A phenomenological study of the mechanical properties of long‐fiber filled injection‐molded thermoplastic composites

Abstract

Tensile and flexural tests on specimens cut from rectangular injection‐molded plaques show that long‐fiber filled thermoplastic composites are complex, non‐homogeneous, anistropic material systems. Like all fiber‐filled materials, they exhibit through‐thickness nonhomogeneity as indicated by differences between tensile and flexural properties. The in‐plane orientation of fibers in through‐thickness layers causes the material to have in‐plane anisotropic properties. However, these long‐fiber filled materials exhibit an unexpectedly large level of in‐plane nonhomogeneity. Also, the effective mechanical properties of these materials are strongly thickness dependent. The thinnest plaques exhibit the largest differences between the flow and cross‐flow tensile properties. These differences decrease with increasing thickness. A methodology for part design with this class of materials is discussed.

Polypropylene hybrid composites reinforced with long glass fibres and particulate filler

“…However, long glass fibres (LGF) are used more and more often as a reinforcement, since it is known that longer fibres with the same fibre diameter (i.e. with higher fibre aspect ratio) provide higher stiffness, tensile strength and toughness compared to shorter ones [3][4][5][6].…”

Injection moulding of long glass fibre reinforced polyamide 6-6: guidelines to improve flexural properties

“…existence of a fountain flow) [5], the core layer is thicker when the fibre length increases [6,7,12]. In addition, other studies have shown that whatever is the reinforcement length (short or long) the skin layers thickness remains roughly the same whereas the core layer thickness increases when the cavity thickness is higher [13,14]. This typical multi-layered structure also greatly influences the mechanical performances of the manufactured parts [10].…”

Injection moulding of long glass fiber reinforced polyamide 66: Processing conditions/microstructure/flexural properties relationship

“…produce flow perturbations and weld lines and act on the material anisotropy and heterogeneity. 6,13,27 Mechanical properties increase requires both the control of the fiber reinforcement orientation and the improvement of its efficiency (increase of fiber/matrix interface quality and fiber aspect ratio). 25,28−31 The strength of composite materials based on discontinuous fibers depends on both the interfacial shear strength and the matrix strength.…”