Polyimides from 3,3 '-dioxo-[1,1 ']-spirodiphthalan-5,5 ',6,6 '-tetracarboxylic dianhydride

A novel dianhydride, 3,3'-dioxo-[1,1']-spirodiphthalan-5,5',6,6'-tetracarboxlic dianhydride, was synthesized and used as a monomer to prepare polyimides with several diamines via a conventional two-stage procedure. The intermediate poly(amic-acid)s had inherent viscosities of 0.84-1.71 dL/g and could be thermally converted into lightly yellow, transparent, flexible and tough films. Films cast from chemically imidized polyimides were transparent and colorless. The glass transition temperatures (Tg) were > 400 degrees C, and the 5% weight-loss temperatures were > 420 degrees C in N-2 and in air. The solubilities of these polyimides in various solvents were evaluated. The mechanical properties of some polyimides were also tested. (C) 1999 Elsevier Science Ltd. All rights reserved.

Synthesis, properties and crystal structure of charge-transfer salt (DBTTF)(6)HSiMo12O40H2O

Charge-transfer salt (DBTTF)(6)HSiMo(12)O(40)4H(2)O was synthesized by electrocrystallization and characterized by IR spectrum and electronic spectrum. Its magnetic property, conductivity and crystal structure were determined. The title compound consists of heteropoly anions, water molecules and DBTTF columns which are formed by repeated arrangement of tetramer (DBTTF), in the direction of 15 degrees to the a axis in the tunnel constituted by the anions and other type of DBTTF. The title compound is paramagnetic and semiconducting. (C) 1998 Elsevier Science Ltd. All rights reserved.

Effect and mechanism in compatibilization of poly(styrene-b-2-ethyl-2-oxazoline) diblock copolymer in poly(2,6-dimethyl-1,4-phenylene oxide) poly(ethylene-ran-acrylic acid) blends

The compatibilization effect of poly(styrene-b-2-ethyl-2-oxazoline) diblock copolymer, P(S-b-EOx), on immiscible blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and poly(ethylene-co-acrylic acid) (EAA) is examined in terms of phase structure and thermal, rheological and mechanical properties, and its compatibilizing mechanism is investigated by Fourier-transform infrared spectroscopy. The block copolymer, synthesized by a mechanism transformation copolymerization, is used in solution blending of PPO/EAA. Scanning electron micrographs show that the blends exhibit a more regular and finer dispersion on addition of a small amount of P(S-b-EOx). Thermal analysis indicates that the grass transition of PPO and the lower endothermic peal; of EAA components become closer on adding P(S-b-EOx), and the added diblock copolymer is mainly located at the interface between the PPO and EAA phases. The interfacial tension estimated by theological measurement is significantly reduced on addition of a small amount of P(S-b-EOx). The tensile strength and elongation at break increase with the addition of the diblock copolymer for PPO-rich blends, whereas the tensile strength increases but the elongation at break decreases for EAA-rich blends. This effect is interpreted in terms of interfacial activity and the reinforcing effect of the diblock copolymer, and it is concluded that the diblock copolymer plays a role as an effective compatibilizer for PPO/EAA blends. The specific interaction between EAA and polar parts of P(S-b-EOx) is mainly hydrogen bonding. (C) 1998 Elsevier Science Ltd. All rights reserved.

基质辅助激光解吸电离-飞行时间质谱表征6氟双酚A芳香环状聚醚酮(砜)

应用基质辅助激光解吸电离飞行时间质谱,在不同阳离子剂的存在下,对6氟双酚A聚芳醚酮(砜)环状低聚物的结构进行了确认,研究了环状化合物对金属离子的选择性及激光质谱表征含氟环状低聚物的适宜条件.

谷物中噻吩甲氯残留量的气相色谱-质谱测定

应用气相色谱－ 质谱法确证及测定谷物( 糙米、玉米) 中噻吩甲氯的残留含量，试样采用水—丙酮提取，提取液经与石油醚液—液分配后， 再以硅酸镁载体(Florisil)柱净化，气相色谱—质量选择检测器选择离子监测方式(GC-MSD-SIM)进行测定和阳性确证。噻吩甲氯选择监测离子的种类为m/z287、288、323，其丰度比约为46:100:11。采用外标法定量，方法检出限为0.010 ×10-6。

尼龙1010/6及尼龙1010/66基本物理性能与组成的关系

尼龙1010/6 和尼龙1010/66 的基本物理性能随着组成的改变而改变,尼龙1010 含量高时,共聚物密度大于计算值;含量低时,共聚物密度小于计算值.尼龙1010 含量20%左右时,共聚物具有较大吸水率

Phase transition temperature of HPT(2,3,6,7,10,11-hexa-n-pentyloxytriphenylene) from molecule dynamic simulation

Molecule dynamics simulation was used on HPT(2,3,6,7,10,11-hexa-n-pentyloxytriphenylene), which is a discotic Liquid crystal. From analyzing the energy and displacement varying with the temperature, the phase transition temperature of PM6MPP can be predicted. The deviations of T-g, T-m and T-i due to the MD time scale are small enough that it should be possibly used to predict the material properties especially when more powerful computers are available.

Compatibilizing effect of polystyrene-block-poly(4-vinylpyridine) for poly(2,6-dimethyl-1,4-phenyleneoxide) chlorinated polyethylene blends

The compatibilizing effect and mechanism of compatibilization of the diblock copolymer polystyrene-block-poly(4-vinylpyridine) P(S-b-4VPy) on immiscible blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/chlorinated polyethylene (CPE) were studied by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), mechanical properties and FTIR measurements. The block copolymer was synthesized by sequential anionic polymerization and melt-blended with PPO and CPE. The results show that the P(S-b-4VPy) added acts as an effective compatibilizer, located at the interface between the PPO and the CPE phase, reducing the interfacial tension, and improving the interfacial adhesion. The tensile strength and modulus of all blends increase with P(S-b-4VPy) content, whereas the elongation at break increases for PPO-rich blends, but decreases for CPE-rich blends. The polystyrene block of the diblock copolymer is compatible with PPO, and the poly(4-vinylpyridine) block and CPE are partially miscible.

Structure and Conformation of 2,3,6, 7,10,11-hexakispentyloxytriphenylene by TEM and Computer Simulation

Experimental electron diffraction patterns and high resolution images were used to determine the space group and unit cell dimensions of 2,3,6,7,10,11-hexakispentyloxytriphenylene. Subsequently the molecular conformation was calculated by energy minimized package in Cerius2. Using this method, we got the HPT crystal structure: space group: P6/mmm; lattice type: hexogonal; the lattice parameters are a = b = 20.3 angstrom, c = 3.52 angstrom, = = 90 degrees, = 120 degrees. The core of HPT is not perpendicular to the column. The angle between a axis and HPT core plane is 9 degrees which cannot be seen in b-c projection. The simulated ED patterns and HREM images are good agreement with the experimental ED patterns and HREM images.