阻燃型DOPO-马来酸酐改性的环氧树脂研究

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和马来酸为原料,经过加成和闭环反应,合成了DOPO-马来酸酐(DOPO-MA)。并通过质谱、红外谱图和核磁共振谱确认了其结构。研究了DOPO-MA用量对环氧酸酐体系的阻燃和力学等性能的影响。研究结果表明:与纯环氧酸酐体系相比较,DOPO-MA改性环氧酸酐体系的力学性能略有降低,但阻燃性能有明显提高。     

含磷环氧树脂/纳米氢氧化铝阻燃体系的研究

合成了反应型阻燃剂9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO),与环氧树脂反应将阻燃元素磷引入到环氧树脂分子结构中,合成了阻燃的含磷环氧树脂。利用DTA研究了含磷环氧树脂／纳米氢氧化铝(ATH)等组成的阻燃环氧树脂体系的固化反应动力学,表观活化能△E为68.23kJ／mol,反应级数n为0.90。应用TGA初步评价了体系阻燃性能,700℃时成炭率15.73％,计算氧指数为24,初步表明有较好的阻燃效果。     

DOPO与环氧树脂反应特性的研究

通过环氧值滴定和红外光谱研究了9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与环氧树脂E-20的反应特性,用红外谱图确认了DOPO与E-20进行反应的程度以及DOPO含磷阻燃环氧树脂的初步结构。采用DTA分析方法研究DOPO与E-20的反应动力学,测得DOPO与E-20反应的动力学参数lnA0为20.88,表观活化能E为96.42kJ/mol,反应级数n为0.74。实验结果表明,在120℃下添加15%催化剂,反应90min可获得最佳阻燃效果。     

无卤含磷阻燃剂协效氢氧化镁阻燃乙烯-醋酸乙烯酯共聚物的研究

采用新型阻燃剂9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和双马来酰亚胺(BMI)反应,合成了一种无卤含磷阻燃剂(DB).以乙烯-醋酸乙烯酯共聚物(EVA)为基体树脂,KH550硅烷偶联剂改性氢氧化镁(MH)为主阻燃剂(KH550-MH),DB为协效阻燃剂,制备了EVA复合材料,研究了DB含量对复合材料的力学性能、加工性能、垂直燃烧性、吸水率的影响.结果表明:添加少量DB可提高EVA复合材料的阻燃性能和改善加工性能.     

DOPO基环三磷腈阻燃剂的制备及在高玻璃化转变温度层压板中的应用

采用六-(4-醛基-苯氧基)环三磷腈(HAP)与9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)在溶液体系中亲核加成制备六-(磷杂菲-羟甲基-苯氧基)-环三磷腈(HPHMPC)阻燃剂,以此为添加型阻燃剂加入到环氧树脂体系中制备高玻璃化转变温度(T_g)的玻璃纤维基层压板。考察了阻燃剂含量对板材阻燃、耐热、介电等性能及剥离强度的影响。结果表明:阻燃剂HPHMPC与环氧树脂具有很好的相容性,能有效地阻燃玻璃纤维布基环氧板材,当板材树脂中HPHMPC阻燃剂含量为19.2%时,板材的阻燃等级达到UL 94 V-0级,T_g为194.6℃,并具有较高的热稳定性和较低的热膨胀系数。     

DOPO制备方法的比较与选择

综述了阻燃剂9，10-二氢-9氧杂-10-瞵杂菲-10-氧化物(DOPO)的制备过程，对每一步中间产品的制备方法做了详细的评述，着重对反应过程物料配比、反应温度、反应时间、体系压力等工艺参数以及提纯方法进行了比较、分析，提出了建议。     

高强度高透明性聚酰亚胺膜的制备与性能研究

采用4-氨基苯基-3,5-二乙基-4-氨基苯基-9,10-二氢-9-氧杂-10-磷杂菲-10-磷酰基乙烷(ADADOPPE)和2-(4-氨基苯基)-5-氨基苯并恶唑(AAPBO)以不同摩尔比与2,3,3′,4′-联苯四甲酸二酐(α-BPDA)共聚制备一系列聚酰亚胺(PI)薄膜。通过FTIR、TGA、TMA、极限氧指数仪和UV-Vis等仪器对薄膜进行结构表征及性能研究。结果表明:含ADADOPPE不对称二胺单体的PI膜比传统PI膜有出色的透明性并具有较好力学性能,其中PI-C-3薄膜的截止波长为401.5 nm,最大透过率达到82.25%,拉伸强度为136.4 MPa。     

三聚氰胺氰尿酸盐/磷系阻燃剂协效阻燃环氧树脂覆铜基板的研究

采用磷系阻燃剂DOPO及含磷环氧树脂（DOPO-EP）分别与氮系阻燃剂三聚氰胺氰尿酸盐（MCA）组成氮-磷协同体系阻燃环氧树脂覆铜基板。采用垂直燃烧、微型量热分析考察了体系的阻燃性能及燃烧性参数,研究了相同磷元素和MCA含量下两个体系的协同阻燃效果及阻燃机理。结果表明：DOPO-EP/MCA比DOPO/MCA具有更高的协同阻燃效率,表现出更优异的阻燃性能。     

无卤阻燃不饱和聚酯浸渍树脂的研究

将无卤阻燃剂DOPO引入到不饱和聚酯中制备得到无卤阻燃不饱和聚酯绝缘浸渍树脂，并通过红外光谱、热重测试及阻燃性能实验分析加入阻燃剂对树脂各项性能的影响。结果表明：采用MTHPA作为载体，将DOPO先与甲基四氢苯酐（MTHPA）反应，再与顺丁烯二酸酐（MA）发生加成反应，可以提高DOPO的加成转化率，树脂均匀，固化后透明，阻燃性好，阻燃等级达到UL94 V0级；随着磷含量的提高，树脂的热稳定性下降，磷含量控制在2.7%左右较为合适；当不饱和酸与饱和酸的摩尔比为1∶1至1.5∶1，同时采用复配引发阻聚体系时，树脂具有较好的反应活性和存放稳定性。     

铝-空气电池钙钛矿型氧电极的研究

制备La0.6Ca0.4CoO3钙钛矿型氧化物作为铝-空气电池氧气还原的催化剂,并对此催化剂做了X射线衍射(XRD)、热重分析(TGA)等结构测试.研究掺杂不同化合物对氧电极性能的影响.测定催化电极在6 mol/L KOH中的阴极极化曲线,并且组装成铝-空气电池,来考察电极的电化学性能.结果表明:钙钛矿型氧化物La0.6Ca0.4CoO3掺杂金属氧化物即混合催化剂是一种良好的催化剂,有利于促进阴极的氧气还原,改善电极的电化学性能.     

Effects of NOx and SO2 in cathode stream on the performance of PEMFC

Anegative effect of NOx,mainly NO2,onthe performance ofproton exchange membrane fuel cell(PEMFC)[1-3]was reported·The negative effects of NO2with concentrations ranging from4×10-5%(in volume,the same as follow)to 5×10-4%were re-ported to be reversible …     

Electrical modeling of liquid crystal displays-LCDs

An investigation into the complex dielectric permittivity of nematic liquid crystal (NLC) on homogeneous (or planar, molecular director axis parallel the surface of the cell) and homeotropic (molecular director axis perpendicular the surface of the cell) alignments led to the conception of special equivalent electric circuits representing different dielectric mechanisms that are present in liquid crystal displays (LCDs). In our study, NLC cells with and without polyvinyl alcohol-PVA alignment were subjected to a frequency range of 10/sup -1/ Hz to 10/sup 7/ Hz, revealing four distinct mechanisms of dielectric dispersion. In the NLC cells without PVA, the dielectric dispersion at very low frequencies (10/sup -1/ Hz10/sup 7/ Hz) dielectric dispersion was attributed mainly to the rotation of NLC molecules around their own axes. While, in the NLC cells with PVA, the dielectric dispersion at low frequencies (1 Hz相似文献   

磷灰石结构电解质La_(10-x)Si_6O_(27-1.5x)的合成及电性质

以La_2O_3和SiO_2为原料,采用凝胶注模工艺合成了具有磷灰石结构晶相的固体电解质材料La_(10-x)Si_6O_(27-1.5x)(x=0,0.5).通过X射线衍射光谱法(XRD)对所得化合物的结构进行表征.在300～800 ℃的温度范围内,利用电化学阻抗谱详细研究了La_(10-x)Si_6O_(27-1.5x)陶瓷的烧结温度和La元素的含量对La_(10-x)Si_6O_(27-1.5x)电导率的影响.结果表明:陶瓷样品的烧结温度对其电导率的影响较大,La_(10)Si_6O_(27)的电导率随着陶瓷样品烧结温度的上升而提高,1 650 ℃烧结的La_(10)Si_6O_(27)在800℃电导率为3.46×10~(-2) S/cm,约是1 550 ℃烧结样品的6倍.La_(9.5)Si_6O(26.25)的电导率随着陶瓷样品烧结温度上升呈先上升后下降的变化趋势,当烧结温度高于1 600℃时,晶粒和晶界内有大量未知相析出,这可能是导致其电导率反而下降的直接原因.     

Performance of 20 Gb/s quaternary intensity modulation based on binary or duobinary modulation in two quadratures with unequal amplitudes

2/spl times/10 Gb/s quaternary intensity modulation signals (4-IM) can be generated by combining two modulation signals with unequal amplitudes in quadrature phases or orthogonal polarizations. Two 10-Gb/s nonreturn-to-zero (NRZ) amplitude-shift keying (ASK) signals and a quadrature phase-shift keying (QPSK) modulator allow to generate 4-IM with the same bandwidth as an NRZ-ASK signal (QASK). Measured sensitivity at a bit error rate (BER) of 10/sup -9/ and chromatic dispersion (CD) tolerance are -21.6 dBm and /spl sim/+130 ps/nm, respectively. Two duobinary 10-Gb/s data streams and a QPSK modulator allow to generate a 9-constellation point quaternary intensity signal (QDB), with the same bandwidth as a duobinary signal. A stub filter with frequency response dip at 5 GHz was used to generate the duobinary signals. Detected as a 4-IM, this scheme features a sensitivity and a CD tolerance of -21.2 dBm and /spl sim/+140 ps/nm, respectively. By combining the two duobinary 10-Gb/s data streams with unequal amplitudes in orthogonal polarizations, a 9-constellation point quaternary intensity signal was also obtained (QPolDB). Sensitivity and CD tolerance were -20.5 dBm and /spl sim/+340 ps/nm, respectively. They became -18.4 dBm and /spl sim/+530 ps/nm, respectively, when the frequency response dip of the stub filter was changed to 6 GHz. A polarization and phase-insensitive direct detection receiver with a single photodiode has been used to detect all generated quaternary signals as 4-IM signals.     

Absolute cerebral blood flow measured by dynamic susceptibility contrast MRI: a direct comparison with Xe-133 SPECT

Absolute regional cerebral blood flow (CBF) was measured in ten healthy volunteers, using both dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI) and Xe-133 SPECT within 4 h. After i.v. injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.), the bolus was monitored with a Simultaneous Dual FLASH pulse sequence (1.5 s/image), providing one slice through brain tissue and a second slice through the carotid artery. Concentration C(t) is proportional to -(1/TE) ln[S(t)/S(0)] was related to CBF as C(t) = CBF [AIF(t) x R(t)], where AIF is the arterial input function and R(t) is the residue function. A singular-value-decomposition-based deconvolution technique was used for retrieval of R(t). Absolute CBF was given by Zierler's area-to-height relation and the central volume principle. For elimination of large vessels (ELV), all MRI-based CBF values exceeding 2.5 times the mean CBF value of the slice were excluded. A correction for partial-volume effects (CPVE) in the artery used for AIF monitoring was based on registration of signal in a phantom with tubes of various diameters (1.5-6.5 mm), providing an individual concentration correction factor applied to AIF data registered in vivo. In the Xe-133 SPECT investigation, 3,000-4,000 MBq of Xe-133 was administered intravenously, and CBF was calculated using the Kanno Lassen algorithm. When ELV and CPVE were applied, DSC-MRI showed average CBF values from the entire slice of 43 +/- 10 ml/(min 100 g) (small-artery AIF) and 48 +/- 17 ml/(min 100 g) (carotid-artery AIF) (mean +/- S.D., n = 10). The corresponding Xe-133-SPECT-based CBF was 33 +/- 6 ml/(min 100 g) (n = 10). The relationships of CBF(MRI) versus CBF(SPECT) showed good linear correlation (r = 0.74-0.83).     

电测系统中一种信号前处理电路及应用

文中提出一种电流积分式信号前处理电路,可对毫秒级变化的１０＾７￣１０＾－１５Ａ弱电流信号或５ｍＶ￣５０Ｖ电压信号连续线性转换,对１０＾－１２Ａ量级快变弱电信号可实现快速处理。     

POS工作参量定标关系的数值模拟

利用通用的２－１／２维铨电磁网格粒子模拟程序对等离子体断路开关工作电压与等离子体密度的关系作了数值模拟研究。提出了临界工作电压的概念,并获得了等离子体密度在１０＾１１至１０＾１３ｃｍ＾－３范围内变化、负载为强流电子束二级管时临界工作电压与等离子体密度的定标关系。该定标关系在较低和较高等离子体密度区解析的融蚀模型的预期有显著差别,而在１０＾１２ｃｎｍ＾－３附近区域则基本一致。     

基于层次分析法的带电跨越方式选择

在进行带电跨越施工时,选择合适的方式很关键。围绕着带电跨越方式选择这一核心问题,对层次分析法中1-9标度法、10/10-18/2标度法和9/9-9/1标度法这3种标度法进行比较,计算结果表明10/10-18/2标度法较优。基于改进的层次分析法,构造了选择带电跨越方式的层次分析结构模型,并以某条线路施工为例,对3种带电跨越方式进行综合评估和计算,计算结果表明,该条线路施工中最优的带电跨越方式为索道跨越。     

复合BaTiO3的Li0.5La0.5TiO3固体电解质的制备和性能

采用高温固相法合成具有高离子电导率的固体电解质Li0.5La0.5TiO3,并以Li0.5La0.5TiO3为母体,通过复合高介电纳米BaTiO3制得一系列不同复合量的复合电解质。对样品进行XRD、SEM分析,并应用交流阻抗技术测试其电导率。母体钛酸镧锂(LLTO)为存在超结构的立方晶体,30℃时晶粒电导率为1.1×10-3S/cm。在复合样品中,LLTO与BaTiO3形成具有棒状结构的钙钛矿型固溶体(Li、La、Ba)TiO3。在低的复合量下(小于10%),复合样品的晶粒电导率比纯样晶粒电导率高。120℃时,母体与复合5%样品的晶粒电导率分别为0.84×10-2、2.39×10-2S/cm,活化能分别为0.22、0.40eV。     

类钙钛矿复合氧化物La_(2-x)Sr_xNiO_4的合成及电学性能

采用柠檬酸硝酸盐燃烧法合成了La2-xSrxNiO4(LSN)阴极材料,并系统地研究了LSN的热膨胀性能、电子电导率,并考察了基于Ce1.8Sm0.2O1.9(SDC)电解质的LSN电极极化性能.结果表明,自燃烧产物经1 000℃煅烧2 h形成了单一的K2NiF4结构,25～800℃范围内,LSN材料的热膨胀系数在13.7×10-6～14.3×10-6K-1. La1.4Sr0.6NiO4电子电导率最高,为151.5～155.7 S/cm(600～800 ℃).极化测试结果显示,未掺杂的LSN具有最小的极化电阻(0.48Ω·cm2,800℃),电流密度为0.3 A/cm2时,过电位约为0.083 V.