Recycled Glass Fiber Research Articles

Experimental study on mechanical property and microstructure of cement mortar reinforced with elaborately recycled GFRP fiber

Mechanically recycled glass fiber reinforced polymer (GFRP) has increasingly been reused in concrete, while its physicochemical properties need to be tailored for achieving effective reinforcement. To this end, fibers were carefully separated from three sources of GFRP recyclates via a process consisting of vibratory screening, followed by hydraulic selection and aerodynamic separation. The influence of the elaborate fiber selection on the physical-mechanical properties and microstructures of mortars were investigated with mechanical testing, X-ray micro-CT and Scanning Electron Microscopy (SEM) analysis. Results indicated that the fine selected GFRP fibers apparently enhanced the mechanical properties and reduced the shrinkage of mortars, with the highest compressive and flexural strength of 47.3 MPa and 9.83 MPa, respectively. The reinforcement mechanisms were mainly attributed to (i) the porosity of mortar ameliorated by the modified fiber uniformity; (ii) the increased fiber-cement adhesion thanks to the rough and hydrophilic surface of recycled GFRP fibers; and (iii) the protective resin coating of recycled GFRP fibers against alkali corrosion.

Chemical recycling of End-of-Life wind turbine blades by solvolysis/HTL

The focus of this contribution is to highlight the challenges of chemical recycling of End-of-Life glass fiber composite (GFRP) waste from wind turbine blades utilizing solvolysis/HTL (hydrothermal liquefaction) methods based on subcritical water as solvent. A multitude of investigations have been published during the years regarding solvolysis of newly produced composite laminates and known thermoset composition (epoxy, polyester, and vinyl ester). However, a real wind turbine blade is more complex and constitutes of thermosets, thermoplastics, and other materials such as balsa wood. It is a very challenging task to separate these materials from each other within the wind turbine blade structure, so the premise for recycling is a mixed waste stream where little is known about the chemical composition. In the present study, the solvolysis process for GFRPs based on sub/supercritical water at 250-370 °C and 100-170 bar process conditions with catalyst (acid and base) and additives (alcohols and glycols) was studied and optimized. The samples used are representative for End-of-Life wind turbine blades. The aim is therefore to investigate if it is possible to develop a general process that can accept all material constituents in a real wind turbine blade, resulting in recycled glass fibers and a hydrocarbon fraction that can be used as a refinery feedstock.

Upgrading and reuse of glass fibre recycled from end-of-life composites

The value of recycled glass fibres is significantly reduced due to the loss of fibre strength and surface functionality that occurs during recycling. Results are presented from the ReCoVeR project on the regeneration of the strength of thermally conditioned glass fibres. Thermal recycling of end-of-life glass fibre reinforced composites or composite manufacturing waste delivers fibres with virtually no residual strength or value. Composites produced from such fibres also have extremely poor mechanical performance. Data is presented showing that a short hot alkali treatment of glass fibres which have been heat treated at typical composite recycling temperatures can more than triple their strength and restore their ability to act as an effective reinforcement in second life composite materials. Glass fibre recovered from fluidised bed recycling of composite materials exhibited much greater levels of mechanical abrasion damage. However, the strength of these fibres could also be increased to levels required in composite reinforcement by longer or more aggressive alkali treatment. The implications of these results for real materials reuse of recycled glass fibres as replacement for pristine reinforcement fibres are discussed.

Additive Re-Manufacturing of Mechanically Recycled End-of-Life Glass Fiber-Reinforced Polymers for Value-Added Circular Design.

Despite the large use of composites for industrial applications, their end-of-life management is still an open issue for manufacturing, especially in the wind energy sector. Additive manufacturing technology has been emerging as a solution, enhancing circular economy models, and using recycled composites for glass fiber-reinforced polymers is spreading as a new additive manufacturing trend. Nevertheless, their mechanical properties are still not comparable to pristine materials. The purpose of this paper is to examine the additive re-manufacturing of end-of-life glass fiber composites with mechanical performances that are comparable to virgin glass fiber-reinforced materials. Through a systematic characterization of the recyclate, requirements of the filler for the liquid deposition modeling process were identified. Printability and material surface quality of different formulations were analyzed using a low-cost modified 3D printer. Two hypothetical design concepts were also manufactured to validate the field of application. Furthermore, an understanding of the mechanical behavior was accomplished by means of tensile tests, and the results were compared with a benchmark formulation with virgin glass fibers. Mechanically recycled glass fibers show the capability to substitute pristine fillers, unlocking their use for new fields of application.

Regenerating performance of glass fibre recycled from wind turbine blade

The value of recycled glass fibres is reduced significantly due to loss in strength and surface functionality during recycling. This work investigates the potential of a variety of treatments to regenerate the strength and surface functionality of glass fibres recycled from retired wind turbine blades using an in-house developed fluidised bed process. It was found that soaking in hot NaOH solution could provide approximately a 130% increase in the tensile strength of recycled glass fibre; concluding that changes to surface morphology due to etching was the re-strengthening mechanism. The interfacial adhesion between recycled glass fibre and polypropylene was also examined. A significant reduction in interfacial shear strength was observed after recycling which is attributed to the loss of original sizing after recycling. Regenerating the interfacial shear strength between recycled glass fibre and polypropylene proved challenging with the use of aminopropyltriethoxysilane coupling agent alone, however, a twofold increase in the interfacial shear strength was attained by modifying the polypropylene matrix with maleic anhydride. It was found that NaOH and silane treatments restored the interfacial shear strength between interfacial shear strength and epoxy to that obtained with as received glass fibres. This work shows that substantial improvements in recycled glass fibre strength and fibre-polymer adhesion can be achieved after utilising various regeneration treatments, in turn producing recycled glass fibres with significantly enhanced reinforcement potential.

A Novel Polymer Concrete Composite with GFRP Waste: Applications, Morphology, and Porosity Characterization

Composite materials reinforced with recycled fibers gather a great deal of interest with regards to construction applications. A novel polymer concrete composite was proposed, comprised of a surface layer and a structural composite reinforced with recycled glass fibers. The novel multi-material composite included a large amount of glass-fiber-reinforced polymer (GFRP) waste (30%), which is expected to help protect the environment. Large panels comprised of this polymer concrete composite, which reproduce the appearance of natural stone, were manufactured. A new methodology for porosity analysis of a large panel comprised of a multi-material composite was proposed, utilizing three-dimensional (3D) X-ray computed tomography (CT). The volume of pores was distributed between the constituent composite materials and then statistically analyzed. Homogeneous distribution of the pores within the novel multi-material composite was found. The observed mean porosities of the composite panel were 0.146% for the surface layer material and 31.3% for the structural composite material. The mean density of the panel, determined by the CT density method, was 1.73 g/cm3. The composite materials porosity provides a favorable effect for achieving lightweight structures. Using scanning electron microscopy (SEM) analysis, it was observed that a good connection interface between the constituent composite materials existed.

Fire resistance and mechanical properties of powder-epoxy composites reinforced with recycled glass fiber laminate

In this article the effect of type and content of fractions of recycled glass fiber reinforced plastics (GFRP) on the mechanical properties and flame resistance of epoxy composites (EP) were investigated. For this purpose, post-production waste of glass fabric reinforced laminate with epoxy matrix containing 15 wt % of aluminum diethylphosphinate (AlDPi), 10 wt % of melamine polyphosphate (MPP) and 15 wt % of zinc borate (ZB) was ground and sieved to obtain four fractions of grain size: >1 mm (A), 1–0.5 mm (B), 0.25–0.5 mm (C) and

Heat Distortion Temperature and Shear Property Examination of Composites Using Recycled Glass Fibres and Recycled PPCP

Pollution from plastic materials has become a severe problem all around the world. Plastics, due to their long lasting properties are utilized majorly in almost every application from packaging, electrical appliances, vehicle parts etc. the major concern related to plastics are that they are non-degradable and hence are harmful for environment. Several researches have been done in utilizing plastic material in addition with some other materials to form a composite material which has better properties than pure substances. Plastics with glass fibres are one such of composition where the new material formed can be used for several day to day applications. Hence the present work focuses on, manufacturing of a composite material from recycled glass fibres and recycled polypropylene co-polymers (PPCP) in varying ratios. A total of six specimens are made and results for Heat deflection temperature (HDT) 70:30 has the best results compared to other compositions. Results are also calculated for shear strength for the same composition of specimen, which shows better results compared to wood material (plywood). This experiment provides a solution for utilizing the waste plastic material found in waste lands and scrapyards which continuously pollute the environment.

DSC and Weathering Test of Composite formed of Six Configurations of RPPCP and RGF materials

The exploration of different materials is at its peak nowadays. This pace has not only gone towards discovering new material but inventing new, by making composites of different materials. Now this stream has gone into making composites of different polymers to make them suitable enough to compete and overtake metals. In this study, Polypropylene Copolymer (PPCP) is mixed with Glass Fibre Reinforced Polyester (GFRP) to form the Recycled PPCP or RPPCP. Further, a composite material is formed by the amalgamation of RPPCP and Recycled Glass Fibre (RGF) in different proportions. These samples of different proportions are created and tested in weatherometer and DSC analysis. In both of the tests, the outcome has been in favor of the sample with 70% RPPCP and 30% RGF proportion of the composite.

Tensile properties and interfacial shear strength of recycled fibers from wind turbine waste

The rapid growth of composites combined with imminent recycling legislation have increased the interest in reusing and recycling of composite waste. Tensile strength and interfacial shear strength (IFSS) of recycled fibers are critical factors contributing to the final properties of recycled products. Here, we focus on the tensile properties of recycled glass fibers from scrap wind turbine blades and their interface strength with polylactic acid (PLA). The single fiber tensile and pull-out tests are used to characterize the fibers recovered through mechanical and thermal processes. It is shown that while pyrolysis can significantly degrade the recovered fibers, ground fibers with a gage length of 20 mm feature characteristic strength comparable to that of virgin fibers. The effect of the fibers surface coating on the IFSS are investigated, with results showing an interface between ground fibers and PLA that is 14% and 26% stronger than pyrolyzed and virgin fibers, respectively.

Mechanical and thermal performance of recycled glass fiber reinforced epoxy composites embedded with carbon nanotubes

Recycling and reusing of Fiber-reinforced polymer (FRP) composite is gaining a major attraction. In this study, the recycling process is achieved by subjecting the discarded FRP composite materials to the high-temperature environment, which leads to decomposing of thermoset matrix yielding only the fibers. These recycled glass fibers are used in terms of discontinues fibers as reinforcement in polymeric composites. But the strength and quality of the obtained recycled glass fiber composite are lower. It is also inevitable that the interface/interphase of FRP composites plays a vital role in governing their properties and performance. With respect to this, the present article focuses on the mechanical performance of neat epoxy, randomly oriented discontinuous glass fiber/epoxy (RODGE) composite, Carbon nanotube reinforced RODGE (CNT-RODGE) composite, and Functionalized Carbon nanotube reinforced RODGE (FCNT-RODGE) composite. The results revealed that FCNT-RODGE composite possessed the highest tensile and flexural strength, followed by CNT-RODGE, RODGE, and neat epoxy composite. This can be attributed to strong interfacial bonding, which in turn results in better stress transfer. Thermal characterization using Differential Scanning Calorimetry (DSC) was also conducted to obtain the glass transition temperature (Tg) of all the composites experimented in this study. It showed that CNT-RODGE composite had the lowest Tg value. Fractography of the fractured samples was also analysed by Scanning Electron Microscope (SEM) micrographs. It revealed the results which were in good agreement with the tensile characteristics.

Mechanical Properties of Recycled Tire Wires and Glass Fibers Reinforced Concrete

Concrete is a versatile construction material with various uses. It is has poor tensile strength and good compressive strength mechanical properties. In past, an effort has been made to improve concrete mechanical properties by mixing with various foreign materials such as synthetic and natural fibers, steel wires and plastics. However, there is research gap in literature to study comparative use of recycled and new materials for improving concrete mechanical properties. This research work experimentally investigates use of new glass fibers and recycled tire fibers in 0.5%, 1% and 1.5% in weight mixes with concrete to study concrete mechanical properties performance gains such as compressive, flexural and split tensile strength properties. Experimental results indicated as compared to control plain concrete specimen, use of recycled steel fiber and glass fibers in concrete mix increased flexural property of concrete by 19.64% and 24.56% whereas split tensile strength of concrete is enhanced by 8.15% and 12.02%, respectively. Similarly, compressive strength of concrete is improved by 5.34% and 7.87% respectively. Also, optimum blend percentage of recycled tire fiber and glass fiber for enhanced performance gains in concrete mechanical properties is one percent. Finally, use of recycled steel fibers and glass fibers in concrete exhibited similar concrete mechanical property performance gains however, recycled steel fibers has 78% direct cost reduction as compared to glass fibers.

Study on the reinforcement effect and the underlying mechanisms of a bitumen reinforced with recycled glass fiber chips

Abstract The majority of discarded fiber reinforced polymer (FRP) composites worldwide are dumped as waste in landfills, entailing major environmental concerns. Recycling and reusing these discarded FRP composites remain a big challenge. In this work, a possible method for using the recycled glass fiber chips (GFC) as a reinforcement material for bitumen used in pavement is proposed to solve this issue. For this purpose, GFC with different lengths and diameters were chosen and dispersed evenly into bitumen with three mass contents. To gain a throughout understanding of the reinforcement effect of GFC in bitumen, a range of basic properties, such as the high-temperature performance, low-temperature performance and water resistance, were thoroughly investigated by the dynamic shear rheometer (DSR) test, bending beam rheometer (BBR) test, single-edge notched beam (SENB) test and surface free energy (SFE) test. Furthermore, the underlying mechanisms of reinforcement through the addition of GFC was revealed by using scanning electron microscopy (SEM). It is interesting that GFC can not only significantly improve the high-temperature performance of bitumen, such as the stiffness, rutting resistance, and creep and recovery behaviors, but also inhibits low-temperature cracking and improve the water resistance of asphalt mixture. These results are attributed to the stable three-dimensional structure created by the network of GFC in the bitumen. The GFC also enhances the material behavior through a bridging function and the specific pull-out behavior. The optimal geometry of GFC as a reinforcement additive was determined to be a diameter of 0.5–0.71 mm and a length of 10–12 mm, the optimal mass content was found to be 5% from this study. Based on the present investigation, it is highly recommended to use the recycled GFC as a reinforcement material in bitumen in both high- and low-temperature regions. Besides, the application of the recycled GFC can reduce the environmental footprint as well as costs.

Recycled Glass Fiber Composites from Wind Turbine Waste for 3D Printing Feedstock: Effects of Fiber Content and Interface on Mechanical Performance.

This research validates the viability of a recycling and reusing process for end-of-life glass fiber reinforced wind turbine blades. Short glass fibers from scrap turbine blades are reclaimed and mixed with polylactic acid (PLA) through a double extrusion process to produce composite feedstock with recycled glass fibers for fused filament fabrication (FFF) 3D printing. Reinforced filaments with different fiber contents, as high as 25% by weight, are extruded and used to 3D print tensile specimens per ASTM D638-14. For 25 wt% reinforcement, the samples showed up to 74% increase in specific stiffness compared to pure PLA samples, while there was a reduction of 42% and 65% in specific tensile strength and failure strain, respectively. To capture the level of impregnation of the non-pyrolyzed recycled fibers and PLA, samples made from reinforced filaments with virgin and recycled fibers are fabricated and assessed in terms of mechanical properties and interface. For the composite specimens out of reinforced PLA with recycled glass fibers, it was found that the specific modulus and tensile strength are respectively 18% and 19% higher than those of samples reinforced with virgin glass fibers. The cause for this observation is mainly attributed to the fact that the surface of recycled fibers is partially covered with epoxy particles, a phenomenon that allows for favorable interactions between the molecules of PLA and epoxy, thus improving the interface bonding between the fibers and PLA.

Degradation of E-glass fiber mechanical properties during composite sheet molding compound production for automotive applications

Abstract

Remanufacturing of end-of-life glass-fiber reinforced composites via UV-assisted 3D printing

Purpose The purpose of this study is to demonstrate the potential of three-dimensional printing technology for the remanufacturing of end-of-life (EoL) composites. This technology will enable the rapid fabrication of environmentally sustainable structures with complex shapes and good mechanical properties. These three-dimensional printed objects will have several application fields, such as street furniture and urban renewal, thus promoting a circular economy model. Design/methodology/approach For this purpose, a low-cost liquid deposition modeling technology was used to extrude photo-curable and thermally curable composite inks, composed of an acrylate-based resin loaded with different amounts of mechanically recycled glass fiber reinforced composites (GFRCs). Rheological properties of the extruded inks and their printability window and the conversion of cured composites after an ultraviolet light (UV) assisted extrusion were investigated. In addition, tensile properties of composites remanufactured by this UV-assisted technology were studied. Findings A printability window was found for the three-dimensional printable GFRCs inks. The formulation of the composite printable inks was optimized to obtain high quality printed objects with a high content of recycled GFRCs. Tensile tests also showed promising mechanical properties for printed GFRCs obtained with this approach. Originality/value The novelty of this paper consists in the remanufacturing of GFRCs by the three-dimensional printing technology to promote the implementation of a circular economy. This study shows the feasibility of this approach, using mechanically recycled EoL GFRCs, composed of a thermoset polymer matrix, which cannot be melted as in case of thermoplastic-based composites. Objects with complex shapes were three-dimensional printed and presented here as a proof-of-concept.

Development of FRC Materials with Recycled Glass Fibers Recovered from Industrial GFRP-Acrylic Waste

Fiber-reinforced concrete (FRC) and engineered cementitious composite materials have demonstrated promising requisite in construction industry owing to its superior mechanical and durability properties. In this study, a sustainable approach was taken, i.e., to use industry waste as a reinforcement with improved interfacial bonding leading to enhanced mechanical performance of FRC. An efficient in situ recycling process allowed the authors to extract glass fibers from glass fiber-reinforced polymer acrylic waste. Concrete mixes with low fiber dosages including 0.1%, 0.2%, and 0.3% (by volume) of recycled as well as virgin glass fibers were prepared. The slump of concrete was maintained ∼150 mm by using high water-reducing admixture (HWRA). Notably, lower amount of HWRA was required for raw glass fibers vis-à-vis recycled ones due to its hydrophobic nature. Overall, FRC enclosing 0.3% recycled glass fiber demonstrated >20% enhancement in compressive, split tensile, and flexural strength as compared to control (after 28 days of curing), also supported by morphological analysis.

Recycled Glass Fibres from Wind Turbines as a Filler for Poly(Vinyl Chloride)

This paper presents the method of using glass fibre with carbon deposit (GFCD), derived from the recycling of wind turbine blades, for production of composite materials based on poly(vinyl chloride) (PVC). Composite materials containing from 1 to 15 wt% of GFCD were produced by plasticising with a plastographometer and then by pressing. The processability and performance were studied. Mechanical properties in static tension, impact strength, and thermal stability were determined. Glass transition temperature was also determined by means of the dynamic mechanical thermal analysis (DMTA). The GFCD percentage of up to 15 wt% was found not to slightly affect the change in the processability, thermal stability, and glass transition temperature. PVC/GFCD composite materials are characterised by a definitely greater elastic modulus with simultaneous decrease of tensile strength and impact strength. An analysis with scanning electron microscopy revealed good adhesion between the filler and the polymer matrix.

Re-Formative Polymer Composites from Plastic Waste: Novel Infrastructural Product Application

A novel re-formative polymer composite manufacturing route has been developed by UK and Qatar-based Universities. This novel process recycles domestic-waste thermoplastic material, without the requirement for intensive filtering or washing operations. The produced polymer can be reinforced with recycled glass fibres, forming a structurally load-bearing composite, which may potentially be suitable for use in applications, including utility poles, railway sleepers, and fencing. Thus, infra-red (IR) analysis showed the presence of polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) in the commingled material. Differential scanning calorimetry (DSC) was used to determine glass transition temperatures and melting temperatures of each of the associated polymer types. Dynamic mechanical thermal analysis (DMTA) was used to determine the storage and loss modulus of the bulk commingled component. Lastly, flexural and tensile strengths of the re-formative polymer with differing proportions of glass fibre were assessed, giving a range of strengths at each glass fibre proportion for possible compositional variation in the polymer type. The recycled polymer is considered a viable structural material for replacing both wooden and concrete components, generating a polymer recycling route with concomitant environmental benefits. This plastic recycling route therefore offers a solution towards achieving climate change targets with a purposeful end-product component.

Effect of different lengths and dosages of recycled glass fibres on the fresh and hardened properties of SCC

An experimental and analytical investigation was carried out to examine the feasibility of using recycled glass fibres in self-compacting concrete (SCC). Different fibre volume fractions (0·5, 1, 1·5 and 2%) and different fibre lengths (10, 20 and 30 mm) were used to assess both the fresh and hardened properties of fibre-reinforced SCCs. The fresh properties were assessed in terms of flowability and viscosity, while the hardened properties of 130 specimens were characterised in terms of ultrasonic pulse velocity, compressive strength, flexural strength and impact resistance. The specimens were thus tested experimentally to characterise their mechanical properties and impact resistance. Backscattered electron images and elemental maps were used to identify the crystalline structure of the cementitious matrix, and energy-dispersive X-ray spectroscopy was employed to determine the qualitative or semi-quantitative chemical compositions of the cementitious mix composition. The surface topography and morphology of the embedded glass fibres in the matrix were also evaluated. The results showed that increasing the volume fraction and length of the recycled glass fibres improved both mechanical properties and impact resistance. Moreover, it was found that the mechanical properties and impact resistance could be linearly correlated to the recycled glass fibre volume fraction.