Synthesis And Properties Of Two Microcellular Foam

With its unique structure,microcellular foam has stood out from traditional foams.It was widely used in construction industry,automobile field,aerospace realm and artificial organ.In this paper,ZIF-8 nanoparticles were added into PMMA by in-situ synthesis then PMMA/ZIF-8 in-situ composite was successfully prepared.PMMA/ZIF-8 microcellular foam was prepared by supercritical CO2 foaming using ZIF-8 nanoparticles as nucleating agents.In addition,PP,POE were blended and crosslinked to prepare PP/POE crosslinked blend,then PP/POE microcellular foam with high open porosity was successfully prepared using supercritical CO2 foaming.The following is the specific research content:Firstly,ZIF-8 nanoparticles were synthesized by adding 2methylimidazole and zinc acetate in PMMA solution.The amount of ZIF-8 nanoparticles was regulated by controlling the quality of zinc salt and organic ligand.The morphology,distribution and crystal structure of ZIF-8 nanoparticles were investigated.The result showed that the average size of ZIF8 nanoparticles were 43.8 nm,45.1 nm and 56.2 nm when the amount of ZIF-8 nanoparticles were 1 wt.%,2 wt.%and 4 wt.%,respectively.They were uniformly dispersed in PMMA,showing almost the same crystal form and functional group as ZIF-8 synthesized in methanol.Furthermore,the addition of ZIF-8 nanoparticles improved the thermal stability and glass transition temperature of PMMA.Secondly,the adsorption capacity of CO2 in PMMA/ZIF-8 in-situ composite was measured by gravimetric method and the result showed that the addition of ZIF-8 nanoparticles enhanced the adsorption capacity of PMMA for CO2.The effects of different factors on the adsorption capacity were discussed and results showed that the environment of low saturation temperature and high saturation pressure was more conducive to the adsorption of PMMA for CO2.It was found that ZIF-8 nanoparticles played the role of heterogeneous nucleation agent in the foaming process and significantly improved the structure of PMMA foam.The effects of different foaming processes on the cell structure were researched and results showed that the microcellular foam material with small cell size and great cell density could be prepared at the environment of low saturation temperature and high saturation pressure.The compression test results showed that PMMA/ZIF-8 microcellular foam had higher compressive yield strength than pure PMMA foam.Finally,PP/POE crosslinked blend was prepared using melt blending and crosslinking in mixer.It was found the crystallization temperature of PP was higher by approximately 7? because of the addition of POE crosslinked system.What's more,the crystallinity of PP decreased from 43.2%to 38.1%by POE crosslinked system.PP/POE microcellular foam was prepared using supercritical CO2 foaming.Through regulating saturation temperature,saturation pressure,POE content and the amount of crosslinking agent,PP/POE microcellular open-cell foam whose cell size was 5.54 ?m,cell density was 2.21 ×1010 cell/cm3,and the open-cell content was 86.4%were successfully prepared.