Compatibilized the thermosetting blend of epoxy and redistributed low molecular weight poly(phenylene oxide) with triallylisocyanurate

Vinyl‐containing low molecular weight PPO (R‐PPO) was prepared by redistribution reaction between commercially available PPO and maleic anhydride (MAH) and used to modify epoxy resin (EP). TAIC was furthermore used as the compatibilizer of EP/R‐PPO system in this study. The curing reaction kinetics, compatibility of the components, morphology, dielectric properties and impact toughness of EP/R‐PPO/TAIC systems were investigated. The experimental results showed that the cured EP/R‐PPO (80/20) system had two phase morphology, the R‐PPO particles of about 1 µm were evenly dispersed in continuous epoxy phase. After addition of TAIC, the EP/R‐PPO/TAIC systems were transferred to single phase. The glass transition temperature of cured EP/R‐PPO/TAIC (80/20/10) system was 150.2 °C. With the increase of TAIC content, the dielectric constant (D_k) and dissipation factor (D_f) of cured EP/R‐PPO/TAIC systems were both reduced. The dielectric constant and dissipation factor at 1MHz of cured EP/R‐PPO/TAIC (80/20/10) system was 2.72 and 0.006, respectively. Compared with those of cured EP/R‐PPO (80/20) system (D_k = 2.82 and D_f = 0.0078 at 1MHz), they decreased by 3.6% and 23.1%, respectively. With the increase of TAIC content, the impact strength of cured EP/R‐PPO (80/20) system increased and reached to a maximum value (2.41 kJ/m²) when TAIC content was 10 phr, which was improved by 23% compared with that of cured EP/R‐PPO (80/20) system (1.96 kJ/m²). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43293.     

Thermal behaviors of flame‐retardant polycarbonates containing diphenyl sulfonate and poly(sulfonyl phenylene phosphonate)

Potassium diphenyl sulfonate (SSK), poly(sulfonyl phenylene phosphonate) (PSPPP), and their mixtures are proved to be effective flame‐retardants for polycarbonates (PCs) by measuring the limited oxygen index values and UL‐94 of blends. The flame‐retardant systems are characterized by thermogravimetric analysis under dynamic conditions. The resulting data, together with the analysis of the activation energies, demonstrates that the additives accelerate thermodegradation, especially in the early stage, and different additives cause a different process in the final stage. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 882–889, 2003     

Graphene and poly(ionic liquid) modified polyurethane sponges with enhanced flame‐retardant properties

Graphene (Gr) and poly(ionic liquid) (PIL) modified polyurethane (PU) sponges with enhanced flame‐retardant properties were prepared by the direct dip coating of Gr and ionic liquid (IL) monomers onto a PU sponge followed by the polymerization of IL monomers under thermal initiation. With a content of 1.5% Gr in IL, the limiting oxygen index (LOI) of PU–PIL–Gr was 26.1%, whereas the neat PU sponge showed an LOI of only 17.9%. The horizontal flame test results indicate that PIL–Gr prevented horizontal flame spread and eliminated melt dripping. Compared with that of the neat PU sponge, the peak heat release rate of PU–PIL–Gr decreased about 22.0%. These improvements on flame retardancy might have been due to a hybrid flame retardant originating from Gr (which acted as carbon source) and PIL (which contained the flame‐retardant elements) in the PU sponge and the formation of protective layers, which isolated the oxygen and heat more effectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45477.     

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.     

Mechanical and dielectric properties of cured 1,2‐bis(vinylphenyl)ethane resin modified with poly(phenylene oxide)

1,2‐Bis(vinylphenyl)ethane (BVPE) could be cured without curing agents at relatively low temperatures (～ 180°) in a nitrogen atmosphere. Cured BVPE (CBVPE) resin showed exceptionally low dielectric constant (? = 2.50 at 10 GHz) and low dielectric loss tangent (tan δ = 0.0012 at 10 GHz), and had excellent thermal resistance. Its 5 wt % weight‐loss temperature was 425°C in a nitrogen atmosphere and glass transition temperature was over 400°C. Poly(phenylene oxide) (PPO) was used to improve the toughness of CBVPE resin. PPO was an effective modifier to toughen CBVPE resin: when using 30 wt % of the modifier, the tensile strength and elongation of the modified CBVPE resin were 75 MPa and 26%, respectively. The modified CBVPE resin also showed excellent dielectric properties (? = 2.45 at 10 GHz, tan δ = 0.0015 at 10 GHz). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1252–1258, 2004     

The flame‐retardant properties and mechanisms of poly(ethylene terephthalate)/hexakis (para‐allyloxyphenoxy) cyclotriphosphazene systems

Para‐allyl ether phenol derivative of cyclophosphazene (PACP) was prepared and used as a filler to modify the flame‐retardant properties of poly(ethylene terephthalate) (PET) by melting‐blending. The mechanism of flame‐retardant was discussed and the influences of flame‐retardant contents to the mechanical properties were studied. The results revealed that the incorporation of only 5 phpp PACP (0.37 wt % phosphorus containing) into PET matrix can distinctly increase the flame retardancy of PET/PACP composition, and it has a little effect on the mechanical properties of PET. The high flame‐retardant performance of PET/PACP composite was attributed to the combination of condensed‐phase flame retardant and gas‐phase flame retardant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42711.     

Synthesis and properties of novel flame‐retardant poly(amide‐imide)s containing phosphine oxide moieties in main chain by microwave irradiation

Eight new flame‐retardant poly(amide‐imide)s with high inherent viscosities containing phosphine oxide moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7, with eight ;aromatic diamine 8a–h by two different methods such as solution and microwave‐assisted polycondensation. Results showed that the microwave‐assisted polycondensation by using a domestic microwave oven proceeded rapidly, compared with solution polycondensation and were completed within about 10–12 min. The resulting poly(amide‐imide)s 9a–h showed high thermal stability and flame‐retardant properties. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties of the PAIs 9a–h were investigated by using thermal gravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetry (DSC). Char yield measurements at 600°C demonstrated that incorporating phosphine oxide moieties in polymer backbone markedly improves their flame retardancy. All of the earlier polymers were soluble at room temperature in various organic solvents such as NMP, DMF, DMSO, DMAc, and concentrated sulfuric acid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4263–4269, 2006     

Preparation of submicrometer mesoporous iron–tin oxide hydroxide and its flame‐retardant and smoke‐suppressant properties on flexible poly(vinyl chloride)

A submicrometer mesoporous structured iron–tin oxide hydroxide [FeSnO(OH)₅] was synthesized via a hydrothermal method and characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and the Brunauer–Emmett–Teller method. Blank poly(vinyl chloride) (PVC) and a flexible PVC treated with FeSnO(OH)₅ were investigated by limiting oxygen index (LOI) testing, cone calorimetry testing (CONE), tensile properties testing, and thermogravimetric analysis (TGA)–differential scanning calorimetry. The PVC sample treated with 5 phr FeSnO(OH)₅ (PVC5) showed the best integration properties among the studied samples. Compared with those of the untreated PVC sample, the LOI value of PVC5 increased 5.6%, and its tensile strength also improved; the average heat‐release rate, average specific extinction area, and total smoke production of PVC5 decreased about 13.4, 28.0, and 48.8%, respectively. The char residue of PVC5 after CONE contained oxides and chlorides and was dense; this reduced the release of hydrogen chloride. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46218.     

Recycling of waste poly(ethylene terephthalate) into flame‐retardant rigid polyurethane foams

Waste poly(ethylene terephthalate) (PET) textiles were effectively chemical recycling into flame‐retardant rigid polyurethane foams (PUFs). The PET textile wastes were glycolytically depolymerized to bis(2‐hydroxyethyl) terephthalate (BHET) by excess ethylene glycol as depolymerizing agent and zinc acetate dihydrate as catalyst. The PUFs were produced from BHET and polymeric methane diphenyl diisocyanate. The structures of BHET and PUFs were identified by FTIR spectra. The limiting oxygen index (LOI) of the PUFs (≥23.27%) was higher than that of common PUFs (16–18%), because the aromatic substituent in the depolymerized products improved the flame retardance. To improve the LOI of the PUFs, dimethyl methylphosphonate doped PUFs (DMMP‐PUFs) were produced. The LOI of DMMP‐PUFs was approached to 27.69% with the increasing of the doped DMMP. The influences of the flame retardant on the foams density, porosity, and compression properties were studied. Furthermore, the influences of foaming agent, catalyst, and flame retardant on the flame retardation were also investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40857.     

The crystallization behaviors of copolymeric flame‐retardant poly(ethylene terephthalate) with organophosphorus

The crystallization behaviors of copolymeric flame‐retardant poly(ethylene terephthalate) (PET) with organophosphorus were studied using differential scanning calorimetry (DSC). The results indicated that the degree of tacticity of molecular chain of PET declined due to the presence of organophosphorus which had an important impact on isothermal and nonisothermal crystallization behaviors apparently. In the process of isothermal crystallization, the more organophosphorus the samples contained, the faster the samples crystallized and it resulted from the special structure of PET copolymer with organophosphorus in it. The equilibrium melting temperature of PET decreased from 284.87 to 260.72°C as the content of organophosphorus increased from 0 to 0.96 wt%, whereas in the process of nonisothermal crystallization, the Avrami exponent n decreased with the growth of the content of organophosphorus, and the addition of organophosphorus made the nucleation mechanism and the growing geometry less complicated. POLYM. COMPOS., 34:867–876, 2013. © 2013 Society of Plastics Engineers     

Application of functionalized graphene oxide in flame‐retardant polypropylene

A surface functionalized graphene oxide (FGO) was prepared by a simple and efficient method of treating graphene oxide (GO) with pentaerythritol (PER) in water using an ultrasound process. After the PER was grafted onto the surface of the GO, the GO became hydrophobic instead of hydrophilic and precipitated as a dark brown material. The results of Fourier‐transform infrared analysis, X‐ray photoelectron spectroscopy, X‐ray diffraction, and transmission electron microscopy demonstrated that the PER had been successfully attached to the GO. Subsequently, the FGO was incorporated into the intumescent flame‐retardant‐polypropylene system. The presence of FGO improved the flame‐retardant efficiency as evidenced by the limiting oxygen index (LOI) and vertical burning test (UL‐94) test. Analysis by scanning electronic microscopy indicated that the FGO promoted the formation of a continuous, intact residual char layer on the surface of the polymer, which acts as an insulating barrier to protect the base material. As a result, it delayed the peak of heat release rate and increased the residual mass obtained on combustion of the polymer. J. VINYL ADDIT. TECHNOL., 21:278–284, 2015. © 2014 Society of Plastics Engineers     

Curing behavior and dielectric properties of hyperbranched poly(phenylene oxide)/cyanate ester resins

A novel hyperbranched poly(phenylene oxide) (HBPPO) modified 2,2′‐bis(4‐cyanatophenyl) isopropylidene (BCE) resin system with significantly reduced curing temperature and outstanding dielectric properties was developed, and the effect of the content of HBPPO on the curing behavior and dielectric properties as well as their origins was thoroughly investigated. Results show that BCE/HBPPO has significantly lower curing temperature than BCE owing to the different curing mechanisms between the two systems, the difference also brings different crosslinked networks and thus dielectric properties. The dielectric properties are frequency and temperature dependence, which are closely related with the content of HBPPO in the BCE/HBPPO system. BCE/2.5 HBPPO and BCE/5 HBPPO resins have lower dielectric constant than BCE resin over the whole frequency range tested, while BCE/10 HBPPO resin exhibits higher dielectric constant than BCE resin in the low frequency range (<10⁴ Hz) at 200°C. At 150°C or higher temperature, the dielectric loss at the frequency lower than 10² Hz becomes sensitive to the content of HBPPO. These phenomena can be attributed to the molecular relaxation. Two relaxation processes (α‐ and β‐relaxation processes) are observed. The β‐relaxation process shifts toward higher frequency with the increase of temperature because of the polymer structure and chain flexibility; the α‐relaxation process appears at high temperature resulting from the chain‐mobility effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The damping and flame‐retardant properties of poly(vinyl chloride)/chlorinated butyl rubber multilayered composites

The alternating multilayered damping composites, which were consisted of chlorinated butyl rubber (CIIR) layers and poly(vinyl chloride) (PVC) layers, were first prepared through multilayered coextrusion technology. The multilayered structure was controlled by adjusting the layer number or the thickness ratio of CIIR layer and PVC layer. The damping and flame‐retardant properties of the CIIR/PVC multilayered damping composites were investigated by dynamic mechanical analysis, the limiting oxygen index, and thermogravimetric analyzer, respectively. The results showed that the effective damping temperature range was broadened with increasing the layer number, since multilayered structure resulted in partial overlap of the loss peaks of CIIR and PVC. Meanwhile, the flame‐retardant properties of the multilayered composites were also enhanced with increasing the layer number. Less surface area of CIIR contacting oxygen in the confined burning space, rather than the formation of char residue, could effectively retard the combustion of the material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41259.     

Bio‐based Mg(OH)2@M‐Phyt: improving the flame‐retardant and mechanical properties of flexible poly(vinyl chloride)

Two novelty bio‐based multifunctional metallic phytate coated (M‐Phyt, M ≡ Cu, Zn) Mg(OH)₂ (MH@M‐Phyt) were designed and incorporated into flexible poly(vinyl chloride) (PVC). MH@M‐Phyt was incorporated into PVC materials in a powder form. The morphology of the interface between MH and M‐Phyt and their binding states were characterized by TEM and X‐ray photoelectron spectroscopy (XPS), respectively. The TEM images of MH@M‐Phyt indicated that M‐Phyt was successfully coated on the MH surface. Additionally, from the XPS spectra M‐Phyt and MH were connected by Mg–O–P bonds. The flame retardancy and mechanical properties of the PVC composites were investigated through the limiting oxygen index, cone calorimetry and mechanical tests. The char residues were analyzed by SEM. The results revealed that the MH@M‐Phyt powder functioned well in PVC, with a flame retardancy, smoke density, tensile strength and elongation at break better than those of PVC/MH. With 10 phr loading, the peak heat release rate of PVC/MH@Zn‐Phyt and PVC/MH@Cu‐Phyt decreased by 33.5% and 24.6%, respectively, benefitting from the formation of firmer and denser char layers on the char residues. © 2019 Society of Chemical Industry     

Synthesis and characterization of new flame‐retardant poly(amide‐imide)s containing phosphine oxide and hydantoin moieties in the main chain

Six new flame‐retardant poly(amide‐imide)s (PAIs) 9a–f with high inherent viscosities containing phosphine oxide and hydantoin moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7 with six hydantoin derivatives 8a–f by two different methods such as solution and microwave assisted polycondensation. Results showed that the microwave assisted polycondensation, by using a domestic microwave oven, proceeded rapidly, compared with solution polycondensation, and was completed in about 7–9 min. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties and flame retardant behavior of the PAIs 9a–f were investigated using thermal gravimetric analysis (TGA and DTG) and limited Oxygen index (LOI). Data obtained by thermal analysis (TGA and DTG) revealed that these polymers showed good thermal stability. Furthermore, high char yields in TGA and good LOI values indicated that these polymers are capable of exhibiting good flame retardant properties. These polymers can be potentially utilized in flame retardant thermoplastic materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5062–5071, 2006     

Synthesis and characterization of inherently flame‐retardant and anti‐dripping thermoplastic poly(imides‐urethane)s

A series of thermoplastic poly(imide‐urethane)s (TPIUs), based on 4,4′‐diphenylmethane diisocyanate (MDI) and pyromellitic anhydride (PMDA) as hard segments and poly(tetrahydrofuran) (PTMG) as soft segments, has been prepared by a two‐step polymerization process. The objective of this study is to prepare a type of intrinsically flame‐retardant polyurethane by incorporating PMDA as a flame retardant in the main chains. The thermal behavior and flame retardancies of the TPIUs have been characterized by thermal gravimetric (TG) analysis and limiting oxygen index (LOI), UL‐94 vertical burning, cone calorimeter tests. The results indicate that the TPIUs display outstanding performance. The temperature at 5% mass loss (T_5%) and LOI value increase with the hard‐segment contents, while the total heat released (THR) and peak heat release rate (p‐HRR) show the opposite trend. Furthermore, the T_5% of TPIU211 (molar ratio: MDI : PTMG : PMDA = 2 : 1 : 1) is 33.2°C higher than that of the conventional thermoplastic polyurethane TPU211 (molar ratio: MDI : PTMG : 1,4‐butanediol = 2 : 1 : 1), and the THR and p‐HRR of TPIU211 are 14.62% and 64.02% lower than the respective parameters of TPU211. In addition, UL‐94 vertical burning tests show that the TPIUs exhibit excellent antidripping effects. The ultimate tensile strengths of the TPIUs reached 23.1?37.6 MPa with increasing hard segment contents, which meets the requirement of mechanical properties with regard to practical use. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40801.     

Synthesis of thermosetting poly(phenylene ether) containing allyl groups

New thermosetting poly(2-allyl-6-methylphenol-co-2,6-dimethylphenol)s (3) have been developed by oxidative coupling copolymerization of 2-allyl-6-methylphenol (1) with 2,6-dimethylphenol (2), followed by thermal curing. Copolymerization was conducted in nitrobenzene in the presence of copper(I) chloride and pyridine as the catalyst under a stream of oxygen, producing high molecular weight copolymers (M_n∼50,000) with broad molecular weight distributions (M_w/M_n∼35). The structure of resulting copolymers 3 was characterized by IR, ¹H, and ¹³C NMR spectroscopy. Cross-linking reactions of copolymers were carried out by thermal treatment in the absence or presence of a peroxide (3 wt%, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-butane). The 10% weight loss and glass transition temperatures of the cured copolymers were 436 °C in nitrogen and 235 °C, respectively after curing at 70 °C for 1 h and 300 °C for 1 h. The average refractive index of the cured copolymer (3b) film was 1.5407, from which the dielectric constant (ε) at 1 MHz was estimated as 2.6. The ε and dissipation factor of copolymer-films at 1 MHz were directly measured from their capacitances as 2.5-2.6 and 0.0015-0.0019, respectively.     

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.     

Zinc hydroxystannate and zinc stannate as flame‐retardant agents for flexible poly(vinyl chloride)

The flame‐retardant and smoke‐suppressant properties of inorganic tin compounds such as zinc hydroxystannate (ZHS) and zinc stannate (ZS) were investigated in a comparison with alumina trihydrate, magnesium hydroxide, and Sb₂O₃ through the limiting oxygen index test and smoke density test. The flame‐retardant mechanisms were studied through the char yield test, SEM, quantitative analysis, thermogravimetry and differential thermal analysis. The thermal degradation in air of flexible PVC treated with the above compounds was studied by thermal analysis from ambient temperature to 800°C. The results showed that tin compounds such as ZHS and ZS could be used as a highly effective flame retardant for flexible PVC, and it appears that the tin compound may exert its action in both the condensed and vapor phases, but mainly in condensed phases as a Lewis acid. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1469–1475, 2005     

Pervaporation membranes based on imide‐containing poly(amic acid) and poly(phenylene oxide)

Three imide‐containing poly(amic acids) were synthesized and used for homogeneous and composite membrane preparation. The transport properties of composite membranes consisting of an imide‐containing poly(amic acid) top layer on an asymmetric porous poly(phenylene oxide) support were studied in the pervaporation of aqueous solutions of organic liquids (ethanol, isopropanol, acetone, and ethylacetate) and organic/organic mixtures (ethylacetate/ethanol, methanol/cyclohexane). For most of the aqueous/organic mixtures, the composite membranes exhibited dehydration properties. Dilute aqueous solutions of ethylacetate were an exception. In these solutions, the composite membranes exhibited organophilic properties, high permeability, and selectivity with respect to ethylacetate. In the pervaporation of methanol/cyclohexane mixtures, methanol was removed with very high selectivity. To account for specific features of pervaporation on the composite membranes, the sorption and transport properties of homogeneous membranes prepared from polymers comprising the composite membrane [imide‐containing poly(amic acids) and poly(phenylene oxide)] were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2361–2368, 2003