Glass Fiber-reinforced Thermoplastic Research Articles

Lessons learned from the sustainable recycling process of a wind blade made with a new thermoplastic resin

The use of thermoplastic resins instead of thermoset ones in wind turbine blade manufacturing is being investigated and validated in a global scale due to some theoretical improvements such as costs saving during production, shorter cycle’s time and a better circular recovery of the raw materials at the End of Life. The initial objective of this paper was to manufacture and test a small wind turbine blade (SWTB) glass fiber-reinforced thermoplastic (GFRT) resin composites, recycle it, and use the products obtained from the recycling process (fibers and resin) to remanufacture a new thermoplastic SWTB. But loss of fibers higher than estimated during the recycling process made to get away from the original aim of testing both blades (1st and 2nd recyclable blades). At least, some lessons learned were obtained to improve future developments. Nevertheless, this study provides an example of how to recycle a small WT blade and to remanufacture it using the same raw materials.

Influence of Plasma Treatment on Surface Characteristics of Aluminum Alloy Sheets and Bonding Performance of Glass Fiber-Reinforced Thermoplastic/Al Composites.

This study focuses on modifying the surface of an AA 5052-H32 aluminum alloy using plasma treatment. Discharge power, exposure time, and working gas were adjusted as process parameters to improve the adhesion between the aluminum alloy and glass fiber-reinforced thermoplastic (GFRTP) polycarbonate composite. The surface composition and morphology of the aluminum alloy sheet were analyzed by X-ray photoelectron spectroscopy and scanning electron microscopy, and surface roughness and wettability were evaluated using a surface roughness-measuring instrument and contact angle goniometry, respectively. The bonding performance of GFRTP/aluminum alloy was also assessed. The surface of the aluminum alloy was subjected to chemical treatment prior to plasma treatment. The results revealed that nitrogen plasma treatment led to a substantial increase (25%) in bonding strength due to the synergistic effect of rough surface mechanical bonding and chemical bonding through functional groups between the aluminum alloy and GFRTP. However, the improvement in surface wettability by plasma treatment is time dependent and may gradually diminish over time due to the re-adsorption of hydrocarbon contamination from the surrounding air.

Assessing the tensile properties of interlayer hybrid thermoset-thermoplastic composites

Though fiber reinforced thermoset composites exhibit excellent rigidity and strength while being lightweight, they suffer from low toughness and brittle failure, which is unfavorable. On the other hand, fiber reinforced thermoplastic composites are good energy absorbers, damage resistant and recyclable; however, these materials exhibits insufficient rigidity. As a solution, the interlayer hybridization of glass fiber reinforced thermoset (GTS) and glass fiber reinforced thermoplastic (GTP) composites is proposed. This study aims at investigating the tensile properties of interlayer hybrid thermoset-thermoplastic composites. In this regard, two non-hybrid and two hybrid composite samples (GTS2-GTP and GTS4-GTP) were fabricated using common fabrication techniques: hand lay-up and hot compression molding. Both hybrid composite samples were fabricated in such a manner that GTP was sandwiched between two GTS plates. Based on the tensile test results, the failure strain of GTS sample was improved due to the interlayer hybridization with GTP. Non-hybrid composite samples exhibited one load drop in their tensile stress-strain behavior, while interlayer hybrid composites showed two load drops, which resulted in toughness increment. Moreover, hybrid thermoset-thermoplastic composites outperformed non-hybrid composites in terms of post-impact tensile properties.

Fabrication and axial compression test of thermoplastic composite cylindrical sandwich structures with hierarchical honeycomb core

A hierarchical thermoplastic composite honeycomb sandwich cylindrical structure consisting of continuous glass fiber reinforced thermoplastic (GFRTP) composite skins and hierarchical honeycomb core was designed and fabricated by the means of filament winding and interlocking method. Axial compression tests were conducted to evaluate the load bearing capacity and reveal the failure modes. The results show that local buckling and face crushing were the primary failure modes for sandwich cylindrical structures. The mechanical properties including the specific energy absorption (SEA) and the ultimate loading capacity of sandwich cylindrical structure are 5.45 and 15.24 times greater than that of the hierarchical core. Besides, the hierarchical thermoplastic composite honeycomb sandwich cylindrical structures also perform better on loading-capacity efficiency when compared with structures as referenced.

Application of Glass Fiber and Carbon Fiber-Reinforced Thermoplastics in Face Guards.

Face guards (FGs) are protectors that allow for the rapid and safe return of athletes who are to play after sustaining traumatic facial injuries and orbital fractures. Current FGs require significant thickness to achieve sufficient shock absorption abilities. However, their weight and thickness render the FGs uncomfortable and reduce the field of vision of the athlete, thus hindering their performance. Therefore, thin and lightweight FGs are required. We fabricated FGs using commercial glass fiber-reinforced thermoplastic (GFRTP) and carbon fiber-reinforced thermoplastic (CFRTP) resins to achieve these requirements and investigated their shock absorption abilities through impact testing. The results showed that an FG composed of CFRTP is thinner and lighter than a conventional FG and has sufficient shock absorption ability. The fabrication method of an FG comprising CFRTP is similar to the conventional method. FGs composed of commercial FRTPs exhibit adequate shock absorption abilities and are thinner and lower in weight as compared to conventional FGs.

Process chain based data capture for a flexible and reliable life cycle inventory of a glass fiber-reinforced thermoplastic lightweight structure

In recent years, fiber-reinforced polymers (FRP) found their way into automotive serial production. This was motivated by vehicle weight reduction resulting in decreased fuel consumption in the use phase. Due to the complexity of FRP manufacturing processes, only few data for life cycle inventory (LCI) are available in databases. Furthermore, a widespread range of LCA results can be attained in dependence of the actual process parameters and part design. In order to keep up with the composite technology development, a process chain based data capturing is required taking into account deviations from the target state. This contribution therefore suggests the combination of LCI with process chain analysis. In the FOREL project FuPro, an innovative process chain for manufacturing of functionalized hollow profiles made of glass fiber-reinforced thermoplastics was developed. It comprises several steps, which cannot be evaluated using state-of-the-art databases. Hence, technologically and ecologically relevant data were captured. For this purpose, a gate-to-gate perspective was used. The process steps of plasma treatment and IR heating are selected. The presented course of action provides a resilient and flexible basis for LCA, which prospectively allows a goal-oriented multi-criteria analysis and derivation of best practice process management.

Characterization of Esthetic Orthodontic Wires Made from Glass‐Fiber‐Reinforced Thermoplastic Containing High‐Strength, Small‐Diameter Glass Fibers

In this work, we investigated the properties of a glass‐fiber‐reinforced thermoplastic (GFRTP) composed of small‐diameter (ϕ = 5 μm), high‐strength glass (T‐glass) fibers and polycarbonate for esthetic orthodontic wires formed using pultrusion. After fabricating such GFRTP round wires, the effects of varying fiber diameter (5 to 13 mm) on the mechanical properties, durabilities, and color stabilities were evaluated. The results showed that the mechanical properties of GFRTPs tend to increase with decreasing fiber diameter. Additionally, it was confirmed that the present GFRTP wires containing T‐glass fibers have better flexural properties than previously reported GFRTP wires containing E‐glass fibers. Meanwhile, thermocycling did not significantly affect the flexural properties of the GFRTP wires. Furthermore, the GFRTP wires showed color changes lower than the acceptable threshold level for color differences on immersion in coffee. From these results obtained in the present work, the GFRTP wires containing high‐strength glass fibers have excellent properties for orthodontic applications. Our findings suggest that the GFRTPs might be applied to all phases of orthodontic treatment because their properties can be tuned by changing the fiber properties such as fiber type and diameter.

Complex fibers orientation distribution evaluation in short glass fiber-reinforced thermoplastic (PA66 GF50)

The use of composites made of polyamide 6.6 matrix and short-glass-fibers in automobile industry is progressive due to its low density and cost. The injection molded short glass fiber-reinforced (SGFR) thermoplastics structural parts such as intake, manifold and engine mount housing, induce complex fiber orientation distributions (FOD). This microstructure governs the macroscopic properties such as the mechanical stiffness and fatigue resistance. To estimate the FOD on such industrial parts at complex angles and ribs, we rely on simulation results and micro tomography analysis. The interest of this paper is to develop a semi-automated, quick and efficient orientation tensor identification approach from 2D microscopic images, which is capable of observing relatively larger surface compared to micro tomography. We finally conclude by comparing it with micro tomography and simulation results. Furthermore, we investigate its relevance with fatigue service ability.

Color stability of glass-fiber-reinforced polypropylene for non-metal clasp dentures

PurposeThe purpose of this study was to investigate the color stability of a glass-fiber-reinforced thermoplastic (GFRTP), for use in non-metal clasp dentures (NMCDs). MethodsGFRTPs composed of E-glass fibers and polypropylene with 2 mass% of pigments were fabricated using injection molding. According to our previous study on the optimum fiber content for GFRTPs, we prepared GFRTPs with fiber contents of 0, 10, and 20 mass% (GF0, GF10, and GF20). Commercially available NMCD and PMMA materials were used as controls. The color changes of GFRTPs at 24h, and at 1, 2, and 4 weeks of coffee immersion at 37°C were measured by colorimetry, using the Commission Internationale de l’Eclairage (CIE) Lab system. The color stabilities of the GFRTPs were evaluated in two units: the color difference (ΔE∗) and National Bureau of Standards (NBS) units. ResultsAfter immersion, none of the GFRTPs showed visible color change. From the colorimetry measurement using the CIE Lab system, the ΔE∗ values of the GFRTPs were 0.65–2.45. The NBS values of the GFRTPs were 0.60–2.25, all lower than the threshold level of 3.0, demonstrating clinically acceptable color changes. On the other hand, an available polyamide-based NMCD material exhibited “appreciable” color change, as measured in NBS units. ConclusionsThe results indicate that the GFRTPs showed clinically acceptable color stability and might be satisfactory for clinical use. Therefore, GFRTPs are expected to become attractive materials for esthetic dentures.

Three-dimensional progressive failure modeling of glass fiber reinforced thermoplastic composites for impact simulation

In this study, a three-dimensional (3D) progressive failure material model was developed for glass fiber reinforced thermoplastic (GFRP) composites to predict the nonlinear mechanical response under impact loads. For the formulation of progressive failure, the material property degradation model (MDM) was constructed using a continuum damage mechanics (CDM) model based on the 3D Hashin failure criteria. The proposed progressive failure formulations were implemented in the user-defined material model (UMAT) in the commercial nonlinear finite element analysis (FEA) software LS-Dyna. Then, the progressive failure model was verified experimentally with flexural and impact tests. Finally, it was found that the proposed 3D progressive failure model can be used to predict not only damage progression and impact behavior, but also interlaminar delamination.

Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

Thrust Force Analysis in Drilling Glass Fiber Reinforced/Polypropylene (GFR/PP) Composites

Glass fiber reinforced thermoplastic (GFRTP) composites are an important alternate to the conventional engineering materials owing to their good application-oriented properties. Drilling is unavoidable and an important operation used in automotive and aerospace industries in the assembly stage. The reduction of thrust force is required to minimize delamination. This paper examines the parameters that influence the thrust force on drilling glass fiber reinforced polypropylene (GFR/PP). The experiments are conducted using the Box–Behnken experimental design method. An empirical relation is established for determining the thrust induced in the drilling of GFRTP. The factors that affect the drilling process and their interaction are analyzed and presented in detail.

INJECTION MOLDING OF FLAT GLASS FIBER REINFORCED THERMOPLASTICS

During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

Properties enhancement of short glass fiber-reinforced thermoplastics via sandwich injection molding

This article demonstrates using sandwich injection molding in order to improve the mechanical properties of short glass fiber-reinforced thermoplastic parts by investigating the effect of fiber orientation, phase separation, and fiber attrition compared to conventional injection molding. In the present case, the effect of short glass fiber content (varying from 0–40 wt%) within the skin and core materials were studied. The results show that the mechanical properties strongly depend not only on the fiber concentration, but also on the fiber orientation and the fiber length distribution inside the injection-molded part. Slight discrepancies in the findings can be assumed to be due to fiber breakage occurring during the mode of processing. POLYM. COMPOS., 26:823–831, 2005. © 2005 Society of Plastics Engineers

加熱小型ダイスによる高性能ＧＦＲＴＰねじの転造

A new form rolling technique to produce high performance GFRTP (glass fiber reinforced thermo plastic) thread by heating mini die is developed. GFRTP is widely used due to its superior properties, such as high strength, lightweightness, corrosion resistance and electrical insulation. Thus, the high performance GFRTP fastner is desired in various industrial fields. The form rolling is a standard technique for metal threads. It is supposed that the form rolling of GFRTP rods, in which the glass fibers are arranged along the axis of rods, makes possible for fiber to flow into threads during form rolling period, and the cost effective high performance GFRTP bolts would be available. In order to obtain precise thread shape and high strength, it is considered that the material temperature should be higher than the glass transition temperature and ultrasonic heating has been applied in form rolling process. However, sufficient thread shape could not be obtained, because the high temperature of the inner part causes total material deformation and the forming pressure becomes small. To cope with this problem, a new heating mini die is designed to apply local heating and large local form rolling pressure. It is found that the precise thread shape is achieved and the glass fibers flow into threads by the proposed heating mini die.

Ultrasonic welding and characteristics of glass-fiber reinforced plastic: comparison between the paper-making method and the impregnation method

The characteristics of glass-fiber reinforced plastic are influenced greatly by the type of matrix, the type or shape of the fiber and the method of reinforcement. For instance, the future of glass-fiber reinforced thermoplastic (GFRTP) as a practical material is noteworthy due to it's wide range of elastic deformation and its strength, which latter is as great (weight for weight) as that of metal. As GFRTP has a wide application, an effective welding method is sought, for use along with conventional mechanical fastening and bonding methods. The basic research of the author on stampable sheet has established that the ultrasonic welding method is effective for GFRTP welding [1]. This paper reports on the possibilities of ultrasonic welding, on the characteristics of the joint strength and on the workability of the welded products. A comparison has been made between two kinds of fiber-reinforced plastic, produced by different manufacturing processes [2].