Abstract:In the current study, the model, previously developed by Wilson, was reviewed and extended to predict the mechanically induced spreading of E-glass fiber bundles. The widths of the as-received E-glass fiber bundles were increased by 200–250% when subjected to a series of reciprocating motions. A 350–450% increase in the widths of the bundles was observed when the tension was released (tension-release mechanism) and the reciprocating motions repeated. The effect of the number of rods, angles and distances betwe… Show more
“…The static bars could be adjusted both vertically and horizontally, with eyelets at the front enabling multiple tows to be processed simultaneously. Tow spreading has been used in the literature 15,16 to reduce fibre crimp, but was used here to reduce the melt flow distance of the polymer to enable more intimate contact between the fibres and matrix during consolidation. 17 Figure 1.(a) Spreading section of the tow coating rig consisting of a number of static bars to increase tension and spread the fibre bundles.…”
A processing route is presented to manufacture discontinuous carbon fibre reinforced polypropylene (CF.PP) composites, using much longer fibre lengths (25mm) and higher volume fractions (up to 45%) than previously reported in the literature. Carbon fibre tows are coated with different ratios of polypropylene, blended with a maleic anhydride coupling agent, to investigate the influence of the interfacial shear strength at the microscale on the macroscale composite properties. Improvements in the tensile performance at the macroscale (70% increase) are not as high as those reported for the interfacial shear strength at the microscale (300%), following the addition of the coupling agent.Consequently, the tensile strength of the CF.PP material is only 45% of values reported for carbon fibre/epoxy systems, however, the tensile stiffness is comparable. This demonstrates the potential for using CF.PP for structural applications, following further process optimisation to overcome the current high levels of porosity (3.3% at 0.45Vf) to improve the tensile strength.
“…The static bars could be adjusted both vertically and horizontally, with eyelets at the front enabling multiple tows to be processed simultaneously. Tow spreading has been used in the literature 15,16 to reduce fibre crimp, but was used here to reduce the melt flow distance of the polymer to enable more intimate contact between the fibres and matrix during consolidation. 17 Figure 1.(a) Spreading section of the tow coating rig consisting of a number of static bars to increase tension and spread the fibre bundles.…”
A processing route is presented to manufacture discontinuous carbon fibre reinforced polypropylene (CF.PP) composites, using much longer fibre lengths (25mm) and higher volume fractions (up to 45%) than previously reported in the literature. Carbon fibre tows are coated with different ratios of polypropylene, blended with a maleic anhydride coupling agent, to investigate the influence of the interfacial shear strength at the microscale on the macroscale composite properties. Improvements in the tensile performance at the macroscale (70% increase) are not as high as those reported for the interfacial shear strength at the microscale (300%), following the addition of the coupling agent.Consequently, the tensile strength of the CF.PP material is only 45% of values reported for carbon fibre/epoxy systems, however, the tensile stiffness is comparable. This demonstrates the potential for using CF.PP for structural applications, following further process optimisation to overcome the current high levels of porosity (3.3% at 0.45Vf) to improve the tensile strength.
“…[8][9][10][11] A different set of modifications, referred to as 'clean filament winding', have also been reported in detail. [12][13][14][15][16][17] The reduction of waste (resin, solvent) and fewer emissions to the atmosphere are emphasized in these works. The resin bath is replaced with a combination of a resin impregnation unit and spreading stations for tow bundles.…”
Fibre-reinforced polymer composites are increasingly used to make pipes and pressure vessels. The relationship between wet-winding manufacturing, composite microstructure, and the mechanical performance is complex due to many process parameters and material properties involved. Efficient manufacturing aspirations however drive process innovations that include new, radically different tow impregnation methods. In this work, the process–property–performance relationship is experimentally construed for hoop-wound carbon fibre/epoxy composite cylinders. The difference between cylinders produced by a new tow impregnation system and cylinders from the reference impregnation system was investigated. Winding speed and cylinder wall thickness were considered as two additional variables. The results indicate that, within current scope, composite microstructure is relatively insensitive to the winding speed and to final cylinder thickness. Meanwhile, un-optimized changes for tow impregnation affect the void content, the size distribution of voids and the interlaminar failure mode in short beam shear.
“…The primary function of the fibre spreading unit is to initiate partial de-cohesion of the binder and to enable the lateral spreading of the filaments with a concomitant decrease in the thickness. 1,2 The details of this unit were presented previously. 32 The array of fibres are directed under the resin impregnation unit-(b) where the partially spread fibres are impregnated at the resin delivery head-(c).…”
Section: Description Of the Modified Low-pressure Impregnation Pultrumentioning
confidence: 99%
“…The term “fibre spreading” is used here in the context of spreading the filaments in a bundle prior to impregnation. 1 Fibre spreading results in a decrease in the thickness of the bundle with a concomitant increase in the width. 2 This enhances the through-thickness impregnation rate.…”
The focus of the current research was to demonstrate a modified pultrusion technique at an industrial site using a commercial production machine. In this instance, the conventional resin bath was replaced by a custom-designed compact impregnation unit. The dimensions of the impregnator were 310 mm × 400 mm × 9 mm. The relatively short length of the impregnator, when compared to a 5 litre resin bath, meant that it had to be efficient in impregnating the reinforcing fibre bundles. This was achieved using a fibre spreading unit and a facility to inject the resin under low-pressure. The design basis for the fibre spreading unit and the impregnator are presented along with the methodology that was used to select the pultrusion speed and die temperature. The pultrusion experiments were performed using filled and unfilled vinyl ester resin and E-glass fibres. The profile of the 0.5 metre-long die was rectangular with dimensions of 32 mm × 2.2 mm. The fibre spreading unit and the impregnator were retrofitted to the pultrusion line with ease. The physical, mechanical and thermo-mechanical properties were determined for the pultruded composites using the resin bath and the modified technique. The properties of the latter were found to be equivalent or marginally superior when compared to the resin bath-based production method. However, in the modified pultrusion technique, when compared to conventional resin bath-based pultrusion, the volume of waste resin generated was 97% lower. The volume of solvent required to clean the equipment after production was reduced by 90%.
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