Comparison of the Processing of Epoxy Resins in Pultrusion with Open Bath Impregnation and Closed-Injection Pultrusion

Strauß, Sebastian; Senz, Andreas; Ellinger, Jessica

doi:10.3390/jcs3030087

Cited by 12 publications

(11 citation statements)

References 10 publications

(11 reference statements)

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“…To evaluate the suitability of the vinyl ester resin for the pultrusion process when modified with COOH functionalized MWCNTs, viscosity tests of neat vinyl ester resin and MWCNTs-dispersed vinyl ester nanocomposite were conducted. This is because the viscosity of the resin is one of the most critical parameters in the pultrusion process [ 29 ]. Four contents of MWCNTs were examined: 0.0% (neat), 0.5 wt.%, 1.0 wt.%, and 2.0 wt.%.…”

Section: Pre-pultrusion Preparation and Analysis Methodsmentioning

confidence: 99%

“…The pultrusion process used in this study incorporates four principal steps, which are (1) provision of fiberglass roving and preforming, (2) open bath impregnation, (3) curing process in die, and (4) take-off unit [ 29 ]. The pultrusion process was performed using a speed-controlled gear motor running at a constant pull speed of 3.0 mm/s.…”

Section: Pultrusion Processmentioning

confidence: 99%

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Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester

et al. 2020

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Glass fiber-reinforced polymer (GFRP) reinforcing bars have relatively low shear strength, which limits their possible use in civil infrastructure applications with high shear demand, such as concrete reinforcing dowels. We suggest that the horizontal shear strength of GFRP bars can be significantly improved by nanomodification of the vinyl ester resin prior to pultrusion. The optimal content of functionalized multiwalled carbon nanotubes (MWCNTs) well dispersed into the vinyl ester resin was determined using viscosity measurements and scanning electron micrographs. Longitudinal tension and short beam shear tests were conducted to determine the horizontal shear strength of the nanomodified GFRP reinforcing bars. While the tensile strength of the GFRP reinforcing bars was improved by 20%, the horizontal shear strength of the bars was improved by 111% compared with the shear strength of neat GFRP bars pultruded using the same settings. Of special interest is the absence of the typical broom failure observed in GFRP when MWCNTs were used. Differential scanning calorimetry measurements and fiber volume fraction confirmed the quality of the new pultruded GFRP bars. Fourier-transform infrared (FTIR) measurements demonstrated the formation of carboxyl stretching in nanomodified GFRP bars, indicating the formation of a new chemical bond. The new pultrusion process using nanomodified vinyl ester enables expanding the use of GFRP reinforcing bars in civil infrastructure applications.

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Section: Pre-pultrusion Preparation and Analysis Methodsmentioning

confidence: 99%

Section: Pultrusion Processmentioning

confidence: 99%

Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester

et al. 2020

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“…Next to LCM processes where the flow lengths can reach up to meters, capillary effects manifest themselves also in continuous composite manufacturing. For instance, resin bath impregnation pultrusion (Strauß et al, 2019;Vedernikov et al, 2020) is a common technique for manufacturing fiber reinforced profiles of varying cross-sectional complexity. Irfan et al (Irfan et al, 2017 modified the resin bath where the rovings are impregnated before entering the mold where they are shaped into the final cross-sectional profile.…”

Section: Capillary Effects In Continuous Composite Manufacturingmentioning

confidence: 99%

Capillary Effects in Fiber Reinforced Polymer Composite Processing: A Review

et al. 2022

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Capillarity plays a crucial role in many natural and engineered systems, ranging from nutrient delivery in plants to functional textiles for wear comfort or thermal heat pipes for heat dissipation. Unlike nano- or microfluidic systems with well-defined pore network geometries and well-understood capillary flow, fiber textiles or preforms used in composite structures exhibit highly anisotropic pore networks that span from micron scale pores between fibers to millimeter scale pores between fiber yarns that are woven or stitched into a textile preform. Owing to the nature of the composite manufacturing processes, capillary action taking place in the complex network is usually coupled with hydrodynamics as well as the (chemo) rheology of the polymer matrices; these phenomena are known to play a crucial role in producing high quality composites. Despite its importance, the role of capillary effects in composite processing largely remained overlooked. Their magnitude is indeed rather low as compared to hydrodynamic effects, and it is difficult to characterize them due to a lack of adequate monitoring techniques to capture the time and spatial scale on which the capillary effects take place. There is a renewed interest in this topic, due to a combination of increasing demand for high performance composites and recent advances in experimental techniques as well as numerical modeling methods. The present review covers the developments in the identification, measurement and exploitation of capillary effects in composite manufacturing. A special focus is placed on Liquid Composite Molding processes, where a dry stack is impregnated with a low viscosity thermoset resin mainly via in-plane flow, thus exacerbating the capillary effects within the anisotropic pore network of the reinforcements. Experimental techniques to investigate the capillary effects and their evolution from post-mortem analyses to in-situ/rapid techniques compatible with both translucent and non-translucent reinforcements are reviewed. Approaches to control and enhance the capillary effects for improving composite quality are then introduced. This is complemented by a survey of numerical techniques to incorporate capillary effects in process simulation, material characterization and by the remaining challenges in the study of capillary effects in composite manufacturing.

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“…Closed-injection impregnation was an efficient impregnation strategy in recent years. Once launched, it was favored by many pultrusion manufacturers and was used in the pultrusion of epoxy-based, polyurethane-based composites [9,10]. With closed-injection impregnation technology, high-speed pultrusion can be achieved by optimizing the pulling speed, injection pressure, and structural parameters of the impregnation box, and the maximum production speed can reach 3 m/min by KraussMaffei's iPul technology at K2019 exhibition [11].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Impregnation Process of Reactive Injection Pultrusion for Glass Fiber/PA6 Composites

Ding

Yang

et al. 2022

Polymers

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Pultrusion of thermoplastic composites has been the hotspot of manufacturing high-performance thermoplastic composites in recent years. The optimization of process parameters in the pultrusion usually needed repeated attempts, which wasted lots of manpower and material resources. A numerical simulation method can accelerate the optimization of process parameters. In this work, the impregnation process of reactive injection pultrusion for glass fiber reinforced nylon 6 (GF/PA6) composites was modeled and numerically simulated by a finite element/controlled volume (Fe/CV) method. Based on Darcy’s law, the impregnation process can be regarded as the two-phase flow (liquid resin and air) in porous media (undirectional glass fibers). The distribution of resin flow during the impregnation was explored. The effects of pulling rate and injection pressure on the impregnation time and resin reflux distance were analyzed, and the appropriate range of relevant process parameters was determined. The results showed that increasing the pulling rate can significantly control the reflux distance of resin in the impregnation mold and shorten the impregnation time, but too high a pulling rate would increase the impregnation time. Increasing the injection pressure can greatly shorten the resin impregnation time, but it would significantly increase the resin reflux distance. This work can effectively guide the subsequent optimization of process parameters of reactive injection pultrusion for GF/PA6 composites.

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Comparison of the Processing of Epoxy Resins in Pultrusion with Open Bath Impregnation and Closed-Injection Pultrusion

Cited by 12 publications

References 10 publications

Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester

Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester

Capillary Effects in Fiber Reinforced Polymer Composite Processing: A Review

Numerical Simulation of Impregnation Process of Reactive Injection Pultrusion for Glass Fiber/PA6 Composites

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