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.

Theoretic Study of 3-(4-N-Maleimido)-phenyl-2,4-dihydro-2H-1,3-benzoxazine Molecular Structure,Spectrum and Thermodynamic Properties

The geometric structures,electronic absorption spectrum,and thermodynamic pro-perties of 3-（4-N-maleimido）-phenyl-2,4-dihydro-2H-1,3-benzoxazine molecule were studied at the B3LYP/6-311＋G＊ level by density functional theory.The results show that three rings of this molecule are in different planes.In gas,absorption wavelength of the lowest energy excitation was obtained at 503 nm,and solvents made it blue-shifted by 3-7 nm,both corresponding to the electron transition of HOMO → LUMO.At 298.15 K,the standard molar formed enthalpy and free energy of the title compound molecule were-549.43 and-273.37 kJ·mol-1,respectively.

Synthesis of benzoxazine-based phenolic resin containing furan groups

A novel benzoxazine-based phenolic resin containing furan groups（PFB） was synthesized via simple two-step reactions and the structure of PFB was confirmed by FTIR and ~1H NMR spectra.Differential scanning calorimetry（DSC） showed that the polybenzoxazine cured from PFB had good heat resistance and lower polymerization temperature compared with that of benzoxazine-based phenolic resins.

Synthesis of a novel benzoxazine containing benzoxazole structure

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;H NMR spectra.The DSC was utilized to probe the curing behavior of Boz-BOA and exhibited a narrow melting peak and curing exothermic peak.

Synthesis of 3-Phenyl-6-formyl-3, 4-dihydro-2H-1, 3-benzoxazine

A novel benzoxazine monomer containing aldehyde group, 3-phenyl-6-formyl-3, 4-dihydro-2H-1, 3-benzoxazine （Ald-B）, was synthesized via the Mannich condensation of formaldehyde, p-hydroxybenzaldehyde and aniline. Its structure was characterized by Fourier transform infrared spectroscopy （FTIR）, proton nuclear magnetic resonance （^1HNMR）. The side reaction in the synthesis is discussed.

Terresoxazine,A Novel Compound with Benzoxazine Skeleton from Tribulus terrestris

Terresoxazine, a novel benzoxazine derivative was isolated from the fruits of Tribulus terrestris. Its structure was determined as 7-hydroxy-3, 3a-dihydro-5H-pyrrolo-[1,2-a] [3,1] -benzoxazin-1(2H)-one, on the basis of the spectral techniques and X-ray crystallographic analysis.

Morphological, mechanical and thermal properties of cyanate ester/benzoxazine resin composites reinforced by silane treated natural hemp fibers

This present study deals with the reinforcement of thermosetting resin blends composed of cyanate ester(CE) and benzoxazine(BOZ) resins with natural hemp fibers(NHFs). These NHFs were initially treated by using a silane coupling agent(SCA) in order to chiefly enhance their distributions as well as adhesions within the CE/BOZ resin matrix,then incorporated with various weight amounts ranging from 5 wt% to 20 wt% with a regular interval of 5 wt%. The obtained results showed that at the maximum treated fiber loading(20 wt%), distinctive enhancements in the mechanical properties in terms of flexural strength and microhardness were obtained. Besides, the thermal stability and glass transition temperature(Tg) were appreciably enhanced and were higher than those of the pure CE/BOZ resin properties. With respect to the astonishing properties of the NHFs, these enhancements could be possibly due to the good dispersion and adhesion of the treated NHFs inside the CE/BOZ resin achieved upon using the SCA. Therefore,we believe herein that these renewable and cheap NHFs have considerable potential to be used as reinfocer materials for CE/BOZ resin composites to be used in various industrial sectors.

Non-isothermal curing kinetics and thermal properties of benzoxazine-phenolic copolymers

Using novolac phenolic resin, aniline and formaldehyde as raw materials, benzoxazine-phenolic copolymers with different percentages of benzoxazine rings were prepared. FT-IR was adopted to characterize the molecular structure of the novolac-type phenolic resin and the benzoxazine-phenolic copolymer BP31. In order to understand the curing process of the copolymers, the curing behavior and curing kinetic characteristics were studied by differential scanning calorimetry （DSC）, and the catalytical effect of phenolic hydroxyl on the curing behavior of copolymers was investigated. To investigate the thermal properties of this resin, the thermal degradation behaviors of the cured samples were studied by thermal gravimetric （TG） method, and glass-transition temperatures （Tg） of the cured copolymers were also evaluated by DSC. The dynamic Ozawa method was adopted to determine the kinetic parameters of the curing process as well. The activation energy is 78.8 kJ/mol and the reaction rate constant is in the range from 40.0 to 5.2 （K/min）＂ according to reaction temperatures. The Ozawa exponent decreases from 2.4 to 0.7 with the increase of reaction temperature, and curing mechanism is expounded briefly according to the results. TG result shows that the highest char yield of copolymers is 50.3%. The highest Tg of copolymers is 489 K, which is much higher than that of pure benzoxazine resin.

The Spatial and Electronic Effects of Substituent Groups on the Thermal Curing of Bio-Based Benzoxazines

To explore the influence of substituent groups on thermally induced curing,eight new bio-based benzoxazines containing different substituent groups with different electron negativity and volumes were synthesized.The thermal curing of these bio-based benzoxazines was studied in detail.Combined with the curing reaction kinetics,simulation and calculation of Highest Occupied Molecular and Lowest Unoccupied Molecular values,the spatial and electronic effects of different substituent groups on the curing of benzoxazine was explored.It was found that when the substituent was located at the position directly connected to the N atom,the steric hindrance effect of the group was dominant.When the substituent group was located on the benzene ring connected to the O atom,both the electronic effect and the spatial effect influenced the curing of benzoxazine.When an electron-withdrawing group was connected ortho position to the O atom,the curing reaction was promoted due to the decreased electron cloud density of O-on the oxazine ring,making the C-O bond easier to break.When an electron-donating group was connected to the meta position of the O atom it also promoted the curing reaction,possibly because it increased the electron cloud density of the+CH2 reaction site and thereby facilitated electrophilic substitution via attack of+CH2 on the cross linking reaction centre.This work provides a deeper understanding of how spatial and electronic effects of substituents affect the curing of benzoxazine.

Recent Advances in Flame Retardant Bio-Based Benzoxazine Resins

Benzoxazines have attracted wide attention from academics all over the world because of their unique properties.However,most of the production and preparation of benzoxazine resins depends on petroleum resources now,especially bisphenol A-based benzoxazine.Therefore,owing to the environmental impacts,the development of bio-based benzoxazines is gaining more and more interest to substitute petroleum-based benzoxazines.Similar to petroleum-based benzoxazines,most of bio-based benzoxazines suffer from flammability.Thus,it is necessary to endow bio-based benzoxazines with outstanding flame retardancy.The purpose of this review is to summarize the latest advance in flame retardant bio-based benzoxazines.First,three methods of the synthesis of bio-based benzoxazines are introduced briefly.Furthermore,the curing mechanism of benzoxazine and the effect of branched chains on the curing behavior are also discussed and summarized.Subsequently,this review focuses on fully bio-based benzoxazines,partly bio-based benzoxazines,and bio-based benzoxazine composite materials in terms of flame retardancy as well as thermal stability and some other special properties.Finally,we give a brief comment on the challenges and prospects of the future development of flame retardant bio-based benzoxazines.

A New and Efficient Synthesis of 2H-3, 1-Benzoxazine Compounds

2H-3, 1-Benzoxazine derivatives were synthesized by cyclocondensation of 5-nitro-2- cyanoaniline with relative ketone or aldehyde with ZnCl2 as a catalyst. This is a new efficient synthetic route of 2H-3, 1-benzoxazine cyclic compounds.

Thermal Polymerization of Cyanate Ester-Benzoxazine:Study of a Functional Model Compound

A novel benzoxazine(BOZ)monomer is synthesized by a pot method with solvent-free to blend with cyanate ester(CE).A soluble intermediate is obtained after being cured for 20 h at 80℃.The two model compound and the blends are analyzed with the infrared radiation(IR),nuclear magnetic resonance(NMR)spectroscopy,and differential scanning calorimetry(DSC).The results show that an intermediate of the iminocarbonate and BOZ structures is formed by the ring-open BOZ reacting with the cyanate groups and ring-unopened BOZ.Moreover,rearrangement and ring-opening occur in the postcure of the intermediate to form the alkyl isocyanurate structure with polybenzoxazine.

Synthesis of some new N,N'-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines

The synthesis of a new series of six-membered N,N′-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines （5a-e） was achieved in excellent yields by Mannich-type condensation of N,N′-diarylsubstituted methylene-bis-o-hydroxybenzyl amines （4a- e） with formaldehyde in chloroform at reflux. These amines （4a-e） were obtained by the reduction of N, Nr-diarylsubstituted methylene-bis-o-hydroxybenzyl imines （3a-e） with NaBH4, which inturn were obtained by the condensation of methylene-bissalicylaldehyde （2） with various substituted arylamines.

苯并噁嗪与木质素磺酸钠协同阻燃聚酯复合材料的性能分析

为提高聚对苯二甲酸乙二醇酯(PET)的阻燃性能,以苯并噁嗪(BOZ)和木质素磺酸钠(SLS)为改性材料,制备了以PET为基体的聚酯复合材料。采用扫描电镜观察聚酯复合材料的表面形貌,通过热失重分析、差示扫描量热分析、极限氧指数(LOI)测试和垂直燃烧实验(UL-94)表征聚酯复合材料的热性能和阻燃性能,利用能量色散X射线光谱仪分析残炭情况,并使用电子万能试验机测试力学性能。结果表明:BOZ和SLS在PET基体中没有出现明显的团聚现象;当BOZ和SLS的质量比为1∶0.5、总添加量(质量分数)为10%时,聚酯复合材料的结晶度、熔融温度和残炭量相比纯PET均有所提高;聚酯复合材料的LOI值提高到了26.4%,UL-94等级达到了V-1等级,燃烧时的熔体滴落被有效抑制;残炭分析结果表明,聚酯复合材料的阻燃遵循凝聚相阻燃机理;聚酯复合材料的拉伸强度和断裂伸长率相比纯PET有所下降,但聚酯复合材料的杨氏模量相比纯PET有所提高。该研究可为聚酯复合材料的阻燃研究提供参考。

杂萘联苯双马来酰亚胺封装基板材料的制备与性能

针对高精密度电子芯片对封装基板材料耐热性不断提出新的要求,合成了一种杂萘联苯双马来酰亚胺(DHPZBMI)和新型固化剂二烯丙基联苯二酚(DABP)来制备高耐热性封装基板材料。通过熔融共混的方式,使用DHPZBMI、DABP与苯并噁嗪(BOZ)改性商用N,N’-(4,4’-二苯基甲烷)双马来酰亚胺(BDM)树脂,并采用与玻璃纤维布热压的方式制备出复合材料。通过差示扫描量热分析和红外光谱研究了树脂体系的固化过程,同时,进行了流变性能、热性能、力学性能等测试。研究结果表明,体系有宽温域(>100℃)加工窗口,5%热失重温度(T5%)高于395℃,有良好的热稳定性。DHPZBMI的加入有效提高了树脂体系的耐热性,25%的DHPZBMI摩尔添加量使得树脂体系的玻璃化转变温度(Tg)提高了20℃,且随DHPZBMI的增加而升高,最高达288℃。复合材料的Tg也呈现出相同的趋势,BDDB/GF-1的Tg高达314℃。其复合材料弯曲强度最高为821 MPa,弯曲模量达41.2 GPa,介电损耗低至0.011,热膨胀系数低于45×10-6K-1,与铜箔的剥离强度达1.025 N/mm。整个体系具有良好的综合性能,在封装基板领域具有广阔的应用前景。

硅氧烷改性苯并噁嗪研究进展

苯并噁嗪树脂因其优异的性能得到广泛关注,但同时存在固化温度较高、固化时间较长、脆性大等问题研究人员对此进行了一系列改性研究。硅氧烷具有柔韧性好、表面张力低等特点,利用硅氧烷改性苯并噁嗪已成为相关研究的热点方向。本文主要简述了近年来硅氧烷改性苯并噁嗪的合成、性能及应用的新进展,并对其新研究方向进行了展望。

取代基对氰基官能化苯并噁嗪树脂固化反应及热稳定性的影响

基于含不同取代基的酚与间氨基苯甲腈合成了3种含氰基苯并噁嗪单体(PH-bn、mPHbn、aPH-bn),并固化得到苯并噁嗪树脂(poly(PH-bn)、poly(mPH-bn)、poly(aPH-bn))。采用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(^(1)H-NMR)、凝胶渗透色谱(GPC)对苯并噁嗪单体的结构与组成进行了表征,通过差示扫描量热分析(DSC)比较了取代基对固化行为的影响,并进一步探讨了固化反应机理。此外,采用热重分析(TGA)和热重分析-红外联用(TGA-FTIR)研究了3种固化物的热稳定性和热解机理。结果表明:噁嗪环与部分氰基在固化过程中同时发生交联反应。给电性甲基的存在使得体系的固化反应峰值温度增加、热稳定性降低;而吸电性醛基使得体系的固化反应峰值温度降低,同时醛基的交联反应使体系的热稳定性显著增加。poly(aPH-bn)的5%失重温度为380℃,800℃时N_(2)气氛下残炭率高达67.3%。

二胺型苯并噁嗪改性双酚A环氧树脂及其玻璃纤维复合材料性能研究

为了延长环氧树脂漆的适用期,提高其耐热性,使用苯并噁嗪树脂对其进行共混改性。以溶液共混方式制备了环氧树脂漆(EP)与苯并噁嗪树脂(BZ)的共混树脂体系(E/B-x),讨论了BZ的加入对共混树脂的黏度、流变特性、凝胶化活化能、固化行为、表面特性及玻布增强复合材料的耐热性、力学性能的影响。结果表明:BZ的加入使共混树脂的黏度明显降低,凝胶温度及凝胶活化能增加,迟滞了EP的固化反应,延长了其适用期;少量BZ的加入不会改变EP的玻璃化转变温度(Tg),当BZ加入量达到40份时,与EP复合材料相比,E/B-40复合材料的干态和湿态Tg分别提高了12.6%和11.7%;随BZ加入量的增加,复合材料的弯曲强度先下降后上升,E/B-40复合材料的弯曲强度和弯曲模量可达569 MPa和27.9 GPa,与EP复合材料相当。

香草醛基苯并噁嗪树脂的绿色合成及性能

为探索六元环及其数量对苯并噁嗪树脂阻燃性和热性能的影响,通过绿色溶剂合成了香兰素-甘氨酸钠型苯并噁嗪单体(XG-BOZ,不含六元环)、香兰素-烟酰胺型苯并噁嗪单体(XY-BOZ,单六元环)、香兰素-二氨基二苯基甲烷型苯并噁嗪单体的合成(XD-BOZ,2个六元环)和香兰素-三聚氰胺型苯并噁嗪单体(XS-BOZ,3个六元环)。热分析和燃烧性能测试表明,XY-BOZ的热性能和阻燃性优于XG-BOZ、XD-BOZ和XS-BOZ。XY-BOZ在氮气下的700℃时残炭率为60.9%,其热释放速率峰值为64.6 W/g,热释放总量为6.8 kJ/g,理论极限氧指数(LOI)为41.8%。测试了XY-BOZ和XG-BOZ在不同加热速率的热分解行为,通过热降解动力学计算法(Flynn-Wall-Ozawa法)计算出在质量转化率为5%时,单六元环的XY-BOZ的降解反应的表观活化能(E_(a)为140 kJ/mol),无六元环的XG-BOZ的E_(a)为50.7 kJ/mol,比单六元环XY-BOZ的E_(a)低了63.8%。

含磷苯并噁嗪UV-LED固化防火涂层

为了获得低吸水率的防火涂层,合成了含磷苯并噁嗪,并将其用于制备环氧丙烯酸酯涂料,以LED-385 nm为光源对涂料进行光固化,研究了涂层的防火性能、附着力、铅笔硬度、耐酸碱性和耐水性。为了降低防火涂层中含磷元素的用量,同时保持涂层的防火性能,在上述体系中引入了盐酸多巴胺,并在此基础上探索了磷氮协同作用对涂层性能的影响。结果表明:2种含磷苯并噁嗪衍生物(DPOBH和DOPOBH)中,DPOBH对涂层防火性能、附着力和硬度的提升作用优于DOPOBH。添加3.7%DPOBH的涂层(EA/DPOBH3.7)的UL-94为V-0等级,硬度为B,附着力为1级,酸质量损失率仅为0.40%,碱质量损失率为2.13%,吸水率仅为0.82%。添加0.5%盐酸多巴胺所得涂层(EA/DPOBH3.5-N0.5)的UL-94为V-0等级,硬度为2H,附着力为1级,耐酸碱性提升。综上可知,在含磷苯并噁嗪环氧丙烯酸酯光固化涂层中磷氮协同作用可有效提升环氧丙烯酸酯涂层的防火性能和耐酸碱性能,降低吸水率。