Short Glass Fiber Research Articles

Study on Recycling of Waste Glass Fiber Reinforced Polypropylene Composites: Examination of Mechanical and Thermal Properties

This study presents the preparation of short glass fiber reinforced polypropylene (PP/FG) composites using with waste (post-consumer) polypropylene composite containing long glass fiber (PP/LFG) obtained from the recycling of battery covers of trucks. Waste PP/LFG composite parts were mechanically grinded before adding to PP/FG composites. An injection molding machine was used to produce the PP/FG composite test samples loading with recycled waste PP/LFG composite in the range of 1-20% by weight. Effects of recycled waste PP/LFG content on the mechanical, thermal, and morphological properties of the PP/FG composites were investigated. The following three different tests, at various waste PP/LFG ratios, were conducted: Izod/Charpy Impact test, bending test, and tensile test. Mechanical test results showed that mechanical strength of prepared PP/FG composites were not influenced by content of waste PP/LFG material up to 10 wt.%. Differential scanning calorimetry (DSC) was used for the evaluation of thermal parameters such as melting point and crystallization temperature of the polymer matrix in the composites studied. Furthermore, by analyzing the values of thermal effects determined using the DSC method, it was possible to determine the degree of crystallinity. The DSC results showed that crystallinity %, melting, and crystallization temperatures of PP/FG composites were not influenced to adding waste PP/LFG at different ratios. The morphology of composite materials was investigated by SEM analysis. Good fiber dispersion was observed in the PP matrix for PP/FG composites containing short glass fiber prepared with all ratios of recycled waste PP/LFG material containing long glass fiber.

Effect of the Interface/Interphase on the Water Ingress Properties of Joints with PBT-GF30 and Aluminum Substrates Using Silicone Adhesive

The aim of this work is to analyze the difference between silicone/composite and silicone/metal interphases, both in terms of water diffusion behavior and failure of the aged joints. For that, silicone joints with two different suhbstrates were prepared. The substrates were polybutylene terephthalate with 30% of short glass fiber (PBT-GF30) and 6082-T6 aluminum. It is assumed that the water uptake of the joints is equal to the water uptake of the substrate, adhesive, and interphase. Therefore, knowing the first three, the last could be isolated. To study the water diffusion behavior of the complete joint, rectangular joints were prepared, immersed in water and their water uptake was measured. The water immersion was conducted at 70 °C. It was concluded that the aluminum/silicone joints absorbed more water through the interphase region than the PBT-GF30/silicone joints, since the difference between the expected water uptake and the experimentally measured mass gain is significantly higher, causing adhesive failure of the joint. The same was not observed in the PBT-GF30/silicone, with a more stable interphase, that does not absorb measurable quantities of water and always exhibits cohesive failure.

Investigation of the effect of using geogrid, short glass, and steel fiber on the flexural failure of concrete beams

This research studies the flexural behavior of concrete beams reinforced with biaxial geogrids, distributed short glass and steel fibers. No longitudinal steel reinforcement bars were used. Therefore, an amount of short glass and steel fibers was used to improve the concrete beam behavior against flexural failure. Eleven specimens of single reinforced (flexural reinforcement) concrete beams and double reinforced (compression and flexural reinforced) concrete beams using two biaxial geogrids sheet layers, with randomly distributed short glass and steel fibers were cast. The samples were tested using two points of load along the beam specimen span with an increment of loading by 5 KN to evaluate several parameters. The studied parameters are using geogrids as a main flexural reinforcement, using geogrid sheet layers as a flexural and compression reinforcement, using short glass and steel fibers as an additional reinforcement of concrete with various ratios 0.25 %, and 0.75 %. The test results indicated that the use of geogrid layers as the main flexural reinforcement improved the behavior of the concrete beam specimens at failure. As well as; more enhancement of beam specimens at failure was observed when using short glass and steel fibers with geogrid reinforcement in concrete beams. The tested beam specimens which were reinforced by geogrids in the flexural and compression zone using 0.75 % of steel fibers gave better results due to modes of failure, toughness, failure load capacity, crack width, and post cracking stiffness.

Effect of adhesive modification and surface treatment of laminates on the single lap bonding joint properties of carbon fibre composites

ABSTRACT In this study, the effects of adhesive modification, surface treatment of laminates, and their combined effects on the bonding properties of adhesive joints were studied using tensile shear tests, SEM micro-morphology characterisation, EDS energy spectra, analysis of the load-displacement curve, failure mode, and element content on the bonding surface. The test group corresponding to surface treatment of the laminate exhibited the best tensile shear performance. Surface treatment by 20% NaOH increased the tensile shear strength and failure displacement by 30.41% and 106.72%, respectively, compared to that obtained with only surface polishing using 320# sandpaper. In the adhesive modification test group, the tensile shear strength of the joint was the largest with an adhesive modification by 3 wt.% short glass fibres, while the tensile shear strength and failure displacement increased by 7.96% (18.63 MPa) and 10.2%, respectively, compared with those without adhesive modification. To further improve the wettability and interfacial bonding strength between the glass fibre and adhesive, a 3 wt.% short glass fibre was pretreated with KH-550 silane coupling agent. The tensile shear strength of the joint improved to 19.06 MPa, and the maximum failure displacement was 1.59 mm, which were 2.31% and 2.58% higher than those without KH-550 silane coupling agent pretreatment on the glass fibre, respectively. Furthermore, adhesive modification by KH-550 treated 3 wt.% short glass fibre was underwent combining with laminate surface treatment with 20% NaOH. The bonding strength was higher than that obtained using 3 wt.% GF adhesive modification pretreated with KH-550, while lower by 10.49% compared with that corresponding to the surface treatment of the laminate by 20% NaOH. This was primarily attributed to the pores produced by the hydrolysis reaction between NaOH and the KH-550 silane coupling agent, which weakened the load-bearing capacity of the joint.

Design and Fabrication of an In Situ Short-Fiber Doser for Fused Filament Fabrication 3D Printer: A Novel Method to Manufacture Fiber–Polymer Composite

Fused filament fabrication (FFF) 3D-printed parts are mostly used as prototypes instead of functional parts because they have a weaker mechanical strength compared to their injection molded counterparts. Various methods including a fiber-reinforced polymer composite were proposed to enhance the properties of FFF 3D-printed parts. A new concept to fabricate a polymer composite via FFF 3D printing is proposed, where fiber is deposited during printing, instead of using a premixed composite filament. In order to investigate the workability of this concept, a new device is needed. Firstly, the design requirements were identified, and a fiber doser that can be mounted on a commercial 3D printer was designed. Prototype testing was conducted to improve the design. The improved fiber doser was able to deposit varied fiber contents during FFF 3D printing. Thermogravimetric analysis (TGA) was used to quantify the fiber contents of the fabricated composites. With this newly designed doser, short glass fiber–polylactic acid (PLA) composites with three different fiber contents (1.02 wt.%, 2.39 wt.%, and 4.98 wt.%) were successfully manufactured. A new technique to manufacture a polymer composite is proven; nevertheless, the mechanical and tribological properties of the newly fabricated composites are under investigation and will be reported in a subsequent article.

Compressive and flexural behavior of glass fiber-reinforced concrete

Utilizing fibre-reinforced concrete is still a difficulty for present engineers. Generally, it is acknowledged that the mechanical, cracking and fracture qualities of fibre-reinforced concrete are much better than those of conventional concrete. The addition of fibres to the concrete matrix mitigates its fragility. Typically, short fibres are utilised in concrete to prevent cracks caused by drying and autogenous shrinkage. Currently, there is a substantial increase in the use of short alkali-resistant glass fibres. This experiment was conducted to examine the influence of glass fibre reinforcement on the compressive and flexural behaviour of concrete. This research investigates the characteristics of glass fibres reinforced concrete (GFRC) after 7 and 28 days of curing, such that GFRC may be employed in construction. Concrete containing short alkali-resistant glass fibres of 36 mm in length and 1% volume fraction (VF) was developed for this purpose. The testing findings revealed that the average compressive strength of GFRC after 28 days of curing was 72.06 MPa. The flexural properties of GFRC are determined, and the 7-day and 28-day average bending strengths of GFRC concrete samples are 6.46 MPa and 7.94 MPa, respectively, indicating that GFRC responds well under loading conditions.

Investigation of Orientation Angle of Short Glass Fiber in Polyethylene Pipe Using X-ray CT

Investigation of Orientation Angle of Short Glass Fiber in Polyethylene Pipe Using X-ray CT

Development and Characterization of Short Glass Fiber Reinforced-Waste Plastic Composite Filaments for 3d Printing Applications

Development and Characterization of Short Glass Fiber Reinforced-Waste Plastic Composite Filaments for 3d Printing Applications

Identification of hybridization strategies for combining fused filament fabrication with unidirectional tape reinforcement

Additive manufacturing processes such as fused filament fabrication (FFF) enable highly individualized production with thermoplastics, can thus produce load-path-optimized components and therefore lightweight structures. Since the mechanical properties of FFF are lower than those of traditional processes, discontinuous and continuous fibers are used to improve the mechanical properties. Currently the reinforcement effect of continuous fibers cannot be fully utilized in FFF due to the lack of impregnation of the fibers and only low processing pressures during hybridization. To tackle this challenge, four strategies for hybridization of pre-impregnated unidirectional (UD) carbon fiber tapes with polyamide 6 (PA6) matrix and FFF-printed parts are investigated in this work. The strategies differ in the timing of the application of consolidation steps, i.e. a controlled application of heat and pressure in the interface between FFF-layers and UD-tape. With the use of mechanical pull-out tests, the maximum achievable shear stresses of the interface are investigated. Additional computed tomography (CT) scans of the interfaces allow the four hybridization strategies to be evaluated. It is shown that even a single consolidation in the right process step significantly increases the adhesion between UD-tape and FFF layer leading to about 100–200% increased shear stresses before delamination occurs. To ensure the transferability of the hybridization strategies to other material systems and to validate the results, filaments of pure PA6 as well as PA6 with short glass and carbon fibers were used for the FFF process.

Effect of Short Glass Fiber Reinforcement on Physical, Mechanical Properties and Fire Performance of Wood Plastic Composites

Aim of study: This study aimed to improve some physical, mechanical properties, and fire resistance of wood-plastic composites (WPCs) with short glass fiber reinforcement (SGFR). Materials and Methods: The WPCs were reinforced with different ratios of short glass fiber (SGF). The effect of reinforcement on the water absorption (WA), thickness swelling (TS) as physical properties, flexural strength, modulus of elasticity, and tensile strength as mechanical properties were determined. The fire resistance performance was also evaluated by the limit oxygen index (LOI) test. Main results: The reinforcement improved the physical properties. The WA and TS values decreased with increasing glass fiber content. Flexural strength increased up to 28%, while 24% for tensile strength. There was a substantial enhancement in the modulus of elasticity (up to 122%). The glass fiber reinforcement also improved the fire performance of WPCs. Highlights: The higher properties could be obtained by synthetic fiber reinforcement for WPCs.

Study on model of flexure response of carbon fiber textile reinforced concrete (CTRC) sheets with short AR-glass fibers

This paper investigated the effects of adopting short alkali-resistant glass fibers on the mechanical properties of fine-grained concrete matrix. In addition, four-point bending tests have been carried out in order to analyze the flexural behaviors of carbon fiber textile reinforced concrete (CTRC) sheets. In this study’s experiments, 19 serial specimens were tested, with consideration given to the short fiber lengths and content, and reinforcing ratio of carbon fiber textiles. It could be found from the test results that the fine concrete matrix had higher mechanical properties with the increases in the lengths and content levels of the fibers. Furthermore, this study’s bending tests of the CTRC revealed that the bending strength and deformability were significantly improved with increases in the fiber content and the reinforcing ratio of carbon textiles. By utilizing short fibers, the cracking load of the CTRC sheets had been improved by 80.35%. The maximum improvement of the ultimate bending load was more than 6 times compared with the specimens without carbon fiber textiles and short fibers. Finally, a trilinear model was proposed to describe the flexural load-displacement curve of the CTRC sheets reinforced by short fibers. It was determined that the predicted data agreed well with the experimental data.

Synergistic Enhancement of Flame Retardancy Behavior of Glass-Fiber Reinforced Polylactide Composites through Using Phosphorus-Based Flame Retardants and Chain Modifiers.

Flame retardancy properties of neat PLA can be improved with different phosphorus-based flame retardants (FRs), however, developing flame retardant PLA-based engineering composites with maintained mechanical performance is still a challenge. This study proposes symbiosis approaches to enhance the flame retardancy behavior of polylactide (PLA) composites with 20 wt% short glass fibers (GF). This was first implemented by exploring the effects of various phosphorus-based FRs up to 5 wt% in neat PLA samples. Among the used phosphorus-based FRs, the use of only 3 wt% of diphosphoric acid-based FR (P/N), melamine coated ammonium polyphosphate (APPcoated), and APP with melamine synergist (APP/Mel) resulted in achieving the V0 value in a vertical burning test in the neat PLA samples. In addition to their superior efficiency in improving the flame retardancy of neat PLA, P/N had the least negative effect on the final mechanical performance of PLA samples. When incorporated in PLA composites with 20 wt% GF, however, even with the use of 30 wt% P/N, the V0 value could not be obtained due to the candlewick effect. To resolve this issue, the synergistic effect of P/N and aromatic polycarbodiimide (PCDI) cross-linker or Joncryl epoxy-based chain-extender (CE) on the flame retardancy characteristics of composites was examined. Due to the further chain modification, which also enhances the melt strength of PLA, the dripping of composites in the vertical burning test terminated and the V0 value could be reached when using only 1 wt% PCDI or CE. According to the scanning electron microscopic analysis, the use of noted chain modifiers further homogenized the distribution and refined the particle size of P/N within the PLA matrix. Hence this could synergistically contribute to the enhancements of the fire resistance performance of the PLA composites. Such incorporation of P/N and chain modifiers further leads to the enhancement of the mechanical performance of PLA composites and hence the resultant product can be proposed as a promising durable bioplastic engineering product where fire risk exists.

The impact of accelerated aging on the mechanical and thermal properties and VOC emission of polypropylene composites reinforced with glass fibers

Abstract This paper presents the impact of accelerated aging on selected mechanical and thermal properties and VOC emission of polypropylene composites filled with glass fiber with different fiber contents. Due to their positive properties (good thermal and mechanical properties, low weight), glass fiber reinforced thermoplastics are becoming increasingly important. Fiber reinforced thermoplastics are mainly produced by injection molding and extrusion, whereby the extrusion compounding process is primarily used to prepare fiber-filled granulates while the injection molding process is used to manufacture products. In this study, short glass fiber reinforced thermoplastics (polypropylene) are produced on a twin screw extruder. Then, tensile test specimens are produced by injection molding. The glass fiber content is between 20 and 40 wt%. In order to investigate the long-term stability, the test specimens are artificially aged in accordance with ASTM 1980. The thermal, mechanical, and emission properties were evaluated by means of differential scanning calorimetry (DSC), tensile tests, and TDS-GC-MS analysis prior to and after accelerated aging. The objective of this study was to investigate the effects of thermal aging on crystallinity and mechanical properties and on VOC emission of glass fiber reinforced isotactic polypropylene.

Mechanical characterization of aesthetic orthodontic brackets by the dynamic indentation method.

The objective of this study is to investigate the mechanical properties, such as the dynamic hardness and indentation elastic modulus, of commercially available aesthetic orthodontic brackets, such as ceramic and plastic brackets, by the dynamic micro-indentation method. Five ceramic brackets, which were made of alumina (both monocrystalline and polycrystalline forms) or zirconia, and two plastic brackets, which were made of glass fiber-reinforced polycarbonate or polyamide, were tested. There were significant differences in the mechanical properties of the monocrystalline and polycrystalline alumina brackets. The mechanical properties of the glass fiber-reinforced plastic bracket were significantly superior to these of the non-glass-fiber-reinforced plastic bracket. The differences in the crystal structures of the ceramic brackets surface affected the dynamic hardness and indentation elastic modulus. Furthermore, the short glass fibers contained in the plastic bracket might contribute to the improvement of the mechanical properties.

Fused Filament Fabrication of Short Glass Fiber-Reinforced Polylactic Acid Composites: Infill Density Influence on Mechanical and Thermal Properties.

Fused Filament Fabrication (FFF) is one of the frequently used material extrusion (MEX) additive manufacturing processes due to its ability to manufacture functional components with complex geometry, but their properties depend on the process parameters. This paper focuses on studying the effects of process parameters, namely infill density (25%, 50%, 75%, and 100%), on the mechanical and thermal response of the samples made of poly(lactic acid) (PLA) reinforced with short glass fibers (GF) produced using FFF process. To perform a comprehensive analysis, tensile, flexural, compression, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) tests were used. The paper also aims to manufacture by FFF process of composite structures of the fuselage section type, as structural elements of an unmanned aerial vehicle (UAV), and their testing to compression loads. The results showed that the tensile, flexural and compression strength of the additive manufactured (AMed) samples increased with the increase of infill density and therefore, the samples with 100% infill density provides the highest mechanical characteristics. The AMed samples with 50% and 75% infill density exhibited a higher toughness than samples with 100% infill. DSC analyses revealed that the glass transition (Tg), and melting (Tm) temperature increases slightly as the infill density increases. Thermogravimetric analyses (TGA) show that PLA-GF filament loses its thermal stability at a temperature of about 311 °C and the increase in fill density leads to a slight increase in thermal stability and the complete degradation temperature of the AMed material. The compression tests of the fuselage sections manufactured by FFF made of PLA-GF composite showed that their stiffening with stringers oriented at an angle of ±45° ensures a higher compression strength than the stiffening with longitudinal stringers.

Development and Characterization of Phosphate Glass Fibers and Their Application in the Reinforcement of Polyester Matrix Composites.

This study focused on the production and characterization of phosphate glass fibers (PGF) for application as composite reinforcement. Phosphate glasses belonging to the system 52P2O524CaO13MgO (11-(X + Y)) K2OXFe2O3YTiO2 (X:1, 3, 5) and (Y:0.5, 1) were elaborated and converted to phosphate glass fibers. First, their mechanical properties and chemical durability were investigated. Then, the optimized PGF compositions were used afterward as reinforcement for thermosetting composite materials. Polyester matrices reinforced with short phosphate glass fibers (sPGF) up to 20 wt % were manufactured by the contact molding process. The mechanical and morphological properties of different sPGF-reinforced polyester systems were evaluated. The choice between the different phosphate-based glass syntheses (PGFs) was determined by their superior mechanical performance, their interesting chemical durability, and their high level of dispersion in the polyester matrix without any ad sizing as proven by SEM morphological analysis. Moreover, the characterization of mechanical properties revealed that the tensile and flexural moduli of the developed polyester-based composites were improved by increasing the sPGF content in the polymer matrix in perfect agreement with Takayanagi model predictions. The present work thus highlights some promising results to obtain high-quality phosphate glass fiber-reinforced polyester parts which can be transposed to other thermosetting or thermoplastic-based composites for high-value applications.

Effect of using fibre reinforced epoxy adhesive on the strength of the adhesively bonded Single Lap Joints

In this paper, the static strength and elongation of the adhesively bonded Single Lap Joints (SLJs) at failure are enhanced by using glass fibres reinforced with epoxy adhesive. Commercially available Araldite, a standard epoxy adhesive, is utilised as the binding agent, while Aluminium plate and Glass Fibre Reinforced Plastic (GFRP) are used as metal and composite adherend materials, respectively, in the experiment. The performance of glass fibre reinforced epoxy adhesives in terms of strength improvement has been tested for two types of SLJs: MTM (Metal-to-Metal) and MTC (Metal-to-Composite). The strength controlling parameters considered during the experiment are certain variables such as the alignment of the bundle of long glass fibres along the loading direction, the size of glass fibres and the weight ratio of short glass fibres reinforced with epoxy adhesive in the overlap region of the SLJ. The effects of these controlling parameters on the strength and elongation have been discussed. In addition, the bundles of long glass fibres are overlaid at the fillet region along the loading axis, extending beyond the overlap ends to observe the effect of the peel stress at the overlap ends and examine its effect on the failure strength of the SLJ. The experimental results show that there is a substantial increase in failure load and elongation. Fractography analysis has also been carried out to analyse the fracture surfaces using a Scanning Electron Microscope (SEM).

Novel AA7075/AA2124-SiC-17p laminated structures for aerospace applications: A Comparative study into the mechanical performance of PA6 and PA66 composite interlayers

Multimaterial designs consisting of metallic and polymeric material are aimed to reach high lightweight potential. This study presents novel hybrid structures with different interlayer of thermoplastic composites not previously reported in the literature for multi-laminated composites. The metal-polymer-metal hybrids comprise of polyamide 6 (PA6) or polyamide 6,6 (PA66) composite reinforced with 15% of short glass fiber as a sandwich layer. AA7075/AA2124-SiC-17p composite laminates are bonded through hot pressing connection. Mechanical properties of the structures are experimentally investigated from the point of maximum shear strength between dissimilar laminates, resistance to fracture and energy absorbing capacity. Scanning electron microscope (SEM) analysis of fracture surfaces is carried out after mechanical characterization. Short beam three-point-bending tests show that the laminate on which the load is applied is of great importance for the asymmetric hybrid structures. Shear dominant failure is only visible when the bending load is performed from the AA7075 surface. Single-edge notched bending (SENB) test results indicate that there is no significant difference between two configurations in terms of the Mode-I fracture toughness. V-notch Charpy impact tests reveal that the interlayer of PA6 composite contributes to a 13.15% more absorbed energy than that of the PA66 interlayer.

Thermomechanical Characterization of E‐Glass Fiber Reinforced Random Polypropylene

AbstractThe thermomechanical properties of short glass fiber (GF) reinforced polypropylene random copolymer (PPR) composites are investigated. Four composites with different fiber content, namely 10, 15, 20, and 30 wt%, are prepared using melting mixing. For fibers up to 15 wt% the composites exhibit enhanced thermal stability as compared to the random polypropylene. The use of fibers also improve the mechanical strength of the matrix. In particular, PPR/GF30% demonstrates the highest Young modulus, yield strength, and storage modulus values, while PPR/GF10% has the best ductility among the composites. Incorporation of 10 wt% fibers also increases the yield strength and storage modulus of the PPR matrix by approximately 1.6 and 1.2 (for temperatures higher than 60°C) times, respectively. These results suggest that GF reinforced PPR is a composite suitable for advanced technological applications.

Effect of severe thermo-oxidative aging on the mechanical behavior and fatigue durability of short glass fiber reinforced PA6/6.6

The work deals with the fatigue lifetime estimation of Short Fiber Reinforced Thermoplastics (SFRP), with a focus on conjugated effects of thermal aging. Two materials containing 35% (V35) and 50% (V50) weight ratio of short glass fibers were aged for 500 h at 200°C in air and compared to the same materials in a Dry-As-Molded (DAM) state. Monotonic and fatigue tests were performed in samples machined out of injected plates and cut along three different orientations to the injection one (0°, 45°, 90°) in order to capture the anisotropy of the skin-core microstructure, classical in injected SFRP.Monotonic tensile tests evidenced the stiffening and embrittlement of the Polyamide matrix reported in the literature, nevertheless with an acuity depending on the matrix ratio and fiber orientation. Stress-controlled fatigue tests were performed at constant amplitude, frequency (10 Hz), temperature (200°C) and stress ratio R = 0.1. The fatigue curves of V35 are more affected by aging than those of the V50 material. The combined results from the mean strain evolutions and SEM observations confirmed that the initiation approach for fatigue lifetime estimation was still valid in aged composites. Several fatigue criteria, among the most recently reported in the literature, were evaluated from this database. The effect of aging on the cyclic evolution of the different Fatigue Indicator Parameters (FIP) involved in the criteria was analyzed preliminarily. For the present fatigue conditions, the best criteria for unaged materials (i.e cyclic creep energy-based ones) were shown to still be the best for aged materials. Finally, the ability to predict fatigue lifetime for aged composites from the identification of the fatigue criterion in the unaged state was evaluated.