两种DMSO法PAN原丝性能和结构的对比研究

对国产DMSO法聚丙烯腈(PAN)原丝与美国DMSO法PAN原丝的性能和结构进行了对比,找出了国产PAN原丝和美国PAN原丝在质量均一性、断面形状、取向度和结晶度、相对分子质量、共聚组分等方面存在的差别,为进一步提高我国PAN原丝的内在质量提供了科学依据。研究结果表明:美国PAN原丝比国产PAN原丝有较高的强度、模量、相对分子质量、结晶度及取向度,较低的纤度、断后延伸率及各种不均率等优良性能。     

炭黑添加剂对PAN原丝性能的影响

用炭黑改性聚丙烯腈原丝制得了中孔率大大提高的活性炭纤维。考察了炭黑对聚丙烯腈——二甲基亚砜纺丝溶液粘度、可纺位及纺得纤维微观结构、元素组成、力学性能和热性能的影响。由于炭黑具有纳米级的位径和粗糙的表面，因此可均匀分散于聚丙烯腈溶液及纤维中并与聚丙烯腈大分子结合，使其溶液粘度，粘流活化能增大。结晶度减小，但对其热性能影响不大。     

基于晶体角度研究聚丙烯腈基原丝及其碳纤维性能

纤维内晶体的结晶度、晶体尺寸等均会对聚丙烯腈基原丝及碳纤维的性能产生影响。从晶体角度出发,采用X射线衍射仪、光学显微镜、扫描电子显微镜等对碳纤维及其原丝的结构、性能进行测试,分别对干喷湿纺与湿法纺丝制备的高低细旦化原丝及碳纤维、不同碳化程度碳纤维进行对比,分析纤维内部晶体结构对碳纤维特性的影响。结果表明:干喷湿纺工艺及高倍拉伸更容易获得较高力学性能的碳纤维。     

两种HNO3法PAN原丝的性能和结构对比

本文对国产HNO3法聚丙烯腈(PAN)原丝与日本HNO3法原丝的性能和结构进行了比较,总结了国产原丝与国外原丝存在的差距．     

聚丙烯腈基纤维的结构设计及其演变性研究

为了制备高性能的聚丙烯腈基碳纤维,借助高温DSC曲线分析、透射电镜和扫描电镜等分析方法,通过对制备碳纤维的不同类型原丝进行分析,对聚丙烯腈基纤维的结构设计及其演变性进行了研究,结果发现在聚合、纺丝过程中要避免结构缺陷的引入,才能制备具有理想的物理化学结构和精细组织结构的原丝,只要丙烯腈质量分数达0．97以上,第二、三单体的微量变化不足以引起原丝和碳纤维性能发生大的变化,原丝微观组织结构不断演变和转化,某些结构缺陷会遗传到碳纤维中,质量较高PAN纺丝液质量分数纺丝液制取的纤维表面沟槽小而浅．     

浅谈提高聚丙烯腈基碳纤维性能的几种关键技术

从国外研究较多的共聚单体、聚丙烯腈原丝的改性、上油油剂等三个方面论述了提高聚丙烯腈基碳纤维性能的几种关键技术。聚丙烯腈原丝的热性能与共聚单体的种类和加入量有重要关系。共聚单体的加入促进纤维预氧化反应 ,使碳纤维性能和炭化收率都得到提高。各种各样的化学试剂用于改性聚丙烯腈原丝后 ,对改善最终碳纤维的结构和性能有重要的作用。油剂的使用对聚丙烯腈原丝的质量 ,如耐热性、亲水性、集束性、分纤性及加工毛丝率等有重要的影响     

聚丙烯腈原丝取向结构和力学性能研究

以两段拉伸法制备聚丙烯腈(PAN)原丝,以广角X射线衍射方法研究其微观取向结构,单纤维拉伸实验测得原丝的力学性能,声速法测定其取向系数和模量。结果表明,随着拉伸比的增加,原丝中分子链取向增加,其杨氏模量和断裂强度也随之提高,而断裂伸长率则下降。不同拉伸比的PAN原丝取向系数与Crawford和Kolsky取向模型的理论曲线比较吻合。     

用DSC研究选择聚丙烯腈原丝的共聚单体

本文主要利用差示扫描量热分析(DSC)研究了聚丙烯腈的共聚物及其原丝的热性能，研究结果发现国产原丝具有相似的放热单峰，而日本某公司的原丝具有两个峰，分峰使聚丙烯腈原丝放热峰宽化，避免了在预氧化、碳化时放热集中产生熔化、断丝现象．聚丙烯腈原丝的纺丝、溶解、氨改性等加工过程不能明显改变其放热峰的形状，而共聚单体的种类和组成配比才是最重要的因素，通过适当的共聚单体选择、配比设计可以制得具有与日本原丝放热峰相似的聚丙烯腈聚合物或原丝。     

浅析聚丙烯腈基碳纤维焦油形成的原因

根据聚丙烯腈基碳纤维生产工艺路线,从原丝、预氧化、碳化工艺及结构上分析了聚丙烯腈基碳纤维焦油形成的原因。其主要原因为碳化前纤维缺陷结构的遗传、碳化中分子键的热断裂和分子链的无规热裂解。     

聚丙烯腈纤维预氧化前处理研究进展

综述了前人在聚丙烯腈原丝预氧化前处理方面的研究成果,介绍了前处理的作用机理及作用效果。研究发现,聚丙烯腈原丝的改性处理可显著提高纤维的结构和性能,并影响原丝在预氧化过程中的热力学和动力学,进而影响最终碳纤维的质量。     

Effects of Carbon Yarn Size on the Mechanical Properties of Plain Woven C/SiC Composites

The effects of yarn size on the mechanical properties of silicon carbide composites reinforced with a plain woven carbon cloth with two sizes of yarns (1 and 3 k) were investigated. The experimental results show that the composite fabricated with 1 k yarns exhibits greater stiffness and strength than the composite fabricated with 3 k yarns. Microstructural observations revealed the existence of matrix microcracks in both the composites under the as-processed condition due to the large difference of thermal expansion between the fibers and the matrix, which are more severe for the composite with 3 k yarns. The fractured surfaces of the composite with 1 k yarns showed extensive fiber pull-out in contrast to the yarn pull-out in the composite with 3 k yarns. The larger interyarn and intrayarn voids due to difficulties of matrix infiltration in the composite with 3 k yarns represent the primary contribution to the diminished mechanical properties. Unequal yarn sizes give rise to different yarn waviness, which may be another source of difference in the mechanical properties of composites.     

国产CCF300碳纤维4轴向无屈曲织物层合板力学性能对比研究

设计制备了两种4轴向碳纤维无屈曲织物(NCF):第一种织物全部采用东丽公司T700 12k碳纤维,第二种织物中66.7%碳纤维采用国产CCF300 3k碳纤维(与东丽T300 3k碳纤维相当)。对该两种织物层合板0°、90°和±45°4个方向的抗拉伸、抗弯曲和抗层间剪切性能进行了测试与对比研究。结果表明:在现有生产条件下,国产CCF300 3k碳纤维最多可以代替4轴向NCF中66.7%的进口T700 12k碳纤维;国产碳纤维NCF层合板各方向归一化后的抗拉伸强度比进口碳纤维NCF层合板低18.7%～26.1%,而其他性能没有显著差别;两种NCF层合板的抗拉伸和抗层间剪切破坏模式相似。     

纤维束丝数对平纹编织C/SiC复合材料力学性能的影响

通过对2种丝束平纹编织碳纤维布增强SiC（C/SiC）复合材料的力学性能实验,研究了纤维束丝数（1 k和3 k）对复合材料性能的影响.实验结果表明：1 k C/SiC复合材料的拉伸模量、拉伸强度、压缩模量、压缩强度、面内剪切强度和弯曲强度分别为90.8 GPa,281.8 MPa,135.8 GPa,452.2 MPa,464.3 MPa和126.8 MPa,分别比3 k C/SiC高39%,15.8%,25%,132%,29.3%和30.2%.纤维束粗细不同是导致纤维束弯曲度和复合材料孔隙率差异的主要原因,对压缩强度的影响最大,对拉伸强度的影响最小.     

Electrical and Optical Properties of Transparent Conducting Homologous Compounds in the Indium–Gallium–Zinc Oxide System

The homologous compounds In_{1− x} Ga_{1+ x} O₃(ZnO) _k (where k = 1, 2, or 3) were prepared at a temperature of 1400°C. The solubility limits (as determined via X-ray diffractometry) were 0.47 < [In]/([In] + [Ga]) < 0.67 for the k = 1 member, 0.35 < [In]/([In]+[Ga]) < 0.77 for the k = 2 member, and 0.29 < [In]/([In]+[Ga]) < 1.00 for the k = 3 member. Four-point-conductivity and diffuse-reflectance measurements were performed on as-fired and reduced samples. The band gap that was determined from diffuse reflectance increased as the Ga³⁺ content increased and k decreased. The conductivity increased as k decreased and the In³⁺ content increased. A maximum conductivity of 250 S/cm was obtained for k = 3 and [In]/([In]+[Ga]) = 1 after reduction. The minimum absorption edge of 325 nm was obtained for k = 2 and [In]/([In]+[Ga]) = 0.35 prior to reduction. The potential for metastable phases in the In-Ga-Zn-O system with enhanced transparent-conducting properties has been discussed.     

Discovery of N-arylalkyl-3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives as HCV NS5B polymerase inhibitors

The metal ion chelating β-N-hydroxy-γ-ketocarboxamide pharmacophore was integrated into a quinazolinone scaffold, leading to N-arylalkyl-3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives as hepatitis C virus (HCV) NS5B polymerase inhibitors. Lead optimization led to the identification of N-phenylpropyl carboxamide 9 k (IC(50) =8.8 μM). Compound 9 k possesses selectivity toward HCV1b replicon Ava.5 cells (EC(50) =17.5 μM) over parent Huh-7 cells (CC(50) =187.5 μM). Compound 9 k effects a mixed mode of NS5B inhibition, with NTP-competitive displacement properties. The interaction between 9 k and NS5B is stabilized by the presence of magnesium ions. Docking studies showed that the binding orientation of 9 k occupies the central portions of both magnesium-mediated and NTP-ribose-response binding sites within the active site region of NS5B. As a result, 3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives are disclosed herein as novel, mainly active site inhibitors of HCV NS5B polymerase.     

Enhanced bone cell functions on poly(ε-caprolactone) triacrylate networks grafted with polyhedral oligomeric silsesquioxane nanocages

Poly(ε-caprolactone) triacrylate (PCLTA) developed in our laboratory is a photo-crosslinkable, injectable, and biodegradable polymeric biomaterial for diverse tissue engineering applications. To engineer its physical properties for bone regeneration, we incorporated PCLTA networks with a photo-reactive methacryl isobutyl polyhedral oligomeric silsesquioxane (POSS), which is a silicon-based monomer with a nano-sized cage. Homogeneous nanohybrid networks were prepared by photo-crosslinking POSS with two PCLTAs having molecular weights of ∼7000 and ∼20,000 g/mol at the POSS weight compositions (?_POSS) of 0–20%. The lower-molecular-weight PCLTA resulted in amorphous networks while the higher one resulted in semi-crystalline networks. POSS nanocages tethered in the PCLTA networks greatly enhanced the mechanical and rheological properties, but did not significantly alter the surface wettability and the capability of adsorbing serum proteins from cell culture media. Better mouse pre-osteoblastic MC3T3-E1 cell attachment, spreading, and proliferation were found on the stiffer PCLTA20k networks than on the PCLTA7k ones, and on the networks with ?_POSS of 10–20% than the networks containing no POSS. Mineralization of MC3T3-E1 cell cultured for two weeks showed a significantly higher alkaline phosphatase activity and more mineralized nodules on the PCLTA20k networks with ?_POSS of 10–20%, in correlation with their enhanced mechanical properties. The present results indicated that this series of nanohybrid PCLTA/POSS networks with improved mechanical properties and osteoconductivity has great potential as scaffolding materials for bone repair and regeneration.     

ZH-03树脂对苯酚和2,4-二氯苯酚的吸附机理研究

在静态条件下,研究了水溶液中新型树脂ZH-03吸附苯酚和2,4-二氯苯酚的热力学特性,测定了在288k、303k、318k和下降到288k温度下的吸附等温线。结果表明,在稀溶液中ZH-03吸附剂对苯酚和2,4-二氯苯酚的吸附同时符合Langm u ir和F reund lich模型。该树脂对苯酚的吸附是一个放热过程,而对2,4-二氯苯酚的吸附属于吸热过程,同时不同温度下的吸附等温线和热力学计算结果都证明了在树脂ZH-03对2,4-二氯苯酚吸附行为中存在着化学吸附。     

In Vivo Anti-Tumor Activity of Polypeptide HM-3 Modified by Different Polyethylene Glycols (PEG)

HM-3, designed by our laboratory, is a polypeptide composed of 18 amino acids. Pharmacodynamic studies in vivo and in vitro indicated that HM-3 could inhibit endothelial cell migration and angiogenesis, thereby inhibiting tumor growth. However, the half-life of HM-3 is short. In this study, we modified HM-3 with different polyethylene glycols (PEG) in order to reduce the plasma clearance rate, extend the half-life in the body, maintain a high concentration of HM-3 in the blood and increase the therapeutic efficiency. HM-3 was modified with four different types of PEG with different molecular weights (ALD-mPEG(5k), ALD-mPEG(10k), SC-mPEG(10k) and SC-mPEG(20k)), resulting in four modified products (ALD-mPEG(5k)-HM-3, ALD-mPEG(10k)-HM-3, SC-mPEG(10k)-HM-3 and SC-mPEG(20k)-HM-3, respectively). Anti-tumor activity of these four modified HM-3 was determined in BALB/c mice with Taxol as a positive control and normal saline as a negative control. Tumor weight inhibition rates of mice treated with Taxol, HM-3, ALD-mPEG(5k)-HM-3, ALD-mPEG(10k)-HM-3, SC-mPEG(10k)-HM-3 and SC-mPEG(20k)-HM-3 were 44.50%, 43.92%, 37.95%, 31.64%, 20.27% and 50.23%, respectively. Tumor inhibition rates in the Taxol, HM-3 and SC-mPEG(20k)-HM-3 groups were significantly higher than that in the negative control group. The efficiency of tumor inhibition in the SC-mPEG(20k)-HM-3 group (drug treatment frequency: once per two days) was better than that in the HM-3 group (drug treatment frequency: twice per day). In addition, tumor inhibition rate in the SC-mPEG(20k)-HM-3 group was higher than that in the taxol group. We conclude that SC-mPEG(20k)-HM-3 had a low plasma clearance rate and long half-life, resulting in high anti-tumor therapeutic efficacy in vivo. Therefore, SC-mPEG(20k)-HM-3 could be potentially developed as new anti-tumor drugs.     

Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3压电陶瓷的电学性能研究

采用固相烧结法制备了0.40Pb(Mg1/3Nb2/3)O3-(0.6-x)PbZrO3-xPbTiO3压电陶瓷,系统研究了其组分变化对晶体结构、介电和压电性能的影响。研究结果表明,所有样品均属于钙钛矿结构,无第二相产生。随着组分的变化,存在三方相向四方相的转变,并且在x = 0.38附近获得准同型相界组分,呈现出最优的电学性能,最高的压电系数d33 = 520 pC/N,居里温度TC = 238 °C,平面机电耦合系数kp = 0.60,厚度机电耦合系数kt = 0.52,纵向机电耦合系数k33 = 0.73。     

Effect of Rare-Earth Additives on Electromechanical Properties of Modified Lead Titanate Ceramics

The influence of rare-earth additives, such as La, Nd, Sm, and Gd, and poling conditions on the electromechanical properties of (Pb_{1−3 x /2}Ln _x )(Ti_0.98Mn_0.02)O₃ compositions, x = 0.04–0.12, were investigated. The type and amount of additive were found to affect the lattice anisotropy, dielectric constant, and electromechanical properties. A large electromechanical anisotropy ( k _t / k _p ) could be obtained in 10 mol% Sm-modified and 8 mol% Gd-modified lead titanate ceramics, and seemed to correlate to a low Poisson's ratio.