Carbon Fiber Reinforced Polyimide Composites Research Articles

Short Carbon Fiber-Reinforced PMR Polyimide Composites with Improved Thermo-oxidative and Hygrothermal Stabilities

A series of short carbon fiber-reinforced polyimide composites (SCF/PI) with different SCF loadings was prepared by thermal curing of B-staged molding powders, which were obtained by impregnating short carbon fibers with PMR monomer solution in ethyl alcohol, followed by thermally baking up to 220°C. The B-staged molding powders possess good melt-flowing characteristics and processing properties. Experimental results demonstrated that the fully-cured SCF/PI composites exhibited high thermal stability with the glass transition temperatures determined by dynamic mechanical analysis (DMA) of 412-432°C and the decomposition temperatures at 5% of weight loss in the range 497-512°C. The SCF/PI composites also had good mechanical properties, which were affected by the SCF loading. The tensile strength and the flexural strength of SCF/PI composites increased as the SCF loadings increased and then decreased gradually. SCF-20/PI has the highest tensile strength of 101 MPa and SCF-10/PI gave the highest flexural strength of 154 MPa. The SCF/PI composites exhibited a great improvement in impact toughness in comparison with PMR-15. Despite the impact strength of SCF/PI being slightly decreased as the SCF loading was increased, it was still within the range of 15-23 J cm~2.Furthermore, SCF/PI composites exhibited excellent thermal-oxidative and hygrothermal stabilities. The SCF/PI composites showed a weight loss of less than 6% after isothermal aging for 500 h at 320°Cinair. There was no significant difference in thermogravimetric analysis (TGA) and DMA curves for SCF-20/PI after hygrothermal treatment at 120°C under 2 atm for 50 h

Effect of degree of cure and fiber content on the mechanical and dynamic mechanical properties of carbon fiber reinforced PMR‐15 polyimide composites

AbstractA unidirectional continuous carbon fiber reinforced polyimide composite is fabricated using the PMR‐15 polyimide as a matrix. Mechanical and dynamic mechanical properties of the composite are studied. The effect of variation of the fiber content ranging from 55% to 70% by volume on the properties of the composite is determined. The effects of the laminate thickness and degree of curing of the matrix on the Izod impact strength are examined. The effect of the degree of curing of the matrix on the dynamic mechanical spectrum is studied. Finally, variables such as humidity, environment temperature, vacuum, and pressure during laminate processing, and variation of monomer composition are discussed in terms of change in matrix structure, which is reflected in a variation of Tg between batches.