Preparation And Properties Of Unidirectional Poly(Phthalazinone Ether) Composite Laminates

The continuous fiber reinforced thermoplastic composites possess higher impact resistance than traditional thermosetting composites, especially followed by recycling and low-cost with the easy designability, so that they have attracted more and more attention in high-tech fields in recent years, expecially in aerospace, national defense and so on. Poly(aryl ether)s containing phthalazinone moities developed by our group are a series of high performance thermoplastics. These resins not only have excellent mechanical properties and high temperature properties (Tg=250-310℃), but also can be soluble in some organic solvents. Their solubility provides many choices for the process of the material. So the novel poly(phthalazinone ether)s are the ideal candidate for the composites matrix.In the study, three thermoplastics of poly(phthalazinone ether sulfone ketone)s (PPESK), copoly(phthalazinone ether sulfone)s (PPBES), poly(phthalazinone ether nitrile ketone)s (PPENK) were choosed as the matrix, and the continuous carbon fiber was choosed as the reinforced material. The method of solution impregnation and compression molding were adopted to prepare the unidirectional composites. The solution impregnation processing was investigated owing to its effect on the properties of the resulting composites. The research shows that the decrease in the concentration of the polymer solution can lead to the increase in the fiber volume content of the compound sites. With the increase of the fiber volume content, the flexural strength and the short-beam interlaminar shear strength of the composites increase firstly and then go down. The best fiber volume content of CF/PPESK, CF/PPBES and CF/PPENK are55%,63%,68%, respectively. For the compression molding processing, the mechanical properties of the composites are influenced by the molding temperature, the molding pressure and the dwell time, respectively. The results show all of the flexural strength and modulus and the short-beam interlaminar shear strength of the three composites increase firstly and then decrease or increase firstly and then keep constant with the increase of the molding temperature, the molding pressure and the dwell time, respectively. CF/PPESK composites can acquire the best mechanical properties with the molding temperature being350℃, the molding pressure being8MPa and the dwell time being20min; for CF/PPBES composites, the molding temperature being350℃,molding pressure being4MPa and the dwell time being20min are the optimum processing condition; CF/PPENK composites should be processed at harder condition with the molding temperature being38O℃, molding pressure being8MPa and the dwell time being60min. All of the three composites have excellent high temperature properties and good wet-hot resistance. The flexural strength retention rates of the CF/PPESK and CF/PPBES are73%and75%at200℃, respectively and the retention rate of the CF/PPENK is55%up to250℃. The saturated water absorptivity of the composites are0.4%,0.3%and0.5%respectively. The flexural strength retention rates of the CF/PPESK and CF/PPBES under humidity are64%and60%at200℃, respectively and the retention rate of the CF/PPENK under humidity is43%at250℃. The SEM reveals that the fracture mode of the composites is the debonding failure between the fiber and the resin. FT-IR shows that there are no chemical characteristic groups on the surface of the fiber. All evidences imply that the main combination pattern between the fiber and the resin are mechanical interlocking and Van der Waals Bonding.