qualitatively characterize themiscibility and the morphology, meanwhile, Flory-Huggins theory was used to obtainthe polymer-polymer interaction parameters for the blending system, based on themeasurements of glass-transition temperatures of PC and SAN components in thealloys and their changes of the specific heats at the Tgs. This method was desirable forthe quantitative characterization of the miscibility for partially misciblepolymer-polymer blending systems, such as PC/ABS alloys.It was found from the DSC investigations of PC/ABS alloys that, when ANcontent in the SAN was 24 wt%, the Tg of the PC-rich phase got a biggest decreaseand the Tg of the SAN-rich phase increased most, indicating that the miscibility of thePC/ABS alloy with this composition was at optimum. The fact that the raising degreeof Tg of the SAN component was larger than the drop extent of Tg of the PCcomponent after blending implied that SAN appeared to be dissolved more in thePC-rich phase than did PC in the SAN-rich phase. On the other hand, no obviousinfluence on the Tgs of both PC-rich phase and SAN-rich phase was found with thechange of PB content in ABS resin.In terms of the interaction parameters (χ12 ) of PC/ABS alloys, it was found thatwhen AN content of SAN was 24 wt%,χ12 reached its lowest level, 0.0167, alsodemonstrating the miscibility of PC/ABS was the best at this SAN composition. Aslong as the effect of PB content in ABS resin was concerned, the calculated χ12changed little, with the change of PB contents. These results corresponded to thoseobtained from the measurements of Tgs . IIIBased on the SEM analyses of the PC/ABS alloys, ABS component wasuniformly dispersed into PC matrix, and the size of the dispersed phases was about0.5μm, when AN content in SAN was 24 wt%. The phase interface became blurry.These results also indicated that miscibility of the alloys was the best at thiscomposition and provided supports for the conclusions from DSC and χ12 analysis.It was shown from the experimental results of DSC that the addition ofcompatibilizing agents, ABS-g-MAH and/or SMA, improved the miscibility ofPC/ABS alloys to a certain extent. The alloy morphology and compatibility modifiedby ABS-g-MAH was better than that by SMA.In order to solve the problems concerning the poor thermal stability, narrowwindows for processing, and the deterioration of mechanical properties of PC/ABSalloys mixed with halogen-antimony flame retardants, a thermal gravity analysis wasused to study the thermal decomposition behaviors of decabromodiphenylether/antimony flame retardants and PC/ABS alloys mixed with the flame retardantsat different compositions and temperatures. By this way, a number of methods toimprove the thermal stability of the alloys were discussed.It was founded that the phosphate with low molecular weights decomposedbelow 200℃, much lower than the decomposition temperature of PC/ABS alloys,while the thermal decomposition behavior of decabromodiphenyl ether was similar tothat of PC/ABS alloys. However, the compounding of decabromodiphenyl ether withantimony (3/1 wet.) moved the thermal decomposition to the lower temperature range,resulting in the deterioration of thermal stability of the PC/ABS alloys. Thedecomposition of decabromodiphenyl ether/antimony (3/1) could be postponed byadding the third component, such as zinc oxide or calcium oxide, but the flameretardancy of the alloys was also affected negatively. On the other hand, thedecomposion temperature of the compounding flame re...
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