Flame Retardant Polyamide Research Articles

Enhancing flame retardancy in 3D printed polyamide composites using directionally arranged recycled carbon fiber

Combining recycled carbon fiber (rCF) and 3D printing technology has shown great potential for fabricating functional prototypes and production parts used in the aerospace and automotive industries. However, it is still a challenge to design flame-retardant 3D printed parts with high mechanical properties and flame-retardant rating. In the work, a flame-retardant polyamide (PA)-based composite for material extrusion 3D printing was prepared by utilization of rCF, polyhedral oligomeric silsesquioxanes (POSS), and 9,10-Dihydro-9-oxa-10-phosphaphenanthrene (DOPO)-based flame retardant. The 3D-printed composites have high thermal stability, mechanical properties, and excellent flame retardancy with a V-0 rating. With the benefits of material extrusion 3D printing, directionally arranged rCF in 3D printed composites could effectively inhibit the fire spread, extend the time to ignition (TTI), reduce the total heat release (THR) and total smoke release (TSR) of 3D printed composites. The directional flame-retardant mechanism is mainly the thermal conductivity mechanism of the condensed phase and the promotion of stable ordered carbon layer formation. It provides a promising path for designing high-performance flame-retardant materials.

Enhancing flame retardancy and heat insulation performances of polyamide 66 composite film by adding CNC/Al2O3 nanohybrids

Polyamide 66 (PA66) has garnered significant attention due to its exceptional properties; unfortunately, its flammability is challenging. Adding flame retardants (FRs) is a primary approach to enhance PA66 flame retardancy. This study developed a highly flame-retardant PA66 composite film by adding corn-like functional nanohybrids (CNC/Al2O3). Interestingly, CNC/Al2O3 nanohybrids not only formed hydrogen bond interactions with PA66 but also improved crystallization properties as heterogeneous nucleating agents, resulting in the excellent mechanical properties of PA66 composite film. Remarkably, the incorporation of 3 wt% CNC/Al2O3 nanohybrids into PA66 matrix contributed to increasing the LOI to 28.5 %. The pHRR, THR, and TSR were reduced obviously by 55.7 %, 15.3 %, and 65.2 %, respectively. The excellent flame retardancy of PA66 composite film was attributed to the forming of a compact carbon layer catalyzed by the CNC/Al2O3 nanohybrids. Besides, the homogeneous distribution of CNC/Al2O3 nanohybrids endowed the composite film with excellent heat insulation, and the heat insulation rate was up to 31.9 %. Thus, such PA66 composite films with excellent flame retardancy, heat insulation, and mechanical properties could meet the broader application requirements.

Effect of different IFS (MWCNTs, BN, and ZnO) on flame retardant, thermal and mechanical properties of PA6/aluminum diisobutyl phosphinate composites

AbstractIn this paper, the effects of the synergistic flame retardation of aluminum diisobutyl phosphinate acid (APBA) with three inorganic fillers of different dimensions (multi‐walled carbon nanotubes [MWCNTs] [1‐dimensional], hexagonal boron nitride [BN] [2‐dimensional], and zinc oxide [ZnO] [3‐dimensional]), respectively, on the properties of nylon 6 (polyamide 6 [PA6]) materials were investigated. It was shown that under the same additive amount, with the increase of spatial dimension of inorganic fillers, the thermal stability and residual carbon capacity were improved. Which would catalyze the formation of more and denser carbon layers in the matrix material, effectively blocked the transfer of oxygen and heat, enhanced the cohesive‐phase flame retardancy of synergistic flame‐retardant PA6 composites, and exerted a better synergistic flame‐retardant effect with APBA. So that the flame‐retardant properties of PA6 composites were gradually improved, and the mechanical properties were also gradually increased. The comprehensive performance of three types of inorganic fillers gradually improves in the order of MWCNTs < BN < ZnO. When the addition amount of ZnO was 2 wt%, the vertical combustion grade (UL‐94) of PA6 composite was V‐0, and the limiting oxygen index (LOI) was as high as 36.5%. The tensile strain increased by 19.11% and impact strength increased by 20.26% compared with PA6, and PA6/APBA‐Zn can be used as a flame retardant PA6 composite material with balanced overall performance.Highlights Diisobutylaluminium hypophosphite and inorganic fillers have efficient synergistic flame retardant effects in PA6. With the increase of spatial dimension of inorganic fillers, the better the synergistic flame retardant effect in PA6. The flame retardant can degrade to release the phosphorous free radicals. Inorganic fillers can cross‐link with the PA6 substrate and promote the charring.

Polymer-type flame retardants based on a DOPO derivative for improving the flame retardancy of polyamide 6: Preparation, properties and flame retardancy mode of action

A polymer-type flame retardant (PFR) based on a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative was synthesised here to improve the flame retardancy of polyamide 6 (PA6). The chemical structure and thermal property of the PFR were characterised by Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PFR and PA6 were melt-blended to obtain a flame-retardant polyamide 6 (FRPA6). Its thermal property, mechanical property and flame retardancy were characterised via TGA, DSC and tensile, impact, vertical burning and limiting oxygen index (LOI) tests. Its flame-retardant mode of action was analysed by scanning electron microscopy, FTIR spectroscopy, cone calorimetry and pyrolysis-gas chromatography-mass spectrometry. The FRPA6 with a phosphorus content of 3000 ppm passed the UL-94 V-0 rating, and the LOI of the FRPA6 with a phosphorous content of 5000 ppm reached 28.8 %. Compared with pure PA6, the peak heat release rate, total heat release and effective heat of FRPA6–5000 were reduced by 35.4 %, 21.9 % and 26.5 %, respectively. These results indicate that the flame-retardant mode of action of PFR mainly involved the quenching effect of phosphorus-containing radicals in the gas phase.

High efficiency of flame-retardant polyamide 56/10-(2, 5-dihydroxyphenyl)-10-hydrogen 9-oxygen-10-phosphine-10-oxide composites inspired by polyoxometalate

Polyamide 56 (PA56) as a bio-based polymer has some flame retardancy but is not good enough to satisfy the security requirements. In this communication, nickel phosphomolybdate (PMoNi) was synthesized and applied to modify the fire-retardant efficiency of 10-(2,5-dihydroxyphenyl)-10-hydrogen 9-oxygen-10-phosphine-10-oxide (DOPO-HQ) in PA56. An efficient synergistic effect is found between DOPO-HQ and PMoNi. The content of DOPO-HQ in PA56 to achieve the UL-94 V-0 rating is decreased from 15 wt% to 3 wt% by incorporating 1 wt% PMoNi into the system. It inspires the condensed-gas transition of phosphorus in DOPO-HQ and improves the fire-retardant efficiency by enhancing gas-phase effect. This work provides an effective method for preparing fire-retardant PA56 composites.

Study on polymerization kinetics of copolymerized flame-retardant polyamide 66: Apparent rate constant and reaction activation energy

The research of polymerization kinetics and reaction mechanism on flame-retardant polyamide 66 (FRPA66) is of great significance for its industrial production. Here, FRPA66 is prepared by one-step melt polycondensation of nylon 66 salt and a reactive flame retardant DPDA. By exploring the relationship of viscosity-average molecular weight versus reaction time at different polymerization stages, the apparent rate constant of FRPA66 is calculated to be 41.8 dL g−1s−1. Besides, molecular simulation analysis demonstrates that the reaction activation energy of DPDA and nylon 66 salt in pre-polymerization stage is 312.04 kcal/mol, indicating that the pre-polymerization time can be extended to make up for the lack of pre-polymerization power of FRPA66. In the final polymerization stage, reasonable control of releasing pressure and polymerization time can promote the self-condensation of a small part of DPDA, thus improving the molecular weight of FRPA66. Finally, based on the polymerization kinetic and reaction mechanism, FRPA66 containing 5% DPDA can reach V-0 level.

Block it and rock it: Smoke suppressants that form a protective layer in PA 6.6

To ensure fire safety, polymers are filled with flame retardants and smoke suppressants. To meet the highest requirements, it is essential to understand the decomposition of those polymeric materials. This study reveals interactions between polymer, smoke suppressants, and flame retardants, and discusses their impact on the materials’ flame retardancy, smoke emission, smoke toxicity, and particle emission in conventional loadings to provide deeper general understanding. Low melting oxide glass, melem, spherical silica, sepiolite, melamine polyphosphate, and boehmite in an aluminum diethylphosphinate flame-retarded polyamide 6.6 were investigated. All smoke suppressants improve the protective layer and act as an adjuvant. Silica and melem performed best under forced flaming conditions. Spherical silica reduces the peak of heat release rate by 39% and the total heat evolved by 14%, whereas 10 wt% melem lowers the total smoke production by 41%. Melem alters the mode of action of aluminum diethylphosphinate from gas to more condensed phase activity. This change reduces flame inhibition and hence smoke toxicity, but further improves the protective layer due to charring reactions in the decomposition mechanism. In addition, the sizes of the smoke particles decrease because of the prolonged time in the pyrolytic zone. This study highlights that interactions between polymer, flame retardants, and smoke suppressants can significantly determine the smoking and burning behavior.

A novel phosphorus-nitrogen-based hyperbranched polysiloxane for improving the fire safety of PA6 with suppressed melt droplets and good mechanical properties

The combustible defects of polyamide 6 (PA6), especially the flammable melt-dripping behavior, have greatly limited its application in some particular fields. In this work, a halogen-free hyperbranched polysiloxane (PBDSi) containing DOPO and Schiff base was designed via Michael's addition reaction and dehydration-condensation reaction. Results showed that the char yield (Yc) of PBDSi attained 37.9 wt%, confirming the satisfactory charring behavior of PBDSi for preparing flame-retardant PA6. Just by adding 3 wt% of PBDSi, the serious melt droplets of PA6 were suppressed effectively. The prepared PA6/PBDSi-3 with 5 wt% of PBDSi could achieve the highest value of limited oxygen index (LOI) of 27.2 %, while that of PA6 is 21.0 %. Meanwhile, PA6/PBDSi-3 obtained an apparent reduction in the peak heat release rate (PHRR) value of 31.1 % compared with pure PA6. The cooperated effect of DOPO, Schiff base, and polysiloxane that contributed to generating a silicon-phosphorous-rich char layer and releasing incombustible volatiles that were determined to be the essential factor for the improved fire safety of PA6/PBDSi were explored intensively. Inspiringly, PA6/PBDSi composites exhibited a slight mechanical loss concerning PA6, overcoming the great challenge of developing additive flame-retardant materials to balance mechanical properties and fire safety.

Preparation of high‐efficient flame retardant PA6 via DOPO‐ITA initiated ring‐opening polymerization of caprolactam

AbstractIt has been a long‐term challenge to synthesize intrinsically flame retardant polyamide 6 (FRPA6) with high‐molecular weight. In this work, through the ring‐opening polymerization of caprolactam initiated by 9,10‐dihydro‐10‐[2,3‐di(hydroxycarbonyl)propyl]‐10 phosphaphenanthrene‐10‐oxide (DOPO‐ITA), intrinsically flame retardant PA6 with high‐molecular weight was successfully prepared. Its chemical structure, thermal stability, mechanical and combustion properties, as well as the retarding mechanism were thoroughly characterized in detail. The FRPA6 containing 3.0% retardant could achieve a V‐0 rating with an LOI value of 31.2%. An interesting phenomenon was observed during V‐0 tests. The melt drip slowly extended downward to form a long strip after moving fire, which was in favor of its heat release in a short time, thereby effectively prevented it from igniting the cotton. That is, a facile method to prepare intrinsically high‐efficiency fire retardant polymer via ring opening and polycondensation was proposed.

Facile preparation of inherently flame-retardant polyamide 6 filaments with enhanced anti-dripping enabled by the synergistic charring effect

The absence of inherently flame-retardant polyamide 6 (FR-PA6) with enhanced anti-dripping and melt spinnability has significantly limited its further application in textiles. In this work, a binary reactive flame retardant composed of commercial 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phosphaphenanthrene-10-oxide (DDP) and synthesized polydiphenylsiloxane (PDPS) was employed to fabricate FR-PA6 through a facile synthetic route. The prepared FR-PA6 containing 5 wt% DDP and 5 wt% PDPS (FR-PA6-5-5) exhibited a UL94 V-0 rating with no melt-droplets during combustion, a 31.0% reduction in heat release rate and a 18.8% decrease in total heat release compared to pure PA6 in cone calorimetric tests. The improved fire safety of FR-PA6-5-5 was contributed to the gas-phase quenching and dilution effect and the condensed-phase barrier effect, which was enhanced by the synergistic charring effect achieved through the formation of P(=O)-O-Si. Additionally, FR-PA6-5-5 exhibited excellent melt spinnability as demonstrated by the successful preparation of filaments with a tensile strength of approximately 2.27 cN/dtex.

Improving the hygroscopicity and flame retardancy of polyamide 6 fabrics by surface coating with β-FeOOH and sulfamic acid

The combustion of polyamide 6 (PA6) fabrics releases toxic smoke, which will pollute the environment and threaten human life and health. Herein, a novel eco-friendly flame-retardant coating was constructed and applied to PA6 fabrics. Needle-like β-FeOOH with a high surface area was firstly constructed onto the surface of PA6 fabrics by the hydrolysis of Fe3+, sulfamic acid (SA) was then introduced by a facile dipping and nipping method. The growth of β-FeOOH also endowed the PA6 fabrics with certain hydrophilicity and moisture permeability, resulting in improved comfortability. The limiting oxygen index (LOI) of the prepared PA6/Fe/6SA sample was increased to 27.2% from 18.5% of control PA6 sample, and the damaged length was reduced to only 6.0 cm from 12.0 cm of control PA6 sample. Meanwhile, the melt dripping was also eliminated. The heat release rate and total heat release values of the PA6/Fe/6SA sample were decreased to 318.5 kW/m2 and 17.0 MJ/m2, respectively, compared with those of control PA6 (494.7 kW/m2 and 21.4 MJ/m2). The analysis results indicated that nonflammable gases diluted flammable gases. The observation of char residues demonstrated that the stable char layer was formed, which effectively inhibited the transfer of heat and oxygen. The organic solvent-free coating does not contain any conventional halogens/phosphorus elements, which provides a useful methodology to produce environmentally friendly flame-retardant fabrics.

Additive manufacturing of flame retardant polyamide 12 with high mechanical properties from regenerated powder

PurposeThis paper aims to develop flame-retardant (FR) polyamide 12 (PA12) nanocomposite from regenerated powder via selective laser sintering (SLS), an additive manufacturing technique.Design/methodology/approachFirst, the morphology, processibility, thermal and mechanical properties of PA12 regenerated powder, consisting of 50 wt% new and 50 wt% recycled powder, as well as corresponding printed specimens, were evaluated to characterize the effects of previous SLS processing. Second, flame-retardant PA12 was developed by incorporating both single and binary halogen-free flame retardants into the regenerated powder.FindingsIt was found that the printed specimens from regenerated powder had much higher tensile and impact properties compared to specimens made from new powder, which is attributed to better particulate fusion and coalescence realized in higher temperature SLS printing. The effect of FRs on thermal, mechanical and flame retardant properties of the PA12 composites/nanocomposites was investigated systematically. It was found that the nanoclay, as a synergist, improved both flame-retardant and mechanical properties of PA12. UL94 standard rating of V-0 was achieved for the printed nanocomposite by incorporating 1 wt% nanoclay into 15 wt% phosphinates FR. Moreover, on average, the tensile and impact strength of the nanocomposite were increased by 26.13% and 17.09%, respectively, in XY, YZ and Z printing orientations as compared to the equivalent flame retardant composite with 20 wt% of the phosphinates FR.Originality/valueThis paper fulfills the need to develop flame retardant parts via SLS technology with waste feedstock. It also addresses the challenge of developing flame retardant materials without obviously compromising the mechanical properties by making use of the synergistic effect of nanoclay and organic phosphinates.

Analysis on the Application of Polyamide (PA) materials to Replace Existing Materials in Hair Dryer Housings

This paper demonstrates and explains various properties of Acrylonitrile butadiene styrene (ABS), the material used for the housings of hair dryers, and analyzes the advantages and disadvantages of Flame retardant Polyamide (PA) materials as an alternative replacement of existing materials from the same aspects under current situations where the development of flame retardants and applications is becoming more and more vital. ABS materials cost less during the manufacturing processes, have a longer usage life, and is more environmentally friendly. PA materials have better flame retardancy and temperature resistance. By making addition to PA materials, its properties can be further improved. From the review, it is indicated that it is likely to replace the existing design with the materials that has PA materials as the base, with the addition of glass fiber and graphene, which is proved to have a better performance in terms of heat resistance, flame retardancy, durability, and is UV resistant in the meantime.

Flame Retardancy and Mechanical Properties of Melt-Spun PA66 Fibers Prepared by End-Group Blocking Technology

Preparing flame-retardant polyamide 66 (PA66) fibers through melt spinning remains one of the biggest challenges nowadays. In this work, dipentaerythritol (Di-PE), an eco-friendly flame retardant, was blended into PA66 to prepare PA66/Di-PE composites and fibers. It was confirmed that Di-PE could significantly improve the flame-retardant properties of PA66 by blocking the terminal carboxyl groups, which was conducive to the formation of a continuous and compact char layer and the reduced production of combustible gas. The combustion results of the composites showed that the limiting oxygen index (LOI) increased from 23.5% to 29.4%, and underwriter laboratories 94 (UL-94) passed the V-0 grade. The peak of heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) decreased by 47.3%, 47.8%, and 44.8%, respectively, for the PA66/6 wt% Di-PE composite compared to those recorded for pure PA66. More importantly, the PA66/Di-PE composites possessed excellent spinnability. The prepared fibers still had good mechanical properties (tensile strength: 5.7 ± 0.2 cN/dtex), while maintaining good flame-retardant properties (LOI: 28.6%). This study provides an outstanding industrial production strategy for fabricating flame-retardant PA66 plastics and fibers.

Influence of the Crystal Structure of Melamine Trimetaphosphate 2D Supramolecules on the Properties of Polyamide 6.

To explore the influence of the crystal structure difference of melamine trimetaphosphate (MAP) on the application performance of its polymer composites, an intumescent flame retardant with the optimal crystal type was designed and synthesized to improve the mechanical properties and flame retardancy of polyamide 6 (PA6). I-MAP and II-MAP were obtained using different concentrations of MA and sodium trimetaphosphate (STMP) in an acidic aqueous solution. The morphology, chemical composition, and thermal stability were comprehensively characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The dispersion, mechanical properties, and flame retardancy of PA6/I-MAP and PA6/II-MAP were evaluated by SEM, stress and strain, limiting oxygen index test (LOI), vertical burning test (UL-94), cone calorimetry (CONE) test, and char residue analysis. The conclusion is as follows: I-MAP and II-MAP have a greater influence on the physical properties of PA6 but less influence on the chemical properties. Compared with PA6/I-MAP, the tensile strength of PA6/II-MAP is 104.7% higher, the flame rating reaches V-0, and PHRR is reduced by 11.2%.

No business as usual: The effect of smoke suppressants commonly used in the flame retardant PA6.6 on smoke and fire properties

As most of polymeric materials are inherently flammable, flame retardants (FR) are commonly used to reduce their fire risks. Nevertheless, these flame retardant materials are often detrimental to smoke parameters like specific optical density or smoke toxicity. The influence of several smoke suppressants (SP)-zinc stannate, zinc phosphate, titanium oxide and hydrotalcite-were investigated with respect to flame retardancy, smoke emission, particle emission and smoke toxicity in a diethyl aluminum phosphinate (AlPi) flame retardant polyamide 6.6 (PA6.6). It was shown that the interaction between SP, FR and polymer is crucial for smoke and fire properties and can change the mode of action of the FR as well the decomposition mechanism of the polymer. Small amounts of SP show less effect on forced flaming behavior and the optical density, but they can influence flammability and the particle size distribution of the soot particles. The flame retardancy was significantly enhanced by 5 wt.-% zinc stannate in PA6.6 under forced flaming conditions. The charring mechanism was improved, and the mode of action of AlPi switched from the gas to the condensed phase. This resulted of in a reduced PHRR and TSP and an increase in residue yield. The smoke toxicity and optical density were reduced in the smoke density chamber as well. The smoke particles shifted to smaller sizes as the time in the pyrolytic zone increased. The formation of a dense char is assumed to be the key factor to enhance smoke suppression and flame retardancy properties.

Thermal Stabilities and Flame Retardancy of Polyamide 66 Prepared by In Situ Loading of Amino-Functionalized Polyphosphazene Microspheres.

The flame-retardant polyamide 66 composites (FR-PA66) were prepared by in situ loading of amino-functionalized polyphosphazene microspheres (HCNP), which were synthesized in the laboratory and confirmed by a Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM). The thermal stabilities and flame retardancy of FR-PA66 were measured using thermogravimetric analysis (TGA), a thermogravimetric infrared instrument (TG-IR), the limiting oxygen index (LOI), the horizontal and vertical combustion method (UL-94), and a cone calorimeter. The results illustrate that the volatile matter of FR-PA66 mainly contains carbon dioxide, methane4, and water vapor under heating, accompanied by the char residue raising to 14.1 wt% at 600 °C and the value of the LOI and UL-94 rating reaching 30% and V-0, respectively. Moreover, the addition of HCNP decreases the peak of the heat release rate (pHRR), total heat release (THR), mass loss (ML), and total smoke release (TSR) of FR-PA66 to 373.7 kW/m2, 106.7 MJ/m2, 92.5 wt%, and 944.8 m2/m2, respectively, verifying a significant improvement in the flame retardancy of PA66.

Synthesis and Characterization of a New Copolymer Consisting of Polyamide 1210 and Reactive Phosphorus-Nitrogen Flame-Retardant.

The thermal stability and reactivity of organophosphorus flame-retardants play a critical role in synthesizing copolymerized flame-retardant polyamides. Herein, this work successfully synthesizes a flame-retardant CEPPA-DDA salt (CDS) with both good thermal stability and high reactivity by reacting 2-carboxyethyl phenyl phosphonic acid (CEPPA) with 1,12-dodecanediamine (DDA). Flame-retardant polyamide 1210 (FRPA) is further prepared by copolymerizing the CDS, DDA, and sebacic acid (SEA). The test results show that the introduction of CDS can significantly improve the flame-retardant properties of FRPA. Specifically, the flame-retardant polyamide 1210 (FRPA-7) with 7 wt% CDS addition can reach V-0 grade according to UL-94 standard, accompanying limiting oxygen index value of 30.2% and tensile strength of 38.62MPa. Compared with pure polyamide 1210, the peak heat release rate and total heat release rate of FRPA-7 reduce by 24.11% and 9.40%, respectively. This study provides a simple strategy to prepare flame-retardant polyamides with high flame retardancy and good mechanical properties, which are expected to show great potentials in future industrial applications.

Molecular design of reactive flame retardant for preparing biobased flame retardant polyamide 56

As resource and environmental issues become increasingly prominent worldwide, bio-based polyamides demonstrate appealing prospects due to their renewable and low carbon emission characteristics. The preparation of intrinsically flame-retardant polyamides by copolymerization of reactive flame retardants with biomass monomers becomes a hot research topic at present. In this work, reactive flame retardant (r-FR) is synthesized, showing excellent solubility and temperature resistance. Subsequently, flame retardant polyamide 56 (FRPA56) are prepared by one-step melt polycondensation. Specifically, when the r-FR content is 6wt%, FRPA56 has a high limiting oxygen index of 28.4%, and the vertical combustion reaches V-0 level, demonstrating excellent flame-retardant performance. Moreover, FAPA56 also owns outstanding temperature resistance and mechanical properties even with a r-FR content of 8wt%, in which the melting temperature and tensile strength are 246.1 °C and 71.05 MPa, respectively. This work develops an effective strategy for constructing intrinsically flame-retardant polyamide material, which can meet the requirements of engineering plastics and exhibit satisfactory performance in the field of textile.

Preparation and Characterization of Cyclodextrin Coated Red Phosphorus Double-Shell Microcapsules and Its Application in Flame Retardant Polyamide6.

Using the melamine borate and crosslinked β−cyclodextrin as shell materials, the double−shell microcapsules (Mic−DP) of red phosphorus (RP) was prepared, and its flame−retardant effect on polyamide 6 (PA6) was investigated. Compared with RP, Mic−DP showed lower hygroscopic and better inoxidizability. The limiting oxygen index (LOI) of PA6/13%Mic−DP was 27.8%, and PA6/13%Mic−DP reached V−0 rating. After the addition of 13% Mic−DP, the total exothermic (THR), peak exothermic (PK−HRR), and average effective thermal combustion (AV−EHC) rates of PA6 decreased. In addition, in order to investigate its flame−retardant mechanism, the pyrolysis gas chromatography−mass spectrometry (Py−GC−MS), scanning electron microscopy (SEM), and Fourier transform infrared (FT−IR) methods were used, and the results showed that mic DP acted as a flame retardant in the gas and condensed phases. The Mic−DP exhibited good compatibility and dispersibility in PA6.