A Study Of Phase Behaviour Of Miscible PVME/SAN Blends

PVME was miscible with SAN below 10% of AN. In the miscible window, different miscible blends were gotten by the change of the copolymerisation ratio of SAN. Preview study of miscibility usually is how to make blends miscible while the microstructures of the miscible blends were not reported. This paper investigated the raicrostructure and phase transition of PVME/SAN with AFM and SALS.The main results of my research go as follows:1. A series of SAN were synthesized whose Mn were about 5. 0 X10⁴ and D about 1. 35-1. 49.2. The miscibility of polymer blends depended on â–³x between two polymers and cosolvent. From 1. 14 (dichlorothane) and 0.54 (tetrahydrofuran) to 0.08 (toluene) of â–³x , the cast-film changed from immiscible state to the miscible state. With the high â–³x , the miscibility depended on the â–³x , while the miscibility depended on the interaction parameter of polymer blends with low â–³x.3. The thickness of the cast-film was about 50-100um which was far greater than the mean gyration radius of chains of PVME(5. 17nm) and SAN(8. 62nm).the cast-films were in the three dimension states.4. The results of PVME/SAN in its miscible window were tested with DSC. The influencing factors of the casting films in initial states were investigated. The results showed that initial state of the casting films depended on their initial the solvent.5. By AFM, some droplets in the casting films of PVME/SAN in the miscible window were found and the size of the droplets in the films enlarged with the increase of AN in SAN. Thepapers believed that the chains of the polymer blends were in the state between the coil model and sphere model. 6. With SALS, the phase transitions of the casting films of PVME/SAN blends were investigated, and the experimental results showed that the phenomena of LCST appeared in certain content of AN in SAN of the blends. Meanwhile, the extent of mixture ratio blends of PVME/SAN with LCST narrowed with the increase of AN in SAN. The scope of q (scattering vector) narrowed also with the increase of AN of SAN of different blends at the beginning of phase transition. The change of q can give an evidence for conjecture of the existence of transition states of chains. The dynamics researches of the casting films showed that the experimental results followed the CAHN linearity law.