BMI和BCE为基础的多元共聚热固性高性能基体树脂研究

用熔融预聚法对二苯甲烷双马来酰亚胺（BDM,即BMI）/二烯丙基双酚A（DABPA）和双酚A二氰酸酯（BCE）/溴化环氧树脂（BCE）各二元体系分别预聚再热混,制成溶解性、稳定性和反应性、粘接性好的多元共聚树脂。经阶梯式固化,并通过FTIR、DSC、DMA、TGA和SEM等手段测试了固化树脂的性能。结果表明,该树脂的玻璃化温度（Tg）为230.7℃,耐热指数（Z）为197℃,热膨胀系数（CTE）为7.0104×10-5/℃,介电常数ε为3.61,介电损耗tanδ（1MHz）为0.007,弯曲强度为131.83MPa,冲击强度25.0kJ/m2,氧指数为31,吸水率为0.44%。此耐热性、介电性能和力学性能等综合性能优异的阻燃型树脂适合做刚性覆铜板（CCL）和先进复合材料的高性能基体树脂。     

3，3’-二乙基-4，4’-二苯甲烷型多马来酰亚胺／聚苯醚树脂的固化反应研究

热固性聚苯醚(PPO)已成为高性能印制电路板用树脂(PCB)发展的主流。本课题组的前期研究表明,3,3,-二乙基-4,4,-二苯甲烷型多马来酰亚胺(PEDM)/烯丙基化PPO是一种新型高性能PCB用树脂。文章采用红外光谱和裂解气相色谱,对PEDM的含量为PPO 10%的PEDM/烯丙基化PPO树脂的固化反应进行研究,结果表明,PEDM分子的不饱和双键与PPO的烯丙基和羟基在加热过程中发生了反应。     

聚苯醚改性双马来酰亚胺三嗪树脂及其复合材料性能研究

由双马来酰亚胺(BMI)和氰酸酯(CE)树脂合成了一种高玻璃化转变温度(Tg)、低介电常数(ε)、低介质损耗因数(tanδ)的双马来酰亚胺三嗪树脂(BT树脂),并以高性能树脂聚苯醚(PPE)对其进行改性,制备了ε=2.76,tanδ=0.002 5的改性BT树脂.FTIR分析表明:CE、BMI分别自聚而成为各自均聚物,PPE以聚合物合金的形式分散在BT树脂中,BT树脂改性前后的DMA曲线均显示出两个玻璃化转变温度.由PPE改性BT树脂制备的复合材料具有优异的介电性能(ε=3.51,tanδ=0.005 5)和低吸水率(0.37%/24 h),改性BT树脂与玻璃纤维之间具有良好的界面黏结性能.     

POSS/CE杂化复合材料的制备与介电性能研究

为制备介电常数(ε)低、介电损耗因子(tanδ)小的集成电路板用树脂基体,以笼型倍半硅氧烷(POSS)对双酚A型氰酸酯(CE)树脂进行改性,制备出一种POSS/CE无机-有机杂化复合材料。着重探讨了POSS用量和后处理工艺等对POSS/CE树脂体系介电性能的影响。结果表明:当w(POSS)=2%(相对于CE单体质量而言)、后处理工艺为240℃/3 h时,改性体系的介电性能相对最好,其测试频率为60 MHz时的ε(为2.9)和tanδ(为0.004 5)分别比纯CE树脂降低了9.4%和35.7%;该改性体系的表观活化能为51.9 kJ/mol。     

双马来酰亚胺树脂基电子封装模塑料研究

以双马来酰亚胺树脂为基体树脂,2,2′-二烯丙基双酚A为改性剂,研究了树脂/改性剂比例、固化促进剂及其用量对体系固化行为的影响,然后将树脂体系用于电子封装模塑料制备,并将产品性能与环氧模塑料进行了对比。结果表明,以咪唑作为固化促进剂,用量为体系总质量的3%时,不同树脂/改性剂比例体系的非等温固化放热峰均在200℃以下,满足现行环氧模塑料固化工艺要求。通过配方设计得到的双马来酰亚胺树脂基模塑料固化物的玻璃化转变温度(Tg)可达256℃,热分解温度(T_(d1%))可达415℃,与环氧模塑料相比,T_g和T_(d1%)分别提高了109℃和21℃,固化物耐热性能优异,同时具有较好的粘附强度和介电性能,在高功率器件封装领域具有良好的应用前景。     

烯丙基化合物对双马来酰亚胺树脂的改性研究

为了得到综合性能更好的双马来酰亚胺(BMI)树脂,本文以二烯丙基双酚A(BA)和二烯丙基双酚S(BS)为共改性剂,对BMI树脂进行了改性,考察了共改性剂配比、固化后处理时间对改性BMI树脂体系的影响.采用动态力学分析(DMA)对改性后的BMl树脂浇铸体的热性能进行了初步分析.结果表明,BA/BS(摩尔比)为7/3的浇铸体的玻璃化转变温度(Tg)高达349.5℃,延长固化后处理时间可使浇铸体的Tg大幅提高.     

苯并噁嗪和双马来酰亚胺共混树脂性能的研究

将苯并噁嗪(BOZ)和双马来酰亚胺树脂(BMI)按照不同的配比进行共混固化,制备了浇铸体和玻璃纤维增强的层压板。测试结果表明,BOZ和BMI共混的树脂浇铸体线性收缩率为0.85%~0.93%,小于BMI的1.3%略高于BOZ的0.73%。浇铸体和层压板的弯曲强度均随着BOZ含量的增加而上升,并且层压板吸水率还具有不断降低的趋势;其电气绝缘性能较佳。同时该共混树脂体系具有较好的耐热性,其Tg最高达到257℃比单纯BOZ的Tg提高了近50℃。DSC结果表明BOZ/BMI树脂体系的固化反应相对二者各自固化反应向低温移动,使体系中的BMI在相对较低的温度就固化完全。     

巯基-烯/环氧光-热双重固化体系的制备与表征

通过光引发的巯基-烯点击化学反应和热引发的环氧开环反应制备了以烯丙基环氧树脂(DADGEBA)为基体树脂的巯基-烯/环氧杂化材料。通过实时红外(RT-FTIR)和傅里叶红外光谱(FT-IR)跟踪了双固化反应过程,以及不同官能度硫醇化合物对光聚合反应速率和转化率的影响。采用动态机械热分析(DMA)、热失重分析(TGA)和拉伸性能测试方法对烯丙基环氧树脂的光固化、热固化和光-热双固化3种固化材料的热力学性能和机械力学性能进行了对比研究。结果表明,烯丙基环氧树脂光-热双固化反应结合了光固化和热固化的优点,固化物的拉伸强度可以达到48 MPa,断裂伸长率为15%,玻璃化转变温度(T_g)为68℃,失重5%的热分解温度为343℃。     

聚醚酮改性BMI树脂的固化反应动力学研究

采用非等温DSC(差示扫描量热)法、FT-IR(红外光谱)法、Kissinger-Crane法、Ozawa法和T-β(温度-升温速率)外推法研究了PEK(聚醚酮)改性BMI/DBA(双马来酰亚胺/二烯丙基双酚A)树脂体系的固化动力学过程。研究结果表明:采用Kissinger-Crane法得到的动力学参数与Ozawa法的求解结果相近,PEK改性BMI/DBA的固化反应遵循1级反应机制;BMI/DBA/PEK树脂体系的固化温度为130~210℃,后处理温度为240℃。     

DCPD酚型环氧/DCPD苯酚树脂的固化及应用研究

通过DSC分析研究了不同软化点的双环戊二烯(DCPD)酚型环氧与DCPD苯酚树脂在溴化阻燃树脂体系中的固化反应特性并测试了其FR-4覆铜板的性能。结果表明:体系固化反应温度范围较大,DCPD酚型环氧软化点为50,80、90℃时,树脂体系反应活化能分别为98.3,82.3与74.2 kJ/mol。其制成板材的Tg在150℃以上,介电性能良好。随着DCPD酚型环氧树脂软化点的提高,板材玻璃化温度明显提高,高温高压下其吸水率降低,而热分解温度、粘接性及介电性能无明显变化。     

Victrex® poly(ethersulfone) (PES) and Victrex® poly(etheretherketone) (PEEK)

Properties of two high performance engineering thermoplastics, amorphous polyethersulfone (PES) and semicrystalline polyetheretherketone (PEEK), are discussed. Both resins can be processed by conventional techniques, compounded with high performance fibers, and have high service temperature (up to 300°C). Due to the amorphous character PES can be dissolved and spray coated into metals.     

(Ba_(1-α)Sr_α)_(4.8)(Sm_(0.7)La_(0.3))_(8.8)Ti_(18)O_(54)陶瓷的微波介电性能

采用固相合成法制备了(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54(α=0.1～0.5)系陶瓷,表征了该陶瓷的相组成和显微结构,测试了微波介电性能.结果表明:α=0.3时,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷为单相的新钨青铜结构固溶体.α>0.3时,相继出现了第二相BaLa2Ti4O12和La0.66TiO2.993.随α的增加,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷的相对介电常数(εr)先增大后有所波动,品质因数(Qf)先增大后减小,谐振频率温度系数(τf)单调减小.α=0.3时,在1 350℃烧结的陶瓷的微波介电性能最佳:εr=98.77,Qf=5184GHz,τf=10.9×10-6/℃,优于不掺杂的BaO-Sm2O3-TiO2陶瓷的.     

Photopyroelectric Spectroscopic Studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) Ceramics

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.     

Calcium silicate hydrate (II) (“C-S-H(II)”)

This semicrystalline phase, originally named ‘calcium silicate hydrate(II)’ by Taylor (1950), has been studied with X-rays, electron optics, chemical investigation of silicate anion type, infrared spectra, and thermal methods. It is structurally related to jennite (C₉S₆H₁₁) and probably also to the fibrous CSH of cement pastes, the three phases forming a sequence of decreasing crystallinity. The specimen studied had approximate composition C₂SH_3.2 after standing over saturated CaCλ₂ at about 15°C. CSH(II) contains metasilicate chains and pyrosilicate groups and has a disordered layer structure. Much of the water can be lost reversibly without significant change in lattice parameters.     

Poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid)

Summary In the present work we describe, the synthesis and characterization of a new gel obtained by crosslinking a cooligomer of butadiene-acrylic acid (BuAA), by reaction with acrylonitrile and acrylic acid. The purified product was characterized by FTIR, elemental analyses and scanning electronic microscopy. The thermal properties were studied and swelling indexes were determined in different solvents and at different pH values. The capacity of poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid) [gel A] to separate different organic substances, such as amino acids and colorants, was determined.     

Photooxidative stability of substituted poly(phenylene vinylene) (PPV) and poly(phenylene acetylene) (PPA)

The addition of side groups to improve the photooxidative stability of polymers used in polymer-based light-emitting diodes (LEDs) is explored. Infrared spectroscopy and computational chemistry techniques are used to study the effects of chemical substitution of the reactive vinylene moiety in poly(phenylene vinylene) (PPV). The bond order of the vinylene group in small oligomers is calculated using semiempirical techniques to assess the improvement in stability toward oxidants such as singlet oxygen. We find that PPV dimers allow relative comparisons across a range of possible substitutions. Experimental results correlate well with these calculations. The addition of electron-withdrawing substituents, such as nitrile groups, to the vinylene moiety is found to be particularly effective in reducing the reactivity of alkoxy-substituted PPV toward singlet oxygen. The photooxidative stability of a poly(phenylene acetylene) (PPA) derivative is also studied. It appears that this family of polymers is more stable toward photooxidation than are its PPV analogs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2451–2458, 1998     

Chemical cross-linking of conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) using poly(ethylene oxide) (PEO)

Hybrid films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were prepared with different molecular weights of poly(ethylene oxide) (PEO). The cross-linking reaction between PEO and PEDOT:PSS was performed at high temperature and confirmed by using differential scanning calorimeter (DSC), contact angle measurement, and solid-state ¹H NMR. The effect of chemical reaction on the conductivity and morphology of these hybrid films was studied by using 4-point probe and atomic force microscope (AFM), respectively. As-spun PEO/PEDOT:PSS films have lower electric conductivity due to the addition of nonconductive PEO, and exhibits no molecular weight dependence on conductivity. After chemical cross-linking reaction at high temperature, only PEDOT:PSS films with lowest molecular weight PEO additives show enhanced conductivity with increasing reaction time. AFM result indicates that the heat-treated PEO/PEDOT:PSS hybrid films show grain-like morphology compared to ethylene glycol treated PEDOT:PSS films which shows continuous PEDOT domain. In the present work we demonstrate that the cross-linking reaction can be used to improve the wet stability of PEDOT:PSS nanofiber, showing good water resistance and excellent dimensional stability.     

Thermal studies of blends of poly(phenylene sulfide) (PPS) with poly(phenylene sulfide sulfone) (PPSS) and with poly(phenylene sulfide ether) (PPSE)

The miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures T_g of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control T_g and melting temperature T_m of PPS by varying amounts of PPSE in blends. The melt crystallization temperature T_mc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE. The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ?2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t_1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases.