Researach On The Rheological And Thermomechanical Properties Of PEO/PMMA Blends And Composites

Polymer blending technology is a simple and effective method for preparing new polymer materials,and has important application value in engineering and scientific fields.Blends of poly(ethylene oxide)/poly(methyl methacrylate)(PEO/PMMA)blends have been a hot topic in many blend systems.Carbon nanotubes(CNTs)are often used as fillers to expand and improve polymer properties due to their large specific surface area,high modulus,high strength,and good thermal stability.Studies have shown that the rheological properties of composites are sensitive to changes in the internal structure of the polymer and dispersion of the nanofillers.Understanding the rheological and thermomechanical properties of polymers is critical to improving the processing behavior of polymer composites.In this paper,PEO/PMMA blends and PEO/PMMA/MWCNTs composites were prepared by melt blending.The thermomechanical properties,rheological behavior and mechanism of the composites with different composition ratios and different MWCNTs concentrations were explored in detail.The specific research results are as follows:(1)The thermomechanical properties and rheological behavior of PMMA/PEO blends with different composition ratios was systematically analyzed.The DMA results show that each component PEO/PMMA blends show a single glass transition temperature(Tg),indicating the miscibility of the PEO/PMMA blends.In addition,the shift of the loss modulus peak to the high temperature indicated that PMMA improves the heat resistance of the blends.The studies on the crystallization behavior of PEO/PMMA blends show that the crystallization propertie of blends was significantly inhibited by the addition of PMMA.Further analysis of the internal structure of the blend by fourier transform infrared spectrometer(FTIR)revealed that the miscibility of the PEO/PMMA blends system is attributed to the entropy effect rather than the enthalpy effect.The rheolog,ical experiment results show that the PEO/PMMA blends of various component ratio exhibit similar rheological behavior to pure PEO,the double logarithmic curve of storage modulus(G')and loss modulus(G")versus dynamic frequency(?)on the low frequency region conform to the terminal scale rule for each component blend.The addition of PMMA enhances the melt viscoelasticity of PEO/PMMA blends.(2)The thermomechanical properties and rheological behavior of PEO/PMMA/MWCNTs composites with different MWCNTs content was fully investigated.The DMA result shows that the glass transition temperature of nanocomposite slightly shift toward the high temperature when the MWCNTs were added,indicating that the MWCNTs inhibit the movement of the polymer molecular chain during the heating process.Studies on the crystallization behavior of composite systems show that the addition of MWCNTs greatly improves the crystallization ability of PEO in the composite and promotes the crystallization of PEO.Besides,the PEO/PMMA/MWCNTs composites have the same crystallization peak as pure PEO in the wide-angle X-ray diffraction(WAXD)results,indicating that the crystal structure of the nanocomposite is consistent with PEO.The results of microstructure and rheological experiments show that the lower nanotubes were well dispersed in the matrix,no agglomerates appear.As the MWCNTs content increased to 4 wt.%,significant micron-scale clusters formed by the aggregation of MWCNTs were observed,and these agglomerates and nanoparticles form a network structure by overlapping the substrates.The appearance of liquid-like to solid-state transition can be explained by the fact that nanofillers act as entangled attractants in the matrix reducing the mobility of the polymer chain,resulting in the increase in modulus and viscosity of the composite at low frequencies.Moreover,the result of creep-recovery experiments exhibits that the addition of MWCNTs increases the melt elasticity of the composite.The zero shear viscosity of the nanocomposite with 4 wt.%MWCNTs content does not exist is related to the formation of a large network of MWCNTs at a higher nanofiller concentration.In addition,the low concentrations MWCNTs increase the thermal decomposition temperature of the composite in the thermogravimetric analysis(TGA)result.