Preparation Of Water-based High-temperature Resistance Sizing Agent And Study On Properties Of Carbon Fiber Composites

Carbon fiber(CF)reinforced polyether ether ketone(PEEK)occupied an important position in composites due to its excellent properties.Polyether ether ketone(PEEK),a semi-crystalline thermoplastic special engineering plastic with outstanding thermostability,solvent resistance and mechanical properties,has been widely used in the field of biological medicine,rail transit,aerospace and so on.However,the high melt viscosity of PEEK leads to poor wettability,and eventually causes defects in the interphase of CF/PEEK composites.In addition,PEEK resin is difficult to interact strongly with CF due to the inert surface of CF,resulting in poor interfacial performance.It is one of the key factors that improved the comprehensive properties of CF/PEEK composites on interfacial adhesion.A series of water-based sizing agents for PEEK resin were prepared by the method of sizing to improve the interfacial properties of CF/PEEK composites.The study contents of this paper are as follows:In this work,a series of soluble phenolphthalein polyaryl-ether-ketone polymers with different carboxyl contents(PEKC-COOH)were synthesized and employed to prepare water-based sizing agents.PEKC-COOH showed high solubility and excellent thermal properties,with over 239.5?of T_g value,which were much higher than that of PEEK(148.4?).The preparation of water-based PEKC-COOH sizing agent containing different carboxyl groups was through the method of emulsion solvent evaporation.It has solved problem of enhacing CF/PEEK composites composites by using commercial epoxy sizing agent and solvent sizing agent.The sizing agents exhibit good storage stability with particle sizes between 60.6 and 75.0 nm.Compared to unsized CF/PEEK composites,the bending strength and interlaminar shear strength of the CF-5/PEEK composites were enhanced by52.9%and 53.3%,respectively.The protocol provides an effective and green method towards water-based sizing agent for enhancing the interfacial properties of CF/PEEK composites.In order to further improve the thermal stability of sizing agent,which is expected to match the 5%thermal decomposition temperature of the commercial poly ether ether ketone resin,and to restore its solvent resistance.Broadening the application range of carbon fiber/polyether ether ketone composites in harsh environment,and reaching the prospect of thermoplastic processing thermoset applications.In this work,crosslinkable polyarylether polymer(PEN-PPH)containing phenolphthalein ring and nitrile group was synthesized.A novel water-based crosslinkable polyarylether sizing agent with different concentrations were prepared by emulsion solvent evaporation method.The aim is further to ameliorate the thermal stability and build interface phase with solvent-resistant of CF/PEEK composites.The influence of sizing agent with different concentration on CF/PEEK composites was studied.The excellent heat resistance of the water-based crosslinkable PEN-PPH sizing agents with different concentrations.After crosslinking,the 5%thermal decomposition temperature of the sizing agent has reached 555.3°C and can be stored stably for at least six months.Moreover,the composites modified with PEN-PPH sizing agent performed excellent solvent resistance,with no erosion in ILSS after soaking in a variety of organic solvents.Accordingly,the interfacial enhancement mechanism was illustrated in detail.