UL-94 Rating Research Articles

Fabrication of novel halogen-free flame retardant containing functionalized chitosan from fisheries waste through the sol-gel technology and its fire safety performance in polyurethane resin

Chitosan (CS) derived from fisheries waste, such as shrimp and crab shells, was used to fabricate a bio-based, ecofriendly flame retardant. By reacting the –NH2 groups of CS and the NH2 groups of melamine polyphosphate (MPP) with the NCO groups of polymethylene polyphenyl polyisocyanate (PMPI), a novel intumescent flame retardant, CS-PMPI-MPP, was synthesized. Isophorone diisocyanate (IPDI) was reacted with polyol and aminopropyltriethoxysilane (APTS) to form a polyurethane containing silicon (Si-PU), into which the flame retardant was incorporated to produce a high-polymer composite through the sol-gel technology. The structure, thermal properties, flame retardancy, mechanical properties, toxicity, and char formation of the composites were analyzed. Fourier transform infrared spectroscopy, thermogravimetric analysis, limiting oxygen index, cone calorimeter, UL-94, thermogravimetric analysis with infrared spectroscopy, universal testing machine, scanning electron microscopy, X-ray photoelectron spectroscopy, raman spectroscopy, and smoke density test analyses were performed. The thermogravimetric test results indicated an increase in char yield from 0.5 wt% in pristine polyurethane to 25.9 wt% upon the addition of CS-PMPI-MPP, signifying an enhancement in the thermal stability of pristine polyurethane. According to limiting oxygen index and UL-94 data, the incorporation of CS-PMPI-MPP improved the limiting oxygen index and UL-94 ratings from 18.2 % (Fail) to 26.5 % (V-1), demonstrating the exceptional flame-retardant property of CS-PMPI-MPP within the pristine polyurethane formulation.

Synthesis of decorated polyborosiloxane for enhancing the flame retardancy and mechanical property of epoxy resin

In this work, the decorated polyborosiloxane (MAPBS) with phosphorus-nitrogen components was first synthesized via a hydrolysis-condensation reaction and thus incorporated the MAPBS filler into epoxy resin (EP) to fabricate composites by a simple blending method. It could be found that the MAPBS with epoxy groups showed a good dispersion level in the EP matrix, endowing EP composites with superior flame retardancy and mechanical properties. Thanks to the combination of phosphorus-, nitrogen-, boron-, and silica-containing units in MAPBS filler, the addition of 6 wt% MAPBS made EP achieve significantly improved limiting oxygen index (25.2 ± 0.5%) and UL-94 rating (V1). Meanwhile, cone calorimeter test results revealed that the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of the EP-MAPBS6 composite were reduced by 31%, 62%, and 67%, respectively, as compared to the pure EP. In addition, the MAPBS6 composite exhibited balanced tensile strength (105.1 MPa) and elongation at break (87.6%) among the prepared samples. The present work provides an effective strategy to fabricate EP composites with improved comprehensive performances.

Enhancing flame retardancy and mechanical strength of glass fiber-reinforced biomass polyamide composites with surface-functionalized black phosphorus

Fiber-reinforced polyamide exhibits exceptional mechanical properties and durability; however, its widespread application is impeded by potential fire hazards. In this study, a hybrid material consisting of black phosphorus (BP) and polyhedral oligomeric silsesquioxane (POSS) was synthesized, denoted as BP-CO-POSS. The fire safety of fiber-reinforced polyamide demonstrated significant enhancement upon the incorporation of aluminum diethyl phosphinate (Alpi) and BP-CO-POSS. This enhancement was evident in various aspects, including the suppression of heat release behaviors, reduction in the emission of toxic gases, and an increase in the UL-94 rating. Notably, with the additional inclusion of 0.5 wt% BP-CO-POSS, a substantial decrease in both heat release rate (31.15 %) and total heat release (37.59 %) was observed when compared to the application of Alpi and BP alone, thus affirming the existence of a synergistic effect. This observation was substantiated through a comprehensive analysis of results obtained from both gas and condensed phases. This study offers a practical methodology for the widespread utilization of phosphorus-rich advanced materials, thereby further enhancing the fire safety of fiber-reinforced polymers.

Integrated design of flame retardancy, smoke suppression and structure of carbon fiber reinforced vinyl ester resin composites through intercalation of nanofiber membranes

A novel flame-retardant method based on the intercalation of nanofiber flame-retardant membrane has been studied for composite laminates. Compared to traditional additive flame-retardant method, this method is more efficient, does not affect the composite forming process, and can improve the mechanical properties of composite. Nanofiber flame-retardant membranes (FPm) are prepared from polyether sulfone (PES) and pentaerythritol phosphate ester (PEPA) by electrospinning technique and inserted in the interlayer of carbon fiber reinforced vinyl ester resin (CF/VER) composites. The FPm can improve the flame-retardancy and smoke suppression of the CF/VER composites by promoting the charring of interlayer structure and form a barrier layer. The thickness of the FPm and the flame-retardant performance of the composites are positive correlation. At a FPm’s thickness of 50 μm, the limiting oxygen index (LOI) and UL-94 ratings of the CF/VER composites reached 33.5 % and V-1, respectively. The total heat release (THR) and total smoke release (TSP) are reduced by 26.4 % and 30.4 %, respectively. Due to the interlayer enhancement effect of FPm, the mechanical strength and interlaminar fracture toughness of CF/VER composites are also improved. Especially, when the thickness of FPm is 30 μm, the mode I interlaminar fracture toughness (GIC) of the CF/VER composite increased by 17.4 %. while the flexural strength, interlayer shear strength (ILSS), mode II interlaminar fracture toughness (GIIC) and storage modulus (E’) are all enhanced.

Synthesis of biobased Phosphorus-Nitrogen-Silicon ceramizable flame retardant and its flame retardancy effects on EPS

The rising interest in eco-friendly flame retardants marks a notable trend in the industry. However, the challenge remains that most flame retardants, while achieving high flame retardant properties, struggle to balance environmental sustainability and resource utilization. This work delves into the green synthesis and mechanism of action of ceramizable flame retardants. Using phytic acid (PA) and urea (U) as raw materials, ionic complexation assembly in water, employing polydopamine (PDA) as an adhesive, to develop an environmentally friendly, bio-based synergistic flame retardant (PAU) is conducted. Building upon this groundwork, the addition of the ceramic filler kaolin (KL) and the fluxing agent sodium carbonate (Na2CO3) physically modifies the PAU, resulting in a novel eco-friendly, bio-based, ceramifiable flame retardant (PAUK). Employing the prepared PAUK through an effective surface coating technique, a lightweight and scratch-resistant flame-retardant expanded polystyrene insulation board (EPS-PAUK) is created. The best EPS-PAUK composite in our study exhibits an oxygen index of 52.5, achieves a V-0 UL-94 rating, and features excellent smoke suppression and compression strength up to 67.8 kPa, while nearly maintaining the lightweight characteristics of the EPS insulation boards. This bio-based, ceramifiable flame retardant system offers a new approach for producing lightweight, highly efficient flame-retardant and high-performance polymers.

P/N-containing SiO2 flame retardant particles formed by in-situ hydrolysis for significantly improve the flame retardancy and toughness of epoxy resins

To obtain flame retardants with more efficient and multidimensional flame retardant modes, this work formed P/N-containing silica flame retardants (PBPSi) by hydrolysis and used them in epoxy resins (EP) to give them good flame retardant properties. The hydrolyzed SiO2 flame retardant builds an integrated flame-retardant structure and a concentrated stress-bearing point, the EP has good fire resistant properties and toughness. Allowing the addition of 7-PBPSi/EPPBPSi to enable EP to achieve a UL-94 rating of V-0, and the impact strength of 5-PBPSi/EP reached 52.9 kJ/m2. In addition, PBPSi has good performance in inhibiting heat release and toxic gas release, and the PHRR and THR of 7-PBPSi/EP were reduced by 54.6 % and 24.6 %, respectively, compared with pure EP, the content of CO and CO2 also decreased. The analysis of the flame retardant mechanism indicated that PBPSi played a flame retardant role in the biphasic phase through the catalytic carbon formation in the condensed phase and the synergistic dilution of flammable gases and trapping of free radicals by P/N synergistic.

Integration of N- and P- elements in sodium alginate aerogels for efficient flame retardant and thermal insulating properties

In the field of building energy conservation, the development of biodegradable biomass aerogels with excellent mechanical performance, flame retardancy and thermal insulation properties is of particular importance. Here, a directional freeze-drying method was used for fabricating composite sodium alginate (SA) aerogels containing functionalized ammonium polyphosphate (APP) flame retardant. In particular, APP was coated with melamine (MEL) and phytic acid (PA) by a supramolecular assembly process. Through optimizing the flame retardant addition, the SA-20 AMP sample exhibited excellent flame retardant and thermal insulation properties, with the limiting oxygen index of 38.2 % and the UL-94 rating of V-0. Such aerogels with anisotropic morphology demonstrated a low thermal conductivity of 0.0288 (W/m·K) in the radial direction (perpendicular to the lamellar structure). In addition, as-obtained aerogels displayed remarkable water stability and mechanical properties, indicating significant potential for practical applications.

Diaminodiphenylmethane modified zirconium phosphate: A new strategy for trace addition to improve flame retardancy, smoke inhibition, and compatibility of epoxy resins

AbstractHigh‐efficient flame retardants (ZrP‐DDM) were synthesized successfully via ion‐exchange method, using diaminodiphenylmethane (DDM) modified layered zirconium phosphate (α‐ZrP). Trace addition of ZrP‐DDM in epoxy resins (EP) can enhance the flame‐retardant, smoke‐inhibition, mechanical, and thermal stability properties of EP composites. As shown in the results, ZrP‐DDM exhibits a better synergistic effect than α‐ZrP, and the EP composites containing 0.5 wt% ZrP‐DDM (EP/0.5ZrP‐DDM) show excellent flame‐retardant and smoke‐inhibition properties. Especially, EP/0.5ZrP‐DDM possesses a limiting oxygen index (LOI) of 33.7% with UL94 V‐1 rating, while the EP composites containing 0.5 wt% ZrP (EP/0.5ZrP) has a LOI of 30.1% and fails to achieve the UL94 rating. Furthermore, the peak heat release rate (PHRR), total heat release rate (THR), and smoke density rating of EP/0.5ZrP‐DDM decrease by 10.2%, 3.7%, and 8.2% compared with EP/0.5ZrP. Based on condensed‐phase product analysis, EP/ZrP‐DDM sample provides a gas source for intumescent char layer, and produces a stable phosphorus‐rich crosslinking structures during combustion, thus decreasing the fire hazard of the composite material. Meanwhile, the introduction of ZrP‐DDM has a less impact on tensile strength of EP composites compared with α‐ZrP, suggesting the addition of ZrP‐DDM effectively enhances the compatibility with the EP matrix, thereby maintaining excellent mechanical properties of the EP matrix.

P/N synergistic integrated flame retardants with instant cross-linking at high-temperature for flame retardancy and impact resistance of epoxy resins

With the development of flame retardant technology, intumescent flame retardant (IFR) systems, and instant cross-linking in case of fire have become important directions for epoxy resin (EP) flame retardancy. A carbonized matrix containing a benzoxazine structure was constructed with the triazine structure, and the integrated flame retardant (TRBPO) was constructed by introducing the phosphorus source through a partial ring-opening reaction. It can maintain its structural characteristics during the curing process of EP. When EP materials are exposed to fire, TRBPO will cross-link in the EP matrix and work as the P/N synergistic IFR system to achieve excellent flame retardancy. The results showed that 5 wt% of TRBPO could make EP composites reach UL-94 rating of V-0 with a PHRR of 303.7 kW/m2, and the TSP and TSR were reduced by 48.5 % and 48.9 %, respectively, compared with pure EP. The introduction of TRBPO has a impact resistance effect on EP, and its excellent stress dispersion effect made the impact strength of 5-TRBPO/EP reached 36.49 KJ/m2. The analysis of the flame retardant mechanism proved that the rapid carbon formation function of IFR and the self-crosslinking flame retardancy of TRBPO in the fire are the main reasons for flame retardancy. In addition, the capture of flammable groups in the gas phase is an important source of flame retardant effect.

Fabrication and characterization of mycelium-based composites from Lentinus squarrosulus and Pleurotus ostreatus with improved physico-mechanical properties for versatile applications

This study explores the potential of fungal mycelium-based plate-like composites as sustainable and cost-effective alternatives for synthetic materials. Locally available lignocellulosic waste and fungi isolated locally were used to fabricate mycelium composites. The medium primarily consists of Albizia sawdust and the fungi Lentinus squarrosulus and Pleurotus ostreatus were used. All the composites identified here were subjected to analyses based on scanning electron microscopy, moisture content, dry density, water absorption, flammability, thermal stability, and compression strength following ASTM and ISO standards. The mycelium plates produced with L. squarrosulus mycelium (ASL) exhibited lower dry density and less water absorption. The ASL mycelium plates exhibited a soft and foamy appearance, whereas the P. ostreatus material (ASP) appeared dense mycelium growth only in the top and bottom parts of the plate. The UL-94 rating demonstrated that both samples exhibited superior flame retardancy properties (rated as V1) compared to commercially used expanded polystyrene (EPS). These variations were due to the difference between mycelium density. Therefore, these new bio-composites have the potential to replace conventional packaging or interior construction materials.

Phosphononitrile based bismaleimide electronic packaging substrate with both fire safety and dielectric properties: Assisting 5G communication

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (Dk) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication.

Engineering Ce/P-functionalized g-C3N4 for advanced ABS nanocomposites exhibiting unparalleled fire retardancy, enhanced thermal and mechanical properties

The nanomaterials have been deeply explored as flame retardants for various polymeric materials due to their multifunctionality, but they often fail to significantly increase the limiting oxygen index (LOI) and vertical burning UL-94 rating, thus unable to meet industrial needs (LOI>27.0 % and UL-94 V-0 rating). Herein, we fabricated a cerium/phosphorus-doped g-C3N4 (Ce/P-CN) nanohybrid as a multifunctional high-efficiency fire retardant for acrylonitrile–butadiene–styrene (ABS). The Ce/P-CN nanoflakes featured a strengthening effect towards ABS, 10 wt% of which increased the tensile strength of ABS/(Ce/P-CN) by 33.8 %. Meanwhile, the ABS/(Ce/P-CN) nanocomposites showed remarkably enhanced high-temperature stability and carbonization performances relative to virgin ABS. Ce/P-CN simultaneously improved the anti-ignition, fire retardancy and smoke suppression of ABS due to the barrier effect of g-C3N4 nanoflakes and the catalytic carbonization effect of cerium and phosphorus. Notably, adding 10 wt% Ce/P-CN increased the LOI and UL-94 rating of ABS to 28.6 % and V-0, respectively, demonstrating its high flame-retardant efficiency. Thus, the high flame-retardant efficiency and multifunctionality enable Ce/P-CN to outperform previous flame retardants for ABS. This work offers a novel strategy for the development of high-efficiency g-C3N4 nanoflakes, which endow ABS with improved mechanical robustness and fire retardancy and show broad industrial prospects.

Three-in-one novel flame retardant through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 for improving fire safety and mechanical properties of PBS composites

As one typically sustainable polymer material, poly(butylene succinate) (PBS) is highly necessary to improve its flame retardancy and simultaneously maintain satisfied mechanical performances. In this study, “three-in-one” novel flame retardant was synthesized through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 (labeled as MH@Fe-MOF-P), then it was introduced into PBS matrix to investigate its effect on flame retardancy and mechanical properties. The results indicated that PBS/20MH@Fe-MOF-P exhibited excellent flame retardancy, including that the LOI was 29.6%, the UL-94 rating reached to V0, and the peak of heat release rate (PHRR) decreased by 82.1%. The flame retardant mechanism was ascribed to the synergistic effect of Mg(OH)2, Fe-MOF and organophosphorus on delaying the decomposition and catalyzing the carbonization of PBS. Meanwhile, PBS/20MH@Fe-MOF-P presented better mechanical performances than PBS/20MH and PBS/20MH@Fe-MOF composites, resulting from the special structure of MH@Fe-MOF-P to achieve good dispersion of fillers and strong polymer-filler interface adhesion. This work provides a novel strategy to modify Mg(OH)2 with high flame retardant efficiency, and also broadens the practical applications of PBS materials with balanced comprehensive performances.

Design of reactive linear polyphosphazene to improve the dielectric properties and fire safety of bismaleimide composites

The high-frequency transmission of 5th-Generation Mobile Communication Technology (5G) and more integrated mobile terminals pose a challenge to the safety and dielectric properties of existing electronic packaging materials. This work innovatively designs a linear polyphosphazene compound (PABN) with benzonitrile as the reactive side group. The prepared bismaleimide (BMI)/PABN is an excellent dielectric composite material, breaking the technical barrier of balancing fire safety and dielectric performance. With only 1 wt% PABN, the UL94 rating of BMI composite reaches V0, and the impact strength increases by 48.5 %, demonstrating excellent fire safety and toughness. Specifically, the dielectric constant (Dk) of the composite containing 4 wt% PABN is as low as 2.67, far meeting the requirements of 5G. In addition, the glass transition temperature (Tg) of all BMI/PABN composites is around 290 °C, and the initial decomposition temperature exceeds 400 °C, indicating potential applications in the integration and miniaturization of microelectronic devices.

Multi-element hybrid flame retardants balance flame retardancy and mechanical performance of epoxy coatings

A phosphorus‑silicon‑boron ternary hybrid flame retardant (BSiP) was synthesized using 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide, p-phthalaldehyde, (3-aminopropyl) triethoxysilane and boric acid. The BSiP was applied to modify the performance of epoxy (EP) coatings. A phosphorus‑boron binary hybrid flame retardant BP was incorporated into this system to balance the performance of EP coatings. Using BSiP and BP alone requires 3 wt% and 6 wt% for EP coating, respectively, to achieve the vertical burning UL-94 V0 rating, while 4 wt% BSiP/BP (1/1) is enough for EP coating to achieve the same UL-94 rating. In addition, the impact strength of EP/BSiP/BP is 11.8 KJ/m2, which is 131 % and 103 % more than that of EP and EP/BSiP, respectively. The BSiP and BP work in both the gas phase and the condensed phase, and they have a good synergistic effect on flame retardancy of EP. The blend of BSiP and BP increases the free volume of EP and thus toughens EP coatings. The hybridization of multi-element covalent bonds and physical blending effectively balance the flame retardancy and impact strength of EP coatings.

Preparation of Ar–P–N-structured flame retardant via Kabachnik–Fields reaction for fire safety and mechanical reinforcement of polyurethane

Fire safety of polyurethanes (PUs) has limited their further practical applications. To address this problem, we designed novel phosphorus-based flame retardants (P-FR) by incorporating aryl (Ar) groups via Kabachnik–Fields reaction, realizing π–π interaction-reinforced Ar2 and Ar5. Total heat release and peak heat release rate of PU/Ar5, whose flame-retardancy-index of 5.02 due to reduced combustion time, decreased 23.24 and 9.23 %, respectively, compared with neat PU. Moreover, UL94 rating for PU/Ar5 was improved from V-2 to V-0. These results demonstrate that Ar5 effectively generate a barrier effect that blocks oxygen, fuel, and heat. Sluggish mobility and phase transition are responsible for such enhancement due to a delay effect with the existence of π–π interactions and steric hindrance. Encouragingly, tensile strength and toughness of PU/Ar5 were greatly improved by 1345.8 and 670.3 %, respectively, compared with neat PU. We believe that this study could provide a promising method for introducing specific function to flame retardants to enhance fire safety and mechanical properties of composites.

A green flame retardant coating based on one-step aqueous complexation of phytic acid and urea for fabrication of lightweight and high toughness flame retardant EPS insulation board

Green flame retardants have drawn much attention because of their environmental friendliness. But for the high flame retardancy of flammable polymers, most existing green flame retardants are unsatisfactory, even the flame-retardant process can not achieve high efficiency and environmental protection. In this work, flame retardants and flame-retardant process are addressed in a two-pronged approach. An eco-friendly bio-based synergistic flame retardant (PAU) was synthesized based on phytic acid (PA) and urea (U) through simple complexation assembly in water. The designed flame retardant coating can be directly coated on the surface of any topological shape with polydopamine as an adhesive. Flame retardant expandable polystyrene (EPS-PAU) with light weight and high toughness is prepared with the designed PAU flame-retardant coating. The coated EPS plates exhibit V-0 UL-94 rating and 42.0 % of limited oxygen index and excellent smoke suppression. Moreover, the density of EPS-PAU is slightly increased only by 2.27 % on the basis of the neat EPS, and the hard shell formed using PDA as an adhesive layer is beneficial for the improvement of impact strength. This novel biomass-based PAU system provides a promising strategy for manufacturing polymer products with excellent flame retardancy, smoke inhibition and light weight.

Preparation of microencapsulated nitrogen‑phosphorus‑silicon flame retardant and its effect on high impact polystyrene flame retardancy

High-impact polystyrene is a widely-used construction material due to its superior comprehensive performance, but its susceptibility to fire can lead to the production of toxic and harmful gases. To address this issue, a novel, environmentally-friendly microencapsulated nitrogen‑phosphorus‑silicon flame retardant for high-impact polystyrene was prepared in this study. SiO2, produced by the hydrolysis condensation of tetraethyl orthosilicate, was used as the wall material, while melamine cyanurate was used as the core material. The microencapsulated nitrogen‑phosphorus‑silicon flame retardant was compounded with high-impact polystyrene and aluminum hypophosphite, and the composites were evaluated for their performance in terms of fire behavior, thermal stability, and morphology of the resulting carbon residues. When melamine cyanurate@SiO2 and aluminum hypophosphite were added in a 1:4 ratio, the UL-94 rating of L5 reached V-0, and the LOI value increased to 27.0%. The conical calorimeter test results showed that the peak heat release rate of the L5 composite decreased by 78.7% compared to pure HIPS, and the corresponding total heat release rate decreased by 45.7%. Thermogravimetric analysis results illustrated that the amount of carbon residue increased significantly, from 2.46% to 22.26% of pure high-impact polystyrene. These findings indicate that the prepared microencapsulated nitrogen‑phosphorus‑silicon flame retardant is multifunctional, highly efficient, and can be applied to high-impact polystyrene.

Hierarchical MXene@PBA nanohybrids towards high-efficiency flame retardancy and smoke suppression of robust yet tough polymer nanocomposites at ultra-low additions

Developing efficient flame-retardant MXene-based polymeric materials with enhanced mechanical properties has been a huge challenge. Herein, Prussian blue analogues (PBAs) were used to modify the surface of MXene nanosheets via an electrostatic self-assembly method to construct hierarchical MXene-based nanohybrids (MXene@PBA). Then, MXene@PBA was incorporated into the epoxy matrix to fabricate high-performance epoxy nanocomposites (EP-MXene@PBA). The study indicates that hierarchical MXene@PBA exhibits excellent dispersion performance in the epoxy matrix. Notably, MXene@PBA results in high-efficiency flame retardancy and smoke suppression for epoxy nanocomposites at ultra-low additions. What is very surprising is that only 1.0 wt% MXene@PBA can easily enhance the UL-94 rating of EP-1.0%MXene@PBA to V0. Meanwhile, the peak heat release rate (pHRR), total smoke production (TSP), and peak CO production rate (pCO) are remarkably reduced by 36.70%, 34.28%, and 43.48%, compared to those of the pristine epoxy resin, respectively. Furthermore, the 1.0 wt% MXene@PBA nanohybrids can enhance the flexural and impact strengths of EP-1.0%MXene@PBA. This work provides a feasible strategy for the creation of multifunctional MXene derivatives and their polymeric nanocomposites and holds great promise for many industrial applications.

Turning waste into treasure: Effects of waste polyphenylene sulfide (PPS) microfibers as potential synergists on flame retardancy and mechanical property of polylactic acid

In this work, we prepare flame-retardant and toughened PLA using waste PPS microfibers prepared from waste PPS filter bags. Waste PPS microfibers not only act as synergists to improve the impact properties and flame retardancy of PLA composites, but also act as heterogeneous nucleating agents to promote PLA crystallization. Specifically, when only 5 wt% waste PPS microfibers are added, the crystallinity of the AP/PLA system increases from 3.6% of 15AP PLA to 44.06% of 15AP5PPS PLA. When 10 wt% waste PPS microfibers are added, the UL-94 rating of 15AP10PPS PLA increases to V-0 rating, which is significantly improved compared to the V-1 rating of 15AP PLA. Under the premise of passing the UL-94 V-0 rating, the impact properties of 15AP10PPS PLA and 10AP15PPS PLA are significantly better than 20AP PLA, with an increase of 34.8% and 50.6%, respectively. This study provides a new strategy for polymer flame retardant and toughening modification and waste recycling.