聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(APP)组成复合阻燃剂,对环氧树脂(EP)进行阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.     

星型绿色磷腈阻燃剂的制备及阻燃环氧树脂性能

从分子结构设计出发,以六氯环三磷腈、对羟基苯甲醛、三氯氧磷及新戊二醇等为原料,制备了一种新型阻燃剂六[4-(5,5-二甲基-1,3,2-二氧杂己内磷酰基)苯氧基]环三磷腈(HDDCPPCP),并将其与聚磷酸铵(APP)和多壁碳纳米管(MWCNT)复配,应用于环氧树脂(EP)中,制备了HDDCPPCP/APP/MWCNT/EP阻燃复合材料.利用极限氧指数(LOI)、水平燃烧(UL-94)、锥形量热(CONE)、拉伸、弯曲和冲击等方法研究该阻燃复合材料的燃烧性能、热性能及力学性能.实验结果表明,保持阻燃体系总质量分数为30%,当MWCNT质量分数为2%时,EP2(HDDCPPCP/APP/MWCNT/EP)的各项燃烧参数综合表现较好,其LOI值达到42. 8%,热释放速率峰值(pk-HRR)、热释放速率平均值(av-HRR)、有效燃烧热平均值(av-EHC)及一氧化碳释放率平均值(av-CO)相对EP0分别降低92. 5%,93. 0%,65. 2%和66. 6%,呈现出良好的阻燃、抑烟和抑毒性能; EP2的拉伸强度、断裂伸长率、弯曲强度和弯曲模量较好,分别为110. 46 MPa,6. 24%,1259. 99 MPa,377. 72 MPa.     

石墨烯负载离子液体的制备及其与六苯氧基环三磷腈协效阻燃环氧树脂的性能研究

本文以可膨胀石墨(EG)和1-丁基-3-甲基咪唑六氟磷酸盐离子液体([BMIM]PF_6)为原料,在去离子水中通过绿色、简单的球磨法成功制备出了石墨烯负载离子液体杂化物(GnP@ILs),并对其结构组成进行表征.将GnP@ILs单独或与六苯氧基环三磷腈(HPCTP)混合加入到环氧树脂(EP)中,研究其对EP复合材料综合性能的影响.极限氧指数(LOI)、垂直燃烧(UL-94)和锥形量热测试结果表明,GnP@ILs能提高EP复合材料的阻燃性能,同时与HPCTP复配的EP复合材料(EP/7.2wt%HPCTP/1.8wt%GnP@ILs)的阻燃性能最好,LOI达到33.8%,并通过了UL-94V 0级.EP/7.2wt%HPCTP/1.8wt%GnP@ILs的热释放速率峰值和总热释放量分别降低了55.54%和44.28%.同时,[BMIM]PF_6的加入增强了阻燃剂与EP的界面相容性,EP复合材料的拉伸强度和抗冲强度均明显提高.     

卡拉胶包覆APP微球阻燃水性环氧树脂

以氯化钡提纯k-卡拉胶, 经过氧化氢降解, 通过反相乳液聚合的方式制备了一系列卡拉胶包覆聚磷酸铵(APP)阻燃微球(k-CM/APP); 将其加入到水性环氧树脂(EP)中, 制备了3种钢结构防火涂层EP2, EP3和EP4. 利用红外光谱(IR)、 扫描电子显微镜(SEM)及元素分析(EDS)对k-CM/APP的结构及形貌进行了表征. 利用极限氧指数(LOI)、 垂直燃烧(UL-94)、 背温测试法、 热重分析(TG)、 锥形量热(CONE)、 附着力测试、 IR和SEM等方法分析了涂层的阻燃、 隔热及力学性能. 结果表明, k-CM/APP(3/1)球形结构完整, 800 ℃时的残炭量高达59.5%. 与其它阻燃涂层体系相比, 添加了k-CM/APP(3/1)的EP3防火涂层的极限氧指数达到28.5%, UL-94达到了V-0级, 60 min防火涂层耐火温度为253 ℃. 相比于纯EP涂层, EP3涂层的热释放速率峰值降低了58.26%, 总热释放量降低了20.84%, 附着力达到8.74 MPa.     

阻燃PA66/二乙基次磷酸铝复合材料的研究

通过双螺杆挤出机熔融共混制备了阻燃PA66/二乙基次磷酸铝(ADP)复合材料,采用极限氧指数(LOI)、垂直燃烧(UL94)测试、锥形量热仪(Cone)等研究了PA66/ADP材料的燃烧性能,同时还通过拉伸、弯曲强度测试考察了PA66/ADP复合材料的力学性能.研究表明:ADP添加量为8%时,该体系达到了UL94V-0级,LOI值由25. 3%提高到30. 2%. PA66/ADP材料的热释放速率峰值由1 168 k W/m2下降到535 k W/m2,添加ADP能够显著地增强成炭率,增强隔热作用.     

碳材料表面特性及形貌对阻燃环氧树脂燃烧和热解行为的影响

将制备的4种植物基多孔碳,甘蔗渣炭(SBC)、竹叶炭(BLC)、稻壳炭(RHC)及竹茎炭(BSC),以及购置的椰壳炭(CSC)、果壳炭(NSC)、碳纳米管(CNTs)及可膨胀石墨(EG)分别与聚磷酸铵(APP)复合用于阻燃环氧树脂(EP),研究了碳材料比表面积、表面活性及微观形貌对APP阻燃EP燃烧和热解行为的影响.物理吸附仪、X射线光电子能谱仪(XPS)、扫描电镜研究指出,颗粒状竹茎多孔碳(BSC)的比表面积(2063m2/g)及表面活性基团C—O—、C≡O及COO—的比例显著大于其他碳材料;各种碳材料均以微米级尺度分布于阻燃EP基体.氧指数(LOI)、UL 94垂直燃烧及锥形量热仪研究表明,0.8 wt%BSC或CNTs与3.1 wt%APP协同阻燃EP的LOI分别由EP的24.6%提高到27.3%和27.6%,UL 94均为V-1级,峰值热释放速率分别比EP/APP降低了27%和28%.碳材料的协同阻燃效果主要取决于微观形貌;对于颗粒状多孔碳,其比表面积、O/C比及表面活性基团比例越大,协同阻燃效果越好.热失重分析、共聚焦拉曼光谱及XPS研究证实,碳材料提高了EP/APP复合材料的初始分解温度和残炭量;大的比表面及表面活性,以及管状形貌能够提高环氧树脂复合材料高温残炭量、促进残炭类石墨化转变、改善残炭耐高温氧化性能.     

OMMT-NC-膨胀型阻燃剂三元协同阻燃LLDPE的效果

采用有机蒙脱土(OMMT)和碳酸镍(NC)为阻燃协效剂,与膨胀型阻燃剂(IFR)三元体系协同阻燃线性低密度聚乙烯(LLDPE).采用热重分析(TGA)、氧指数(LOI)测试、UL-94燃烧测试和锥形量热测试(CONE)研究了LLDPE阻燃体系的热稳定性和燃烧性能;采用红外光谱分析(FT-IR)、数码相机和扫描电子显微镜(SEM)对燃烧残余物的结构和形貌进行了分析.结果表明:固定mnLLDPE/mIFR=7/3,当moMMT/m(LLDPE+IFR)=0.04时,阻燃体系的LOI为31.5％,通过UL-94 V-0级测试,LLDPE-IFR-OMMT的残炭率为15.09％,最大热释放速率(PHRR)相比于纯LLDPE降低了50％;向LLDPE-IFR-OMMT体系中添加NC,少量的NC就能显著增加体系的阻燃性能,当mNC/m(LLDPE+IFR)=0.02时,阻燃体系的LOI为32.7％,LLDPE-IFR-OMMT-NC的残炭率达到19.04％,PHRR相比于纯LLDPE降低了57％.OMMT和NC的加入能催化LLDPE-IFR成炭,形成致密的炭层,增加炭层的强度,从而提高复合材料的阻燃性能.     

聚磷酸酯阻燃剂复配蒙脱土及聚磷酸铵对环氧树脂阻燃性能的影响

本文以二氯化磷酸对甲基苯酯和10-(2,5-二羟基苯基)-10-氢-9-氧杂-10-磷杂菲-10-氧化物(ODOPB)为原料,合成了一种新型聚磷酸酯阻燃剂聚磷酸-2-10-氢-9-氧杂-10-磷杂菲-10-氧化物基对苯二酚对甲苯酯(POTP),并采用傅里叶变换红外光谱(FTIR)和核磁共振(~(31)P-NMR,~1H-NMR和~(13)C-NMR)对其结构进行表征.将POTP与蒙脱土(MMT)及聚磷酸铵(APP)组成复合阻燃剂对环氧树脂(EP)进行阻燃改性,通过垂直燃烧(UL-94)、氧指数(LOI)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究其对EP的热性能和阻燃性能的影响.结果表明,当阻燃剂添加量为7%时, EP复合材料UL-94测试等级可达V-0级;当添加阻燃剂为9%时,其LOI值可达到27.6%,最大热释放速率(Pk-HRR)下降了50.1%,热释放总量(THR)下降了27.4%,其残炭量高达29%. CONE测试后的残炭形貌研究显示阻燃EP在高温下形成较稳定的致密膨胀炭层,能有效抑制烟毒性气体释放,隔绝可燃气体与空气的交换,从而提高阻燃EP在高温下的热稳定性和阻燃性能.     

聚磷酸铵-苯并噁嗪微胶囊的制备及其对环氧树脂燃烧性能影响

以多聚甲醛、丙烯胺、苯酚为原料,通过Mannich反应合成烯丙基型苯并噁嗪单体(Bala),并通过核磁共振氢谱(~1H-NMR)确定了其化学结构.将Bala在聚磷酸铵(APP)原位开环聚合后,制备APP微胶囊(BMAPP).傅里叶变换红外(FTIR)和静态接触角测试表明,Bala在APP表面成功聚合,并有效提高APP的疏水性,与纯APP相比,BMAPP的接触角从10.8°提高到了71.3°.将BMAPP添加到环氧树脂(EP)中,制备EP/BMAPP复合材料.通过热重分析仪(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥型量热仪(CONE)和动态热机械分析仪(DMA)对EP和EP/BMAPP的热性能以及燃烧性能进行对比分析.结果显示,10%的BMAPP的成炭效果最佳,有良好的阻燃性能,可使EP的LOI值从22.6%提高到33.6%,并通过UL-94 V-0级,600°C下残炭率达26.3%.同时,BMAPP可大幅度降低EP燃烧过程中烟密度和热释放速率,提高EP的玻璃化转变温度(T_g).BMAPP/EP-10%中,PBala和APP协同后使EP热释放速率峰值(PHRR)由1247 kW·m~(-2)降低到434 kW·m~(-2),生烟速率(SPR)降低67%左右,T_g从169°C提高到了173°C.     

SDS-LDH与CTAB-MMT协同APP阻燃P(BA-VAc)的对比分析

通过极限氧指数(LOI)和垂直燃烧(UL-94),对比分析了十二烷基硫酸钠改性双羟基氧化物(SDS-LDH)和十六烷基三甲基溴化铵改性蒙脱土(CTAB-MMT)协同聚磷酸铵(APP)对聚(丙烯酸丁酯-醋酸乙烯酯)(P(BA-VAc))胶膜阻燃效果的异同.当APP添加量为14.5 wt%,层状无机粒子引入量为0.5 wt%时,P(BA-VAc)/APP/SDS-LDH和P(BA-VAc)/APP/CTAB-MMT的最佳LOI值分别为30.5和30.1.通过热分析法(TGA)探讨了阻燃型复合材料的热降解行为.700℃时,P(BA-VAc)/14.5%APP/0.5%SDS-LDH比P(BA-VAc)/14.5%APP/0.5%CTAB-MMT的残留量高2.7%.采用扫描电镜(SEM)观察复合材料LOI测试后炭层微观形貌.与P(BA-VAc)/15%APP复合材料相比,P(BA-VAc)/14.5%APP/0.5%SDS-LDH和P(BA-VAc)/14.5%APP/0.5%CTAB-MMT燃烧后炭层的外表面更加致密,并且连续性更好.通过傅里叶变化红外(FTIR)和X-射线光电子能谱(XPS)对阻燃材料500℃热氧化炭层进行了分析.SDS-LDH和CTAB-MMT均可促进更多酯化反应和脱水反应发生;相比而言,SDS-LDH具有较好的催化协同成炭效果.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.