The influence of fibre length and concentration on the properties of glass fibre reinforced polypropylene. 6. The properties of injection moulded long fibre PP at high fibre content

Abstract

The results of an investigation of the mechanical performance of injection moulded long glass fibre reinforced polypropylene with a glass fibre content in the range 0-73 weight % are presented. The composite modulus exhibited a linear dependence on fibre content over the full range of the study. Composite strength and impact resistance exhibited a maximum in performance in the 40-50 weight % reinforcement content range. The residual fibre length and fibre orientation in the samples has also been characterised. These parameters were also found to be fibre concentration dependent. Modeling of the composite strength using the measured fibre length and orientation data did enable a maximum in strength to be predicted. However, the position and absolute level of the predicted maximum did not correlate well with the experimental data. Further analysis indicated that deeper investigation of the dependence of the interfacial shear strength and fibre stress at composite failure on the fibre content are required to fully elucidate these results.

Injection moulding of long glass fibre reinforced poly(ethylene terephtalate): Influence of carbon black and nucleating agents on impact properties

“…The impact strength increases almost linearly with the fibre weight content and reaches an asymptote (plateau) when fibres are longer than 6 mm. More recently, the same author reported that the notched impact strength is the highest when fibre contents are in the range 40-50 wt%, whereas the maximum of the unnotched impact strength appears at a fibre content of about 30 wt% only [8]. The impact strength quickly drops above these limits.…”

“…The impact strength quickly drops above these limits. Moreover, as for the tensile or flexural strengths [5,8,10,14,15] different authors evidenced that the residual fibre length and the fibre orientations influence the impact strength [8,21]. In the case of PP reinforced with 50 wt% glass fibres having initial fibre length of 10 mm (reduced to 1.8-2.0 mm after injection moulding), Skourlis et al [22] furthermore highlighted the influence of the thickness of the skin and core layers of the part, induced by the shear and fountain flows during processing.…”

Prediction of Young’s Modulus for Injection Molded Long Fiber Reinforced Thermoplastics

“…During the compounding process, filamentization of fiber bundles and fracture of the resultant monofilaments into elements of a lower aspect ratio lead to the dispersion of fibers into the polymer matrix [12]. For high content fiber composites, the presence of fiber bundles seems to be unavoidable which could result in a reinforcement with a much lower aspect ratio and effective stiffness than well-dispersed fibers, consequently giving a lower and even decreasing stiffness [13]. However, the existing stiffness models assume the fibers are fully and evenly dispersed in the matrix.…”

A microstructural approach for modelling flexural properties of long glass fibre reinforced polyamide6.6

“…The Thomason's works on the LGF reinforced polypropylene can support this hypothesis in this way on reflection, at least in the range of 10 to 40 wt% fibre content. 24 On this base, an empirical model of six parameters (15 conditions Table 1) can be elaborated (equation 3). In that case the material structure (residual fibre length, fibre orientation, crystallinity degree .…”