Effect of trisilanolphenyl‐POSS on rheological,mechanical, and flame‐retardant properties of poly(ethylene terephthalate)/cyclotriphosphazene systems

Poly(ethylene terephthalate) (PET) chips were coated by trisilanolphenyl–polyhedral oligomeric silsesquioxane (T‐POSS) and hexakis (para‐allyloxyphenoxy) cyclotriphosphazene (PACP) using the predispersed solution method, and PET/PACP/T‐POSS hybrids were further prepared by the melt‐blending method. The influence of T‐POSS on the rheological, thermal, and mechanical properties and flame retardancy of PET/PACP composites were discussed. The results suggest that T‐POSS was homogeneously dispersed in the PET matrix, which reduced the negative effects on polymer rheology and mechanical properties. For the PET/4%PACP/1%T‐POSS sample, the tensile strength at break and T_g increased from 29.67 MPa and 81.7 °C (PET/5%PACP) to 34.8 MPa and 85.8 °C, respectively, but the sample also self‐extinguished within 2 s, and the heat release capacity was reduced by 27.9% in comparison with that of neat PET.© 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45912.     

Flame retardancy and mechanical properties of pet‐based composites containing phosphorus and boron‐based additives

Flame retardancy of poly(ethylene terephthalate), PET, was improved using different flame retardant additives such as triphenylphosphate, triphenylphosphine oxide, zinc borate, and boron phosphate (BP). Composites were prepared using a twin screw extruder and subsequently injection molded for characterization purposes. The flame retardancy of the composites was determined by the limiting oxygen index (LOI) test. Smoke emission during fire was also evaluated in terms of percent light transmittance. Thermal stability and tensile properties of PET‐based composites were compared with PET through TGA and tensile test, respectively. The LOI of the flame retardant composites increased from 21% of neat PET, up to 36% with the addition of 5% BP and 5% triphenyl phosphate to the matrix. Regarding the smoke density analysis, BP was determined as an effective smoke suppressant for PET. Enhanced tensile properties were obtained for the flame retardant PET‐based composites with respect to PET. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42016.     

Semiaromatic polyamide poly(hexamethylene terephthalamide)‐co‐polycaprolactam: Thermal and flame‐retardant properties

The poly(hexamethylene terephthalamide)‐co‐polycaprolactam (PA6T/6; 50:50) copolymer was synthesized with a reactive extrusion method and subsequently mixed with a certain content of glass fibers (GFs) and different ratios of flame‐retardant aluminum diethyl phosphinate (AlPi) to fabricate a series of composites. These resulting composites were found to have excellent mechanical (tensile strength = 119–154 MPa) and thermal properties (heat‐deflection temperature = 263–293 °C). It is particularly worth mentioning that the value of the limiting oxygen index reached 29.5% and a UL‐94 V‐0 rating (1.6 mm) was achieved with the addition of 20 portions of AlPi. Also, the values of the peak heat‐release rate and total heat release in cone calorimetry were found to decrease with the addition of the flame‐retardant AlPi, which acted mainly as a flame inhibitor in the gas phase. Through visual observation, scanning electron microscopy after cone calorimetry testing, and thermogravimetric analysis, the condensed‐phase flame‐retardant mechanism of the PA6T/6–GF–AlPi system was confirmed to have a synergetic role. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46451.     

Flame‐retardant properties and mechanisms of epoxy thermosets modified with two phosphorus‐containing phenolic amines

Two phosphorus‐containing phenolic amines, a 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based derivative (DAP) by covalently bonding DOPO and imine (SB) obtained from the condensation of p‐phenylenediamine with salicylaldehyde, and its analog (AP) via the addition reaction between diethyl phosphite and SB, were used to prepare flame‐retardant epoxy resins. The burning behaviors and dynamic mechanical properties of epoxy thermosets were studied by limited oxygen index (LOI) measurement, UL‐94 test, and dynamic mechanical analysis. The flame‐retardant mechanisms of modified thermosets were investigated by thermogravimetric analysis, Py‐GC/MS, Fourier transform infrared, SEM, elemental analysis, and laser Raman spectroscopy. The results revealed that epoxy thermoset modified with DAP displayed the blowing‐out effect during UL‐94 test. With the incorporation of 10 wt % DAP, the modified thermoset showed an LOI value of 36.1% and V‐0 rating in UL‐94 test. The flame‐retardant mechanism was ascribed to the quenching and diluting effect in the gas phase and the formation of phosphorus‐rich char layers in the condensed phase. However, the thermoset modified with 10 wt % AP only showed an LOI value of 25.7% and no rating in UL‐94 test, which was possibly ascribed to the mismatching of charring process with gas emission process during combustion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43953.     

Study of flame‐resistant acrylic fibers reinforced by poly(vinyl alcohol)

Acrylic fibers [polyacrylonitrile (PAN) fibers] have excellent flame‐retardant properties after they are modified by hydrazine hydrate and metal ions; however, their widespread applications are restricted because of poor mechanical properties. To improve the mechanical properties of these modified PAN fibers, poly(vinyl alcohol) (PVA) was added to the spinning solution of PAN as an effective reinforcing agent. The structure of the fibers before and after modification was studied by Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive spectroscopy, and wide‐angle X‐ray diffraction. The mechanical properties and flame resistance of the fibers after treatment were also tested by a single‐fiber tensile tester and a limiting oxygen index (LOI) analyzer, respectively. We found that the LOI of the modified fibers was reduced from 54.7 to 29.1 after the introduction of 50 wt % PVA; however, the tensile strength was dramatically improved from about 1.50 cN/dtex to more than 4.00 cN/dtex. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43006.     

Flame‐retardancy properties of tris(2‐hydroxyethyl) isocyanurate based charring agents on polypropylene

Tris(2‐hydroxyethyl) isocyanurate based charring agent (TBCA) was synthesized by melt polycondensation with tris(2‐hydroxyethyl) isocyanurate (THEIC) and terephthalic acid as raw materials. It was characterized by Fourier transform infrared spectroscopy, elemental analysis, ¹H‐NMR, and thermogravimetric analysis (TGA). TBCA was blended with ammonium polyphosphate (APP) to form an intumescent flame retardant (IFR) for polypropylene (PP). The charring properties of TBCA was tested by flame retardancy in the PP/APP/TBCA (PP/IFR₂) composite and compared with that of the PP/APP/THEIC (PP/IFR₁) composite. The results show that PP/IFR₂ had lower flame‐retardant properties but better water resistance than that of the PP/IFR₁ composite because PP/IFR₂ could still obtain a V‐0 rating after it had been soaked in water at 70°C for 96 h, whereas PP/IFR₁ could not achieve any rating after 36 h. Their combustion performance was further evaluated by a cone calorimeter test, their thermal degradation processes were studied by TGA, and the morphology of the char residue was observed by scanning electron microscopy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41810.     

Synthesis and performance of a novel nitrogen‐containing cyclic phosphate for intumescent flame retardant and its application in epoxy resin

A novel nitrogen‐containing cyclic phosphate (NDP) was synthesized and well characterized by ¹H, ¹³C, ³¹P NMR, mass spectra and elemental analysis. NDP was used as an additive intumescent flame retardant (AIFR) to impart flame retardancy and dripping resistance for diglycidyl ether of bisphenol‐A epoxy resin (DGEBA) curied by 4,4′‐diaminodiphenylsulfone (DDS) with different phosphorus content. The flammability, thermal stability, and mechanical properties of NDP modified DGEBA/DDS thermosets were investigated by UL‐94 vertical burning test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Izod impact strength and flexural property tests. The results showed that NDP modified DGEBA/DDS thermosets exhibited excellent flame retardancy, moderate changes in glass transition temperature and thermal stability. When the phosphorus content reached only 1.5 wt %, the NDP modified DGEBA/DDS thermoset could result in satisfied flame retardancy (UL‐94, V‐0). The TGA curves under nitrogen and air atmosphere suggested that NDP had good ability of char formation, and there existed a distinct synergistic effect between phosphorus and nitrogen. The flame retardant mechanism was further realized by studying the structure and morphology of char residues using FT‐IR and scanning electron microscopy (SEM). It indicated that NDP as phosphorus‐nitrogen containing flame retardant worked by both of the condensed phase action and the vapor phase action. Additionally, the addition of NDP decreased slightly the flexural strength of the flame retarded DGEBA epoxy resins, and increased the Izod impact strength of these thermosets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41859.     

Thermal stability,flame retardance,and mechanical properties of polyamide 66 modified by a nitrogen–phosphorous reacting flame retardant

Flame‐retardant polyamide 66 (PA66) was prepared by the polymerization between PA66 prepolymer and N‐benzoic acid (ethyl‐N‐benzoic acid formamide) phosphamide (NENP). Compared with the pure PA66, the flame‐retardant PA66 exhibited better thermal stability, as indicated by thermogravimetric analysis results. The limiting oxygen index was 28% and the UL‐94 test results of the flame‐retardant PA66 indicated a V‐0 rating when the content of the NENP prepolymer was 5 wt %. The flammability and flame‐retardant mechanism of PA66 were also studied with cone calorimetry and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, respectively. The mechanical properties results show that the flame‐retardant PA66 resin had favorable mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43538.     

Simultaneously Improving the Thermal,Flame‐Retardant and Mechanical Properties of Epoxy Resins Modified by a Novel Multi‐Element Synergistic Flame Retardant

To obtain epoxy resins with satisfactory thermal, flame retardant, and mechanical properties, a novel multi‐element synergistic flame retardant (PPVSZ) is synthesized through the reaction between P? H of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and C?C of polysilazane (PVSZ) and utilized as a multi‐element synergistic flame retardant for epoxy resins. The flame retardant mechanism is explored by XPS and SEM, confirming that the excellent flame‐retardance efficiency owes itself to an optimal flame retardant way which jointly exerts the flame‐retardant effects in the gaseous and condensed phase. The thermal properties deduced from DSC, TGA, and DMA, indicate the glass transition temperature, maximum weight loss rate, and char yields at 700 °C for EP‐2 increase by about 5.0 °C, 8.4 °C and 8.8%, respectively. Furthermore, mechanical properties such as impact strength, tensile strength, and flexural strength are also increased by 45.38%, 14.16%, and 17.43%, respectively, which show that the incorporation of PPVSZ does not deteriorate the mechanical properties of modified resin. All the results demonstrate that epoxy resins modified by PPVSZ not only have good effect on the flame retardance, but also have good improvement on thermal and mechanical properties, indicating the potential for applications in many fields requiring fire safety.     

Effect of zinc oxide on properties of phenolic foams/halogen‐free flame retardant system

A halogen‐free flame retardant system consisting of ammonium polyphosphate (APP) as an acid source, blowing agent, pentaerythritol (PER) as a carbonific agent and zinc oxide (ZnO) as a synergistic agent, was used in this work to enhance flame retardancy of phenolic foams. ZnO was incorporated into flame retardant formulation at different concentrations to investigate the flammability of flame retardant composite phenolic foams (FRCPFs). The synergistic effects of ZnO on FRCPFs were evaluated by limited oxygen index (LOI), thermogravimetric analysis (TGA), cone calorimeter tests, and images of residues. Results showed that the flame retardant significantly increased the LOI of FRCPFs. Compared with PF, heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC), production or yield of carbon monoxide (COP or COY) and Oxygen consumption (O₂C) of FRCPFs all remarkably decreased. However specific extinction area (SEA) and total smoke release (TSR) significantly increased, which agreed with the gas‐phase flame retardancy mechanism of the flame retardant system. The results indicated that FRCPFs have excellent fire‐retardant performance and less smoke release. And the bending and compression strength were decreased gradually with the increase of ZnO. The comprehensive properties of FRCPFs were better when the amount of ZnO was 1～1.5%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42730.     

Flame‐retardant,glass‐fabric‐reinforced epoxy resin laminates fabricated through a gradient distribution mode

In general, epoxy resin (EP) glue mixed with a high content of flame retardants is used to coat glass fabrics layer by layer to prepare fire‐retardant printed circuit boards (PCBs). However, the addition of the flame retardants not only increases the cost but also greatly deteriorates the processability and mechanical properties of the PCBs. In this study, a gradient distribution mode of composite flame retardants was designed and applied in EP‐based PCB composites. Unlike the traditional uniform distribution mode, in which flame retardants are evenly distributed in every resin layer, the gradient mode concentrates a higher content of the flame retardants on the surface layer, and the concentrations are gradually reduced along the thickness. In this way, the surface resin can quickly form a condensed charring barrier to hold back fire; this effectively protects the underlying resin, which has lower contents of flame retardant. The results of this study show that PCB prepared by the gradient mode obtained satisfactory flame retardance (a UL94 V‐0 rating) with only a 3.5 wt % total amount of flame retardant; this value was much lower than that (6.3 wt %) of composites featuring a uniform distribution. Additionally, the gradient mode also maintained the mechanical properties of PCB better. The tensile, impact, and flexural strengths of the gradient distribution system were obviously higher than those of the uniform distribution one with the same content of flame retardant. On the basis of the mode, a more economic and efficient technology was developed to manufacture flame‐retardant layered PCB. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44369.     

Preparation,characterization and properties of a halogen‐free phosphorous flame‐retarded poly(butylene terephthalate) composite based on a DOPO derivative

A phosphorous flame retardant (DOPO‐MAH) was synthesized through the reaction between of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and maleic anhydride (MAH) and confirmed by FT‐IR, ¹H NMR, and ³¹P NMR techniques. The obtained flame retardant was then melt blended with poly(butylene terephthalate) (PBT) to prepare flame retardant PBT/DOPO‐MAH composites. The composites were characterized by LOI, UL‐94, and mechanical tests as well as scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry analysis. On adding 20 wt % DOPO‐MAH, LOI increased from 20.9 to 25.7 and the UL‐94 V‐0 rating was achieved, whereas the tensile and flexural properties were notably improved. Torque‐time profile during the melt blending and intrinsic viscosity of the composite indicated that DOPO‐MAH acted as both flame retardant and chain extender for the PBT matrix. The results showed that PBT/DOPO‐MAH composite is a promising material for its good comprehensive properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1301‐1307, 2013     

Preparation and properties of a novel flame retardant polyurethane quasi‐prepolymer for toughening phenolic foam

A novel phosphorus‐ and nitrogen‐containing polyurethane quasi‐prepolymer (PNPUQP) was synthesized and incorporated into phenolic foam (PF) in different ratios in order to improve the toughness. The structure of PNPUQP was confirmed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR). The effects of PNPUQP on the flame retardant properties, thermal stability and mechanical properties of modified PF were investigated. The results suggested that the addition of 3 wt % PNPUQP increased the toughness of PF and improved the flame retardancy. The investigation on the morphology of PF and modified PF by scanning electron microscope (SEM) certified the good toughness of the PNPUQP on PF. Additionally, the thermal properties of the foams were investigated by thermogravimetric analysis (TGA) under N₂ atmosphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42424.     

Study on the performance of flame‐retardant esterified starch‐modified cassava dregs‐PBS composites

Esterified starch was used as an interfacial modifier to treat the surface of cassava dregs. The treated fiber was used to prepare flame‐retardant poly(butylene succinate) (PBS)/cassava dregs fiber composites with the incorporation of intumescent flame retardants (IFR). The mechanical performance and flame‐retardant properties of composites were investigated. Experimental data showed that an appropriate cassava fiber loading favored the mechanical performance of composites. When the total filler content was 30 wt % [m(cassava dregs):m(IFR) = 1:5], in comparison with those of composite prepared by 30 wt % IFR, the tensile and impact strengths of composite increased by 40 ± 7 and 62 ± 8%, respectively. Besides, the limited oxygen index value of 37.3% and UL‐94 V0 rate of composite could be achieved. Possible flame retardant mechanism was proposed. The combusted residue of incorporated cassava dregs could play a support effect in the three‐dimensional charred layer formed by the combustion products of IFR and PBS. The three‐dimensional intumescent charred layer, and the formation of incombustible gas, such as NH3, play an important role in insulation, oxygen barrier, thereby effectively improving the flame retardancy and thermal stability of composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46210.     

Joint flame‐retardant effect of triazine‐rich and triazine/phosphaphenanthrene compounds on epoxy resin thermoset

To obtain a more efficient flame‐retardant system, the extra‐triazine‐rich compound melamine cyanurate (MCA) was coworked with tri(3‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide‐2‐hydroxypropan‐1‐yl)?1,3,5‐triazine‐2,4,6‐trione (TGIC–DOPO) in epoxy thermosets; these were composed of diglycidyl ether of bisphenol A (DGEBA) epoxy resin and 4,4′‐diaminodiphenyl methane (DDM). The flame‐retardant properties were investigated by limited oxygen index measurement, vertical burning testing, and cone calorimeter testing. In contrast to the DGEBA/DDM (EP for short) thermoset with a single TGIC–DOPO, a better flame retardancy was obtained with TGIC–DOPO/MCA/EP. The 3% TGIC–DOPO/2% MCA/EP thermoset showed a lower peak heat‐release rate value, a lower effective heat of combustion value, fewer total smoke products, and lower total yields of carbon monoxide and carbon dioxide in comparison with 3% TGIC–DOPO/EP. The results reveal that MCA and TGIC–DOPO worked jointly in flame‐retardant thermosets. The dilution effect of MCA, the quenching effect of TGIC–DOPO, and their joint action inhibited the combustion intensity and imposed a better flame‐retardant effect in the gas phase. The 3% TGIC–DOPO/2% MCA/EP thermoset also exhibited an increased residue yield, and more compositions with triazine rings were locked in the residues; this implied that MCA/TGIC–DOPO worked jointly in the condensed phase and promoted thermoset charring. The results reveal the better flame‐retardant effect of the MCA/TGIC–DOPO system in the condensed phase. Therefore, the joint incorporation of MCA and TGIC–DOPO into the EP thermosets increased the flame‐retardant effects in both the condensed and gas phases during combustion. This implied that the adjustment to the group ratio in the flame‐retardant group system endowed the EP thermoset with better flame retardancy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43241.     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Flexible and flame‐retardant S‐SEB‐S triblock copolymer/PPE nano‐alloy

We observed that modified polyphenylene ether (PPE) was solubilized in thermoplastic styrenic elastomer (TPS) and that a two‐phase lacy structure formed on nanometer scales when the TPS composition was 67 wt % and modified PPE and polystyrene‐block‐poly(styrene‐co‐ethylene‐co‐butylene)‐block‐polystyrene (S‐SEB‐S triblock copolymer) were blended. However, the molecular weight of the outer PS block segments M_outPS and the content of the outer PS block segments ?_outPS were <10,000 g/mol and 20 wt %, respectively. The resulting S‐SEB‐S/modified PPE nano‐alloy exhibited both flexibility and flame retardancy, unlike other materials, where a trade‐off exists between these two properties; that is, the flame retardancy was excellent when the phosphorus additive was present. This combination of properties might be attributed to the two‐phase nanometer‐scale structure consisting of flame‐retardant styrene/PPE domains and a continuous soft, lacy SEB matrix. The results for polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene (S‐EB‐S triblock copolymer)/modified PPE blends were presented for comparison. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40446.     

Simultaneously enhanced fracture toughness and flame‐retardant property of poly(l‐lactic acid) via reactive blending with ammonium polyphosphate and in situ formed polyurethane

The preparation of poly(l ‐lactic acid) (PLLA) with high mechanical and ideal flame‐retardant properties is a great challenge. Herein, a simultaneous toughness and flame‐retardant PLLA composite was successfully fabricated by using a one‐step process which introduces 4,4′‐methylenediphenyl diisocyanate and ammonium polyphosphate (APP) into PLLA/poly(ε‐caprolactone) blends. SEM, Fourier transform infrared spectroscopy and TGA were adopted to confirm that APP participated in the in situ reaction during the melt process. The impact strength was increased to 13.5 kJ m^?2 from 1.0 kJ m^?2 for L8P2A5 composite, indicating the toughening effect of reactive blending. The cone calorimeter test, limiting oxygen index and vertical burning test results indicate that the flame‐retardant properties of the composites are enhanced with increasing APP content. This work provides a method to prepare PLLA with high mechanical properties and enhanced flame retardancy. © 2020 Society of Chemical Industry     

Preparation and characterization of flame retardant phase change materials by microencapsulated paraffin and diethyl ethylphosphonate with poly(methacrylic acid‐co‐ethyl methacrylate) shell

Microcapsules containing paraffin and diethyl ethylphosphonate (DEEP) flame retardant with uncrosslinked and crosslinked poly (methacrylic acid‐co‐ethyl methacrylate) (P(MAA‐co‐EMA)) shell were fabricated by suspension‐like polymerization. The surface morphologies of the microencapsulated phase change materials (microPCMs) were studied by scanning electron microscopy. The thermal properties and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The flame retarding performances of the microcapsule‐treated foams were calculated by using an oxygen index instrument. The DSC results showed that the crosslinking of the polymer shell led to an increase in the melting enthalpies of the microcapsule by more than 15%. The crosslinked P(MAA‐co‐EMA) microcapsules with DEEP and without DEEP have melting enthalpies of 67.2 and 102.9 J/g, respectively. The TGA results indicated that the thermal resistant temperature of the crosslinked microcapsules with DEEP was up to 171°C, which was higher than that of its uncrosslinked counterpart by ～20°C. The incorporation of DEEP into the microPCM increased the limiting oxygen index value of the microcapsule‐treated foams by over 5%. Thermal images showed that both microcapsule‐treated foams with and without DEEP possessed favorably temperature‐regulated properties. As a result, the microPCMs with paraffin and DEEP as core and P(MAA‐co‐EMA) as shell have good thermal energy storage and thermal regulation potentials, such as thermal‐regulated foams heat insulation materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41880.     

An effective flame retardant for poly(ethylene terephthalate) synthesized by phosphaphenanthrene and cyclotriphosphazene

A novel flame retardant [9,10‐Dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxideÔtriphosphazene (DOPO–TPN)] based on phosphaphenanthrene and cyclotriphosphazene was synthesized and used to improve the flame retardancy of poly(ethylene terephthalate) (PET). The structure of DOPO–TPN was characterized by nuclear magnetic resonance, Fourier transform infrared spectroscope (FTIR), and elemental analysis. PET/DOPO–TPN composites with different amount of DOPO–TPN were prepared and the flame retardancy was determined by limiting oxygen index (LOI) and vertical burning test (UL‐94). With the incorporation of 5 wt % DOPO–TPN, the composite achieved a LOI value of 34% and UL‐94 V‐0 rating. The thermal properties of the PET/DOPO–TPN composites were investigated by thermogravimetric analysis. The flame retardant mechanism was investigated by pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), FTIR, and scanning electron microscopy (SEM). The Py‐GC/MS results showed that DOPO based fragments would exist in the gas phase during the pyrolysis of PET/DOPO–TPN composites which demonstrated that DOPO–TPN could act through gas‐phase action to exert flame retardant effect. The results of FTIR and SEM demonstrated that DOPO–TPN could promote the formation of compact and intact char residues to inhibit the heat and combustible gas transmission in condensed phase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45246.