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Effect of short glass fibers and particulate fillers on fatigue crack propagation in polyamides
Author(s) -
Lang R. W.,
Manson J. A.,
Hertzberg R. W.
Publication year - 1982
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760221513
Subject(s) - materials science , composite material , polyamide , perpendicular , nylon 6 , glass fiber , fracture (geology) , fiber , nylon 66 , fracture mechanics , ultimate tensile strength , scanning electron microscope , polymer , geometry , mathematics
The fatigue crack propagation (FCP) behavior (at 10 Hz) of several commercial short‐glass‐fiber and mineral‐reinforced nylon composites has been investigated. The FCP rates can be described in terms of the well‐known Paris relationship. Significant improvement in FCP performance was found for the glass‐fiber‐reinforced materials in comparison to that of the pure matrix materials (nylon 66 and nylon 612). Also, the FCP resistance was found to increase with increasing fiber content and interfacial adhesion for nylon 66. Despite the fact that specimens were cut from injection‐molded plaques, no or only slight effects of orientation were observed by testing specimens with cracks growing parallel and perpendicularly, respectively, to the major flow direction. Electron microscopy studies of fracture surfaces revealed a complex pattern of fiber orientation, varying over the plaque thickness and consisting of layers with fibers oriented mainly parallel, perpendicularly, or randomly to the major flow direction; nevertheless, the specimens behaved quasi‐isotropically. Significant differences in fracture mechanism were observed, depending on the matrix, the interfacial bonding, and the crack speed. In contrast to the fiber‐rein forced nylons, the mineral‐reinforced material exhibited poorer FCP resistance than neat nylon 66, even though the former is superior in tensile and impact behavior.