Study On Percolation Threshold Value And Morphology Of Co-continuous PS/PA6 Blend

One of the methods is that by combining two or more different polymers one can tailor compositions to meet specific end-use requirements. The properties of these polymer blends are, to a large extent, determined by the morphology. Most polymer blends are immiscible due to thermodynamic reasons. Consequently, polymer blending usually leads to a heterogeneous system with a multiphase morphology, such as the dispersed droplet/matrix type and co-continuous morphology etc. In co-continuous morphologies both components are fully interpenetrated throughout the sample. Therefore the blend has not only the properties of each polymer, but some the special properties.Co-continuous morphologies can be obtained over a wide range of volume fractions, the so-called co-continuity interval. In Haake torque rheometer, it was investigated that rotor speed, temperature, mixing time and the copolymer of styrene and maleic acid (SMA), the copolymer of polystyrene and nylon6(PS-g-PA6)-compatibiliser had effect on the percolation threshold value of co-continuous PS/PA6 blend. The results showed that the range of the region of phase co-continuity PS/PA6 was 40/60-65/35 at experimental temperature, rotor speed or mixing time; When compatibiliser was added, the range of the region of phase co-continuity was largely narrowed because of the decreased possibility for recombination and coalescence. At a same mass fraction of PS/PA6, the increase of rotor speed resulted in the increase of PS continuity; the increase of temperature resulted in the decrease of PS continuity; PS continuity in PS/PA6 was lower than that of in PS/SMA(PS-g-PA6)/PA6. The more was mass fraction of compatibiliser, the less PS continuity was.The change of co-continuous morphology during further processing, such as compression and injection moulding, is still one of the main problems about morphology stability. The influence of shear rate on the PS and PA6 continuity was studied and the blend morphology was examined at different temperatures or time using SEM by the quiescent annealing of co-continuous PS/PA6. Co-continuous morphologies of 50/50 wt% PS/PA6 blend stayed co-continuous with annealing but showed an increase in phase size with time and the coarsening of the morphology was speeded at higher temperature. When the compatibiliser was added, the coarsening speed of co-continuous slowed. The more was mass fraction of the compatibiliser, the slower coarsening speed was. Comparing to the different structure compatibiliser PS-g-PA6, the result was that phase size was smaller if graft PA6 was longer because of the more effective of the compatibiliser. The longer graft PA6 of PS-g-PA6 was better than the denser graft PA6 of PS-g-PA6 when preventing the coarsening of the co-continuous morphology.