Structure and properties of CE/CTBN/EP blends: II. Effect of EP on the mechanical properties and thermostability of the CE/CTBN system

Carboxyl‐terminated butadiene‐acrylonitrile rubber (CTBN) has often been used to improve the toughness of cyanate ester (CE) resin while sacrificing modulus and thermostability. In this paper, the addition of the appropriate amount of epoxy resin (EP) to the CE/CTBN system is shown to not only increase the modulus and thermostability of the blend, but also improve the toughness. The values of impact strength showed a maximum for the CE/CTBN/EP 100/5/5 blend. The temperature of 10 % weight loss (T₁₀) improves from 376 °C for CE/CTBN 100/5 to 407 °C for the CE/CTBN/EP 100/5/2.5 blend. It is proposed that addition of the appropriate amount of EP can decrease the mobility and increase the stability of CTBN via the reaction between the terminal carboxyl group of CTBN and the hydroxyl group of EP. But a very high EP concentration will decrease the crosslinking density of CE, consequently reducing the mechanical properties and thermostability of the blends. Copyright © 2004 Society of Chemical Industry     

苦瓜汁的抑菌活性及其热稳定性的研究

采用琼脂扩散法研究了苦瓜汁对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、沙门氏菌的抑菌活性。研究结果表明:苦瓜汁对四种菌均具有较好的抑菌活性,其中对大肠杆菌和沙门氏菌的抑菌活性明显强于对金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性;在100℃以内,苦瓜汁具有良好的抑菌稳定性。     

NMR Structure and Biophysical Characterization of Thermophilic Single-Stranded DNA Binding Protein from Sulfolobus Solfataricus

Proteins from Sulfolobus solfataricus (S. solfataricus), an extremophile, are active even at high temperatures. The single-stranded DNA (ssDNA) binding protein of S. solfataricus (SsoSSB) is overexpressed to protect ssDNA during DNA metabolism. Although SsoSSB has the potential to be applied in various areas, its structural and ssDNA binding properties at high temperatures have not been studied. We present the solution structure, backbone dynamics, and ssDNA binding properties of SsoSSB at 50 °C. The overall structure is consistent with the structures previously studied at room temperature. However, the loop between the first two β sheets, which is flexible and is expected to undergo conformational change upon ssDNA binding, shows a difference from the ssDNA bound structure. The ssDNA binding ability was maintained at high temperature, but different interactions were observed depending on the temperature. Backbone dynamics at high temperature showed that the rigidity of the structured region was well maintained. The investigation of an N-terminal deletion mutant revealed that it is important for maintaining thermostability, structure, and ssDNA binding ability. The structural and dynamic properties of SsoSSB observed at high temperature can provide information on the behavior of proteins in thermophiles at the molecular level and guide the development of new experimental techniques.     

高热稳定性低氯聚苯砜树脂合成及表征

结合缩聚方法和封端修饰方法合成苯酚封端的聚苯砜(PPSU)树脂,利用离子色谱方法对PPSU树脂的氯端基含量进行定量测试,并采用毛细管流变仪和高温注塑等方法对比评估了不同氯端基含量PPSU树脂的热稳定性和颜色.结果表明,通过苯酚封端,PPSU树脂的氯端基含量可由3000 mg/kg以上降至700 mg/kg以下,氯端基含...     

纳米二氧化锆改性聚酰亚胺薄膜的制备及性能

聚酰亚胺（PI）在工程高分子材料领域广受关注,开发新型耐高温、疏水性良好的PI薄膜材料是推动高性能高分子材料在电动汽车等高新技术领域工程化应用的重要突破口。以间苯二胺（MPD）与4,4’-(4,4’-异丙基二苯氧基)二酞酸酐（BPADA）为原料,采用原位掺杂热亚胺化合成PI薄膜,通过向聚酰胺酸（PAA）前驱液中添加纳米ZrO2粉体对聚酰亚胺薄膜进行改性,制得不同ZrO2添加量（0.77%～1.93%,以MPD、BPADA总质量为基准,下同）的复合型PI薄膜。借助XRD、SEM、EDS、FTIR及TGA对复合薄膜进行了结构和形貌表征。结果表明,与纯PI相比,ZrO2添加量为1.93%的复合薄膜初始分解温度为415℃（提高5%）,水接触角为91.7°（提高61%）,表明ZrO2对改善PI薄膜的性能具有重要作用。     

Al2O3对AlPO4催化剂的结构及其缩醛化反应活性的影响

采用溶胶-凝胶法制备了系列AlPO₄-Al₂O₃催化剂,利用XRD、TG-DTA、NH₃-TPD和催化剂评价等方法,研究了制备条件对催化剂结构和缩醛化反应催化性能的影响,结果表明,Al₂O₃的存在不仅能提高AlPO4的热稳定性,而且可以调节催化剂的表面酸性性能。在适宜的缩醛化反应条件下,400 ℃焙烧和Al₂O₃质量分数为15%的AlPO₄-Al₂O₃催化剂样品具有较好的催化活性,1,2-丙二醇转化率达28.1%,AlPO₄-Al₂O₃催化剂的缩醛化反应活性与表面弱酸中心的酸量成顺变关系。     

光热对薄膜CdS／Cu2S太阳电池物理参数的影响

研究了光、热和湿气对ＣｄＳ／Ｃｕ２Ｓ电池效率及电池成结、结电容、二极管特性和光谱响应特性的影响。结果表明，对未成结电池光加速成结作用，对成结电池光引起电池性能下降，这种衰降是不可逆过程。     

Ce:LuAlO3晶体的热稳定性研究

铈掺杂铝酸镥(Ce:LuAlO3)晶体是一种具有钙钛矿结构的新型无机闪烁体.用提拉法试图从n(Lu2O3):n(Al2O3)=1:1的熔体中生长Ce:LuAlO3晶体.实验表明:在缓慢结晶条件下得到的不是Ce:LuAlO3晶体,而是镥铝石榴石[Lu3Al2(AlO4)3].只有急速降温才能够获得Ce:LuAlO3晶体.退火和差热分析表明:Ce:LuAlO3晶体只存在于高温条件下,当温度下降时,它会分解成Lu3Al2(AlO4)3,Lu4Al 2O9和Lu2O3.造成LuAlO3晶体在低温下结构不稳定的原因是Lu离子的半径太小,它只适应于配位数是8的石榴石结构,只有在高温下才能适应配位数是12的钙钛矿结构.     

泥岩与沉积物中粘土矿物吸附有机质的三种赋存状态及其热稳定性

为研究有机质在粘土矿物中的赋存状态和二者的结合方式以及有机质的热稳定性,提取济阳坳陷东营凹陷古近系沙河街组泥质烃源岩和东海陆架表层泥质沉积物中的粘土组分(粒径<2 μm),依次进行索氏抽提、碱性水解和酸性水解处理,得到原始和相继处理过程所得碱解和酸解粘土样品及相应的有机组分,继而进行原始和碱解、酸解粘土样品的微观形貌(SEM)、比表面积(BET)、X-射线衍射(XRD)和热重/微分热重(TG/DTG)分析对比。结果显示,索氏抽提有机质主要赋存于粘土矿物外表面和堆积于孔隙中,碱解有机质主要赋存于粘土矿物边缘破键处,而酸解有机质主要赋存于膨胀型粘土蒙皂石层间。前者为物理吸附或束缚的游离有机质,后两者为化学吸附的结合有机质。有机质与粘土矿物的不同结合关系造成它们热稳定性的差异,显示出二者间复杂的作用关系及其对生烃的多阶段性影响。研究不同赋存态有机质的相对和绝对数量对深入研究油气成因和烃类初次运移具有十分重要的意义。     

耐高温深部调驱剂实验研究

针对低度交联聚合物调驱剂耐温能力的不足,优选出合成耐温调驱剂的主要原料,并通过实验筛选出耐温调驱体系的最佳配方：聚合物HPAM1500mg／L＋酚醛树脂交联剂500mg／L＋有机铬交联剂20mg／L＋盐热稳定剂100mg／L＋除氧剂100mg／L。此调驱体系采用二次交联技术,耐温可达100～110℃。实验结果表明,调驱剂的成胶时间随温度升高而缩短,温度为80—110℃时,胶体强度都在10000mPa·s以上。体系在110℃下成胶之后的老化过程中,随着时间的延长,黏度降低。老化至60d时黏度保留率为70％左右,在110℃的热稳定性较好。此体系具有一定的封堵高渗透大孔道的能力,对于渗透率为（119—306）×10^-3μm。的岩心,此调驱体系的封堵率均在90％以上,但堵而不死,可动性也较强,具有驱替基质中原油的潜力。