Fibre Length Reduction in Natural Fibre-Reinforced Polymers during Compounding and Injection Moulding—Experiments Versus Numerical Prediction of Fibre Breakage

Abstract

Abstract:To establish injection-moulded, natural fibre-reinforced polymers in the automotive industry, numerical simulations are important. To include the breakage behaviour of natural fibres in simulations, a profound understanding is necessary. In this study, the length and width reduction of flax and sisal fibre bundles were analysed experimentally during compounding and injection moulding. Further an optical analysis of the fibre breakage behaviour was performed via scanning electron microscopy and during fibre tensile testing with an ultra-high-speed camera. The fibre breakage of flax and sisal during injection moulding was modelled using a micromechanical model. The experimental and simulative results consistently show that during injection moulding the fibre length is not reduced further; the fibre length was already significantly reduced during compounding. For the mechanical properties of a fibre-reinforced composite it is important to overachieve the critical fibre length in the injection moulded component. The micromechanical model could be used to predict the necessary fibre length in the granules.

The Modelling of Extrusion Processes for Polymers—A Review

“…Different process factors such as screw geometry and speed, fiber dimensions, feed rate, barrel temperature, and polymer viscosity affect fiber breakage in the screws. Some studies [ 71 , 72 , 73 ] have tried to model the fiber damages in screws but modelling was also found to be challenging. For example, Berzin et al [ 73 ] pointed out that it is important to merge modelling software and evolution laws for fiber dimensions.…”

Flexural Properties of Unidirectional Enset Fiber Reinforced Epoxy Composite for Automotive Interior Application

“…For density measurement, the fibers were cut to a length of 1cm and vacuum dried for 24hr at 60 LC [18]. The mass of these fibers, to determine the density, is measured using sensitive balance with accuracy to 10 -5 g. The measured density was 1.4 ± 0.03 g/cm 3 . The fibers were dried for 24hr at 60 LC and subsequently conditioned at 50% relative humidity (RH) and 21 LC for 24 hr.…”

“…Based on their response to different loading, different fibers have been used for different application. As a result, Fiber-reinforced composite materials want to be used in a large number of applications ranging from aerospace systems to automotive, industrial, and consumer products [3]. So far a good number of automotive components previously made with glass fiber composites are now being manufactured using environmentally friendly composites made up of bio-composites [20,21].…”

Editorial for the Special Issue on Discontinuous Fiber Composites

“…Thermoplastics, such as polyamide (PA) or polypropylene (PP), represent most matrix materials used for thermoplastic fiber reinforced parts due to their superior properties compared to other plastics. Glass fibers are frequently used for reinforcement due to their availability, low cost and high strength, although carbon fibers are also being implemented [3], as well as natural [4] and basalt [5] fibers. Discontinuous fiber-reinforced composites can be further classified as short fiber-reinforced thermoplastics (SFT) and long fiber-reinforced thermoplastics (LFT).…”

“…The processing of discontinuous fiber-reinforced composites, such as mold filling in injection molding, or flow through the nozzle during fused filament fabrication, has a profound impact on the arrangement of the fibers within the finished part. As fiber filled polymers are shaped into the final part geometry, the fibers are not only oriented [2,3,[7][8][9][10][11], but they are also broken down [4] and agglomerated [12], resulting in highly anisotropic products. While the anisotropy can be beneficial, when the fibers are aligned in the direction of highest stresses, most design processes of discontinuous fiber-reinforced composites parts do not consider all aspects of the process-microstructure-property relationship.…”