EP Composites Research Articles

Phytic acid doped polyaniline-coupled g-C3N4 nanosheets for synergizing with APP promoting fire safety and waterproof performance of epoxy composites

In this study, polyaniline-coupled graphitic carbon nitride (g-C3N4) doped with phytic acid (CP@PA) hybrids are prepared by an in-situ chemical oxidative method. The CP@PA and APP (Ammonium Polyphosphate) are added into epoxy resin (EP) for EP composites. The characteristic test results show that CP@PA can react with epoxy resin (EP) to promote the curing of EP. And CP@PA disperses in EP uniformly. The cone calorimetry test (CCT) results show that the pHRR, THR, and TSP of EP-8A4CP@PA (the EP sample with 8.0 wt% APP and 4.0 wt% CP@PA) reduce 85%, 76.8%, and 78.9%, respectively than EP-0 (pure EP), which are lower than any other samples. The results of the back temperature test show that EP-8A4CP@PA has better thermal insulation and flame-retardant properties than EP-12APP (the EP sample with 12.0 wt% APP). Moreover, CP@PA promotes the waterproof properties of EP with APP composites by synergizing with APP to form a labyrinth effect. After a comprehensive analysis, the fire protection mechanisms of EP-8A4CP@PA are proposed as follows. CP@PA promote EP charring and make more aromatic structure remain in the char. And CP@PA has a synergistic effect with APP to promote EP to form porous intumescent char layer with a higher graphitic degree, which protects the composites from the flame. As a result, the combination of CP@PA and APP in EP achieved a lower addition of flame retardant and better waterproof and fire safety performance, which provides a specific experimental and theoretical basis for the further application of CP@PA in epoxy resin.

NiFe prussian blue analogue nanocages decorated magnesium hydroxide rod for enhancing fire safety and mechanical properties of epoxy resin

Inspired by the structure of corn, a NiFe Prussian blue analogue nanocages decorated magnesium hydroxide composite was synthesized for the first time using magnesium hydroxide rods (RMH) as the “corn cob”, a Prussian blue analogue (PBA) as the “corn kernels” and polydopamine (PDA) as the membrane linking RMH and PBA. Subsequently, the RMH@PDA@PBA composite was introduced into epoxy resin (EP) to improve its fire retardancy and mechanical properties. The composition, structure and morphology of the RMH@PDA@PBA-incorporated EP composite were investigated. The tensile strength of EP with 3 wt.% RMH@PDA@PBA reached 41.77 MPa, which is higher than that of neat EP (40.51 MPa). The fire-retardant assessments illustrated that the limiting oxygen index and vertical burning tests (UL-94) of EP composite with 3 wt.% RMH@PDA@PBA progressed to 32.3% and the V-0 level as compared to those of virgin EP (24.4% and no rating). In addition, as compared to virgin EP, the peak heat release rate , peak smoke production rate, total heat release at 200 s and total smoke production at 200 s of EP/3RMH@PDA@PBA decreased by 43.1%, 50.0%, 43.9% and 56.3%, respectively. The investigation of the underlying mechanism revealed that the flame retardancy and smoke suppression of EP/3RMH@PDA@PBA were attributed to the endothermic decomposition of RMH, “gauze barrier” mechanism of MgO/FeO, catalytic charring effect of Fe derivatives (MgO/FeO, FeNi 3 , Fe 5 C 2 , Fe 2 N, etc.) and free radical scavenging effect of PBA@Fe[Ⅲ]. Thus, this study on bio-inspired hierarchical nanostructures paves a new pathway for the efficient production of fire-safe polymers. • A novel low-cost RMH@PDA@PBA with corn structure was first prepared. • The RMH@PDA@PBA significantly improves the fire safety of epoxy resin. • 3 wt.% RMH@PDA@PBA endowed epoxy resin with UL-94 V-0 and reduced smoke production. • The addition of RMH@PDA@PBA enhanced the mechanical properties of epoxy resin.

A novel carbon fiber/MXene coalition prepared by a bidirectional diazotization strategy: Properties and applications

A novel carbon fiber/MXene coalition (CF-Ar-MXene) is synthesized via a bidirectional aryl diazonium chemistry method using p-phenylenediamine as a chemical bridge, which effectively combines the two materials with different dimensions and makes full use of the advantages of both. CF-Ar-MXene coalition materials achieve high surface roughness and rich oxygen-containing active groups due to the presence of MXene on the surface of CF, which leads to the favorable interfacial interaction and compatibility between CF-Ar-MXene and epoxy resin (EP) matrix. As expected, after the incorporation of CF-Ar-MXene coalition into EP matrix, the flame retardancy and mechanical properties of EP composites are significantly improved. For example, with the addition of 3 wt% CF-Ar-MXene coalition, the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of EP composites decrease by 42.6%, 48.2% and 32.1%, respectively. Meanwhile, the TG-IR results indicate that the amount of combustible volatile products and toxic gases also significantly decrease. Notably, with 2 wt% loading of CF-Ar-MXene coalition in EP composites, the tensile strength and elongation at break increase by 49.9% and 40.5%, respectively. Therefore, the efficient cooperation between CF and MXene in CF-Ar-MXene coalition and excellent interface compatibility with EP matrix are the main reasons for the excellent flame retardancy and mechanical properties of EP/CF-Ar-MXene composites.

Novel pH-responsive self-healing anti-corrosion coating with high barrier and corrosion inhibitor loading based on reduced graphene oxide loaded zeolite imidazole framework

Utilization of self-healing coating is an efficient strategy for protecting metals from corrosion. However, rational design and synthesis of self-healing nanomaterial with excellent barrier property and high loading rate of corrosion inhibitor is still a challenge. Herein, the obvious physical barrier properties of graphene and the self-healing function of zeolite imidazole framework-8 (ZIF-8) was combined (RGO@ZIF) based on the concept of composite coating with "passive barrier" body and "active self-healing" guest. Herein, as a coordination complex, ZIF-8 can store and release inhibitors (2-methylimidazole) through the formation and cleavage of coordination bonds. Moreover, silica was supported on the ZIF surface (RGO@ZIF@SiO2) to compensate for the negative impact of the remaining voids after ZIF decomposition on the barrier properties of the coatings. The UV–vis results proved that ZIF-8 displayed outstanding pH-responsive activities under acidic conditions, and the loading capacity was up to 63.0%. Therefore, ZIF-8 was proposed as a solid corrosion inhibitor, which is expected to provide a new way to improve the loading rate of inhibitors. The EIS results showed that the impedance values of ZIF/EP, RGO@ZIF/EP and RGO@ZIF@SiO2/EP composites coatings increased inversely with the prolongation of immersion time, attributing to their self-healing performance. Besides, the epoxy loaded 0.7% of RGO@ZIF@SiO2 exhibited the higher impedance value than that of other samples in the whole immersion stage, which can be ascribed to the excellent barrier properties. Moreover, the corrosion products and bubbles on the surface of RGO@ZIF@SiO2/EP (0.7%) sample were the least after 200 h of exposure in salt spray test, further proving its best corrosion protection performance.

Fully aminated rigid-rod aramid reinforced high strength epoxy resin and its composite with carbon fibers

Poly(p-aminophenylene aminoterephthalamide) ((NH2)2-PPTA), a new organo-soluble fully aminated rigid-rod aramid has been synthesized by the polycondensation of nitroterephthalic acid and 2-nitro-1,4-phenylenediamine and then hydrogenation-reduction of the nitro side groups. (NH2)2-PPTA was then used as the modifier of epoxy resin (EP) and carbon fiber (CF)/EP composites and their mechanical properties were systematically investigated. Because all the benzene rings in (NH2)2-PPTA contain amino side groups, (NH2)2-PPTA has excellent solubility in organic solvents and EP. In addition, the amino side groups are able to react with the matrix so as to effectively integrate the rigid-rod (NH2)2-PPTA into the cross-linked molecular network of EP and facilitate the stress transfer between EP and (NH2)2-PPTA. The tensile and flexural properties and notch impact strength of EP are greatly increased with the addition of only 0.5 wt% (NH2)2-PPTA. Unusually high tensile strength and flexural strength have been achieved, which reach 140.6 ± 4.1 MPa and 237.9 ± 12.3 MPa, respectively. Moreover, addition of a small amount of (NH2)2-PPTA also significantly improves the flexural strength, toughness and the interlaminar shear strength of CF/EP composites. Compared with previously reported nanofillers and other rigid-rod polymers, (NH2)2-PPTA shows better reinforcing and toughening effect for EP and CF/EP composites owing to its great solubility, reactivity and inherent great mechanical properties.

A new‐type terephthalonitrile derivative flame retardant of bi‐DOPO compound with hydroxyl and amino groups on epoxy resin

AbstractA new‐type flame retardant DEZ of bi‐DOPO compound containing bi‐hydroxy and two amino groups, was synthesized from terephthalonitrile, hydroxylamine hydrochloride, and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide, and used with curing agent 4,4′‐diamino‐diphenylmethane to prepare flame retard epoxy resin (EP) composites. 1H and 31P nuclear magnetic resonance spectra and Fourier transform infrared spectra have determined the chemical structure of DEZ. The properties of cured EP composites were explicitly evaluated by differential scanning calorimeter, thermogravimetric analysis, the limiting oxygen index (LOI), vertical burning (UL‐94) test, cone calorimetry test, and flexural test. The 1 wt% addition of DEZ could improve the EP composites by almost 14.4% of flexural strength and 29.6% of flexural modulus, respectively. The LOI of EP composites with 5 wt% of DEZ was 29.7% and EP composites reached a V‐0 rating in the UL‐94 test, as well as total heat release was decreased by 11.2%. All EP modified by DEZ exhibited a blow‐out effect in the combustion process, which was due to the release of pyrolysis gases and incombustible gases containing phosphorus radicals and nitrogen compounds.

Application of Carbon Nanotubes from Waste Plastics As Filler to Epoxy Resin Composite.

Carbon nanotubes (CNTs) are promising nanofillers to enhance the mechanical performance of polymers. Through catalytic conversion, waste plastics can be converted into CNTs, which could be an alternative to commercial CNTs (cCNTs). Exploring a practical application of waste-plastic-derived CNTs will largely promote the technology development related to waste plastic management and CNT production. In this work, CNTs produced from plastics, named pCNTs, were applied as fillers to epoxy resin (EP), while commercial CNTs (cCNTs) were used as a reference. The carboxyl groups were effectively inserted on the CNT skeleton by a facile purification and modification. After ultrasonic dispersion, the modified pCNTs (M-pCNTs) were uniformly dispersed and loaded in the EP matrix. Better mechanical properties than EP were attained with a Young’s modulus of 3776.9 MPa, a tensile strength of 37.3 MPa, a fracture strain of 6.32%, and a fracture strength of 111.7 MPa with 2 wt % M-pCNT loading. Thus, pCNTs enhanced the toughness of the EP composites and simultaneously retained the stiffness. It was suggested that CNT pull-out and bridging were predominant toughening mechanisms for pCNT/EP composites. Notably, the coated film developed between residual metal in M-pCNTs and EP built a strong interfacial interaction and reinforced the EP composites.

The effects of chemical grafting 1,6-hexanediol diglycidyl ether on the interfacial adhesion between continuous basalt fibers and epoxy resin as well as the tensile strength of composites

The poor interfacial adhesion between continuous basalt fibers (CBFs) and epoxy resin (EP) is enhanced via chemical grafting aliphatic chains on CBFs surface. 3-aminopropyltriethoxysilane (KH550) play a role of bridge to link 1,6-hexanediol diglycidyl ether (HDE) chains and CBFs surface. Subsequently, CBFs-g-KH550-g-HDE/EP composites are fabricated from laminating process. The existence of HDE chains on CBFs surface not only improve the mutual infiltration between CBFs-g-KH550-g-HDE and EP matrix to reduce the structural defects at interface, but also enhance the interfacial adhesion to promote the effective load transfer between CBFs-g-KH550-g-HDE and EP matrix. Based on these factors, the tensile strength of composite is significantly improved. The reinforcing effect of CBFs-g-KH550-g-HDE is also related with its surface roughness. When sufficient aliphatic chains covered the entire surface of CBFs with a homogeneous thickness (smooth surface), the tensile strength of composite increased by 56 % compared with the neat CBFs/EP counterpart. When limited or excessive molecules are decorated on CBFs surface, the rough surface become structural defects to weaken the reinforcing effects of fibers.

Improving the flame retardancy of epoxy resin with ZIF‐67@GO‐PA nanohybrid as filler

AbstractDespite many important industrial applications, epoxy resin (EP) suffers from high flammability. To solve the problem, functionalized graphene oxide with Co‐MOF and phytic acid (ZIF‐67@GO‐PA) was successfully prepared. Subsequently, 2 wt% of ZIF‐67@GO‐PA nano‐hybrids were added into EP. Base on the fire test results, the limiting oxygen index value of EP/ZIF‐67@GO‐PA enhances to 29.4% and its UL‐94 achieves V‐0 rating. Moreover, compared with pure EP, the peak heat release rate and total release rate are dramatically decreased by 57.4% and 25.7%, respectively. In addition, the fire growth index was reduced by 64.0%. These superior fire safety properties are due to the catalytic effect of metal oxide and phosphorous compounds produced during the combustion of ZIF‐67@GO‐PA, and the barrier effect of the graphene oxide. Because the denser char blocks the diffusion of heat during combustion, the fire hazard of EP composites is reduced.

Functionalizing mesoporous silica with a nano metal–organic phosphonate towards mechanical‐robust, thermal‐resistant, and fire‐safety epoxy resin

AbstractEpoxy resin (EP) has featured many industrial and practical applications, but was plagued by its inherent flammability. Herein, a hybrid flame retardant (mSiO2@TETP) was fabricated by in‐situ immobilizing tin ethylenediamine tetramethylene phosphonate (TETP) on the mesoporous silica (mSiO2) surface, and was used to prepare mechanical‐robust, flame‐retardant, and thermal‐resistant EP composites. It is found that the introduction of only 1.0 wt% mSiO2@TETP into EP leads to a 20.5%, 19.7%, and 12.8% incremental tensile modulus, tensile strength, and impact strength, respectively. The EP composite with 5.0 wt% mSiO2@TETP (EP/mSiO2@TETP‐5) succeeds to the UL‐94 V‐0 grade, with a limiting oxygen index value of 29.0%. And the peak heat release rate, total heat release, peak smoke production rate, total smoke release, and peak CO production rate of EP/mSiO2@TETP‐5 decrease by 54.0%, 52.1%, 53.9%, 51.1%, and 55.7%, respectively in contrast with the values of pure EP. Moreover, the introduction of mSiO2@TETP results in an improvement in both the charring capacity and the initial thermal resistance (an increment in the glass transition temperature) of EP.

Novel bioderived cross-linked polyphosphazene microspheres decorated with FeCo-layered double hydroxide as an all-in-one intumescent flame retardant for epoxy resin

A green and facile strategy for preparing high-efficiency flame retardants is highly desirable given today's increasingly environmentally friendly requirements. In this study, novel bioderived cross-linked polyphosphazene microspheres (PHDTs) were synthesized through polycondensation with tannic acid and 4,4′-dihydroxybiphenyl as co-monomers and decorated by layered double hydroxide (PHDT@FeCo-LDH) to improve the flame retardancy of epoxy resin (EP). Comparison with pure EP revealed that the EP containing 4.0 wt% PHDT@FeCo-LDH exhibited the highest LOI of 29.7 and a UL-94 V-0 rating. Furthermore, the peak heat release rate , total heat release, and total smoke release of the modified EP were significantly reduced and were superior to most of its previously reported counterparts. The PHDTs could be regarded as an all-in-one bioderived intumescent flame retardant for catalyzing the formation of the highly graphitized char layer of a phosphorus-containing cross-linking network in the EP matrix. The transformation of the LDH shell into refractory oxides on the surface of the matrix during combustion further strengthen the structure and thermal stability of the char layer, which effectively inhibited the release of toxic and flammable gases. The flame retardant performance of the modified microspheres was mainly attributed to catalytic charring, free-radical scavenging, and physical barrier effects. Notably, the mechanical properties of the EP composites were improved to meet the requirements of industrial application. This work provides a new methodology for the preparation of high-performance EP composites.

Influence of Beta-Cyclodextrin Functionalized Tin Phenylphosphonate on the Thermal Stability and Flame Retardancy of Epoxy Composites

To enhance the thermal stability and flame retardancy of epoxy resin (EP), beta-cyclodextrin (β-CD) is successfully introduced into the layered tin phenylphosphonate (SnPP), which is incorporated into EP matrix for preparing EP/β-CD@SnPP composites. The results indicate that the addition of β-CD@SnPP obviously improve the thermal stability and residual yield of EP composites at higher temperature. When the amount of β-CD@SnPP is only 4 wt%, EP/4β-CD@SnPP composites pass V-1 rating, and LOI value is up to 30.8%. Meanwhile, β- CD@SnPP effectively suppress the heat release and reduce the smoke production of EP/β-CD@SnPP composites in combustion, and the peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR) of EP/6β-CD@SnPP composites reduce by 28.4%, 33.0% and 44.8% by comparison with those of pure EP. The good flame retardancy and smoke suppression are ascribed to the synergistic effect of excellent carbon-forming capability and fire retardancy of β-CD@SnPP.

Effect of organic-modified nickel phyllosilicate on the non-isothermal cure kinetics and flame retardancy properties of epoxy composites.

In this study, silane agents were employed as organic silicon to synthesize organic-modified nickel phyllosilicates (NiPS), which were then introduced into epoxy resin (EP) to yield composites. The effects of these organic-modified NiPS on the curing behavior and flammability of epoxy composites were then investigated carefully. Though the added NiPS resulted in the initial temperature shifts to high temperature, the whole curing temperature ranges for EP composites became narrow regarding pure EP. Simultaneously, the activation energy of curing was also decreased, implying the lowered energetic barrier during the whole curing process. For all investigated samples, the overall reaction orders varied negligibly, and the predicted curves fitted well with the DSC thermograms. Finally, the positive influence derived from the presence of these organic-modified NiPS on the enhancement of self-extinguishing ability and limited oxygen index were also discussed, and the solid phase flame retardant mechanism was proposed.

Thermal buckling of advanced hybrid composite plates in the co-presence of CNTs and SMAs

The main purpose of the present work is to investigate the simultaneous effects of carbon nanotubes (CNTs) and shape memory alloy (SMA) wires on the thermal buckling behavior of graphite fiber/epoxy (GF/EP) composite plates. The thermal stability equations of hybrid SMA/CNT/GF/EP composite plates are derived based on the first-order shear deformation theory (FSDT), and solved using generalized differential quadrature (GDQ) method. The influences of CNTs and SMA wires on the buckling temperature of the hybrid composite plates are assessed for different geometric parameters, layups and boundary conditions. The numerical results indicate that CNTs have an almost constant effect on the thermal stability of composite plates while SMAs show different performances, depending on the geometric parameters, layups and boundary conditions. Interestingly, it is shown that in some circumstances, the use of either CNTs or SMAs alone does not effectively change the thermal buckling behavior of the composite plates, but their co-incorporation leads to a dramatic enhancement in the buckling temperature of the structure.

TiO2/SiO2/kaolinite hybrid filler to improve the flame retardancy, smoke suppression and anti-aging characteristics of epoxy resin

A multi-functional kaolinite-based compound (AST@Kaol) was prepared by successive loading of TiO2 and SiO2 to the surface of metakaolinite (Kaol), followed by reaction with γ-aminopropyl triethoxysilane (APTES). The hybrid was then introduced to epoxy resin (EP) to enhance flame retardancy, smoke suppression and anti-aging properties. The results demonstrated the presence of only 3 wt% AST@Kaol can increase the value of limit oxygen index (LOI) of EP composite to 27.3% from 25.3% of neat EP, as well as decrease the value of heat release rate, total smoke release and the smoke density by 36.9, 14.3 and 19.9%, respectively, compared to neat EP. Besides, the thermal stability and thermal oxidative resistance of EP composites was enhanced. The mechanism of fire retardancy, anti-ageing and mechanical of the EP composite containing AST@Kaol was also speculated.

Hyperbranched epoxy resin-grafted graphene oxide for efficient and all-purpose epoxy resin modification

Despite great efforts have been made on epoxy resins modification, development of additives that can be used to efficiently and universally modify epoxy composites remains a challenging task. Herein, graphene oxide (GO) sheets were covalently linked with hyperbranched epoxy resin (HBPEE-epoxy) to form HBPEE-epoxy functionalized GO (HPE-GO), which was then incorporated into epoxy resin (EP) matrix to achieve efficient and all-purpose enhancement of the properties of EPs. Compared with unmodified GO sheets, the functionalized HPE-GO sheets were better dispersed and exhibited better interfacial compatibility with the epoxy matrix, and consequently, the mechanical and thermal properties of HPE-GO/EP composites improved significantly compared to unmodified GO/EP composites. The tensile strength, flexural strength, impact strength, and fracture toughness (KIC) of EP composites containing 0.5 wt% HPE-GO increased by 65.0%, 36.2%, 259.1%, and 178.9%, respectively, compared with those for the neat EP. The storage modulus (E'), glass transition temperature (Tg), and thermal stability (T5%) also showed modest improvements. Furthermore, the HPE-GO/EP composites exhibited optimal thermal conductivities and thermal expansion properties, while maintaining higher volume resistivities compared with GO/EP composites. The results of this study support that HPE-GO is a promising, all-purpose modifier for EPs.

Phosphor nitrile functionalized UiO-66-NH2/graphene hybrid flame retardants for fire safety of epoxy

Phosphor nitrile functionalized UiO-66-NH2/graphene (G-U-H) was prepared combined a green mechanochemical method and microwave-assisted rapid method to improve the fire safety of epoxy resin (EP). The scanning electronic microscopy, transmission electron microscope and X-ray diffraction results indicated that the G-U-H exhibited sandwich-like hybrid structure. And the -OH from graphene nanoplatelets and -NH2 from UiO-66-NH2 were grafted with hexachlorocyclotriphosphazene to form covalent bonds. The obtained flame retardant was added to the EP at a different content. The flame retardancy index and cure index of EP composites were calculated, and those of EP-3 were both good. The cone calorimetry test showed that the flame retardancy of EP was improved and the flame retardant mechanism is the combination of condensed phase and gas phase with the synergistic of P, N and other elements. The physical barrier of graphene nanoplatelets and the generated more stable and denser residual char in condensed phase can effectively cut off the heat and mass transmission. In gas phase, the non-flammable gases were generated to help reduce the heat released.

Functionalized graphene with Platelet-like magnesium hydroxide for enhancing fire safety, smoke suppression and toxicity reduction of Epoxy resin

With the rapid development of Graphene based hybrid materials, various of them were fabricated to improve the fire safety of EP. However, the effect of GO content in the hybrid material on flame retardancy of EP composites is rarely reported. In order to find the optimal ratio of GO/Mg(OH)2, platelet-like Mg(OH)2 functioned graphene (GPM) were synthesized with diverse content GO substance and then presented into EP resin for improving its fire retardancy. Various characterizations confirmed its composition, structure and morphology. The incorporation of GPM contains about 1% GO increased the tensile strength by 31.6% compared to that of untreated Mg(OH)2. The GPM contains about 5% GO exhibited the finest fire safety in various EP composites. The fire-retardant assessments illustrated that the limiting oxygen index (LOI) of EP composite with 3 wt% GPM progressed to 27.8% compared with virgin EP (24.4%). In parallel, compared to virgin EP, the peak heat release rate, peak smoke production rate, total smoke production and peak CO production rate of EP/5GPM were diminished by 50.9%, 44.0 %, 25.5% and 53.1%, separately. The mechanism investigation revealed that the prominent flame retardancy and smoke suppression were attributed to the physical barrier of GO, the endothermic decomposition of Mg(OH)2, the barrier effect of MgO and synergistic effect between GO and Mg(OH)2 toward the optimized carbonization. In perspective, hierarchical platelet structure with synergistic effect offered an effective approach for the fire-safe polymer.

High performance epoxy resin composites modified with multifunctional thiophene/phosphaphenanthrene-based flame retardant: Excellent flame retardance, strong mechanical property and high transparency

It is always a challenge to prepare multifunctional epoxy resins (EP) composites with excellent flame retardance, mechanical property and high transparency. In this work, a reactive flame-retardant (BDO) was synthesized from DOPO, 3,5-diamino-triazolz and thiophene-2-formaldehyde, and taken to prepare EP/BDO composites. Surprisingly, benefitting from the synergy of efficient flame retardant unit (DOPO structure), catalytic curing unit (triazole structure) and optical functional structure (thiophene-2-formaldehyde), the EP composites with excellent comprehensive performance was obtained. In detailed, after adding only 5 wt% BDO, the EP composites passed the UL-94 V-0 level, and the limiting oxygen index was increased to 33% from 22.5% of neat EP. At the same time, EP/BDO-5 showed obvious heat suppression and smoke suppression effects. Besides, EP/BDO-5 presented excellent mechanical strength, that the tensile strength and bending strength were increased by 25% and 30% compared with neat EP. Moreover, EP/BDO composites maintained the same good light transmittance as neat EP, and also presented enhanced T g and dielectric property. In addition, the dual phase flame-retardant mechanism was revealed through systematically analyzing residues after combustion and the gaseous phase products of flame retardant. The above results indicated EP/BDO composites with excellent comprehensive performance possessed a great potential application in high-performance composites fields.

A facile method to prepare high-performance thermal insulation and flame retardant materials from amine-linked porous organic polymers

Developing porous functional materials with good thermal insulation and flame retardant properties is of great importance in modern eco-friendly buildings. Herein, we report the one-step synthesis of imine chain monolithic porous phosphorus-containing organic porous polymers (PPOPs) using Schiff base polycondensation reaction and as an example of efficient thermal insulation and flame retardant. Experimental results show that the PPOPs have low thermal conductivity (0.055 W·m−1·K−1) and excellent flame retardant properties. Measurements by microcalorimetry (MCC) showed a peak heat release rate (pHRR) value was 23.9 W·g−1, which is nearly an order of magnitude lower than that of most currently reported flame retardant materials. Using PPOPs in the epoxy resin (EP) matrix, the prepared EP composites exhibited excellent flame retardant properties. Cone calorimeter (CC) tests showed that the peak heat release rate (pHRR) and peak smoke release rate (pSPR) during combustion of PPOPs/EP composites were reduced by 42.0% and 36.4%, respectively, compared with pure EP. Tensile tests showed that the addition of PPOPs improved the mechanical properties of the composites to some extent. In addition, PPOPs can be designed into different shapes for practical applications compared with those fragile inorganic insulation materials and powders that were usually non-processable. Taking these advantages into account, PPOPs have great potential for modern building applications as monolithic foams or coatings with both excellent flame retardancy and thermal insulation properties.