Synthesis And Application Of Flame Retardant Thermotropic Liquid Crystalline Ionomers

Liquid crystalline ionomers (LCI) is a kind of polymer with ion and both has properties of liquid crystal. As a new type of liquid crystal polymer materials,LCI has attracted more and more attentions because LCI itself has unique properties. LCI is easily oriented. The liquid crystal micro-areas of mixture orient and form into fibril structure under shear stress,and finally obtain in situ composite. The melt viscosity of this in-situ composite is low so that the melt flowing properties are improved. At the same time, it can reduce energy consumption in the processing process, which is beneficial to the economic processing.Firstly, three kinds of liquid crystalline ionomers (Y-1, Y-2, Y-3) containing sulfonic acid group were prepared successfully by introducing ion ionomers. By investigating effects of reactive temperature, reactive time and mass ratio of ion ionomer on the yield and melting point of LCI, the optimal experiment conditions were determined. The reactive time of liquid crystalline ionomers Y-1 was 8h,Y-2 was 6h, Y-3 was 6h, reactive temperature of liquid crystalline ionomers Y-1 was 80?, Y-2 was 80?, Y-3 was 50? and mass ratio of ion ionomer were 10%,16%,22%. The molecular structure, texture of liquid crystal melting point, intrinsic viscosity, molecular weight and thermal stability of LCI were investigated by fourier transform infrared spectra (FTIR), wide angel x-ray diffraction (WAXD), polarizing optical microscope (POM), ubbelohde viscosity meter and thermogravimetry analysis (TG).The results demonstrated that the three kinds of LCI possessed the type of nematic liquid crystalline texture. Their melting points were 246?, 197?, 256?, intrinsic viscosities were 0.131,0.249, 0.389, molecular weights were 2562?5607?9661. When loss its weightlessness is 5%, the temperature (Td5%) were 272?, 296?, 312? and the maximum rates of thermal degradation (Vdmax) were 1.28%/?, 0.71%/?,0.59%/?. Moreover,there were flame retardant elements in Y-2 and Y-3.Secondly, PP/EPDM/Y-3 composites were prepared with PP/EPDM and Y-3 of the best synthetic performance through melt-blending method. The influences of Y-3 on mechanical properties, processing properties and microstructures of PP/EPDM were investigated. The results showed that elongation at break and elastic modulus respectively increased by 153.8%,80.0% and its tensile strength increased by 21.5MPa. Besides, it was proved by POM that Y-3 was in favor of forming ? crystallization for PP whose particle size was smaller. Therefore,the strength of PP/EPDM was improved. In addition, the MFR increasing by 20.7% showed that the processing fluidity of PP/EPDM was obviously improved. Meanwhile, vickar and TG test showed thermal stability of PP/EPDM/Y-3 composite was better.Finally, PP/EPDM/Mg(OH)2/Y-3 flame retardant composites were prepared by blending Y-3 and Mg(OH)2. It could be found that the vertical combustibility of composite could reach V-0 and Limiting Oxygen Index was 40.7%. Simultaneously, the mechanical properties,processing properties and thermal stability were excellent.