Browsing by Author "Mai, YW"

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Fracture toughness characterizations of compatibilized polyamide-6 (PA6)/poly(phenylene ether) (PPE) blends
(2001-03-01)
Chiou, KC
;
Chang, FC
;
Mai, YW
;
應用化學系
;
Department of Applied Chemistry
Under the plane-strain condition. the material properties. K-IC and G(IC), of the blends, brittle or with small-scale yielding, increase with increasing elastomer content. To evaluate the critical J-integral for the ductile blends, several methods have been compared to understand the influence of elastomer content and different thicknesses using single-edge notch-bend specimens. For a given thickness, the Fracture toughness increases with increasing elastomer content. Moveover, the slope of the R-curve becomes gradually steeper with increasing elastomer content and decreasing specimen thickness. J(IC) values determined from ASTM E813-89 and modified ASTM E813-81 methods always give the highest and the lowest values, respectively. J(IC) values determined from three other methods are comparable and can be employed to characterize the fracture toughness of the compatibilized PA6/PPE blends. it is noted that J(IC) values determined from the modified ASTM E813-89 and the hysteresis energy methods are apparently independent of thickness Therefore, these two methods may be considered as potential alternative techniques to evaluate the critical J-integral for toughened polymer blends.
Impact specific essential work of fracture of compatibilized polyamide-6 (PA6)/poly(phenylene ether) (PPE) blends
(2001-06-01)
Chiou, KC
;
Chang, FC
;
Mai, YW
;
應用化學系
;
Department of Applied Chemistry
The essential work of fracture (EWF) method has aroused great interest and has been used to characterize the fracture toughness for a range of ductile metals, polymers and composites. In the plastics industry, for purposes of practical design and ranking of candidate materials, it is important to evaluate the impact essential work of fracture at high-rate testing of polymers and polymer blends. In this paper, the EWF method has been utilized to determine the high-rate specific essential fracture work, w(e) for elastomer-modified PA6/PPE/SXM (50/50/5) blends by notched Charpy tests. It is found that w(e) increases with testing temperature and elastomer content for a given specimen thickness. Morphologically, there are two failure mechanisms: shear yielding and pullout of second phase dispersed particles. Shear yielding is dominant in ductile fracture, whereas particle pullout is predominant in brittle fracture.