PBO Fiber Research Articles

Enhanced thermal conductivity and insulating properties of PBO fiber grafted AlN/BN/PBO films for electronic packaging

Enhanced thermal conductivity and insulating properties of PBO fiber grafted AlN/BN/PBO films for electronic packaging

Mussel-inspired polydopamine functionalized PBO fibers as an efficient additive for UHMWPE composites with improved tribological performance

It is important to prepare self-lubricating polymers with low friction coefficient and wear rate. Herein, poly(p-phenylene-2,6-benzobisoxazole) fibers coated with polydopamine (PBO@PDA) were synthesized and introduced to enhance the tribological performances of the UHMWPE composites. The PBO@PDA, with a rough surface and a PDA layer of 13 nm thickness, exhibited a robust interfacial interaction with the UHMWPE matrix. The thermal stability of the UHMWPE composites steadily improved with the increasing content of PBO@PDA due to the enhanced thermal stability and char-forming ability of PBO@PDA. In addition, the presence of PBO@PDA also enhanced the rigidity and crystallinity of the UHMWPE composites. The UHMWPE composite containing 2 wt% PBO@PDA exhibited the best tribological performance with a friction coefficient of 0.042 and a wear rate of 2.38 × 10-5 mm3/N·m, which were maximally reduced by 76 % and 32 %, respectively, as compared with those of pure UHMWPE. The addition of PBO@PDA increases the hardness of the UHMWPE composites, thereby improving their wear resistance. Furthermore, the incorporation of PBO@PDA contributes to the formation of lubricating films. However, the high content of PBO@PDA can lead to aggregation, which deteriorates friction performance. This work offers a feasible approach to reducing the friction and wear on UHMWPE lubricated materials.

Study on interface toughening mechanism based on modified PBO fiber for CFRP/ plastic honeycomb sandwich structure

CFRP (carbon fiber reinforced composites)/honeycomb sandwich structures are widely used in aerospace, automotive, and high-speed rail industries due to their excellent mechanical properties and lightweight characteristics. This study investigates the impact of three designed toughened interfaces on the three-point bending performance of honeycomb structures. The results show that introducing a multiscale toughened interface made of poly(p-phenylene benzobisoxazole) (PBO) fibers grafted with polydopamine (PDA) and multi-walled carbon nanotubes (CNT) increases the peak load and post-peak load of the sandwich structure by 49.7 % and 51.9 %, respectively, and the absorbed energy by 92.4 %. This toughened interface adjusts the stress relationship between the panel, interface, and honeycomb, altering the deformation process and crack propagation mode of the sandwich structure. The micro-nano fibers form fiber bridging at the interface, changing the crack extension mode between the interfaces, transforming the delamination from a single debonding to the combined action of plate core debonding and honeycomb core buckling. Additionally, experimental results show that PBO fibers treated with PDA and CNT exhibit significantly improved surface roughness, Surface area per unit mass, wettability, and tensile strength, which delay and prevent crack propagation at the interface, effectively reducing panel debonding at the bonded joints.

Improving UV aging resistance by loading PDA on the surface of PBO fibers via Fe (III) coordination

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber is currently one of the best-performing organic fibers; however, its low UV aging resistance limits its use. To improve the UV aging performance of PBO fibers, a novel PBO-Fe-PDA fiber was created by depositing a biomimetic structure of polydopamine (PDA) on the surface of PBO fibers with the transition metal ion Fe3+ as the active center. The surface morphology and elemental composition of PBO-Fe-PDA fibers were investigated. It was revealed that Fe3+ formed a coordination bond structure with the oxazole ring, and PDA was successfully loaded onto the surface of PBO-Fe fibers. After UV aging, the crystallinity and crystallographic orientation of PBO fibers significantly decrease, microcrystals inside the fibers slip, and the size of microvoids in the fibers rises. As a result, the strength of PBO fibers was significantly decreased after UV aging. The anti-UV aging capacity of PBO-Fe-PDA fibers, on the other hand, has been enhanced, as evidenced by a slight drop in crystallinity and crystallographic orientation and a significant decrease in the size growth of internal microvoids in the fibers after UV aging. The tensile strength retention of PBO-Fe-PDA fibers after UV aging increased by 93.13% when compared to PBO fibers without altering the fibers’ initial strength. The testing results show that this surface modification method is simple to employ and extends the service life of PBO fibers significantly.

Assessing the stress-transfer capability of mineral impregnated PBO yarns in a limestone calcined clay cement-based (LC3) matrix

Technical textiles made of poly(p-phenylene-2,6-benzobisoxazole) (PBO) represent attractive candidates for strengthening and repairing damaged concrete and masonry structures, due to the outstanding durability and mechanical performance of PBO fibres. Similarly to their aramid counterparts, PBO fibres have proved very effective against dynamic and impact loading. In this contribution, the pull-out behaviour of PBO multifilament yarns embedded into a blended cement-based matrix is investigated, with particular reference to its stress-transfer capacity. In addition to the as-received PBO yarns, impregnation with a cement-based suspension, which can fully preserve the inorganic nature of the composite system, is also evaluated. Experimental results are presented and interpreted using a one-dimensional mechanical model. The findings indicate that mineral impregnation of the yarns provides a 40% increase in the stress-transfer capacity with the matrix, corresponding to a halving of the anchoring length. These performance gains are also supported by a transition in the failure mechanism which shifts from friction-based pull-out to fibre rupture.

Preparation of continuous PBO fiber-filled silicone rubber with high thermal conductivity through simple Wrapping

With the development of the electronics, the demand for flexible thermal materials with high thermal conductivity continues to rise. Here, we report a type of thermally conductive silicone rubber (SR) prepared using continuous poly (p-phenylene benzobisoxazole) fiber (PBO). Through a process consistent with the layer stacking principle, continuous fibers are first immersed with SR or boron nitride (BN)/SR and then wound layer by layer onto a mold. Then, PBO/SR and PBO/BN/SR composites were prepared in the laboratory. In these composites, PBO fibers can directly form numerous thermal paths. Additionally, due to the traction and compression between fibers during the winding process, BN is distributed along the fibers. It allows BN to better form independent thermal paths and, together with PBO fibers, create a thermal network in SR. The thermal conductivity of PBO/SR and PBO/BN/SR composites can reach 5.656 W m−1 K−1 and 7.853 W m−1 K−1, respectively, with PBO and BN contents of 20 vol% and 10 vol%, respectively.

Significantly improved interfacial properties of silicon dioxide nanowire functionalized poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers/polytetrafluoroethylene (PTFE) wave-transparent laminated composites

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber and polytetrafluoroethylene (PTFE) resin have been widely acknowledged as excellent wave-transparent materials for future high-frequency applications due to their exceptional dielectric properties. However, the weak interfacial bonding between these two materials hampers their full potential. In this study, we successfully addressed this limitation by enhancing the surface roughness of PBO fibers and introducing active sites through the in-situ grafting of silica nanowires. The added silica acted as an interfacial anchor on the PBO fiber surface, significantly improving the bonding force between PBO and PTFE. PBO/PTFE wave-transparent laminated composites were fabricated using hot compression molding. The results demonstrate that the PBO (treated with in-situ grown silica)/PTFE laminated composites exhibit superior interlaminar shear strength (ILSS), flexural strength, flexural modulus, and tensile modulus compared to the pristine PBO/PTFE laminated composites. Specifically, these properties are found to be 58.6%, 32.9%, 138.1%, and 25.35% higher, respectively. Additionally, these composites demonstrate low dielectric constant and dielectric loss. Most notably, they achieve a wave transmittance of 91.45% at 10 GHz, indicating significant potential for wide-range applications in next-generation advanced military weapons, such as “lightweight/high-strength/wave-transparent” electromagnetic window materials, as well as civilian communication base stations.

De novo biosynthesis of 2-hydroxyterephthalic acid, the monomer for high-performance hydroxyl modified PBO fiber, by enzymatic Kolbe–Schmitt reaction with CO2 fixation

BackgroundHigh-performance poly(p-phenylenebenzobisoxazole) (PBO) fiber, with excellent mechanical properties (stiffness, strength, and toughness), high thermal stability combined and light weight, are widely employed in automotive and aerospace composites, body armor and sports goods. Hydroxyl modified PBO (HPBO) fiber shows better photostability and interfacial shear strength. 2-Hydroxyterephthalic acid (2-HTA), the monomer for the HPBO fiber, is usually synthesized by chemical method, which has poor space selectivity and high energy consumption. The enzymatic Kolbe–Schmitt reaction, which carboxylates phenolic substrates to generate hydroxybenzoic acids with bicarbonate/CO2, was applied in de novo biosynthesis of 2-HTA with CO2 fixation.ResultsThe biosynthesis of 2-HTA was achieved by the innovative application of hydroxybenzoic acid (de)carboxylases to carboxylation of 3-hydroxybenzoic acid (3-HBA) at the para-position of the benzene carboxyl group, known as enzymatic Kolbe–Schmitt reaction. 2,3-Dihydroxybenzoic acid decarboxylase from Aspergillus oryzae (2,3-DHBD_Ao) were expressed in recombinant E. coli and showed highest activity. The yield of 2-HTA was 108.97 ± 2.21 μg/L/mg protein in the whole-cell catalysis. In addition, two amino acid substitutions, F27G and T62A, proved to be of great help in improving 2,3-DHBD activity. The double site mutation F27G/T62A increased the production of 2-HTA in the whole-cell catalysis by 24.7-fold, reaching 2.69 ± 0.029 mg/L/mg protein. Moreover, de novo biosynthetic pathway of 2-HTA was constructed by co-expression of 2,3-DHBD_Ao and 3-hydroxybenzoate synthase Hyg5 in S. cerevisiae S288C with Ura3, Aro7 and Trp3 knockout. The engineered strain synthesized 45.40 ± 0.28 μg/L 2-HTA at 36 h in the CO2 environment.ConclusionsDe novo synthesis of 2-HTA has been achieved, using glucose as a raw material to generate shikimic acid, chorismic acid, and 3-HBA, and finally 2-HTA. We demonstrate the strong potential of hydroxybenzoate (de)carboxylase to produce terephthalic acid and its derivatives with CO2 fixation.

PBO fiber grafted rGO aerogel/BN/PBO composites with highly improved electromagnetic interference shielding effectiveness and through-plane thermal conductivity

With the advancement of electronic devices, the generation of heat and electromagnetic (EM) waves has increased. Therefore, it is essential to properly manage these heat and EM waves, while ensuring the flame retardancy and mechanical properties of the materials used in these devices. In this study, to compensate for the low thermal and electrical conductivity of Poly(p-phenylene-2,6-benzobisoxazole) (PBO), which was used as the matrix, reduced graphene oxide aerogel (rGOA) with high electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) performance and boron nitride (BN) with high thermal conductivity were selected as fillers (rGOA/BN). To significantly improve the compatibility of the filler with the matrix, PBO fiber was grafted onto the rGOA/BN filler. The fabricated composites exhibited high electrical conductivity of 21.1 S/cm and thermal conductivity of 4.81 W/m∙K, and the EMI SE and tensile strength were improved to up to 78.42 dB and 201.8 MPa, respectively.

Comprehensive studies of the influence of superficial strengthening with the FRCM system on the load‐bearing capacity and deformability of AAC walls

AbstractThis article presents the results of tests on walls made of AAC (autoclaved aerated concrete) strengthened with the FRCM system. The effect of the applied strengthening was determined based on the results of tests on masonry models subjected to compression, diagonal compression and shear. Models of walls without strengthening, strengthened on one and two sides were tested. The research models were built of masonry elements made of autoclaved aerated concrete (AAC) SOLBET OPTIMAL 4/600. The walls were erected on a system thin‐layer mortar, class M5, without filling the head joints. PBO fiber meshes embedded in a mineral matrix were used as superficial reinforcement. The walls were strengthened by applying the PBO‐MX GOLD MASONRY system mortar to the side surfaces of the models and the PBO‐MESH GOLD 22/22 mesh was embedded in it, and then the top layer of the PBO‐MX GOLD MASONRY system mortar was applied. The compressive strength test was performed on 18 models in accordance with the requirements of the PN‐EN 1052‐1: 2000 standard. In the case of compression, additional tests were performed on models weakened by a cut imitating cracking. The diagonal compression test was performed on 18 models in accordance with the requirements of ASTM E519‐81 standard. The shear load test was performed on 27 models in accordance with the requirements of the PN‐EN 1052–3: 2004 standard. A clear increase in load capacity in each type of test was noted in models strengthened on two sides. In models strengthened on one side, the positive effect of strengthening was observed only by increasing the deformability of the wall. Regardless of the test type, the use of surface reinforcement allowed for smoother behavior of the test models after the loss of load capacity in relation to models without strengthening.

Synergistically enhanced interfacial and wave-transparent properties of PBO fiber composites: Constructing self-assembly interphase with different dimensional COF

Naphthalimide-linked covalent organic framework (COF) with two-dimensional (A-COF and B–COF) and three-dimensional structure (M-COF) was designed and applied to self-assembly on PBO fiber surface, and the influences of 2D or 3D COF on interfacial and wave-transparent properties as well as their reinforcing mechanisms of composites were investigated. A-COF and M-COF exhibited higher BET surface area and porosity compared to those of B–COF, and the morphology of 2D and 3D COF respectively presented lamellar nanosheet and random particle aggregation. The dense inner COF layer and numerous nanocrystals were attached on 2D COF@PBO fiber, and 3D COF@PBO fiber surface showed nano-porous structures from M-COF nanoparticle stacking. Compared with pristine PBO fiber composites, transverse fiber bundle tensile (TFBT) strength and interfacial shear strength (IFSS) of A-COF@PBO and B–COF@PBO fiber composites were increased by 38.76% and 51.77%, 37.23% and 43.94% due to lamellar stacking structure of 2D COF, while 15.31% and 19.56% increment for M-COF@PBO fiber composites, which was attributed to the weaker binding force between PBO fiber and 3D COF from interpenetrated structure. The optimal wave transmission efficiency (|T|2) at low frequency was obtained for A-COF@PBO fiber composites, resulting from the highest porosity of A-COF and best interfacial compatibility, while M-COF@PBO fiber composites showed the best |T|2 at high frequency due to the higher porosity and scarce electron-coupling phenomenon of M-COF.

Boosting interfacial adhesion in PBO fiber/epoxy composite by employing finely granular-structured polyaniline as an interfacial intensifier

Poor interfacial adhesion of composites deriving from the surface smoothness and inertness of poly (p-phenylene benzobisoxazole) (PBO) fibers severely constrains the extensive application of the fillers. Constructing the functional coating is generally considered a non-destructive and scalable strategy to simultaneously improve the asperity and activity of PBO fiber surfaces. Herein, we report a facile method to boost the interfacial adhesion in PBO fiber/epoxy composite by employing finely granular-structured polyaniline (PANI) as an interfacial intensifier. Via a mild and efficient in situ polymerization technique, the positively charged micron-scale PANI particles are uniformly anchored onto the negatively charged PBO fibers to form delicate leather-like surface layer containing substantial amino groups. Meanwhile, the resulting PBO fibers maintain excellent mechanical properties. Therefore, the PANI-coated PBO fiber/epoxy composite (PBO@PANI/EP) shows the significant increase in interfacial shear strength (41.0 MPa) and interlaminar shear strength (44.9 MPa), soaring by 60.16 % and 54.83 %, respectively. The debonding behavior and fracture surfaces confirm that the interfacial failure mechanism of PBO@PANI/EP converts from adhesive failure to both cohesive and substrate failure. The strategy in this work to modify PBO fiber surfaces for increasing the interfacial combination of composite is cost-effective and feasible to scale up.

Preparation and Structural Behavior of High-Performance PBO Fibers

To improve the dispersion ability of monomers in the high-viscosity PBO pre-polymerization system, a new large-capacity mixing paddle for PBO pre-polymerization reaction was designed. Through simulated calculation, it was found that the new mixing paddle has good dispersion effect and produced PBO polymer whose intrinsic viscosity was 37.5 dL/g, number-average molecular weight was 92700, and degree of polymerization was 396. Then the PBO fibers were prepared by the dry jet wet spinning technique. The morphology analysis showed that the PBO fibers were well formed, with a diameter of 14 µm. The infrared spectrum analysis verified the structure of PBO fibers. The mechanical test showed that the tensile strength of PBO fibers was 5.04-5.76 GPa and the elongation at break was 3.93% - 4.54%, which means they have good mechanical properties.

Research progress in molecular dynamics of high-performance PBO fibers

This article reviews the application and development of molecular dynamics in the field of poly(p-benzobisoxazole) (PBO) molecules, including the use of molecular dynamics simulations to calculate the theoretical Young’s modulus of PBO molecules and discuss them from the perspective of molecular theory Combine the rotational isomerism state theory with the long molecular dynamics simulation of small fragments to evaluate the limit length of the persistence vector a. The molecular dynamics calculation is used to study the molecular motion behavior of isolated rigid rod molecules such as PBO. Combining computer simulation technology and X-ray diffraction data collected by the imaging board system to analyze the crystal structure of the PBO fiber, and use molecular dynamics and dynamic modeling to establish the PBO/epoxy interface and study its performance.

Development of Graphene /PBO Nanocomposite

The study of graphene/poly (p-phenylene benzobisoxazole) (PBO) nanocomposites in recent years is introduced, while the research interests and application fields of graphene/PBO nanocomposites in the future are prospected in this review. In the process of polymer formation, two modification methods, in-situ polymerization modification and blending modification are mainly used to improve the dispersion uniformity of graphene in the PBO matrix. The polymer can be divided into the surface modification of PBO fiber and the modification of PBO nanofiber according to the existing state of PBO, and the effects of two modification methods on mechanics, thermal characteristics, surface morphology and aging resistance of graphene/PBO nanocomposites are compared.

Latest Research Progress in Modification Technologies of PBO Fibers

This paper focuses on the modification technologies of Poly (p-phenylene benzobisoxazole) (PBO) fibers and their research progress. It is found that the modification of compression resistance, surface inertia, and ultraviolet (UV) aging resistance of PBO fibers can greatly promote the wide application of PBO fibers in advanced composites. More researches are yet to be done on the new modification technologies of PBO fibers in compression resistance, and the future development direction of surface modification and UV aging resistance modification is towards realizing non-destructive modification and large-scale and industrialized online treatment.

An ‘active site anchoring’ strategy for the preparation of PBO fiber derived carbon catalyst towards an efficient oxygen reduction reaction and zinc–air batteries

The PBO–Fe–PDA-900 electrocatalyst developed from PDA protected Fe modified PBO fibers displays an overall superior electrocatalytic activity for the ORR and zinc–air batteries.

Pipeline Processing via the Combination of Heat and Corona Treatments for Improving the Poly(p-phenylene benzobisoxazole) Fiber Surface and Anti-Aging Performances.

Although many strategies have been reported for modified poly(p-phenylene benzobisoxazole) (PBO) fiber surfaces, the absence of approaches with the potential of applications in industries limits the further applications of the fibers in a wide field. Herein, PBO fibers are modified by heat treatment combined with corona discharge treatment, which is a continuous industrialized method. Then, the surface morphology, wettability, orientation, and crystallinity of the PBO fibers are characterized in detail. Systematic experiments demonstrate that the high thermal treatment can improve the orientation and crystallization degree of the fibers, as well as the degradation resistance. In addition, owing to the synergistic mechanism of ozone and high-frequency shock, the corona discharge treatment increases the contents of O and N elements on the surfaces, which improves the superficial properties of the fibers. Based on the modification of PBO fibers, the inter-laminar shear strength between the fiber and the resin for the composite increases to 94.8%, and the tensile strength of the composite increases to 29.2%, compared to those using untreated fibers. In general, the proposed modification strategy not only easily improves the surface properties and the mechanical properties of composites but also can be used with great potential in industrial production.

Experimental studies on stocky masonry pillars strengthened with steel cords and PBO fibres

This paper presents a study of stocky masonry pillars strengthened by stainless steel cords and PBO fibres in bed joints. Ten physical models were used in experimental testing, of which 3 served as reference specimens and the remaining seven were confined in bed joints using different techniques. The pillars were constructed with lime mortar with parameters similar to those used in historical structures. To assure conditions similar to the real objects steel cords and PBO fibres were placed in grooves, which were made in the pillars after the mortar had set. The main failure mechanisms, ultimate load-bearing capacity and longitudinal and transverse deformations were determined through the experimental testing. In addition, the longitudinal stiffness and the stresses at which cracking appears were determined on the basis of observations and analysis of experimental results. The strengthening effectiveness was also determined in relation to the increase in load-bearing capacity, stiffness and cracking stresses. The methods used for strengthening stocky pillars in bed joints increase their load-bearing capacity, stiffness and counteract cracking without any significant impact on the visual appearance of the pillars, which is especially important in the strengthening of historic structures.

Tropocollagen-Inspired Hierarchical Spiral Structure of Organic Fibers in Epoxy Bulk for 3D High Thermal Conductivity.

Polymers are usually considered thermal insulators; however, significant enhancements in thermal conductivity (k) have been observed in oriented fibers and films. Despite being advantageous in real-world applications, extending the linear thermal-transport advantage of polymers into the 3D space in bulk materials is still limited due to the spatially interfacial phonon-conduction barriers. Herein, inspired by the structure of tropocollagen, it is discovered that weaving hierarchically arranged poly(p-phenylene benzobisoxazole) (PBO) fibers with a spiral configuration into an epoxy matrix can yield a 3D continuous thermal pathway. This achieves both a through-plane k of 10.85W m-1 K-1 and an in-plane k of 7.15W m-1 K-1 . Theoretical molecular simulations in combination with classical nonlinear modeling attribute the above spatially thermally conductive achievement to not only the hierarchical molecular, spiral and weaving structure of PBO, but also the noncrystalline chains that carry overlapping phonon density of states, thus thermally bridging adjacent high-k crystals in the PBO fiber. Consequently, the interfacial thermal resistance among high-k PBO crystals is suppressed to be on the order of 10-10 m2 K W-1 in both the through-plane and in-plane directions. Other advantages include being lightweight, mechanically strong, flexible, and non-combustible. This material creates opportunities for organic polymers in high-performance thermal management applications.