Study Of Continuous Fiber Reinforced Poly (Phthalazinone Ether) Composites

Continuous fiber reinforced high performance thermoplastic composites have been extensively used in the field of aerospace, weaponry, and chemical industries because of their inherent properties such as light weight, high strength and stiffness, recyclability, repairability, corrosion resistance, radiation stability, etc. Continuous fiber reinforced high performance thermoplastic composites have attracted more and more attentions.Poly(aryl ether) containing phthalazinone moiety (PPAE) is a novel amorphous high performance thermoplastics with very high glass transition temperatures (T_g =263～305℃), outstanding high temperature stability, excellent mechanical properties and radiation stability. Moreover, PPAE shows good solubility in some organic solvents, therefore the solution processing can be adopted to prepare fiber reinforced composites. Hence, PPAE is a very ideal alternative of matrix for advanced composites potentially used in some harsh environmental conditions. In this work, composite prepregs are prepared by using solution impregnation process. Taking full advantage of the low viscosity of the polymer solution, which impregnates fiber easily, the large bundle carbon fiber (T700-12K) with lower price and E glass fiber as reinforcement are selected to produce unidirectional composites. The processing, structure and properties of continuous carbon fiber and glass fiber reinforced Poly (phthalazinone ether sulfone ketone) (PPESK) composites are investigated. In view of high melting viscosity, which makes it difficult to impregnate and consolidate well in hot-press molding process, the resin matrix is modified by different method, and the effect of properties of composites on properties of resin matrixs, fiber content, interfacial adhesion and processing are studied systematically.CF/PPESK and GF/PPESK composites are produced by solution impregnation and hot-press molding method. The effects of PPESK solution viscosity, fiber impregnation and fiber volume loading on mechanical properties of the final composites are studied systematically. The molding process is optimized by using intimate contacting model simulation, analysis of PPESK rheological property and investigation of dwell time. The results show that the resin solution with low viscosity is more suitable for fiber impregnation. The fiber volume content decreases with increasing viscosities of resin solutions. With increasing fiber volume content, the flexural strength and interlaminar shear strength of PPESK composites go to the peak and then decrease with more fiber volume content. The flexural modulus increases linearly with increasing fiber volume content. Compared with the composites of the same fiber volume content produced by power laminated method, the solution impregnation technique has a big advantage in producing continuous fiber reinforced high performance thermoplastics composites. Moreover, the moisture resistant, heat resistant and interfacial adhesion properties of PPESK composites are also investigated. The results show that CF/PPESK and GF/PPESK composites, which are compared with fiber/epoxy composites, have excellent humidity resistant properties and heat resistant properties. The flexural properties residual of CF/PPESK and GF/PPESK composites at 150℃are above 90%. The interfacial adhesion of CF/PPESK and GF/PPESK composites are not ideal. The fracture modes of composites are interface failure. Fourier transform infrared (FT-IR) spectrum of fiber surface shows that there is no chemical reaction between fiber and matrix. The composite interfacial adhesion is mainly composed of van der Waals' forces and mechanical forces.CF/PPBES and GF/PPBES composites are produced by solution impregnation and hot-press molding method. The effects of PPBES solution viscosity and fiber volume content on mechanical properties of the final composites are studied systematically. The molding process is also optimized. The resuls show that the optimal fiber cntent is 60 vol. % for CF/PPBES composite and 57 vol. % for GF/PPBES composite; the mechanical and humidity resistant properties of PPBES composites are both better than those of PPESK composites. CF/PPBES and GF/PPBES composites have excellent heat resistant properties. The flexural properties residual of CF/PPBES and GF/PPBES composites at 150℃are above 88%.The analysis of the fracture surfaces of CF/PPBES and GF/PPBES composites indicates that the interfacial adhesion of CF/PPBES and GF/PPBES composites is better than that of CF/PPESK and GF/PPESK composites. Matrix failure has been found to be the dominant fracture mode for CF/PPBES composite. For GF/PPBES composite, interfacial failure and matrix failure are observed at the same time.Polyethersulfone (PES) with lower melting viscosity and better toughness is introduced to PPESK. CF/PPESK/PES and GF/PPESK/PES composites are produced by solution impregnation and hot-press molding method. The effect of addition of PES on the resultant composites was studied. The results show that when the PES mass fraction is less than 20%, the resin matrix still has excellent heat resistance. The addition of PES significantly lowers the melting viscosity of resin matrix and substantially increases the toughness of matrix, which improves interfacial adhesion and consolidation of composites. The fracture mode of CF/PPESK/PES composites changes from interface failure to matrix failure; the fracture mode of GF/PPESK/PES composites changes from interface failure to matrix failure as the main form and both interface failure and matrix failure are in coexistence. However, the overmuch addition of PES increases the viscosity of polymer solution, which results in insufficient impregnation of fibers in solution impregnation process. Hence, the mechanical properties of CF/PPESK/PES and GF/PPESK/PES composites have the peak value with increasing PES mass fraction. After optimizing process, with 7% PES mass fraction, the flexural strength, flexural modulus and interlaminar shear strength of CF/PPESK/PES composites are 1470.9MPa, 137.4GPa and 62.8MPa, respectively; the flexural strength, flexural modulus and interlaminar shear strength of GF/PPESK/PES composites are 959.2MPa, 45.2GPa and 55.1MPa, respectively. CF/PPESK/PES and GF/PPESK/PES composites have excellent humidity resistant properties. After being exposed to boiling water for 45h, the maximum moisture content, flexural strength and modulus residual of CF/PPESK/PES composite are 0.66%, 93.4% and 93.7%, respectively; the maximum moisture content, flexural strength and modulus residual of GF/PPESK/PES composite are 0.76%, 85.3% and 88.5%, respectively. The flexural properties residual of CF/PPESK/PES and GF/PPESK/PES composites at 150℃are above 89%.Polyetherimide (PEI) with lower melting viscosity and better toughness is introduced to PPESK. CF/PPESK/PEI and GF/PPESK/PEI composites are produced by solution impregnation and hot-press molding method. The effect of addition of PEI on the final composites was studied. The results show that when the PEI mass fraction is less than 20%, the resin matrix still has excellent heat resistance. The addition of PEI has no impact on solution impregnation, significantly lowers the melting viscosity of resin matrix and substantially increases the toughness of matrix, which improves interfacial adhesion and consolidation of composites. The fracture modes of CF/PPESK/PEI and GF/PPESK/PEI composites change from interface failure to matrix failure. The mechanical properties of CF/PPESK/PEI and GF/PPESK/PEI composites increase with increasing PEI mass fraction. After optimizing process, with 20% PEI mass fraction, the flexural strength, flexural modulus and interlaminar shear strength of CF/PPESK/PEI composites are 1566.1MPa, 128.3GPa and 68.1MPa, respectively; the flexural strength, flexural modulus and interlaminar shear strength of GF/PPESK/PEI composites are 936.5MPa, 52.2GPa and 64.2MPa, respectively. CF/PPESK/PEI and GF/PPESK/PEI composites have excellent humidity resistance. After being exposed to boiling water for 45h, the maximum moisture content, flexural strength and modulus residual of CF/PPESK/PEI composite are 0.46%, 95.4% and 96.9%, respectively; the maximum moisture content, flexural strength and modulus residual of GF/PPESK/PEI composite are 0.67%, 87.5% and 92.5%, respectively. The flexural properties residual of CF/PPESK/PEI and GF/PPESK/PEI composites at 150℃are above 87%.