Preparation And Properties Of Modified Polymer Blended Microspheres

In this paper,a new method for preparing polymer blended microspheres is studied.PS/ES-403 blended microspheres,PS/EVA blended microspheres and PS/EVA/nano-Ca CO₃ blended composite microspheres are prepared via a phase inversion process.The morphology and microstructure of these microspheres are analyzed via scanning electron microscopy(SEM),transmission electron microscopy(TEM),differential scanning calorimetry(DSC),thermogravimet ric analysis(TGA),Fourier infrared analyzer(FTIR),and laser particle size analyzer.The mechanical properties and softening temperature are measured using impact tester,universal testing machine and thermal deformation tester.The PS/ES-403 blended microspheres are prepared by adding initiator to styrene monomer dissolved with linear saturated polyester(ES-403)and then processing polymerization after compound emulsifier,and the dispersant are mixed into the monomer mixture.The test results show that the surface of the blended microspheres is rough and there is a clear two-phase structure inside.When the polyester content is 14%,the blended microspheres with an average particle size of 365.3 nm and a distribution are obtained.Impact properties,adhesion properties,and thermal properties significantly increased compare to pure polystyrene,however,melt flow properties reduced.PS/EVA blend microspheres are also prepared via the phase inversion process.The effects of emulsifier content and dispersant content on the particle size of the blended microspheres are analyzed.The effects of EVA on the surface and internal structure of the blended microspheres and on the thermal properties and mechanical properties of the blended microspheres are discussed.The test results show that when the emulsifier content is 15wt%and the dispersant content is 2.0wt%,the blended microspheres with a particle size below 1 micron and a narrow distribution can be obtained.The surface of the blended microspheres is rough.Both spherical and dumbbell-shaped microspheres existed and obvious two-phase structure are observed.Vicat softening point increased first and then decreased.When the EVA content is 18%,the heat resistance of the blended microspheres reached the highest value.As the content of EVA increased,the impact strength increased gradually,while the tensile strength and flexural strength increased at first and then decreased,and reached the highest value when the EVA content is 15%.PS/EVA/nano-Ca CO₃ blended composite microspheres are obtained by dispersing nanometer calcium carbonate in styrene monomer dissolved with EVA.The effects of nanometer calcium carbonate on the microstructure and morphology are analyzed.The effects of the nano-Ca CO₃ content on the particle size,mechanical properties and thermal properties of the blended microspheres are discussed and the compared with PS/nano-Ca CO₃ microspheres.The test results show that the shape of blended microspheres mostly is spherical.The nanometer calcium carbonate exists both inside and on the surface.The TEM of PS/EVA/nano-Ca CO₃ blended microspheres exhibited three-phase structure.With the increasing of the amount of nano-calcium carbonate,the particle size gradually increased;meanwhile the impact properties,the bending properties and the thermal properties of PS/EVA/nano-Ca CO₃ microspheres are significantly improved,but the tensile strength reduced.The mechanical performance of the PS/nano-Ca CO₃ microspheres also are significantly improved comparing with PS microspheres.