2. Tensile Modulus Tensile modulus of CF can mainly be determined by carbonization/graphitization temperature (Fig. 2-1). Also, the nature of precursors (PAN, rayon, pitch) affects on the easiness of reaching a certain level modulus. Fig. 2-1 Modulus vs. Temperature 'TORAYCA' modulus covers 230 GPa - 650 GPa with various kinds of strength (Fig. 2-2). In laboratory, even higher modulus fiber can be obtained. Presicely speaking, stress-strain curve (such as Fig. 1-1) is not linear, and modulus tends to increase as strain becomes larger (strain stiffening effect). Fig. 2-2  Torayca fiber propertie