Flame Retardancy Properties Of Poly Research Articles

Synergistic effect between ammonium polyphosphate-functionalized poly(lactic acid) and phosphated avocado seed on the flame-retardant properties of poly(lactic acid)/ethylene–vinyl acetate copolymer composites

Synergistic effect between ammonium polyphosphate-functionalized poly(lactic acid) and phosphated avocado seed on the flame-retardant properties of poly(lactic acid)/ethylene–vinyl acetate copolymer composites

Enhancing anti‐meltdrop and smoke suppression properties of flame retardant poly(ethylene terephthalate) fabric by fiber‐blending method

AbstractFlame retardant poly(ethylene terephthalate) (FRPET) fabrics are widely used in daily life. However, the meltdrop and visible smoke produced during combustion significantly limit its further application. This study proposes a simple but effective method of fiber‐blending to improve the above shortcomings. On the basis of synergistic flame retardancy of nitrogen and phosphorus, the FRPET was blended with flame retardant viscose (FRV) and intrinsic nitrogen‐containing flame retardant fibers (NIFRFs), to prepare the binary and ternary blended FRPET samples labeled as NIFRF/FRPET and FRV/NIFRF/FRPET, respectively. The limiting oxygen index and cone calorimeter test show that the ternary‐blending could effectively suppress the combustion of FRPET fiber composite. The smoke density test and UL‐94 vertical combustion test indicate that ternary‐blending could better improve the meltdrop characteristics and smoke suppression property than binary‐blending. Among all samples, FRV/PMIA/FRPET (1:4:5) owns the highest LOI of 32.6% and lowest smoke density of 61.37. The investigation of residual char utilizing scanning electron microscopy, the X‐ray photoelectron spectroscopy and the Laser Raman spectroscopy demonstrates that the FRPET meltdrop would adhere to the surface of component fibers to avoid droplets. Besides, fiber‐blending could increase the yield and degree of graphitization of residual char, which is conducive to improving samples' flame retardancy through the condensed phase. This work may provide a workable strategy to expand the application areas of FRPET fabrics.

Design, synthesis, flame retardancy and dielectric properties of novel aromatic hyperbranched benzoxazine

Two kinds of novel aromatic hyperbranched benzoxazines (HBs), HB-Tppa1 and HB-Tppa2, were designed and prepared by using 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), p-phenylenediamine (PPA), paraformaldehyde and phenol through two different synthetic routes via Mannich condensation reaction. Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H and 13C NMR) spectroscopy were employed to characterize the featured structures of these (HB-Tppa)s. HB-Tppa1 exhibits greater molecular weight than HB-Tppa2, owing to a priority of forming the hyperbranched structure for preparing HB-Tppa1 without adding capped phenol in the first step. The greater reaction enthalpy (ΔH) value of HB-Tppa1 has been provided by differential scanning calorimeter (DSC), indicating that the mass fraction of benzoxazine rings in HB-Tppa1 is higher than that of HB-Tppa2. The thermal and flame retardancy properties of poly(HB-Tppa1) superior to poly(HB-Tppa2) are affected by these mentioned factors. Besides the high glass transition temperature (Tg, ≥ 320 °C), the low total heat release (THR) and heat release capacity (HRC) values of poly(HB-Tppa)s in the range of 5.4–11.7 kJ/g and 41.5–50.5 J/(g K), respectively, suggest that they are potential nonignitable materials. Moreover, the poly(HB-Tppa)s exhibit low dielectric constants (2.27 ≥ k ≥ 2.15) in the high-frequency range of 2 to 18 GHz, which may perform well in next-generation integrated circuits.

Electrochemical exfoliation of water-dispersible graphene from graphite towards reinforcing the mechanical and flame-retardant properties of poly (vinyl alcohol) composites

Functional graphene is a very efficient support material to improve the performance of polymer composites, but the commercial application of functional graphene is hindered by its complex preparation procedure and high pollution. Herein, the water-dispersible graphene nanosheets (DGNS) were prepared by a simple and eco-friendly electrochemical method assisted with an anionic surfactant DNS86, and then DGNS were mixed into poly (vinyl alcohol) (PVA) matrix to fabricate PVA composite films. DGNS could be well dispersed in PVA matrix and form strong interfacial interaction with PVA molecular chains. The tensile strength, tensile modulus and storage modulus of PVA composite film containing 0.3 wt% DGNS were increased by 50.1%, 50.4% and 154.5%, respectively, compared to those of pure PVA. Moreover, the addition of DGNS also improved the flame retardancy of PVA composite films, achieving an obvious reduction (60.9%) in the peak heat release rate with the load of 2.0 wt% DGNS. The analysis revealed that the addition of DGNS could facilitate the formation of the compact and highly graphitic char residues, retarding the heat and mass transfer to protect underlying matrix during combustion process. This paper will supply a promising strategy to industrially produce functionalized graphene nanosheets for graphene-based reinforced composites.

Kinetic study on the synergistic effect between molecular weight and phosphorus content of flame retardant copolyesters in solid‐state polymerization

Abstract2‐Carboxyethyl(phenyl phosphinic) acid has been proved to modify flame retardant properties of poly(ethylene terephthalate) (PET) through copolymerization; however, there is no industrial technological breakthroughs in polyester industrial yarns which requires high strength and modulus, because it is related to the coordinated control of molecular weight and flame retardancy. In this work, the influence of solid‐state polymerization reaction kinetics and parameters on flame retardancy retention have been investigated, based on the prepared precursors optimized at 6,000 ppm phosphorus content and 0.64 dL/g intrinsic viscosity (I.V). Results showed that the copolyester polydispersity index increase was significant compared to PET with molecular weight increase. The I.V of optimized precursor could be increased to 1.31 dL/g at 220°C in 20 hr, but at higher phosphorus content loses up to 7%. Flame retardant component deteriorates with increasing reaction rate and temperature as a result of severe side reactions. Optimized precursor at the optimum temperature (210°C) reacted for 20 hr, copolyester with the phosphorus content of 5,910 ppm and the I.V of 1.12 dL/g (( was about 3.5 × 104 g/mol) was prepared. The coordination between high molecular weight and flame retardant performance was realized.

Phytic Acid Modified Boron Nitride Nanosheets as Sustainable Multifunctional Nanofillers for Enhanced Properties of Poly(l-lactide)

A sustainable multifunctional nanofiller (f-BNNSs) based on boron nitride nanosheets and biobased phytic acid was prepared using (γ-aminopropyl) triethoxysilane as a coupling agent. The structure of f-BNNSs was analyzed systematically using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental mapping. The influence of f-BNNSs on the crystallinity, polymorphism, crystallization kinetics, thermal stability, thermal conductivity, and flame retardant properties of poly(l-lactic acid) (PLLA) was systematically investigated. f-BNNSs show remarkable nucleating effects on the crystallization of PLLA, and the crystallization rate increases with increasing f-BNNSs loading. Upon addition of 20 wt % of f-BNNSs, the crystallization half-time of PLLA/f-BNNSs nanocomposite decreases from 12.0 to 1.0 min at 130 °C compared to PLLA. The presence of f-BNNSs in PLLA/f-BNNSs nanocomposites favors the formation of ordered α form irrespective of the loadings of f-BNNSs. Thermal stability and...

Engineering carbon nanotubes wrapped ammonium polyphosphate for enhancing mechanical and flame retardant properties of poly(butylene succinate)

The performance of CNTs with different amounts and dispersion states were explored in the flame retardant system as PBS/APP. Herein, A series of CNTs wrapped ammonium polyphosphate (named CAPP) were successfully prepared and characterized, and then blended into Poly(butylene succinate) (PBS) as an additive-type flame retardant. The obtained PBS/CAPP contributes to forming much more graphitized char layers to reduce the heat transfer and toxic gases release. For instance, PBS-3 containing 20% CAPP1 wrapped by only 1% of CNTs shows the best anti-dripping effect and the lowest toxic gases release, where CO2 and CO yield dramatically reduced by about 68.3% and 72.6%. With the same content of CNTs, the tensile strength, elongation at break and unnotched impact strength of PBS-3 increased about 10.8%, 14.2% and 5.3% than PBS-5 (CNTs added directly). Thus, the well dispersion state of moderate CNTs has a positive impact on improving mechanical properties, flame retardancy and smoke suppression.

A new direction in design of bio‐based flame retardants for poly(lactic acid)

SummaryA novel bio‐based nitrogen‐rich and phosphorus‐rich flame retardant (Phyt/PEI‐TA) was synthesized and characterized by Fourier transform infrared, inductively coupled plasma, and thermogravimetric analysis (TGA). Thermal degradation and flame retardant properties of poly(lactic acid) (PLA) containing 20 wt% Phyt/PEI‐TA were investigated by TGA, cone calorimetry, and microcalorimeter of combustion (pyrolysis combustion flow calorimeter) measurements. Thermogravimetric analysis results showed that introduction of newly developed Phyt/PEI‐TA to PLA significantly improved its thermal stability, as signaled by much more amount of PLA char formed compared to the reference sample. Surprisingly, the use of Phyt/PEI‐TA did not decrease the onset degradation temperature of PLA. In agreement with TGA results, the cone calorimetry results approved excellent flame retardancy of PLA upon addition of Phyt/PEI‐TA (36% reduction in peak of heat release rate compared to that of neat PLA). Based on the analysis performed on the remainder of char after cone calorimeter test as well as analyses on heat release rate curves, the condensed phase action by promoting the formation of char was identified as principal impact of the Phyt/PEI‐TA on flame retardancy of PLA. Finally, the performance of developed bio‐based flame retardant was compared with more than 60 flame retardant systems previously reported in the literature.

Manufacturing, mechanical and flame retardant properties of poly(lactic acid) biocomposites based on calcium magnesium phytate and carbon nanotubes

A bio-flame retardant, calcium magnesium phytate (CaMg-Ph), was synthesized via the reaction of calcium chloride and magnesium chloride with phytic acid from renewable source. Poly(lactic acid) (PLA) biocomposites were fabricated using CaMg-Ph as a bio-sourced phosphorous additive combined with acid-treated carbon nanotubes (CNT). The thermal, mechanical and flame retardant properties of PLA biocomposites were evaluated by thermogravimetric analysis (TGA), tensile and cone calorimeter tests. The addition of the combinations (19 wt% CaMg-Ph and 1 wt% CNT) into PLA resulted in a slight increase in tensile strength (52.8 MPa), compared to 20 wt% CaMg-Ph (50.4 MPa), indicating the reinforcement effect of the CNT. The addition of 10, 20, and 30 wt% CaMg-Ph led to significant reduction in PHRR by 22%, 33%, and 38% respectively with a similar trend in THR. PLA/CaMg-Ph19/CNT1 showed lower PHRR (35.0%) and higher char yield (18.4 wt%) compared to PLA/CaMg-Ph20, suggesting the preferable flame retardant properties.

Morphology, thermal and dynamic mechanical properties of poly(lactic acid)/expandable graphite (PLA/EG) flame retardant composites

This work reports on the effect of expandable graphite (EG) on the morphology, thermal and dynamic mechanical properties of flame retardant poly(lactic acid) (PLA)/EG composites. The composites were prepared by melt-mixing and their structure, morphology, melting and crystallization behaviour, as well as their dynamic mechanical properties, were investigated. It was found that graphite layers still existed in an aggregate structure with poor filler dispersion resulting in a lack of interfacial adhesion between EG and the PLA matrix. The presence of EG did not favour the crystallization of PLA, increased the glass transition temperature and showed a reduction in the crystallinity of the composites. The composites with higher filler contents showed enhanced storage and loss moduli. The glass transition temperatures from the loss modulus and damping factor curves varied inconsistently with EG content. The use of commercial EG as filler in PLA can preserve the thermal properties of injection moulding grade Cereplast PLA.

Effects of bridged DOPO derivatives on the thermal stability and flame retardant properties of poly(lactic acid)

Three bis P-C bridged 9,10-dihydro-9-oxa-10-phosphaphe nanthrene-10-oxide (DOPO) derivatives including ethyl-(DiDOPO1), phenethyl-(DiDOPO2) and naphthalene-(DiDOPO3), were synthesized and incorporated in poly(lactic acid) (PLA). Then, the flame retardant and thermal properties of the obtained PLA composites were investigated in detail. At 10 wt% addition of the derivatives, all PLA composites achieved a V-0 rating (UL-94, 3.2 mm), and the LOI values of PLA/DiDOPO1, PLA/DiDOPO2 and PLA/DiDOPO3 increased from 20.0% (pure PLA) to 36.4%, 27.1% and 24.3%, respectively. The introduction of DiDOPO1, DiDOPO2, and DiDOPO3 decreased the peak heat release rate value of PLA composites from 561 kW/m2 (pure PLA) to 490, 488 and 434 kW/m2, respectively. In addition, the derivatives significantly enhanced the thermal stability of PLA especially under air condition. It was found that the bridged DOPO derivatives shows a dominant flame inhibition role in PLA. Furthermore, the investigation of the residue micromorphology of PLA composites revealed that a cross-linked structure likely formed with the increased of aromatic groups in the molecule.

Simultaneous enhancements in the mechanical, thermal stability, and flame retardant properties of poly(1,4-butylene terephthalate) nanocomposites with a novel phosphorus–nitrogen-containing polyhedral oligomeric silsesquioxane

A novel functionalized POSS greatly reinforced the mechanical, thermal stability, and flame retardant properties of PBT.

Preparation of microcellular poly(lactic acid) composites foams with improved flame retardancy

In this study, flame-retardant poly(lactic acid) foams with satisfactory cell structures were prepared by microcellular foaming technology using phosphorus-containing flame retardant and graphene as the charring agent. The introduction of 5–30 wt% flame retardant increased the limited oxygen index value of poly(lactic acid) from 19.0 to 26.5–37.8% and simultaneously increased the foam expansion of poly(lactic acid) foams from 4.4 to 5.8–17.5. In addition, all the prepared poly(lactic acid)/flame-retardant composites passed the UL-94 V-0 rating. The addition of 0.5 wt% graphene increased the limited oxygen index value of poly(lactic acid)/flame-retardant composite with flame-retardant content of 15 wt% from 27.9 to 29.2%, and more graphene additions improved the antidripping behavior of poly(lactic acid) composites. The possible mechanisms of the effects of the resultant cellular structure on the flame-retardant properties of poly(lactic acid) composites were also discussed.

Effect of ethyl cellulose microencapsulated ammonium polyphosphate on flame retardancy, mechanical and thermal properties of flame retardant poly(butylene succinate) composites

Ethyl cellulose, a widely used bio-degradable shell material, microencapsulated ammonium polyphosphate (MAPP) was added to the bio-degradable poly(butylene succinate) (PBS) to improve its flame retardancy, compatibility, and thermal stability. The MAPP was well characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), water contact angle, and thermogravimetric (TG) analysis. The SEM results indicate the improved dispersion of MAPP into PBS matrix and the formation of the strong interfacial adhesion between MAPP and PBS than APP. With the incorporation of MAPP and char-forming agent into PBS, the limiting oxygen index of the composite was increased to 35.5 %, and the sample can pass the UL-94 V-0 rating, while the un-microencapsulated counterpart cannot reach the rating. The cone calorimeter test showed that the peak heat release rate was decreased by 46.7 % and the burning time was also prolonged compared to the pure PBS. The increased melt flow index and rheology test indicated the increase of viscosity and the improvement of anti-dripping properties. Moreover, the mechanical properties and thermal stability of MAPP composite were also obviously enhanced after the microencapsulation by mechanical, dynamical mechanical thermal analysis, and TG analysis.

Synthesis and properties of flame-retardant poly(vinyl alcohol)/pseudo-boehmite nanocomposites with high transparency and enhanced refractive index

Abstract Flame-retardant nanocomposites with high transparency based on poly (vinyl alcohol) (PVA) and pseudo-boehmite nanorods have been fabricated by synthesis of pseudo-boehmite nanorods and subsequent solution blending with PVA. The morphology and physical properties of PVA/pseudo-boehmite nanocomposites have been characterized systematically. Scanning electron microscopy investigations showed the homogeneous dispersion of pseudo-boehmite nanorods within PVA matrix even at very high nanorods loadings. The nanocomposites with 37.5 wt% pseudo-boehmite nanorods exhibit limit oxygen index (LOI) as high as 30.0 with the transmittance of more than 90% at the visible region and the enhanced refractive index. Moreover, the incorporation of the pseudo-boehmite nanorods increases the modulus and the tensile strength of PVA, indicating the significantly enhanced surface hardness of the nanocomposite. It is considered that the prepared PVA nanocomposites are not only useful as flame-retardant fibers, a long term pursued target for PVA fabrics, but also as optical appliances with its excellent transparency and high refractive index.

Mechanical, thermal, and fire retardant properties of poly(ethylene terephthalate) fiber containing zinc phosphinate and organo-modified clay

The effect of zinc bisdiethylphosphinate (ZnPi) and organoclay on mechanical, thermal, and flame retardant properties of poly(ethylene terephthalate) (PET) fiber was investigated. ZnPi was preferred due to its fusible character at spinning temperature and organoclay was used for synergistic interaction. The mechanical, thermal, and flame retardant properties of fibers were examined by tensile testing, thermogravimetric analysis (TG), and micro combustion calorimeter (MCC). The tensile strength of the PET fiber reduced with the addition of both ZnPi and organoclay. The TG results showed that the inclusion of ZnPi increased the char residue. The MCC results showed that the addition of organoclay increased the barrier effect of formed char which depends on char amount, thickness, and integrity and reduces the maximum heat evolved during the test. This result was also important in terms of showing that the organoclay was effective in thermally thin samples.

Synergistic Effect Between Organically Modified Montmorillonite and Ammonium Polyphosphate on Thermal and Flame-Retardant Properties of Poly(Butyl Acrylate/Vinyl Acetate) Copolymer Latex

Hexadecyl trimethyl ammonium bromide modified montmorillonite (1631-MMT) was successfully synthesized via an ion exchange reaction and characterized through Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Various poly(butyl acrylate/vinyl acetate) P(BA-VAc) copolymer P(BA-VAc)/1631-MMT emulsions were prepared via in-situ polymerization method using potassium persulphate (K2S2O8, KPS) as an initiator. Ammonium polyphosphate (APP) was introduced for obtaining P(BA-VAc)/APP/1631-MMT flame-retardant latex. The flame retardancy and thermal behavior of the latex films were investigated through limiting oxygen index (LOI) and vertical burning test (UL-94) and thermo-gravimetric analysis (TGA/DTA [differential thermal analysis]) analysis. Compared with the P(BA-VAc)/APP composite, the LOI value of P(BA-VAc)/APP/1631-MMT sample was increased from 27.7 to 30.3 with a concentration of 1631-MMT 0.5 wt% in composition, and its UL-94 was raised to V-0 from no rating. TG date showed that the amount of residues increased significantly when 1631-MMT was added. The morphology and microstructure of the residues generated during LOI testing were investigated by scanning electron microscopy (SEM). The outer surface of the P(BA-VAc)/APP/1631-MMT charred layer was more continuous and compact than that of P(BA-VAc)/APP.

Combination effect of melamine polyphosphate and graphene on flame retardant properties of poly(vinyl alcohol)

A novel flame retardant poly(vinyl alcohol) (PVA)/melamine polyphosphate (MPP)–graphene nanocomposite has been prepared by solvent blending. Results from X-ray diffraction (XRD) and transmission electron microscopy (TEM) suggest that an excellent dispersion of exfoliated graphene and MPP in the PVA matrix was achieved. The thermal and flammability properties of the nanocomposite were investigated using thermogravimetry, cone calorimetry, and flammability tests (UL 94 and LOI). The presence of both MPP and graphene in the polymer matrix led to an enhanced thermal stability and significantly reduced flammability for the nanocomposite. PVA composites filled with 10wt% MPP and 1wt% graphene (PVA/G1/MPP10) achieved the LOI value of 29.6 and UL-94 V0 grade. Compared to pure PVA, the peak heat release rate (PHRR) of PVA/G1/MPP10 is reduced by about 60%. Meanwhile, the mechanical properties of PVA/G1/MPP10 composites exhibit almost no deterioration compared with pure PVA. The morphology and composition of residues generated after cone calorimeter tests were investigated by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The SEM images showed the compact and dense intumescent char jammed with graphene sheets was formed for PVA/G1/MPP10 during combustion. The results of XPS confirmed that carbon content of the char for PVA/G1/MPP10 is increased obviously by the combination effect of the flame retardant MPP and graphene.

A method for simultaneously improving the flame retardancy and toughness of PLA

AbstractIn order to modify the brittleness and flame retardant properties of poly(lactic acid) (PLA), a series of flame retardant toughened PLA composites were prepared using poly(ethylene glycol) 6000 (PEG6000) as a toughening and charring agent together with ammonium polyphosphate (APP) as an acid source and blowing agent. The fire and thermal behavior of PLA/PEG/APP composites was evaluated by limiting oxygen index (LOI), UL‐94, cone calorimeter, and thermogravimetric analysis (TGA). The results showed that the PLA/PEG/APP system had good charring ability and could improve the flame retardancy of PLA. When the content of APP in the composites was more than 5 wt%, all samples could reach UL‐94 V‐0 rating. The results of mechanical property tests demonstrated that the brittleness of PLA was also improved after blended with PEG6000. All the PLA/PEG/APP composites with an APP content of less than 10 wt% showed an obvious neck and fracture behavior, that is, the tensile behavior of PLA was changed from brittle to ductile. Copyright © 2010 John Wiley & Sons, Ltd.

Synergistic effect of organically modified layered double hydroxide on thermal and flame-retardant properties of poly(butyl acrylate–vinyl acetate)

Organically modified layered double hydroxide (O-LDH) was successfully synthesized by coprecipitation and characterized through Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). O-LDH/poly(butyl acrylate–vinyl acetate) (P(BA-VAc) emulsion was prepared via in situ polymerization, then ammonium polyphosphate (APP) was introduced to obtain the O-LDH/APP/P(BA-VAc) flame-retardant latex. The flame retardancy and thermal behavior of the latexes after evaporation of water were investigated by the limiting oxygen index (LOI) test, vertical burning test (UL-94), and thermal gravimetric analysis (TGA). Compared with the APP/P(BA-VAc) composite, the LOI value of O-LDH/APP/P(BA-VAc) containing 0.5 wt.% O-LDH at the same total additive loading increased to over 30.0%, and its UL-94 increased from no rating to V-0. TG data show that the amount of residues increases obviously when O-LDH is added. The LOI values increased with increasing amounts of char residues. The morphology and microstructure of residues generated during the LOI test were investigated by scanning electron microscopy (SEM). FTIR and X-ray photoelectron spectroscopy (XPS) were used to determine the composition of the residues formed after combustion at 450 °C for 5 min to support a fundamental analysis of the mechanism of char formation.