Polyvinyl Alcohol Fibers Research Articles

Elasticity and Load-Displacement Behavior of Engineered Cementitious Composites produced with Different Polymeric Fibers

Engineered Cementitious Composites (ECC) are ultra-ductile materials, and the fibers used provide superior flexibility and strain capacity. This study investigates the use of two different types of polymeric fibers, Polypropylene (PP) and Polyvinyl Alcohol (PVA), with volume fractions of 1 and 2%, and studies their effect on stress-strain relationships, load-displacement behavior, toughness, and elasticity of ECC mixes produced with two strength levels, 30 and 60 MPa. The results showed that mixtures with PVA fiber ionic coating had a better performance than those with PP fibers due to the chemical reaction between the PVA fibers and the ECC matrix. This performance was confirmed by Scanning Electronic Microscopy (SEM). For normal-strength concrete (30 MPa), the modulus of elasticity increased by 7.8 and 9.6% for mixes with PP and PVA fibers, respectively, while in high-strength mixes (60 MPa), it increased by 9.4 and 10.85%, respectively. Toughness increases with increasing matrix strength, which is associated with an increase in cement content and fiber fraction. This study also investigates the effect of incorporating a PVA solution in ECC mixes, which leads to an increase in yield stress. This behavior was observed in the stress-strain behavior of 60 MPa mixes with 2% fibers which were compared to 30 MPa mixes with 1% fibers.

Mechanical Properties and Microstructure of Highly Flowable Geopolymer Composites with Low-Content Polyvinyl Alcohol Fiber

Geopolymer enhances mechanical properties with polyvinyl alcohol (PVA) fibers, but there has been limited research exploring low PVA fiber dosages for mechanical properties in 3D printing or shotcrete. This study experimentally investigated slag and fly ash-based geopolymer mixtures reinforced with 0.1%, 0.15%, and 0.2% PVA fiber by volume as well as a control group without PVA fibers. These mixtures were prepared using fly ash, quartz sand, slag powder, silica fume, and an aqueous sodium silicate solution as the alkali activator, with the addition of PVA fiber to enhance composite toughness. The mechanical properties of the composites, encompassing dog-bone tensile properties, cubic compressive strength, bending and post-bending compressive strength, and prism compressive properties, were evaluated. Significantly, specimens with 0.15% PVA fibers exhibited optimal performance, revealing a notable 28.57% increase in tensile stress, a 36.45% surge in prism compressive strain, and a 47.59% rise in tensile strain compared to fiber-free specimens. Furthermore, environmental scanning electron microscopy observations were employed to scrutinize the microscopic mechanisms of composites incorporating PVA fibers, slag, and fly ash. In comparison to fiber-free specimens, prism compressive specimens with 0.15% PVA fibers demonstrated a 27.17% increase in post-cracking loading capacity, a 44.07% increase in post-cracking ductility, a 50.00% increase in peak strain energy, and a 76.36% increase in strain energy ratio.

Utilization of Novel Basalt Fiber Pellets from Micro- to Macro-Scale, and from Basic to Applied Fields: A Review on Recent Contributions

Fiber-reinforced cementitious composites (FRCC) are one of the leading engineering materials in the 21st century, as they offer proficiency in enhancing strength, ductility, and durability in structural engineering applications. Because the recently developed basalt fiber pellets (BFP) offer combined strands of fibers encased in a polymer matrix, they are being prevalently studied to explore new possibilities when used in brittle materials such as mortar and concrete. Hence, this paper synthesizes the intensive research efforts and contributions to this novel class of fibers conducted by the authors. Specifically, it reviews the fresh, mechanical, and durability properties of FRCC incorporating single BFP or hybrid with polyvinyl alcohol fibers and modified with slag/fly ash and nano-materials and its suitability for different field applications. In addition, the nano- and meso-scale modeling of such matrices are described. BFP significantly contributes to improving post-cracking flexural behavior by toughening the cementitious matrix and minimizing strength losses when exposed to harsh environments. All results show promising progress in the development of high-performance FRCC comprising BFP, with potential success for structural and pavement applications.

Effect of the solid content of spinning solutions on the structure properties of large-diameter polyvinyl alcohol fiber

Effect of the solid content of spinning solutions on the structure properties of large-diameter polyvinyl alcohol fiber

Bonding Evaluation of Nanosilica-Modified Slag-Based Composites Comprising of Basalt Pellets and Polyvinyl Alcohol Fibers for Shear Joints

Bonding Evaluation of Nanosilica-Modified Slag-Based Composites Comprising of Basalt Pellets and Polyvinyl Alcohol Fibers for Shear Joints

Bioactive PVA nanofiber mat loaded with artichoke bracts extract as a promising wound dressing biomaterial

The chronic wounds and burn wounds are considered as one of the most important medical conditions that must be properly managed due to the psychological and physical stress that cause for patients, as well as creating a huge financial burden on patients and global health care systems. Nowadays, there is a growing interest in developing nanofiber mats loaded with different types of plant extracts to meet the urgent need for advanced wound dressings. In this study, polyvinyl alcohol (PVA) nanofiber mats loaded with Cynara scolymus L. extract (CSE) were developed in three concentrations (10 wt%, 20 wt% and 40 wt%) by electrospinning. The morphology and chemical properties of the resulting nanofibers were identified using SEM and FTIR analysis. The results demonstrated the presence of evenly distributed, and bead-free nanofibers and the successful loading of the extract into the PVA fibers. The results proved the antimicrobial activity of PVA/CSE nanofiber mats against the most important microbial species that attributed to wound infections. Additionally, the hydrophilicity and the antioxidant activity of these nanofibers were determined by contact angle test and DPPH assay, respectively. The results demonstrated a hydrophilic nature and a high antioxidant activity for the nanofiber mats. Mechanical testing showed that increasing the percentage of CSE in nanofiber mats resulted in an improvement in tensile strength. The MTT test was performed to detect the toxicity of PVA/CSE nanofiber mats on L929 fibroblast cells and no cytotoxicity was found. Also, LC-MS/MS evaluation of CSE identified the significant amounts of phytochemicals which could enhance wound healing. All these findings enhance the opportunity of using these nanofibers as a promising bioactive wound dressing material.

Fiber Synergy of Polyvinyl Alcohol and Steel Fibers on the Bond Behavior of a Hybrid Fiber-Reinforced Cementitious Composite.

Based on multi-scale characteristics inherent in the cracking process of cementitious composites, fibers with different geometric dimensions are simultaneously used to restrain the formation and development of cracks at different scales. Accordingly, hybrid fiber-reinforced cementitious composites (HyFRCCs) exhibit excellent bond behavior and deformation capacity in terms of tension and compression, accompanied by higher damage tolerance. Using these benefits of the mechanical properties of HyFRCCs, the structural performance of HyFRCC structures under complex loading conditions can be improved. To objectively evaluate the contributions of all fibers to the mechanical properties of HyFRCCs, steel macro-fibers, and polyvinyl alcohol (PVA) micro-fibers were used to design several reinforced cementitious composites. Four of the specimens were mono-fibrous cementitious composites, three specimens were cementitious composites reinforced with hybrid fibers, and one was a non-fibrous cementitious composite. The synergy effect of the steel and PVA fibers was analyzed using various fiber combinations. The results indicated a significant enhancement of the bonding properties of HyFRCCs through the incorporation of PVA and steel fibers. Specifically, the peak bond strength, peak slip displacement, and residual bond strength exhibited increments ranging from 31.0% to 41.7%, 60.6% to 118.4%, and 34.6% to 391.3%, respectively, in comparison to the reference test block. Notably, the combined presence of the PVA and steel fibers consistently demonstrated a positive confounding effect on the residual bond strength. However, negative confounding effects were observed in terms of the peak bond strength and peak slip displacement, particularly with 1.0% steel fiber content and 0.5% PVA fiber content.

Experimental investigation of the compressive and shear behaviours of grouted and hollow masonry constructed with PVA fibre-reinforced mortar and grout

Polyvinyl alcohol (PVA) fibres are ultra-high-performance fibres that can be used to reinforce cementitious composites. This study experimentally investigated the compression and shear behaviours of grouted and hollow masonry constructed with fibre-reinforced mortar (FRM) used for the joints and/or PVA fibre-reinforced grout (FRG). In this regard, the effect of increasing the fibre content of 6 mm PVA fibres in the FRM on the behaviour of masonry was investigated. Moreover, the effect of changing the fibre length (8 mm and 13 mm PVA fibres) and the fibre content of 13 mm PVA fibres in the FRG on the behaviour of masonry was investigated. This was accomplished by constructing and testing 31 masonry prisms and 29 masonry assemblages. The behaviour of PVA-reinforced masonry was evaluated based on compressive strength, shear strength, modulus of elasticity, modulus of rigidity, compressive strain at peak compressive stress, shear strain at peak shear stress, compression ductility index and compression toughness. In addition, the compression and shear stress-strain curves, failure modes and crack propagation of PVA-reinforced masonry were compared with unreinforced masonry. It was concluded that using PVA fibres in the grout minimized the masonry face shell spalling, and most of the post-peak deterioration appeared in the form of masonry cracks and less face shell spalling compared with unreinforced masonry. In addition, using PVA-FRM only or PVA-FRM with PVA-FRG could increase the compressive strength of grouted masonry. In contrast, using PVA-FRM did not change the compressive strength of hollow masonry. Furthermore, all grouted assemblages with PVA-FRM and PVA-FRG (except for assemblages with 13 mm PVA-FRG with a fibre content of 0.10% by weight of grout) have similar average shear strength compared with unreinforced assemblages. Finally, As the fibre content of 6 mm PVA fibres in the FRM of hollow assemblages increased, the shear strength and the modulus of rigidity decreased. This study highlights the improvements and drawbacks of using PVA Fibres in mortar and grout on the compressive and shear performances of hollow and grouted masonry.

Development of green engineered cementitious composites with acceptable dynamic split resistance utilising recycled polymer fibres

Using recycled tyre polymer fibres (RTPF) to replace part of polyvinyl alcohol fibres (PVAF) is a strategy to produce green and economical engineered cementitious composites (ECC). This paper systematically investigated the influence of RTPF dosage (0.25–1.0 vol%) on split tensile performance of ECC under different strain rates. Results indicated that replacing PVAF with RTPF up to 0.5 vol% could still show a pronounced strain-hardening behaviour for ECC, although accompanied by a decrease in static split tensile strength. The dynamic split tensile performance of all ECC mixes was strongly sensitive to strain rate and all hybrid fibre reinforced ECC presented a greater strain rate effect than the mono-PVAF reinforced ECC. Under dynamic split tension, the specimens with various RTPF dosages could maintain their structural integrity. This paper suggested that RTPF can be adopted to replace part of PVAF to produce a greener and more economical ECC with satisfactory static and dynamic mechanical performance but the highest substitution amount should be set to 0.5 vol%.

Performance characteristics of micro fiber-reinforced ambient cured one-part geopolymer mortar for repairing

The development of one-part geopolymer mortars has greater potential than the traditional two-part mortars, especially in repair applications, to convert waste into useful beneficial products while simultaneously eliminating the hazards associated with the alkaline solutions. Nevertheless, the inherent brittleness exhibited by the one-part geopolymers displays drawbacks like OPC when subjected to flexural loading. The fibers selection as well as their strengthening effects from literature is considerably scarce, especially for the repairing geopolymer system. This work aims to investigate the influences of fiber types and volume fractions on the workability, physical behavior, and cracking/fatigue resistance of ambient air-cured one-part geopolymer mortar. Reaction kinetics, mineralogical phases, and elemental components were explored by means of the TAM, quantitative XRD, and EDS mapping analysis. The FESEM and X-CT were employed to compare the microstructures and pore characteristics of the fibers-reinforced products. The results show that the copper-plated steel fiber produced the least change in workability, while the basalt fiber produced the lowest flow values. Setting time was the shortest for the basalt fiber reinforced, followed by polyvinyl-alcohol fiber. The steel fiber and carbon fiber would improve the mechanical properties of mortar significantly, especially in the early stage. The fatigue strength of 1 vol% carbon fiber reinforced mortar under 2 million cycles loading was the highest (3.72 MPa). The fibers addition a substantial decrease in sphericity and compactness of the pores (high anisotropy) as evidenced by X-CT data. Moreover, three hydration heat processes occurred after water was added to the one-part geopolymer mortar, which included dissolution of Na2SiO3 particles, network degradation, and a second pozzolanic reaction. More crystalline formation occurred over curing time to form gel networks with high stability and generated different bonding modes with various fibers.

Effects of gold tailings dosage and polyvinyl alcohol fibre content on the frost resistance of ECC

The effects of gold tailings and polyvinyl alcohol (PVA) fibre on the frost resistance of engineered cementitious composites (ECC) were investigated. The ECC were made with three gold tailings dosages and four PVA fibre contents. A water/binder (w/b) ratio of 0.28 was used for all mixtures. Surface damage, mass loss, relative dynamic elastic modulus, compressive strength and damaged layer thickness (DLT) were investigated to assess the frost resistance of the ECC. The results showed that the effect of gold tailings on the frost resistance of the ECC was marginal, but the frost resistance increased with an increase in PVA fibre content. The ECC with the addition of gold tailings had the same excellent frost resistance as those without gold tailings, indicating that it is feasible to replace silica sand with gold tailings at up to 100% replacement. A model to predict the DLT in ECC as a function of gold tailings dosage and freeze–thaw cycles was developed.

Optimization on overall performance of Modified Ultrafine Cementitious Grout Materials (MUCG) and hydration mechanism analysis.

Given the challenges encountered in injecting grout into micro-cracked rock masses, a modified ultrafine cementitious grout material (MUCG) was developed using ultrafine cement, polyvinyl alcohol (PVA) fibers, and a high-efficiency superplasticizer. To identify the optimal ratio of constituents for grouting these rock masses, extreme difference and multiple linear regression analyses were conducted based on test results of flowability and mechanical properties. A mix comprising 9% silica fume, 0.2% bentonite, 0.3% PVA fibers, 0.15% superplasticizer, and 2% setting accelerator was identified as the optimal mix. The microstructure characteristics of the optimal MUCG (MUCGop) grout cemented body were analyzed using XRD, FTIR, BET, and SEM. XRD and FTIR analyses indicated that a substantial amount of C-(A)S-H gel, CH, and AFt were formed within the first 3 days, highlighting the early strength characteristics of MUCGop. Over time, the content of C-A-H stabilized at 22%, the amount of CH decreased from 19% to 14%, whereas the amount of AFt increased to 15.9% by Day 28. Unexpectedly, CaCO3 content increased due to carbonation, reaching 37.3% by Day 28. BET and SEM analyses demonstrated that the specific surface area and porosity (most probable pore size) gradually decreased over time. At various ages, mesopores (cumulative pore diameter, median pore diameter) initially increased and then decreased. Micro-cracks appeared in the cemented body by Day 7, resulting in a slight decrease in strength (3.92%) from Day 3 to Day 7. The formation of well-developed needle-like AFt, C-(A)S-H gel, and small-volume plate-like CH contributed to uniform cementation and a denser structure. From Day 7 to Day 28, there was a slight increase in strength, by an amount of 10.66%. These findings have significant scientific implications for understanding the mechanisms of grouting reinforcement in micro-cracked rock masses.

Compressive behavior of polyvinyl alcohol engineered cementitious composites incorporating steel slag as aggregate

Disposal of the steel by-product steel slag (SS) negatively impacts the environment. The use of SS as an aggregate in engineered cementitious composites (ECC) can prevent pollution and mitigate natural aggregate depletion. In this study, river sand (RS) was replaced by SS with maximum size of 4750 µm, and the properties of ECC with varying contents of SS and polyvinyl alcohol (PVA) fiber were investigated. SS changed the hydration product composition and enhanced the bond stress between the fiber and cementitious matrix, increased the bulk specific density and compressive strength, and reduced the porosity. ECC containing only SS and with high PVA fiber content exhibited superior performance. A 25% SS replacement ratio and 2% PVA fiber content improved the compressive strength, ductility index, and toughness index to 47.5 MPa, 1.45, and 2.60, respectively.

Covalently cross-linked ultrastrong SiO2-loaded polyvinyl alcohol fibers via microfluidic spinning.

Polyvinyl alcohol (PVA) fiber materials have gained immense recognition due to their good biocompatibility and wide applications. However, methods allowing the synergistic enhancement of mechanical strength and toughness of PVA fibers still remain a key challenge. To this end, we developed covalently cross-linked ultrastrong SiO2-loaded polyvinyl alcohol fibers via a microfluidic spinning chemistry strategy. The thermal stretching and annealing processes not only promote the ordered arrangement of molecules, but also facilitate the ring opening reaction and increase crystallinity. Thus, the resulting fiber has a high tensile strength of 866 MPa, a specific toughness of 288 J g-1 and a tensile strain of 80%. This work provides a covalent cross-linking reinforcement method to prepare ultrastrong composite fibers assisted by microfluidic spinning chemistry and thermal stretching, which would lead to the fabrication of mechanically strong fiber materials through a simple pathway.

Effects of microfibre parameters on the tensile properties of fabric-reinforced cementitious mortar

In recent years, Fabric-Reinforced Cementitious Mortar (FRCM) has gained widespread application for strengthening reinforced concrete and masonry structures. This research investigated the influence of microfibre parameters on the tensile characteristics of FRCM, focusing on the fibre type, length, and volume fraction. Three distinct types of microfibres were scrutinized: amorphous metallic (AM) fibres, polyvinyl alcohol (PVA) fibres, and nylon fibres. FRCM coupons were designed and fabricated based on the AC434 standard. A tensile experimental program, following RILEM TC232-TDT, revealed the pronounced advantage of employing AM fibres in the pre-cracking stage by significantly improving the crack stress up to 226% and pre-cracking stiffness of FRCM. Conversely, synthetic fibres such as nylon and PVA were beneficial in the post-cracking stage by enhancing cracked stiffness, peak stress, and tensile toughness. Additionally, it was found that using fibres with shorter lengths improved the tensile behavior of FRCM composites in the post-cracking stage due to better random distribution in the cement-based matrix. Finally, an artificial neural network (ANN) model was proposed to predict the tensile parameters of the FRCM composites incorporating microfibres.

Methodology to design eco-friendly fiber-reinforced concrete for 3D printing

Greater use of locally available supplementary cementitious materials (SCM) to reduce cement content and addition of fiber reinforcement can enhance the performance of 3D printing (3DP) technology in construction. In this study, three classes of eco-friendly 3D printable fiber-reinforced mixtures were targeted, namely ultra-high-performance concrete (UHPC), high-performance concrete (HPC), and conventional concrete (CC). A step-by-step methodology was proposed to maximize the substitution rate of cement with SCM and limestone filler and optimize fiber volume for the successful development of 3D printable fiber-reinforced materials. Binder combinations were initially investigated on the paste level to determine the packing density and robustness. Selected binder systems were narrowed down on the mortar level by evaluating the superplasticizer (SP) demand, plastic viscosity, forced bleeding, final setting time, and 3-day compressive strength. The 6-mm steel and 8-mm polyvinyl alcohol (PVA) fibers were incorporated for further evaluation of key properties of fiber-reinforced concrete. The printability of the fiber-reinforced mixtures was validated using an extrusion-based 3D printer. Developing such print materials with adequate strength and toughness can improve the cost-effectiveness of 3DP construction, and extend 3DP technology to remote areas.

Multivitamin complex-loaded electrospun polyvinyl alcohol core/shell structure fibers for transdermal delivery system: In-silico and experimental studies

Transdermal delivery systems offer a controlled and targeted environment for releasing drugs compared to other delivery systems. This study presents the fabrication of polyvinyl alcohol (PVA) fibers with a multivitamin complex (MV) using the electrospinning technique (ES). The research focuses on understanding how various fiber structures, such as core/shell, simple fibers, and ES parameters, affect the MC release mechanism and cell viability behavior.The vitamin complexes were uniformly encapsulated within the polymeric chains in all structure fibers. PVA simple fibers with and without the vitamin complex don't significantly differ in diameter size. However, the core/Shell fiber has a notable decrease in fiber diameter of 45 %.The fiber with a core/shell structure resulted in a slower release rate of the vitamin complex than simple fiber. According to the Korsmeyer-Peppas model, the release mechanism observed in our study for the simple fibers is classical Fickian diffusion. Instead, core/shell fibers indicate a more anomalous or non-Fickian behavior.The structural configurations of the fibers do not result in statistically significant differences in cell viability. This could be attributed to the identical nature of materials used, including the polymer and MV, across all cases.Finally, a computational chemistry study was used to examine the interaction between polyvinyl alcohol (PVA) and vitamins K3 and B3, like a model of MV. The analysis showed four strong hydrogen bonds between PVA and vitamin B3, whereas the interaction between PVA and vitamin K3 only had one hydrogen bond. Furthermore, the PVA and vitamin B3 interaction had higher energy and was more exothermic and spontaneous than the PVA-vitamin K3 interaction. On the other hand, the PVA-vitamin K4 interaction displayed higher reactivity due to its lower separation energy. In contrast, the PVA-vitamin B3 interaction was more stable.

PVA@tea tree oil‐emulsion core–shell microfiber membranes for extending the shelf life of fruits

AbstractIn this work, a temperature‐regulating and antimicrobial–antioxidant fiber membrane was fabricated using coaxial electrospinning technology. The tea tree oil (TTO) emulsion used as the core solution, polyvinyl alcohol (PVA) as the shell solution for coaxial electrospinning, has been demonstrated. Compared with the original PVA fibers, the average diameter of the fibers is increased after coaxial electrospinning, and the diameter increases with the core flow rate. The diameters corresponding to core flow rates of 0.05, 0.1, and 0.15 mL/h are 561, 597, and 849 nm, respectively. Via in vitro release experiment demonstrated that the quantity of TTO released from the composite membrane increased with the elevation of temperature. The inclusions TTO and polyethylene glycol give the film excellent antibacterial–antioxidant properties and a delayed thermal response. More intriguingly, core–shell fiber membranes containing TTO in the core part are effective in slowing down the formation of oxidation spots on the surface of banana compared with pure PVA membranes. Seven days after wrapping bananas with different membranes, the surface of banana in pure PVA film was full of oxidized spots, whereas banana in PVA core–shell fibers showed only one obvious spot.

Polyvinyl alcohol‐based fiber membranes with high strength and ultraviolet shielding properties for enhancing the shelf life of grapes

AbstractCurrently, the rising environmental concerns caused by nonbiodegradable food packaging materials have promoted the research and development of biodegradable alternatives. Polyvinyl alcohol (PVA) was selected as the substrate, and zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO2NPs) were blended and modified with PVA, respectively. Based on the electrostatic spinning technology to prepare fiber membranes with high strength and UV blocking properties for grapes preservation. The study indicated that the tensile strength of PVA fiber membranes increased by 243% and 209% when ZnONPs and TiO2NPs were added at 1%, respectively. Under UV radiation, the PVA/ZnO composite membranes exhibited superior UV absorption than the PVA/TiO2 composite membranes. After conducting TG tests, it was found that the addition of ZnONPs decreased the thermal stability of the fiber membranes, while TiO2NPs could improve the thermal stability. Both composite membranes could extend grapes' shelf life, but the PVA/ZnO composite membranes were more effective at maintaining freshness than the PVA/TiO2 composite membranes.

Multi-scale analysis of styrene butadiene latex modified PVA fiber concrete

Polyvinyl alcohol (PVA) concrete is a new green building material. In order to make it more widely used, this study used butylbenzene emulsion (SBL) to modify PVA fiber concrete. The enhancement mechanism of SBL on the PVA/cement interface was systematically investigated at multiple scales, including macroscopic mechanical properties, microstructural characteristics, nano-interface interactions. On a macro scale, the addition of SBL and PVA fibers can significantly improve the shear strength and flexural strength of composite concrete at 7 and 28 days, and SBL can make up for the decrease in compressive strength caused by PVA. On a micro scale, the corresponding polymer cement concrete was tested by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). It was observed that some gels and polymers filled the interfacial gap and effectively repaired the interfacial defects. The SBL brought the two interfaces closer together and described its bonding effect at the micro-interface. On the nano scale, SBL/PVA/C-S-H is modeled by molecular dynamics method. Binding energy, Relative concentrations, Radial distribution function, Mean-square displacement and Time correlation function were analyzed and calculated. The results show that SBL reduces the interfacial effect, enhances the interfacial hydrogen bond, van der Waals interaction, Ca-H coordination bond and stability, improves the interfacial adhesion, and further enhances the weak interfacial bond between organic polymer (PVA) and inorganic silicate (C-S-H).