Preparation Of Enameled Wire Coating Of Fluorinated Poly(Ether Ether Ketone)s And Their Properties

Poly (ether ether ketone)(PEEK) is an important high-performance aromatic polymerwhich is used in aerospace, chemical engineering, electronics and other fields for itsexcellent thermal stability, chemical resistance and mechanical properties. However, it isdifficult for PEEK to be used as thin film or coating because it has poor solubility incommom solvents except for concentrated sulfuric acid. In this thesis, fluorinated pendantgroup and the polyethylene glycol (PEG) were introduced into the PEEK chains to improveits solubility, thermal stability and flexibility, which made it possible to be used in theenameled wire coating.First, fluorine-containing poly (ether ether ketone)(FPEEK) was synthesized by anucleophilic polycondensation of hexafluorobisphenol A,4,4，-difluorobenzophenone andhydroquinone. Then the solution of FPEEK in N, N-dimethylformamide (DMF) wasapplied to prepare the insulating coating. The structures and properties of FPEEK werecharacterized by Fourier transform infrared spectroscopy (FTIR), nuclear magneticresonance spectroscopy (NMR), X-ray diffractometer (XRD), thermogravimetric analyzer(TG) and universal testing machine. The influences of the molar fraction ofhexafluorobisphenol A on the properties of FPEEK and FPEEK film were discussed. Theresults indicated that FPEEK obtained with more than60mol%of hexafluorobisphenol Awas soluble in common organic solvents such as chloroform (CHCl3), tetrahydrofuran(THF), methylbenzene, DMF and N, N-Dimethylacetamide(DMAc) at room temperature.The thermal stability, tensile strength and Young’s modulus of FPEEK increased, while theelongation at break decreased with increasing the fluorine content of FPEEK. All insulatingcoatings of FPEEK exhibited good mechanical properties. The adhesion, flexibility andimpact resistance could reach the grade1,50cm and0.5mm respectively.Then fluorinated copolymers containing polyethylene glycol (FPEEK-co-PEG) weresynthesized through nucleophilic copolycondensation of PEG, hexafluorobisphenol A and4,4’-difluorobenzophenone. The influences of PEG content and PEG molecular weight on theproperties of FPEEK-co-PEG and FPEEK-co-PEG film were investigated. With the increase of PEG content, the solubility and thermal stability of FPEEK-co-PEG decreased,the tensile strength and Young’s modulus of the film decreased, while the adhesion nearlyunchanged. When the PEG content increased in the range of0~20%, the elongation at breakof FPEEK-co-PEG increased, the flexibility remained0.5mm and the impact resistancekept50cm. However, the elongation at break, flexibility and impact resistance of the filmdecreased as the PEG content exceeded20%. All of the FPEEK-co-PEGs prepared withdifferent molecular weight of PEG could be dissolved in THF, CHCl3,DMF and DMAc.Compared with FPEEK, the thermal stability and the mechanical properties ofFPEEK-co-PEG decreased due to the low molecular weight. When the PEG content was20%and the molecular weight of PEG was200, the synthesized FPEEK-co-PEG(number-average molecular weight20732) had an excellent mechanical property. Theadhesion, flexibility and impact resistance could reach the grade1,50cm and0.5mmrespectively, which made it more suitable for application in enameled wire coating.