Synthesis of a benzoxazine monomer containing maleimide and allyloxy groups

A novel benzoxazine monomer 3-（4-allyloxy）phenyl-3,4-dihydro-2H-6-（N-maleimido）-l,3-benzoxazine （AMB） was synthesized and structure was confirmed by FT-IR, 1H NMR. Thermal analysis （DSC） of AMB showed the introduction of allyloxy group melting point and exhibited a narrow and symmetric curing exothermic window.     

Studies on thermal and flame retardant behaviour of mixtures of bis(m-aminophenyl)methylphosphine oxide based benzoxazine and glycidylether or benzoxazine of Bisphenol A

The curing of mixtures of bis(m-aminophenyl)methylphosphine oxide based benzoxazine and glycidylether or benzoxazine of Bisphenol A has been studied. In all samples the molar ratio of benzoxazine monomers or the benzoxazine-epoxy system was varied to achieve different phosphorus content. The phosphorus-containing polybenzoxazines have been characterized by dynamic mechanical and thermogravimetric analysis. Limiting oxygen index values indicate good flame retardant properties.     

Synthesis, characterization and thermal degradation of functional benzoxazine monomers and polymers containing phenylphosphine oxide

Three phosphorus-containing bisphenol compounds, bis(4-hydroxyphenyl)phenylphosphine oxide (BHPPO), bis(4-hydroxyphenoxyphenyl)phenylphosphine oxide (BPPPO), and bis(4-hydroxyphenoxy)phenylphosphine oxide (BPHPPO) have been synthesized as starting materials for the synthesis of benzoxazine monomers. Benzoxazine monomers containing phenylphosphine oxide have been prepared and subsequently characterized by FT-IR and ¹H NMR. The monomers are thermally initiated and polymerized via ring-opening polymerization. Thermogravimetric analysis indicates that phosphorylation can have a profound effect on increasing char yield and on thermal degradation temperatures.     

Synthesis, curing kinetics and thermal properties of bisphenol-AP-based benzoxazine

A novel bisphenol-AP-aniline-based benzoxazine monomer (B-AP-a) was synthesized from the reaction of 4,4′-(1-phenylethylidene) bisphenol (bisphenol-AP) with formaldehyde and aniline. The chemical structures were identified by FT-IR, ¹H and ¹³C NMR analyses. The polymerization behavior of the monomer and the types of hydrogen bonding species were monitored by differential scanning calorimetry (DSC) and FT-IR. The curing kinetics was studied by isothermal DSC and the isothermal kinetic parameters were determined. The thermal properties of cured benzoxazine were measured by DSC and thermogravimetric analysis (TGA). The bisphenol-AP-aniline-based polybenzoxazine (poly(B-AP-a)) exhibited higher glass transition temperature (T_g) and better thermal stability than corresponding bisphenol A-aniline-based polybenzoxazines (poly(BA-a)). The T_g value of poly(B-AP-a) is 171 °C. The temperatures corresponding to 5% and 10% weight loss is 317 and 347 °C, respectively, and the char yield is 42.2% at 800 °C. The isothermal curing behavior of B-AP-a displayed autocatalysis and diffusion control characteristics. The modified autocatalytic model showed good agreement with experimental results.     

Synthesis of a novel benzoxazine containing benzoxazole structure

<正>A high-purity benzoxazine(Boz-BOA) containing benzoxazole structure was successfully synthesized by three-step synthetic method using 2-(4-aminophenyl)-1H-benzoxazole-5-amine(BOA) and ortho-hydroxybenzaldehyde.The structure of Boz-BOA was confirmed by FTIR and ~1H NMR spectra.The DSC was utilized to probe the curing behavior of Boz-BOA and exhibited a narrow melting peak and curing exothermic peak.     

Studies on the thermal polymerization of substituted benzoxazine monomers: Electronic effects

To evaluate the influence of the electronic effects on the polymerization temperature, we looked at several 3‐phenyl‐3,4‐dihydro‐2‐H‐1,3‐benzoxazine monomers with electron‐withdrawing or electron‐donating groups in the 6 and 4′ positions. The monomers were synthesized and characterized using different synthetic methods to achieve the best possible results. The thermal polymerization of these benzoxazine monomers was analyzed by differential scanning calorimetry, and the polymerization behavior and the polymer characteristics were related to the electronic character of the substituent and the polymerization mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3353–3366, 2008     

Significant enhancement of thermal stability in the non-oxidative thermal degradation of bisphenol-A/aniline based polybenzoxazine aerogel

Previously we reported synthesis of a new type of organic aerogel from phenolic resins called polybenzoxazines and their transformation into carbon aerogels. Here, we further investigate the thermal degradation behaviors of both bulk polybenzoxazines and polybenzoxazine aerogels using Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA)/FTIR, and gas chromatography/time of flight-mass spectroscopy (GC/TOF-MS). The activation energy (E_a) of the decomposition step was determined using the Kissinger method. It was found that the polybenzoxazine aerogels exhibit much higher degradation temperatures and char yields than the bulk. The decomposition temperatures at 10% weight loss and the char yields at 800 °C of the bisphenol-A/aniline based polybenzoxazine aerogel increased up to 24% and 97% higher, respectively, than the corresponding bulk values. Kinetic investigation indicated that the decomposition reaction of bulk polybenzoxazine exhibits three stages, whereas that of the polybenzoxazine aerogel features four stages with much higher overall activation energy. The enhanced thermal stability of the aerogel is ascribed to its highly porous structure, which increases the residence time of the primary decomposition products, and hence generates greater opportunity to form secondary reactions.     

Development of a DOPO-containing benzoxazine and its high-performance flame retardant copolybenzoxazines

A DOPO-containing benzoxazine, which could not be prepared by the traditional approaches, was successfully prepared from phenol, aniline and DOPO by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with aniline, forming an intermediate imine. The second step is the addition of DOPO to the imine resulting a secondary amine. The third step is the ring closure condensation leading to DOPO-containing benzoxazine. All these structures were confirmed by 1D and 2D NMR spectra. The curing of mixtures of DOPO-containing benzoxazine and benzoxazine of bisphenol A has been studied. In the samples the molar ratio of benzoxazine monomers was varied to achieve different phosphorus content. The phosphorus-containing polybenzoxazines have been characterized by dynamic mechanical thermal analysis and thermogravimetric analysis. Limiting oxygen index values indicates good flame retardant properties.     

Curing kinetics of arylamine-based polyfunctional benzoxazine resins by dynamic differential scanning calorimetry

In this study, the curing kinetics of polyfunctional benzoxazine resins based on arylamine, i.e. aniline and 3,5-xylidine, designated as BA-a and BA-35x, respectively, were investigated. Non-isothermal differential scanning calorimetry (DSC) at different heating rates is used to determine the kinetic parameters and the kinetic models of the curing processes of the arylamine-based polyfunctional benzoxazine resins were proposed. Kissinger, Ozawa, Friedman, and Flynn-Wall-Ozawa methods were utilized to determine the kinetic parameters of the curing reaction. BA-a resin shows only one dominant autocatalytic curing process with the average activation energy of 81-85 kJ mol⁻¹, whereas BA-35x exhibits two dominant curing processes signified by the clear split of the curing exotherms. The average activation energies of low-temperature curing (reaction (1)) and high-temperature curing (reaction (2)) were found to be 81-87 and 111-113 kJ mol⁻¹, respectively. The reaction (1) is found to be autocatalytic in nature, while the reaction (2) exhibits nth-order curing kinetics. In addition, the predicted curves from our kinetic models fit well with the non-isothermal DSC thermogram.     

Photoinitiated cationic polymerization of monofunctional benzoxazine

The photoinitiated ring‐opening cationic polymerization of a monofunctional benzoxazine, 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine, with onium salts such as diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate as initiators was examined. The structures of the polymers thus formed were complex and related to the ring‐opening process of the protonated monomer either at the oxygen or nitrogen atoms. The phenolic mechanism also contributed, but its influence decreased with decreasing monomer concentration. Thermal properties of the polymers were also investigated by differential scanning calorimetry and thermogravimetric analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3320–3328, 2003     

Kinetic modeling of the thermal degradation of polyethylene and polystyrene mixtures

One possible process for recovering valuable chemical and petrochemical products from plastic waste is the stepwise thermal degradation of polymer mixtures. This potentially allows the step by step simultaneous separation of the different product fractions generated by the polymers of the blend. The aim of this paper is to investigate the effect of the mixing scale of the polymers and their interactions in the melt. Several thermogravimetric analyses were performed on small samples of polyethylene (PE) and polystyrene (PS) mixtures. Two types of operating conditions were adopted: the first one is a dynamic analysis with a linear increase of the temperature over time, the latter consists of two sequential isothermal steps. The experimental results confirm that if the mixing scale is poor, the decomposition of each polymer behaves independently of the presence of the other one. Conversely, when the mixing of the two polymers reaches the molecular scale, a co-pyrolysis takes place with partial interactions. A two phase system is assumed: one phase characterized by a larger PS fraction, the other one by a prevailing PE amount. In order to properly predict the kinetic interactions typical of the mixed phases, it was necessary to extend the detailed kinetic model already developed and validated for the single polymers. The resulting two phase model gives a satisfactory explanation of several experimental data from the thermal degradation of PE–PS mixtures.     

Smart synthesis of silver nanoparticles supported in porous polybenzoxazine nanocomposites via a main-chain type benzoxazine resin

Novel silver nanoparticles immobilized on macroporous polybenzoxazine nanocomposites were prepared as catalysts for catalytic reduction reaction.     

3-甲基邻苯二酚/糠胺型聚苯并噁嗪的制备与性能

通过分子设计合成了含有酚羟基的3-甲基邻苯二酚/糠胺型苯并噁嗪(M-f). 通过差示扫描量热法(DSC)测得M-f的放热峰值温度(T_p)为172 ℃, 而间甲酚/糠胺型苯并噁嗪(MC-f)的T_p为244 ℃, 表明酚羟基的引入有利于降低苯并噁嗪的开环固化温度. 通过非等温DSC法研究2种苯并噁嗪单体的固化动力学, Kissinger法和Ozawa法的计算结果均表明M-f的表观活化能低于MC-f. 此外, 通过拉伸剪切强度测试考察了聚苯并噁嗪对于金属基材的黏附性能, M-f聚合物对于铝和低碳钢基材的拉伸剪切强度分别为2.53 MPa和3.09 MPa, 均高于MC-f聚合物.     

Synthesis,polymerization, and thermal properties of benzoxazine based on bisphenol‐S and allylamine

A bifunctional benzoxazine monomer, 6,6′‐bis(3‐allyl‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazinyl) sulfone (BS‐ala), was synthesized from bisphenol‐S, allylamine and formaldehyde via a solution method. The chemical structure of BS‐ala was confirmed by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The polymerization behavior of BS‐ala was investigated by FTIR, solid‐state ¹³C NMR, and differential scanning calorimetry (DSC). The oxazine ring opening polymerization is prior to the addition polymerization of allyl group, and the exothermic peaks corresponding to the two reactions appear partially overlapped in the DSC curve. The storage modulus of the resultant polybenzoxazine at 25°C is about 3.9 GPa, and the glass transition temperature is 254°C. The 5% and 10% weight loss temperatures of the polybenzoxazine are about 335°C and 361°C in both air and nitrogen, respectively. The char yield is about 58% at 800°C in nitrogen, whereas almost no residue is remained at 700°C in air. Copyright © 2012 John Wiley & Sons, Ltd.     

Wavelength dependence of laser polymerization of acrylic monomers

Photopolymerization of multifunctional acrylic monomers using excimer and Nd: YAG lasers operated at five different UV wavelengths is reported. The effects of different wavelengths on the surface and bulk cure both in air and under argon are investigated and discussed.     

A novel benzimidazole moiety‐containing benzoxazine: Synthesis,polymerization, and thermal properties

A novel benzoxazine‐containing benzimidazole moiety (P‐PABZ) was synthesized from 2‐(4‐aminophenyl)‐1H‐benzimidazole‐5‐amine and characterized. With the aid of differential scanning calorimetry and in situ Fourier transform infrared, we found the thermal polymerization of P‐PABZ in bulk started around 140 °C and its favored polymerization pathway. Compared to the benzoxazine derived from 4,4′‐diamine diphenyl methane (P‐MDA), P‐PABZ exhibited lower processing temperature, and the corresponding polymers had higher glass transition temperature and enhanced thermal stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Development of an aromatic triamine-based flame-retardant benzoxazine and its high-performance copolybenzoxazines

An aromatic triamine-based flame-retardant benzoxazine (3), which could not be prepared by the traditional approaches, was successfully prepared by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with an aromatic triamine, forming intermediate (1) with an imine linkage. The second step is the reduction of the imine linkage by sodium borohydride, resulting in intermediate (2) with a secondary amine linkage. The third step is the ring closure condensation of (2), leading to benzoxazine (3). The structures of (1-3) were confirmed by IR, high-resolution mass, ¹H and ³¹P NMR spectra. Benzoxazine (3) was copolymerized with commercial benzoxazines. According to the measurements, thermal properties, flame retardancy, dimensional stability of commercial polybenzoxazines were significantly improved via the incorporation of (3).     

Synthesis,characterization, and polymerization of brominated benzoxazine monomers and thermal stability/flame retardance of the polymers generated

Novel monofunctional brominated benzoxazine 3‐(2,4,6‐tribromophenyl)‐3,4‐dihydro‐2H‐1,3‐benzoxazine (P‐bra) and bifunctional brominated benzoxazine 6,6′‐bis(3‐(2,4,6‐tribromophenyl)‐3,4‐dihydro‐2H‐1,3‐benzoxazinyl) isopropane (B‐bra) were prepared and highly thermally stable polybenzoxazines were obtained by the thermal cure of the corresponding benzoxazines monomers. The chemical structures of these novel monomers were confirmed by FITR, ¹H‐NMR and elemental analysis. FTIR spectra and differential scanning calorimetry (DSC) suggested that the polymerization was thermally initiated and occurred via ring‐opening of the monomer in each case. Thermogravimetric analysis (TGA) indicated that brominatation could have a profound effect on increasing char yield and on thermal degradation temperatures. The results of UL‐94 burn test showed that the polybenzoxazines prepared from P‐bra and B‐bra had good flame retardance. Copyright © 2009 John Wiley & Sons, Ltd.