Synthesis And Properties Of Novel Poly(aryl Ether Ketone)s Resins Containing Phthalazinone Moieties

Poly(phthalazinone ether ketone)resin(PPEKs)is a kind of high-performance special engineering plastics containing phthalazinone in the main chain,which exhibits excellent heat resistance,solubility,mechanical properties and radiation resistance.However,the PPEKs has a twisted non-coplanar structure,which causes the resin to have severe molecular chain entanglement,high melt viscosity,and difficult thermoforming processing,which limits the further application of resin.In this paper,we aimed to improve the thermoforming properties of PPEKs without sacrificing degrading its thermo-resistance and mechanical properties,and to expand the application of the resin.From the point of view of molecular design:on the one hand,we adopted the way of block copolymerization to introduce the chain-segment of PEEKK and PEEK into PPEKs system in order to enhance the regularity of the molecular chain and improve the thermal processing performance of the PPEKs resin;on the other hand,we introduced the bisphenol-fluorenyl group and 2,5-furyl group into PPEKs system,respectively,in order to increase the space between the molecular chains to improve the thermal processing performance of the PPEKs resin.The main work of this paper is as follows:Firstly,three kinds of fluorine-terminated poly(phthalazinone ether nitrile ketone)oligomer PPENK-F and a kind of hydroxyl-terminated semi-crystalline oligomer PEEKK-OH were designed and synthesized.Then,three block copolymers containing phthalazinone moieties PPENK-b-PEEKK were successfully prepared by block copolymerization.The structure and properties of block copolymers were characterized by Fourier Transform Infrared Spectroscopy(FTIR),Proton Nuclear Magnetic Resonance(1H-NMR),Differential scanning calorimetry(DSC)and Thermogravimetric Analyzer(TGA),et al.The results showed that the introduction of regular segments of PEEKK improved the regularity of the segments of PPEKs significantly.All three kinds of PPENK-b-PEEKK have crystal structure and melting point,and own potential excellent thermal forming properties.The solubility test results showed PPENK16000-b-PPEEKK6000 could be partially dissolved in N-methpyrrolidone(NMP)at room temperature.It is more valuable that the heat resistance of the three PPENK-b-PEEKK resins was slightly lower than that of PPENK resins(the Tg of the three block-copolymer was 265-283?,lower than that of PPENK(285?)),it still maintained excellent thermal stability.Meanwhile,the three PPENK-b-PEEKK 5%thermogravimetric temperature(Td5%)and 10%thermogravimetric temperature(Td10%)were basically consistent with those of PPENK.In conclusion,this study shows that it is feasible to introduce the semi-crystalline poly(aryl ether ketone)(PAEK)chain-segment into PPEKs to improve its thermal forming properties.Secondly,in order to study the influence of molecular masses of the semi-crystalline PAEK segment on thermal forming performances of PPEKs,ketimine structure was introduced into the semi-crystalline PEEK systems,and then the soluble precursor PEEKt-F was prepared.On the one hand,the precursor PEEKt-F improved the solubility of PEEK,which was conducive controlling the molecular weight of PEEK accurately.On the other hand,ketimine structure was easy to be removed,which had little effect on properties of the resin.Based on this,in this paper we designed and synthesized five kinds of fluorine-terminated soluble precursor PEEKt-F(PEEKt-F-1-5)with different molecular masses and one kind of hydroxyl-terminated PPENK-OH oligomer,and five types of block copolymer PPENK-b-PEEK(Block-1-5)were prepared successfully by block copolymerization.FTMR,1H-NMR,DSC,TGA,Wide-Angle X-ray Diffraction(WAXD),universal testing machine and rheometer were used to characterize the structure and properties of copolymer.The study results showed that the introduction of semi-crystalline chain-segment PEEK was into PPEKs resin,reducing melt viscosity of the resin.The melt viscosity of Block-5 at 370? was 9270 Pa·s,by 65.7%lower than that of PPENK resin at the same temperature,which significantly improved the thermal forming performance of the resin,and this improvement was enhanced with the increase of molecular masses of the semi-crystalline PAEK.In addition,although the heat resistance and mechanical properties of block copolymer were slightly lower than that of PPENK resin,block copolymer still showed excellent heat resistance and mechanical properties,which can meet the actual requirements.Moreover,in order to study the effects of diphenyl-fluorene with large volume on comprehensive performance of PPEKs,9,9-double(4-hydroxy phenyl)fluorene(BHPF),4-(4-hydroxy-phenyl)-2,3-miscellaneous naphthalene 2,N-1-ketone(DHPZ)and 1,4-double(4-fluorine benzene formyl)benzene(BFBB)were used as monomers to prepare five types of PPEKs with different content of fluorine structure(PPFEKs)by nucleophilic aromatic substitution reaction.FTIR,1H-NMR,DSC,TGA,WAXD,universal testing machine and rheometer were used to characterize the structure and properties of the copolymer.The results showed that the introduction of BHPF units into the PPEKs increased the intermolecular volume of the copolymer,reducing entanglement between the molecular chains.And melt viscosity of PPEKs,from 92,000 Pa·s of PPFEK1000 to 17,000 Pa·s of PPFEK0100,the drop was a whopping 81%,which meant that the processing property of copolymer was improved.Meanwhile,the introduction of BHPF not only did significantly degrade the heat resistance and mechanical properties of PPEKs,but also improved thermal stability of the resin significantly.Therefore,the thermal degradation process of PPFEKs resin was studied by using TGA/FTIR technology system,and it was concluded that the N-N bond in DHPZ was the key to limit the thermal stability of PPEKs.In addition,all the PPEKs showed excellent solubility.Finally,a new furan-containing monomer 2,5-bis(4-fluorobenzoyl)furan(BFBF)was derived from biomass monomer 2,5-furandicarboxylic acid(FDCA).And furan-containing poly(phthalazinone furan ether ketone)(PPFEK)successfully prepared through aromatic nucleophilic substitution action with DHPZ.Then,the effects of 2,5-furanyl on comprehensive properties of PPEKs resin were studied emphatically.Meanwhile,the feasibility of using biomass to replace petroleum-base to prepare high-performance engineering plastics were investigated.The study showed that using BFBF to replace BFBB to prepare PPEKs containing furan moiety could not only significantly reduce the melt viscosity(from 76,888 Pa·s of PPBEK to 3,888 Pa·s of PPFEK,the drop was a whopping 94%)and improved thermo-forming performances of the resin,but also keep excellent mechanical properties,solubility,thermal stability and thermal oxidation stability(Tds%>450?)and thermal resistance performance(Tg=234?).In a word,the introduction of 2,5-furanyl can effectively reduce the melt viscosity of PPEKs resin and dramatically improve its thermal processing performance.More importantly,it has proved that the development of high-performance engineering plastics based on furandicarboxylic acid is effective and feasible.