PBO Fiber Research Articles

Effects of stitching yarn types on flexural fatigue properties of 3D stitched carbon fiber composites

This work investigated the static bending and flexural fatigue properties of 3D stitched composites with different stitching yarns. The carbon and PBO fibers were adopted to reveal the effects of stitching yarn types on the fatigue characteristics and failure propagation of 3D stitched composites at low-stress levels by a high-speed camera. The results show that different stitching yarn types affected the static flexural strength of 3D stitched composites but did not affect their modulus. In addition, different stitching yarn types changed the fatigue failure mechanism of 3D stitched composites. The fatigue life of 3D stitched composites can be effectively improved by using PBO fibers since the PBO fiber can effectively delay shear crack growth and prolong the period of the catastrophic failure stage. This work proposed a new scheme for improving the mechanical properties of stitched composites.

Influence of high-temperature, high-pressure, and acidic conditions on the structure and properties of high-performance organic fibers

Abstract Aramid and poly(p-phenylene benzobisoxazole) (PBO) fibers are two of the most represented organic fibers possessing high strength, high modulus, excellent thermal stability, and chemical resistance, with great potential in oil and gas applications. The reliability of organic fibers for oil and gas applications were systematically evaluated by studying the corrosion behavior and mechanisms in high-temperature and high-pressure (HTHP) hydrogen sulfide (H2S) and carbon dioxide (CO2) corrosive environments. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), elemental analysis, density measurements, and single fiber tensile testing were conducted to study the surface morphology, chemical structure, crystal structure, thermal, and mechanical properties of aramid and PBO fibers, before and after corrosion. After corrosion, the crystallinities of aramid and PBO fibers decreased by 19.4 and 4.4%, respectively, whereas their tensile fracture strengths decreased by 50.34 and 28.18%, respectively. Hence, the corrosion resistance of PBO fiber is better than aramid fiber. The decrease in tensile properties of aramid and PBO fibers can be attributed to the higher internal porosity, more number of surface defects, and lower crystallinity after HTHP H2S/CO2 corrosion. This work provides some fundamental information regarding the selection of high-performance organic fibers for oil and gas applications.

Failure Modes of Masonry Pillars Strengthened with PBO Fibres

The paper presents compression tests of stocky and slender masonry pillars strengthened in bed joints with PBO fibres and an inorganic matrix. Five stocky pillars and four slender pillars were tested under static loading. Physical models were prepared using lime mortar similar to that used in historical structures. Fibres were applied in the grooves that were made after the mortar setting period in order to recreate real-world conditions. One of the models was subjected to preloading before the strengthening was applied. The failure modes, load-bearing capacity, cracking stresses, stiffness and deformations (longitudinal and transverse) were all determined through experimental testing. Strengthening effectiveness in terms of the increase in load-bearing capacity and stiffness, as well as anti-cracking was determined on the basis of the experimental results. The results obtained for the stocky and slender pillars were also compared, indicating the influence of slenderness on strengthening effectiveness. Special attention was also paid to failure modes and the interaction of the PBO fibres with the bed joint. Methods that strengthen pillars in their bed joints using PBO fibres increase their load-bearing capacity, stiffness and cracking resistance, while maintaining a satisfactory visual appearance which is especially important in heritage structures.

Significantly improved interfacial properties and wave-transparent performance of PBO fibers/cyanate esters laminated composites via introducing a polydopamine/ZIF-8 hybrid membrane

Polydopamine hybrid zeolitic imidazolate framework-8 (PDA*ZIF-8) membrane, synthesized by zinc nitrate hexahydrate (ZnNO3•6H2O), 2-methylimidazole (2-MI), and dopamine (DA), uniformly grows on the surface of poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibers by heterogeneous nucleation method to obtain PBO@PDA*ZIF-8 fibers. PBO@PDA*ZIF-8 fibers are then applied as the reinforcement, bisphenol A dicyanate ester (BADCy) as the matrix, and PBO@PDA*ZIF-8 fibers/BADCy wave-transparent laminated composites are prepared by high-temperature molding. Results indicate that PDA*ZIF-8 membrane increases the surface roughness and chemical activity of PBO fibers. The interlaminar shear strength (ILSS) and flexural strength of PBO@PDA*ZIF-8 fibers/BADCy laminated composites are 45.3 and 656.3 MPa, respectively, which are increased by 23.4% and 11.7% compared with those of PBO fibers/BADCy composites (587.4 and 36.7 MPa). The dielectric constant and dielectric loss values at 1 MHz are 2.76 and 0.0046, respectively, lower than PBO fibers/BADCy (3.06 and 0.006). At 0.3–40 GHz, PBO@PDA*ZIF-8 fibers/BADCy laminated composites have excellent wave-transparent performance (The simulated wave-transparent rate is greater than 87%, d = 1.5–3.5 mm). Meanwhile, the corresponding volume resistivity and breakdown strength are 3.7 × 1015 Ω•cm and 23.61 kV/mm, higher than PBO fibers/BADCy composites (2.2 × 1015 Ω•cm and 17.69 kV/mm), respectively.

Facile preparation of ultraviolet resistant “hard armors” on poly(p-phenylene benzobisoxazole) fibers through heat-induced surface treatment

In terms of high-performance organic fibers such as poly(p-phenylene benzobisoxazole) (PBO) fiber, the anti-ultraviolet (UV) property is crucial for their applications in extreme conditions. In this work, excellent UV resistance was obtained through creating a thermal oxidized PBO sheath on PBO fiber. In detail, the peripheral UV sensitive oxazole groups were transformed into non-conjusix-memberedmbered rings after heat-induced gradient thermal oxidation, which could reduce the UV sensitivity of PBO fiber and release energy produced by UV radiation through molecular vibration. The efficiency had been verified through UV-aging tests, and the results indicated that more than 90% of the fiber's tensile strength was retained and the surface defects after 800 h UV aging was also effectively decreased. There were also considerable improvements in the mechanical properties of PBO fiber. For instance, Young's modulus and compressive strength of PBO fiber increased by 33.5% and 74%, respectively, along with the absence of yield zone. Meanwhile, the interfacial shearing strength (IFSS) of PBO reinforced epoxy resin composites increased by 64% with the introduction of non-conjugated structure. The inhomogeneous reduction in rigid-rod backbones resulted in the maintenance of internal microfibrils and decrease in peripheral microfibrils, and accordingly relieved the compressive damage. Enhancement of its interfacial property possibly resulted from increased surface roughness and decreased inert rigid-rod structure.

High-Performance Dental Composites Based on Hierarchical Reinforcements

Use of high-performance fibers such as poly(p-phenylene-2,6-benzobisoxazole) (PBO) improves the mechanical properties of dental fiber-reinforced composites (FRCs). However, the surfaces of high-performance fibers are relatively inert, and the interface with the resin matrix is poor. This has become a limitation restricting the performance of PBO FRCs in dentistry. Nanomaterials were introduced onto PBO fibers to construct various hierarchical reinforcements to obtain a dental FRC with higher flexural performance and optimized interface bonding. Four hierarchical reinforcements were constructed: PBO-ZnO nanoparticles (NPs), PBO-ZnO nanowires (NWs), PBO-ZnO NPs–cage silsesquioxane (POSS), and PBO-ZnO NWs-POSS. Performance following this optimized method was evaluated at macroscale and microscale levels, including measurement of the interfacial properties and mechanical properties of FRCs. The physicochemical characteristics of PBO fibers before and after modification were measured to determine the interfacial bonding mechanisms and to verify the connection between the microinterface and macromechanical properties. The cytotoxicity of the preferred PBO FRC was evaluated using the CCK8 assay. In comparison to other designs, the interfacial shear strength (IFSS) of PBO-ZnO NWs-POSS was the highest (29.31 ± 2.40 MPa). The corresponding FRC had the highest flexural strength under a static load (925.0 ± 39.2 MPa), the flexural modulus (39.39 ± 1.41 GPa) was equivalent to that of human dentin, and in vitro cytotoxicity was acceptable. The interfacial bonding mechanisms of PBO-ZnO NWs-POSS resulted from mechanical interlocking, chemical bonds, hydrogen bonds, and van der Waals forces. In summary, the PBO-ZnO NWs-POSS hierarchical reinforcement was introduced in dental FRCs and showed remarkable enhancement of the IFSS and flexural properties. We verified that the PBO-ZnO NWs-POSS hierarchical reinforcement was successful. This PBO FRC may be applied in dentistry as a new option for endodontic posts. Our study provides an interface design strategy for developing high-performance FRCs reinforced with high-performance fibers for dental applications.

Boosting the Performance of CFRP with High Axial Compression Characteristics Fabricated Using the Filament Cover Method: Surface Modification of Sheath Filament PBO Fiber and Improvement of Reinforcing Fiber Volume Fraction

Boosting the Performance of CFRP with High Axial Compression Characteristics Fabricated Using the Filament Cover Method: Surface Modification of Sheath Filament PBO Fiber and Improvement of Reinforcing Fiber Volume Fraction

Mechanical and Dynamic Mechanical Analysis of PBO Paper-based Composites

Poly ( p-phenylene benzoisoxazole; PBO) paper is a potential raw material for use in honeycomb sandwich composites in the aerospace industry, which are able to sustain high temperatures exceeding 300°C. This work presents a wet-forming method of making PBO paper, consisting of PBO chopped fibers. The paper was impregnated with phenolic resin to simulate honeycomb wall material. The structure and mechanical and dynamic mechanical properties of the raw and impregnated paper were characterized. The performance of PBO paper was tested against p-aramid paper. The comparative results showed the tensile strength of PBO raw paper was 2.17 kN/m, which was slightly worse than p-aramid raw paper: 2.66 kN/m. After impregnation, the tensile strength of the PBO paper was 13.93 kN/m due to the increase in the number of bonding points—better than p-aramid paper: 7.99 kN/m. The tearing resistance value for PBO raw paper versus p-aramid raw paper was 3252 mN against 845 mN. The morphology of the torn samples in the impregnated paper revealed higher levels of PBO fiber pullout than p-aramid fiber, therefore the tearing resistance value was 6000 mN for PBO impregnated paper, which was again superior to p-aramid impregnated paper: 675 mN. The PBO paper also showed higher storage modulus than p-aramid paper after impregnation. Experimental studies showed that PBO paper could be used in load-bearing structures and in honeycomb components where high resistance to deformation and thermal stability is necessary.

Enhancing interfacial adhesion and mechanical performance ofPBOfibers composites through mussel‐inspired molecular regulation of interphase structure

AbstractPoor interfacial properties are always one of the bottleneck problems limiting the development of the PBO fiber/epoxy composites. To solve this, we demonstrated a mussel‐inspired molecular regulation strategy of interphase structure using the layer‐by‐layer construction of rigid (PDA) and flexible (PEI) molecules without fiber structure damage. The precise control on the molecular scale can maximally increase the roughness and polar functional group on the fiber surface, thus enhance the chemical bonding and the mechanical interlocking of the interfacial adhesion. In comparison with the untreated fiber, the IFSS and ILSS value of fiber with (PDA/PEI)n have an increment of 86.85% and 80.08%, respectively. Besides, the overall mechanical performance, such as impact strength and dynamic thermal‐mechanical behavior, was also improved significantly, owing to the improved physical‐mechanical attributes of the interphase. In brief, our study presents a non‐destructive interface regulation of PBO fiber composite to enhance its interfacial adhesion and mechanical performance and optimize its structure/function integrated design.

Surface Graft Modification of Domestic PBO Fiber by Atmospheric Air Plasma

Surface Graft Modification of Domestic PBO Fiber by Atmospheric Air Plasma

Calcia-doped ceria hybrid coating functionalized PBO fibers with excellent UV resistance and improved interfacial compatibility with cyanate ester resins

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers display weak outdoor stability and reliability due to their poor UV resistance and chemically inert surface. In this work, calcia-doped ceria (Ce0.8Ca0.2O1.8) nanoparticles was fabricated via chemical co-precipitation method, and the novel Ce0.8Ca0.2O1.8/P(S-co-BCB-co-MMA) organic–inorganic hybrid coating was then designed and prepared for surface functionalization of PBO fibers (PBO@P-Ce0.8Ca0.2O1.8). Organic-inorganic hybrid coating presents high surface roughness and excellent UV resistance. When the concentration of Ce0.8Ca0.2O1.8 nanoparticles with the particle size of about 50 nm is 0.6 wt%, PBO@P-Ce0.8Ca0.2O1.8–3 fibers (sample 4, 0.6 wt%) present the best interfacial bonding strength with modified bisphenol A cyanate (BADCy) resins, the single fiber pull-out strength between sample 4 and modified BADCy resins reaches the maximum value of 4.6 MPa, 48.4% higher than that of pristine PBO fibers (sample 0, 3.1 MPa). Meanwhile, the tensile strength of sample 4 after 288 h UV aging is increased from 1.4 GPa (PBO fibers) to 4.1 GPa. Overall, functionalized PBO fibers in this work demonstrate higher surface activity, excellent UV resistance and improved interfacial bonding strength with modified BADCy resins, which provides a new idea for functionalizing the surface activity and UV resistance of high-performance polymer fibers.

Facile functionalization strategy of PBO fibres for synchronous improving the mechanical and wave-transparent properties of the PBO fibres/cyanate ester laminated composites

A copolymer of P(S-co-BCB-co-GMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization was coated on the surface of poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibres, followed by grafting 2, 2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (AHHFP) to obtain 6F-PBO@P-GMA fibres. The corresponding 6F-PBO@P-GMA fibres/modified cyanate ester wave-transparent laminated composites are then fabricated. The introduction of copolymer membrane and AHHFP reduces interfacial polarization and enhances the interfacial strength of the wave-transparent laminated composites. The corresponding flexural strength and interlaminar shear strength (ILSS) of the 6F-PBO@P-GMA fibres/modified cyanate ester wave-transparent laminated composites are 701.5 and 46.4 MPa, 19.3% and 12.9% higher than those of laminated composites reinforced by pristine PBO fibres, respectively. Meantime, the obtained wave-transparent laminated composites also possess the lowest complex permittivity, and wide high wave-transparent rate area at X-band (|T|2 > 93.5%, thickness: 0–2.10 mm).

Facile and environment-friendly mussel-inspired surface modification of PBO fibers via dopamine/3-aminopropyltrimethoxysilane co-deposition for advanced composite

The surface of poly(p-phenylene benzobisoxazole) (PBO) fibers was modified by a hybrid coating composed of polydopamine (PDA) and the hydrolysis products of 3-aminopropyltrimethoxysilane (KH551) using a facile and environment-friendly mussel-inspired co-deposition strategy. The surface morphologies and chemical composition of the obtained hierarchical reinforcement (PBO@PDA/Si) were measured for confirming the successful deposition of the coating. Compared to untreated PBO fiber, the surface roughness and wettability of PBO@PDA/Si were increased remarkably. Importantly, PBO@PDA/Si showed a 50.2% increase in the interfacial shear strength (IFSS) of resulting composite without any decrease in its tensile strength (TS). In addition, its atomic oxygen (AO) erosion and hydrothermal aging resistances were significantly improved. The “one-step” mussel-inspired surface modification strategy starts from simple chemistry and cheap raw materials, and may provide a novel and versatile design for fabricating multifunctional hierarchical reinforcements.

Optimization of PBO fibers/cyanate ester wave-transparent laminated composites via incorporation of a fluoride-containing linear interfacial compatibilizer

Bisphenol A dicyanate ester (BADCy) was utilized as the matrix, poly (p-phenylene-2, 6-benzobisoxazole) (PBO) fibers as the reinforcement, and synthesized fluorine-containing linear PBO precursor (preFLPBO) as the interfacial compatibilizer to prepare PBO fibers/FLPBO-m-BADCy wave-transparent laminated composites. The fluorine groups and PBO-like structures could respectively improve the dielectric properties of BADCy matrix and the interfacial compatibility between the BADCy matrix and PBO fibers. Additionally, the partly interpenetrating network formed between preFLPBO and BADCy could significantly improve the mechanical properties. PBO fibers/FLPBO-m-BADCy wave-transparent laminated composites with 7 wt% preFLPBO displayed the optimal comprehensive performances. Dielectric constant (ε) and dielectric loss (tanδ) were respectively 2.90 and 0.0042, and the corresponding theoretical wave-transmittance (|T|2) at 1 MHz was 93.3%, higher than that of PBO fibers/BADCy wave-transparent laminated composites. The minimum percentage of simulated electromagnetic wave-transparent energy (ET (simulation)) of the PBO fibers/FLPBO-m-BADCy (1 mm) wave-transparent laminated composites at 0.3~40 GHz was 87.3%, also better than PBO fibers/BADCy wave-transparent laminated composites (85.9%). The flexural and interlaminar shear strength (ILSS) of PBO fibers/FLPBO-m-BADCy wave-transparent laminated composites were increased from 587.4 and 36.7 MPa to 628.0 and 44.8 MPa, respectively. In addition, the corresponding volume resistivity and breakdown voltage were 2.7 × 1015 Ω·cm and 19.12 kV/mm, respectively.

Grafting of CNTs onto the surface of PBO fibers at high-density for enhancing interfacial adhesion, mechanical properties and stability of composites

To improve the interfacial adhesion and mechanical performance of PBO fiber composites, CNTs were uniformly grafted onto them at a high-density. The grafting of CNTs with massive reactive groups can improve the surface wettability and interfacial interaction of PBO fibers with epoxy resin. The IFSS and ILSS values of themodified composites (PBO-CNT-3) increased by 103.09 and 62.73%, respectively. As CNTs can strengthen interfacial regions of the composites, the mechanical properties (hardness and modulus) of the interphase were enhanced significantly. This led to the effective transfer of interfacial load, elimination of stress concentration, and improvement in the structural stability of the composites. As a result, the impact strength of the modified composites (PBO-CNT-3) was up to 103.76 kJ/m2 (an increase of 56.24%) compared to the original composites. The surface morphology and deformation behavior of the fractured composites indicate that the interfacial failure mode of the composites grafted with CNTs changes from adhesive failure to both cohesive and substrate failure. This strategy of grafting CNTs at a high-density opens a new avenue for the interfacial regulation of structural composites, ultra-capacitor, sensor, and catalytic materials.

The effect of different grafting extent of PBO‐MoS2 hybrids on the tribological performance of TPI‐based composites at high temperatures

AbstractThe self‐assembled hybrids were synthesized as a kind of filler with the function of reinforcing and lubricating, by which can improve its dispersion in the matrix, and enhance the interfacial adhesion with the matrix. However, the effect of the amount of grafting on the hybrid properties is still unclear. In this study, a series of antiwear hybrids with different grafting amount were synthesized and further be used to reinforce thermoplastic polyimide matrix. The method of comparative analysis had been applied to analyze the microstructural morphology, thermal property, mechanical property, and high temperature tribological behavior of these composites. The results indicated that with the increasing grafting amount of MoS2 on the PBO fiber surface in a certain range, the integrated performance of the composite increases.

Surface modification of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane in supercritical carbon dioxide for enhancing interfacial strength

PBO fiber is one of the most promising reinforcements in resin matrix composite because of its excellent mechanical properties. However, the inert and smooth surfaces make it the poor interface adhesion with resin matrix, which seriously limits the application in composites. In this article, we report a method to modify the surface of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane（BisAPAF）in supercritical CO2 to enhance interfacial properties. Chemical structures, surface elemental composition and functional groups, and surface morphology were characterized by FT-IR spectrometer, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were tested by a tensile tester. Static contact angle and microdebonding tests were used to characterize the wetting ability and interfacial shear strength (IFSS) of the fiber and epoxy resin. The results showed that the BisAPAF could be solved in scCO2 and introduced more groups, –NH2, –OH, and –CF3 on the fiber surface, resulting in the mechanical properties and the wettability of PBO fiber slightly improved. Moreover, the fiber surface roughness was also increased obviously. The IFSS between the modified PBO fiber and epoxy resin increased from 8.18 MPa to 31.4 MPa when the treating pressure was 14 MPa. In general, the method to modify PBO fibers surface using BisAPAF in scCO2 can effectively improve their interfacial properties.

UV etched random copolymer membrane coated PBO fibers/cyanate ester wave-transparent laminated composites

Poly (p-phenylene-2,6-benzobisoxazole) fibers treated by random copolymer P(S-co-BCB-co-MMA) membrane and UV etching (UV-PBO@P fibers) are performed as reinforcement, bisphenol AF/amantadine modified bisphenol A cyanate ester (AEAF-co-BADCy) resin as polymeric matrix, and the UV-PBO@P fibers/AEAF-co-BADCy wave-transparent laminated composites were then fabricated. When the P(S-co-BCB-co-MMA) membrane thickness is 62.3 nm and the UV etching time is 96 h, UV-PBO@P fibers display the best interfacial compatibility with AEAF-co-BADCy resin, and the corresponding wave-transparent laminated composites present the optimal comprehensive performance. Interlaminar shear strength (ILSS) and flexural strength are 50.2 and 745.6 MPa, 27.4% and 21.6% higher than those (ILSS of 39.4 MPa, flexural strength of 613.3 MPa) of pristine PBO fibers/AEAF-co-BADCy wave-transparent laminated composites, respectively. And the composites possess low complex permittivity and tanδ, corresponding |T|2 in the X band is 88.9–94.2%. High-frequency structural simulation (HFSS) results demonstrate that the radome from the composites displays high |T|2 of 89.1–93.1% in the X-band, close to the theoretical calculation value. This work provides a certain theoretical guidance for fabricating lightweight, high strength, and high |T|2 polymer matrix wave-transparent composites, and further broadens the application of PBO fibers and cyanate ester resins in aviation/aerospace, 5G communication services, electronic information, and other fields.

Synergistically enhanced ultraviolet aging resistance and interfacial adhesion of poly (p‐phenylene benzobisoxazole) fiber with soluble naphthalimide sizing

AbstractAmino‐terminated naphthalimide (NDI) with ultraviolet (UV) absorptivity was synthesized to sizing on poly(p‐phenylene benzobisoxazole) (PBO) fiber surface, and UV aging resistance PBO fiber and interfacial adhesion of their composites was investigated. Compared with pristine PBO fiber, the surface chemical activity and roughness of NDI‐PBO fiber were increased. In comparison with pristine PBO fiber, tensile strength, intrinsic viscosity ([η]), and diameter of NDI‐PBO fiber showed a better retention, and the enhanced UV‐aging resistance was verified by hardly visible macroscopic defects on NDI‐PBO fiber. Meanwhile, transverse fiber bundle test strength of NDI‐PBO fiber composites was promoted by stronger mechanical interlocking and chemical interaction. The synergistic improvement in UV aging resistance and interfacial adhesion of PBO fiber was attributed to undamaged crystal and molecular structure from UV protection effects of NDI layer and strong chemical bonding between reactive groups of NDI and epoxy matrix.

Comparative studies of nitrogen plasma and argon plasma treatment on the strength of PBO fibre reinforced high-temperature resistant thermoplastic composite

The study involves the processing of a novel poly [1, 4-phenylene-cis-benzobisoxazole] (PBO) fibre reinforced high-temperature thermoplastic composite with polyaryletherketone (PAEK) as the matrix. The PBO fibre and the PAEK film surface was modified using the method of argon and nitrogen plasma treatment. The investigation primarily focuses on evaluating the tensile properties of the fabricated laminates and correlating it with the effect of plasma treatment, surface characteristics, and its fracture surface. A 5% decrease in tensile strength was observed post argon plasma treatment while a 27% increase in strength was observed post nitrogen plasma treatment. The morphology of the failure surface was investigated by scanning electron microscopy and an interfacial failure was observed. Furthermore, the effect of plasma on the wettability of PBO fibres and PAEK film surface was confirmed by the Dynamic Contact Angle analysis and sessile drop method respectively. FTIR spectral analysis was done to investigate the effect of plasma treatment on the chemical structure on the surface. The results of the wettability study showed that the argon plasma treatment of the fibre surface increased its hydrophobicity while nitrogen plasma treatment resulted in the reduction of contact angle.