Glass Fiber Surface Research Articles

Modeling sizing emulsion droplet deposition onto silica using all-atom molecular dynamics simulations

Understanding structure–function relationships of the matrix–fiber interphase is important for the future design of composites with enhanced performance. This interphase structure is determined in part by sizing, an emulsion of epoxy film-former, silane coupling agent , and surfactant applied to fibers prior to work-up and resin impregnation . The multicomponent, microphase-separated nature of sizing makes it difficult to study using experiments and continuum-level simulations. In this study, microsecond all-atom molecular dynamics (MD) simulations are used to elucidate the dynamics of complex multicomponent sizing droplets on glass fiber surfaces. We analyze droplet/surface properties such as spreading factor, component density profiles, and spatial distribution of hydrogen bonds. From these observables, we show that the triblock copolymer surfactant enhances wetting of the epoxy resin film former on the glass surface, whereas the silane coupling agent slows down the spreading by pinning the droplet via siloxyl-surface hydrogen bonding. This work takes a step toward systematic understanding of the functionality of sizing in allowing pre-cured resin to wet glass surfaces in the context of composite lay-up. • Spreading dynamics of sizing droplets on silica depend on their composition. • Coupling agents deposit in rings that pin droplet contact lines and slow spreading.

Influence of graphene nanoplatelet concentration on the electrical, mechanical, and piezoresistive properties of glass fiber/epoxy composites

AbstractThis paper reports the effect of weight concentration of graphene nanoplatelets (GNPs) on the electrical, mechanical, thermo‐mechanical, and piezoresistive properties of unidirectional glass fiber/epoxy composite laminates. The neat (without GNPs) and multiscale laminates (with GNPs) were fabricated with different GNPs contents (0.25, 0.50, 0.75, and 1.00 wt%) using a simple and feasible process based on spray coating followed by vacuum assisted resin infusion. The morphological analysis on glass fiber surfaces evidenced the presence of an effective GNP network formation which tends to be denser as GNPs content increases. As a result, the electrical conductivity and gauge factor measured on top and bottom surfaces of specimens were greatly increased in laminates. Short beam shear and flexural test results showed that the addition of GNPs to the laminates causes a significant reduction in their interlaminar shear strength, flexural strength, and strain to failure with respect to the neat laminate. However, the flexural modulus of laminates does not suffer any apparent change in its reference value and the glass transition temperature was slightly increased in samples with 1.00 wt% GNPs. The fractographic analysis revealed that delamination was the main damage mechanism detected upon mechanical testing, suggesting that relative high concentrations of GNPs cause that interlaminar regions of laminated composites become weaker. In spite of this, excellent strain self‐sensing capabilities and internal damage detection were observed during flexural electromechanical tests performed in beam‐type specimens with higher GNP content.

Highly reusable chitosan-stabilized Fe-ZnO immobilized onto fiberglass cloth and the photocatalytic degradation properties in batch and loop reactors

The new design of the photocatalytic reactor is crucial to study for improving compatibility and scaling up the operation. A compatible loop photocatalytic reactor has been designed and used for rhodamine B decomposition. The photocatalysts were either ZnO or Fe-ZnO immobilized onto fiberglass cloth. The ZnO catalyst exhibited high crystallinity with or without Fe as the dopant. The crystallite size increased with the presence of Fe in the lattices. Most of the crystal parameters matched the standard ZnO data, and the cluster size was comparable to most reported studies. Diffuse Reflectance Spectroscopy (DRS) analysis confirmed the photon absorption shifted to the visible light range. The Fe dopant decreased the ZnO bandgap, and SEM-EDS confirmed the catalysts adhered to the fiberglass surface. The volume, thickness of the substrate solution, and reaction temperature influenced the photocatalytic-degradation rate. The photocatalytic degradation rate was higher under sunlight than ultraviolet irradiation. The reaction rate was lower in the batch reactor than in the loop reactor. The photocatalytic reaction almost completely mineralized RhB and changed the red solution to colorless. The immobilized photocatalyst has been reused more than 50 times without significantly decreasing the catalytic activity.

The influence of carbon-glass/epoxy hybrid composite under mode I fatigue loading: Physical-based characterization

The aim of this study was to characterize the mechanical behavior of a carbon-glass/epoxy hybrid composite under cyclic loading and following physical-based interpretation for mode I delamination modeling. The hybrid composite shows a higher surface roughness due to a micro-change in the crack direction at the carbon/epoxy and glass/epoxy interfaces, with the simultaneous presence of both reinforcements along the entire fracture surface. The organosilane bond (at the glass fiber surface) extends the interphase chain, increasing the deformation interfacial area. In conclusion, the application of the maximal carbon-glass/epoxy interfacial number in hybrid laminates is a feasible option to increase delamination resistance, since a greater amount of energy needs to be overcome to enable damage formation, which results in longer fatigue life.

Modification of the Interfacial Glass Fiber Surface Through Graphene Oxide-Chitosan Interactions for Excellent Dye Removal as an Adsorptive Membrane

Modification of the Interfacial Glass Fiber Surface Through Graphene Oxide-Chitosan Interactions for Excellent Dye Removal as an Adsorptive Membrane

A CRISPR/Cas12a-assisted on-fibre immunosensor for ultrasensitive small protein detection in complex biological samples

Tracking trace amounts of analytes directly from low volumes of complex biological samples remains an ongoing challenge in precision diagnostics, as the commonly used immunosorbent assays have limited sensitivity. Herein, a CRISPR/Cas12a assisted on-fibre immunosensor (CAFI) was developed based on an antibody-analyte-aptamer sandwich structure, in which a single strand DNA aptamer was applied to detect the analyte while triggering the CRISPR/Cas12a fluorescent detection system to amplify the analyte signal. This novel CAFI biosensing system was fabricated on a glass fibre surface with an antifouling PEG polymer brush modified for the detection of a spectrum of small molecules from complex media. In comparison with a conventional ELISA system, CAFI has a 1,000-fold higher sensitivity with the limit of detection for IFN-γ down to 1 fg mL−1 (58.8 aM). It also has a tuneable linear detection range that can be easily adjusted within the range 1 fg mL−1 to 100 pg mL−1 (5 orders of magnitude), meeting the requirements of the demanding diagnostic scenarios. CAFI has successfully been demonstrated by detecting IFN-γ from a diverse complex biological sample type, including human serum, whole blood, perspiration, and saliva. Moreover, CAFI is applicable for the detection of other analytes by simply modifying the capture antibody and detection aptamer, demonstrated here with insulin. All these superior capabilities of CAFI make it a suitable technology to measure proteins in low (100 μL) volume complex biological samples.

A Review of Glass Fibre Recycling Technology Using Chemical and Mechanical Separation of Surface Sizing Agents

Glass fiber is widely used in various modern industrial applications because it has the advantages of good electrical insulation performance and good process ability. Inevitably, some flawed glass fiber generated during manufacturing processes becomes waste and, in recent years, the treatment or recycling of glass fiber waste has become an environmental concern. Since glass fiber is brittle, non-wearing, and can easily generate static electricity after friction, the surface of glass fiber must be coated with a wetting agent (i.e., surface sizing agent) to overcome these disadvantages. However, glass fiber waste cannot be directly recycled as glass raw materials due to the presence of the surface sizing agent and the high content of sodium element. Therefore, there is a need to develop a feasible technology for removal of surface sizing agent in order to recycle glass fiber waste. In this study, two methods were used to remove surface sizing agent from glass fiber waste. After removing the surface sizing agent, the treated glass fiber waste can replace sand particles for manufacturing controlled low-strength material (CLSM). The first method for removing surface sizing agent used different organic solvents such as ethyl acetate to dissolve the surface coating (i.e., surface sizing agent). Then, an optical microscope was used to observe the surface changes before and after such removal treatments. The second method involved grinding glass fiber waste into a fine powder and heating it to a high temperature. An X-ray diffractometer (XRD) and X-ray fluorescence (XRF) were used to analyze the surface characteristics of the glass fiber waste. The experimental results showed that different organic solvents could not effectively remove the surface sizing agent, even if the glass fiber waste was processed by ultrasonic vibration for 5 h. In contrast, after high heating at 800 °C for 2 h, the surface sizing agent could be removed, and glass fiber waste transformed to cristobalite. The CLSM concrete produced by mixing cristobalite with cement in an appropriate proportion can meet the CLSM specification standard in Taiwan.

Synthesis of a self-assembly amphiphilic sizing agent by RAFT polymerization for improving the interfacial compatibility of short glass fiber-reinforced polypropylene composites

This experimental study focuses on the development of an amphiphilic sizing agent to improve the interfacial adhesion and the mechanical properties of short glass fiber (GF)/polypropylene (PP) composites. To solve the critical compatible issue between the hydrophilic GF and the hydrophobic PP, we strategically utilized the reversible addition-fragmentation chain-transfer (RAFT) polymerization to self-assemble and synthesize an amphiphilic sizing agent. This surfactant-free sizing agent can create hydrogen bonds and electrostatic adsorption on GF surfaces and meanwhile can form molecular entanglements, alkyl cations, and σ-π conjugates with PP matrix. The FT-IR analysis shows that a large number of hydrogen bonds are formed on the sizing agent-GF interface. Additionally, the SEM micrographs of the composite fracture surfaces demonstrate strong interfacial compatibility between the sized-GF and the PP matrix. Comparing with the neat GF/PP composites, the tensile and flexural strength of the sized-GF/PP composites are increased by 25.8% and 33.1%, respectively. Their tensile strength and young's modulus are in close agreement to the analytical calculations. In short, this paper presents a new RAFT-based methodology to develop the amphiphilic sizing agents that are able to improve the interfacial compatibility of GF/PP composites and also can be transferred towards real applications for enhancing the mechanical properties of fiber-reinforced composites.

Interlaminar fracture toughness properties of hybrid glass fiber-reinforced composite interlayered with carbon nanotube using electrospray deposition

Abstract The electrospray deposition (ESD) method was used to deposit carbon nanotubes (CNTs) onto the surface of glass fiber (GF). The morphology of the hybrid CNTs-GF was analyzed using a field emission scanning electron microscope, and the images indicated that the CNTs were uniformly and homogenously deposited onto the GF’s surface. Laminated composite based on GF and hybrid CNTs-GF were then fabricated via vacuum-assisted resin transfer molding. The mode I interlaminar fracture toughness was measured using the double cantilever beam test method. The hybrid CNTs-GF showed a 34% increase in fracture toughness relative to the control sample. The mechanism of interlaminar fracture toughness enhancement was elucidated via fractography, where fiber bridging, adhesive and cohesive failures, hackles, and coarse matrix surface were observed along the crack pathways.

Hierarchical epoxy based composites prepared by chemical vapor deposition of carbon nanocoils on glass fibers

ABSTRACT The objective of this work was to grow carbon nanocoils (CNCs) on the glass fiber (GF) surface by chemical vapor deposition (CVD) and to prepare laminated composites by hand lay-Up, where CNC-coated GF is reinforcing phase. Spring-like CNCs were obtained at 600°C, whereas single helix CNCs were found over the glass fiber surface at 700°C. The presence of CNCs on the GF surface was confirmed using SEM analysis, TEM analysis, I–V analysis, etc. The CNC- coated GF-based epoxy composites were characterized for their mechanical properties. C7GE specimen showed lower mechanical properties compared to the GF epoxy specimens, while C6GE composite exhibited the best properties. Flexural strength and flexural modulus improved by about 35%, 56%, respectively, and storage modulus and glass transition temperature also increased by about 42% and 11%, respectively, compared to GF/epoxy specimen. SEM images exhibit good interaction between epoxy and GF when GF is modified by 600°C CNC.

Effect of the addition of aliphatic diamine-functionalized carbon nanotubes on the interfacial adhesion of glass fiber/epoxy composites

To improve the interfacial adhesion of glass fiber (GF)/epoxy composites, the GF surface was treated by dispersing aliphatic diamine-functionalized multi-walled carbon nanotubes (MWCNTs). Carboxyl MWCNTs were first modified by aliphatic diamine with different alkyl chain lengths and then deposited on the surface of GF. The effect of aliphatic diamine chain lengths on the MWCNTs’ dispersion and interfacial properties of resultant composites was investigated in detail. The results showed that uniform dispersion of MWCNTs and strong fiber/matrix interfacial adhesion could be achieved, based on the grafting of 1,8-octanediamine onto MWCNTs. Compared with the control sample, the interlaminar shear, flexural, and tensile strengths of the treated composites increased by 41%, 29%, and 30%, respectively; the interlaminar fracture toughness and storage modulus in the glass region were significantly enhanced; and the glass transition temperature increased by more than 8°C. This work demonstrates that the carbon nanotubes functionalized by appropriate chain lengths of amine modifier can improve the fiber/matrix interfacial interactions and thus enhance the strength, toughness, and stiffness of fiber-reinforced composites.

Photocatalytic Degradation of Skim-Latex-Vapor Odor Using Iron-Doped Zinc Oxide

The photocatalytic degradation of the vapor odor of skim natural rubber latex, which is composed of volatile organic compounds (VOCs-NR), was conducted using iron-doped zinc oxide (Fe-ZnO) photocatalyst nanoparticles. The research objectives were to study the photocatalyst, to develop the photocatalytic reactor used for the photodegradation of VOCs-NR, and to analyze the odor reduction of the degraded VOCs-NR. Fe-ZnO was prepared by the sol-gel method and immobilized onto fiberglass cloth as the support material, followed by annealing. The Fe-ZnO nanoparticles were dispersed on the fiberglass surface. A photocatalytic reactor was developed for the gas phase. The research findings showed that gas chromatography-mass spectroscopy detected 24 dominant chemical components in the VOC-NR stock before photocatalytic degradation. The components decreased to 11 after 30 min, only 3 components remained after 40 min of the photocatalytic process, and no component was observed after 80 min of photoirradiation. An organoleptic test was conducted to validate that the odor degraded to a very low level.

Mode II delamination of carbon-glass fiber/epoxy hybrid composite under fatigue loading

This work proposes a mechanistic model to evaluate and characterize the mode II delamination of carbon-glass/fiber hybrid composites under fatigue loading. To this aim, crack growth was investigated at microscopic and macroscopic levels to measure the delamination propagation based on fracture mechanisms. The energy balance principle method described the energy release of the hybrid composite, evidencing greater energy available for fatigue delamination growth. The physics-based explanation for this enhancement is associated with the rougher fractured surface (tortuous propagation) due to the change in crack direction in the two reinforcements, stiffness synergy between the two fibers, and the silane coupling agent at the glass fiber surface. The proposed mechanistic model was used to analyze the physical-based behavior of the delamination of the hybrid and non-hybrid laminates, evidencing the contribution of each reinforcement to the SERR, with similar results at microscopic and macroscopic levels.

Investigation of the Wetting Process of Glass Fiber with Oligophenylene Sulfide Sulfone

The wettability of reinforcing fillers such as glass and carbon fibers is a significant factor influencing the mechanical properties of the composite. This study focuses on the effect of finishing glass fiber surfaces with different concentrations of oligophenylene sulfide sulfone solution on fiber wettability, which is determined by contact angle and wetting time. The Adam-Schütte method was chosen as a method for determining the contact angle. According to the study results a 1.5% solution of oligophenylene sulfide sulfone in N, N'-dimethylacetamide gives a contact angle of 45°, forming over time a thin film on the fiber surface, which indicates a sufficiently high sizing ability.

Spinning of Endless Bioactive Silicate Glass Fibres for Fibre Reinforcement Applications

Bioactive glasses have been used for many years in the human body as bone substitute. Since bioactive glasses are not readily available in the form of endless thin fibres with diameters below 20 µm, their use is limited to mainly non-load-bearing applications in the form of particles or granules. In this study, the spinnability of four bioactive silicate glasses was evaluated in terms of crystallisation behaviour, characteristic processing temperatures and viscosity determined by thermal analysis. The glass melts were drawn into fibres and their mechanical strength was measured by single fibre tensile tests before and after the surface treatment with different silanes. The degradation of the bioactive glasses was observed in simulated body fluid and pure water by recording the changes of the pH value and the ion concentration by inductively coupled plasma optical emission spectrometry; further, the glass degradation process was monitored by scanning electron microscopy. Additionally, first in vitro experiments using murine pre-osteoblast cell line MC3T3E1 were carried out in order to evaluate the interaction with the glass fibre surface. The results achieved in this work show up the potential of the manufacturing of endless bioactive glass fibres with appropriate mechanical strength to be applied as reinforcing fibres in new innovative medical implants.

Identification of Carbon in Glassy Cesium-Bearing Microparticles Using Electron Microscopy and Formation Mechanisms of the Microparticles

The author previously proposed that glassy cesium-bearing microparticles [resulting uniquely from the Fukushima Daiichi nuclear power station (FDNPS) accident] may have been formed by melting and atomization of glass fibers (GFs) of the high-efficiency particulate air filter in the standby gas treatment system line due to the flame and blast during the hydrogen explosion in Unit 3. Assuming that this hypothesis is correct, Type A could contain or accompany carbon, which ignites spontaneously above 623 K, because of the limited time to be heated up, the inclusion of carbon in the binder applied on the GF surface, and the closely located charcoal filter. As previous studies have not identified carbon, the present analyses were performed with an electron probe microanalyzer to determine whether Type A contains carbon. The results show that Type A contained carbon originating from the binder. Some nonspherical particles were accompanied by Type A, and the film surrounding Type A contained more carbon, which is thought to originate from the charcoal filter. These results cannot be explained by the other mechanisms proposed so far and can be explained consistently only by the author’s proposed hypothesis. Although it may be premature to determine Type A formation mechanisms, this information enables one to limit the temperature conditions of Type A formation.

Roles of the Coupling Agent and Surfactant in Droplet Structure in Sizing Emulsions: A Molecular Dynamics Simulations Study

Sizing emulsions used as glass fiber surface treatments in composites manufacturing are aqueous suspensions of hydrophobic film formers, surface coupling agents, and surfactants. We employ all-atom molecular dynamics simulations to characterize droplet structures in several aqueous blends of the film-former diglycidyl ether of bisphenol A, coupling agent glycidoxypropyl trimethoxysilane, and a triblock copolymer surfactant (Pluronic L35 PEO/PPO copolymer). We show that the quasi-equilibrium states of emulsion droplets are invariant to different initial configurations. We examine the role of the surfactant in determining coupling agent partitioning between the droplet shell and corona and coupling agent cluster size distributions. This work takes a step toward systematic understanding of the sizing chemistry to optimize the interface between the glass and the resin in commercially relevant composites.

Research on drilling CFRP laminate with a thin woven glass fiber surface layer using plane rake–faced twist drill

The delamination produced during drilling CFRP will affect its structural strength seriously. Delamination is closely related to the thrust force during drilling, which is closely related to the tool, so it is particularly important to choose the tools with appropriate geometric structure. Many scholars used tools with different geometric structure to drill CFRP, and then conducted the drilling damage analyses and drilling mechanism researches. It finally came to a conclusion that a drill with a special structure had certain advantages compared with a common twist drill in the drilling process. A new type of plane rake–faced twist drill was used to drill the CFRP laminate with a thin-woven glass fiber surface layer. Experimental results showed that the plane rake–faced twist drill along cutting edge had a constant reference rake angle value, which caused the plane rake–faced twist drill generated smaller thrust force and less drilling damage than the common twist drill. As the reference rake angle of the plane rake–faced twist drill increased, the thrust force and drilling damage decreased. It was revealed the inhibition of the thin-woven glass fiber surface layer on the drilling damage at entrance and exit. Finally, it was proposed that when the plane rake–faced twist drill was used to drill CFRP laminate with a thin-woven glass fiber surface, 46° reference rake angle should be selected.

Properties of Microfibers of Various Compositions as a Component of Cellular Composites

The paper presents studies on the properties of various types of micro-reinforcing fibers to assess their role and effectiveness in the structure formation of the cellular composite. Based on the data on the weight loss after exposure in a model medium of cement, analysis of the alkali resistance of fibers of five different types – basalt fiber, heat-treated basalt fiber, polymer fiber and glass fibers from two different manufacturers – was carried out. It is shown that the fibers have a sufficiently high durability in the medium of hardening cement, which is expressed by a relatively insignificant weight loss of the original fiber after exposure in a model medium for 28 days in ambient conditions. The weight loss for some fibers sharply increases when hardening conditions are changed to hydrothermal ones. The images of fibers exposed in a model medium of cement, obtained using scanning microscopy, were also analyzed, and the character of distribution of acidic and basic adsorption sites on the surface of fibers depending on the type was assessed. Based on the analysis of the obtained data, we can talk about a high number of active sites on the surface of basalt and glass fibers, which ensures the formation of crystalline new formations on them and makes it possible to predict their high adhesion to the cement matrix.

Interfacial flame retardant unsaturated polyester composites with simultaneously improved fire safety and mechanical properties

The low flame retardant efficiency and poor interfacial property are the main problems that confine the wide application of glass-fiber reinforced unsaturated resin (GUPR) composites. Herein, these problems are effectively solved by grafting modified silane coupling agent on the surface of glass fiber and adding multi-element hybrid flame retardant to matrix. Firstly, phosphorus-containing flame retardant interface modifier (PKH550) and Sulfur-containing flame retardant (PCH3-S) were synthesized, and the structures were confirmed by Nuclear Magnetic Resonance spectroscopy (NMR) of 1H and 31P. Then PKH550 was successfully grafted on the surface of glass-fiber. Notably, compared with PGF/UPR 20% which had no rating in UL-94 test, the use of PKH550 modified glass-fiber made MGF/UPR 20% reached the V0 rating, and the limiting oxygen index (LOI) value was as high as 38%. In addition, with the increase addition of PCH3-S, the flame retardant properties of GUPR composites were gradually improved. Finally, the mechanical properties of GUPR composites had been improved further by the plasma method. Compared with the 296.93 MPa tensile strength of PGF/UPR, the tensile strength of P-PGF/UPR prepared after plasma treatment of glass-fiber increased to 319.27 MPa. This work provides a new angle to simultaneously improve the fire safety performance and mechanical properties of materials, which will not only be limited to the application of unsaturated resins, but can also have a rather good application prospects in other flame-retardant materials.