Preparation Of PET-based Conductive Composites And Their Properties

A series of conductive composites with poly(ethylene terephthalate)PET as the polymer matrix and multi-walled carbon nanotubes(MWNT)and carbon black(CB)as electrical nanocomposites were prepared in this thesis.PET/MWNT/PET/MWNT/CB composites were prepared by in-situ polymerization.PET/MWNT、PET/PA6/MWNT composites were prepared by melt blending.Moreover,the structure and properties of the composites were studied by surface resistance meter,tensile testing,field emission scanning electron microscope(FESEM)transmission electron microscope(TEM)and differential scanning calorimmter(DSC),ect.The results showed:The MWNT were well dispersed in the PET matrix by in-situ polymerization method.The electrical conductivity of the composites increased with the increasing of MWNT content.The addition of MWNT had a good crystallization effect on PET.The thermal stability and crystallinity and Mechanical properties of PET/MWNT nanocomposites were good when the contents of MWNT were 0.2 wt%of PET.The results showed that the surface electrical conductivityies of PET/MWNT/CB nanocomposites were 1011 Ω when the contents of MWNT and CB were 0.5 wt%of PET.MWNT and CB can form cosupporting conductive networks and composite conductive paths in PET.The addition of CB and MWNT significantly induced the crystallization of PET,but the ability of CB to induce crystallization was lower than that of MWNT.The optimum conditions of melt blending were as follows:blending temperature 275℃,blending time 14min,screw rotation speed 150rpm.The optimum technological conditions were determined by univariate analysis and stepwise screening.By changing the conditions can improve the conductivity of composite materials 2-3 orders of magnitude.In the PET/PA6 composites,with the change of blending ratio,the structure of "island"-"co-continuous" structure-"island"structure changes.After adding MWNT,MWNT exists in the two-phase system and between the two-phase interface.With the increase of MWNT content,the electrical conductivity of PET/PA6/MWNT composites increased.The crystallinity of PET and PA6 interacts with each other.The addition of MWNT can induce the crystallization of PET and PA6.