Colorless polyimides from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) and various aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

A series of organosoluble and light-colored polyimides (III) was prepared from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) with various fluorinated aromatic bis(ether amine)s via two-step method with thermal or chemical imidization of poly(amic acid)s yielded polyimides. The III series had inherent viscosity of 0.74-1.01 dl/g and showed excellent solubility in a variety of organic solvents. They were soluble in the amide polar solvent, ether-type solvent, and chlorinated solvent. These polyimide films also showed a high optical transparency and less color intensity, with an ultraviolet-visible absorption edge of 369-382 nm and low b^* values (a yellowness index) of 5.0-11.7. Glass-transition temperature of the III series was recorded at 244-319 °C and higher than the isomeric polyimides V series. Compared with the nonfluorinated polyimides IV, the III series showed lighter-colored and lower dielectric constants and moisture absorptions. The good tensile properties and excellent thermal properties of the III series were also observed.     

Effects of cashew nut shell liquid as a plasticizer on cure characteristics,processability, and mechanical properties of 50 : 50 NR/EPDM blends: A comparison with paraffin oil

50 : 50 natural rubber (NR) and ethylene–propylene–diene monomer rubber (EPDM) blends were prepared with different contents of cashew nut shell liquid (CNSL), a natural product obtained from the shells of the cashew nut, as a plasticizer. For comparison, a commercial paraffin oil plasticizer was also used. The effect of plasticizer content on the cure characteristics, processability, and mechanical properties such as tensile strength, elongation at break, and Young's modulus before and after ageing was investigated. Scanning electron microscopy (SEM) was used to observe the blend morphology. The results indicated that the CNSL plasticizer resulted in lower Mooney viscosity and lower cure time of the 50 : 50 NR/EPDM blends. The incorporation of CNSL into 50 : 50 NR/EPDM blends improved tensile strength and elongation at break but decreased Young's modulus. On addition of CNSL the resistance of the blends to heat and weathering ageing improved. Scanning electron micrographs revealed that the morphology of the blend plasticized with CNSL is finer and more homogeneous compared with the blend plasticized with paraffin oil. Overall results indicate that CNSL can be used as a cheaper plasticizer to replace paraffin oil in NR/EPDM blends with improved processability and mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Recycling of ethylene propylene diene monomer (EPDM) waste. III. Processability of EPDM rubber compound containing ground EPDM vulcanizates

The rheological behavior of ethylene propylene diene monomer (EPDM) compounds containing ground EPDM waste (W‐EPDM) of known composition was studied by using a Monsanto processability tester in a temperature range of 90–110°C and a shear rate range of 306.7–1533.24 s^?1. It is found that the shear viscosity decreases slightly with increasing W‐EPDM loading because of wall slip that results from the migration of lubricants from the W‐EPDM. The addition of W‐EPDM to raw EPDM results in a decreased die swell at all temperatures and shear rates. SEM photomicrographs of the EPDM extrudate surface show improved surface smoothness and reduced extrudate distortion when EPDM is blended with W‐EPDM. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2204–2215, 2003     

改性水性硝化纤维素乳液研究

采用醇酸树脂转相乳化法和丙烯酸酯类单体互穿聚合物网络聚合法制备改性硝化纤维素乳液。研究了醇酸树脂、丙烯酸酯类单体乳化剂用量等因素对乳液性能的影响。结果表明，丙烯酸酯类单体改性互穿聚合物网络聚合法制得的乳液效果好.     

Introduction of fluorin into PBO polymer chains: Toward higher thermal stability and lower dielectric constant

A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR), 1,4-benzenedicarboxylic acid (PTA) and various amount of 4'4- (hexafluoroisopro-pylidene) bis (benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jet wet-spinning technique and characterized by means of Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), single fiber tensile testing machine and scanning electron microscopy (SEM). FTIR spectrum of 6FPBO fibers indicated that the fluorine groups had been incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability just as pure PBO fibers. Moreover, dielectric constant spectrum of 6FPBO exhibited that the polymers had low dielectric constant, especially in the range of high- frequency.     

均苯四酸二酐凝华结晶精制的最佳条件研究

研究了均苯四酸二酐（简称均酐或PMDA）凝华结晶精制的最佳条件,并以均酐在定温下的平衡蒸汽压为基础,推导出凝华结晶条件数学关系式．该式把氧化反应的空速,气相组成及捕集温度等工艺参数与捕集率关联起来,并制作出捕集温度对均酐凝华结晶效率和均酐纯度关系曲线图．同时讨论了拉乌尔数学关系式在处理本体系的适应范围．指出在低捕集率情况下,引入修正项后的拉乌尔数学关系式才能与实验值吻合．     

三嗪基含氟扩链剂改性水性聚氨酯的合成

利用三聚氰氯（CC）、八氟戊醇（OFP）和乙醇胺（MEA）间的反应先合成了三嗪基含氟扩链剂CC-F，在此基础上制备出系列三嗪基含氟扩链剂改性水性聚氨酯CC-FPUF。利用FTIR和1HNMR对其结构进行表征，并用DLS、XRD、XPS、SEM、WCA和电子万能试验机探究了CC-FPUF制备中所用CC-F的含量(以CC-F、IPDI、CMA-1044、DMPA、S104、TMP和TEA的总质量为基准，下同）对CC-FPUF的乳液粒径、聚合物形态、胶膜形貌、表面元素组成、疏水性能和力学性能的影响。结果表明，随着CC-F含量的增加，CC-FPUF的乳液粒径、胶膜疏水性能和胶膜拉伸强度均有所增加。当CC-F的含量达到8%（CC-FPUF-8）时，胶膜的水接触角最高达到125.8°，相比不含氟的水性聚氨酯（PU）和CC-FPUF-0（CC-F的含量为0）分别增加了60.9°和34.1°；此时胶膜的拉伸强度最大，相比CC-FPUF-0增加了24.47 MPa。胶膜CC-FPUF-8表现出优异的疏水性能和良好的力学性能。     

Synthesis and properties of new poly(amide imide)s containing trimellitic rings and hydantoin moieties in the main chain under microwave irradiation

Trimellitic anhydride was reacted with 4,4′‐diaminodiphenyl ether in a mixture of acetic acid and pyridine (3 : 2) at room temperature and was refluxed at 90–100°C, and N,N′‐(4,4′‐diphenylether) bistrimellitimide (3) was obtained in a quantitative yield. 3 was converted into N,N′‐(4,4′‐diphenylether) bistrimellitimide diacid chloride (4) by a reaction with thionyl chloride. Then, six new poly(amide imide)s were synthesized under microwave irradiation with a domestic microwave oven through the polycondensation reactions of 4 with six different derivatives of 5,5‐disubstituted hydantoin in the presence of a small amount of a polar organic medium such as o‐cresol. The polycondensation proceeded rapidly and was completed within 7–10 min, producing a series of new poly(amide imide)s in high yields with inherent viscosities of 0.27–0.66 dL/g. The resulting poly(amide imide)s were characterized by elemental analysis, viscosity measurements, differential scanning calorimetry, thermogravimetric analysis, derivative thermogravimetry, solubility testing, and Fourier transform infrared spectroscopy. All the polymers were soluble at room temperature in polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and N‐methyl‐2‐pyrrolidone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3447–3453, 2004     

Preparation and the properties of PMR‐type polyimide composites with aluminum nitride

A new polyimide composite was developed relying on the concept of in situ polymerization of monomer reactants polyimide. High thermal conductive, low dielectric constant and dielectric loss, and thermal‐stable composites were successfully demonstrated by incorporating aluminum nitride powder into the polyimide. The weight percent of aluminum nitride was up to 80%. The thermal and dielectric properties follow the classic composite theories. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3913–3917, 2003     

螺环结构膨胀单体的合成及膨胀性能研究

为解决环氧树脂固化时体积收缩带来的不良影响,用实验室合成的三元醇与二正丁基氧化锡反应制得螺环结构的膨胀单体3,9-二羟甲基-3,9-二(二甲基乙硫基)-1,5,7,11-四氧杂螺环[5,5]十一烷改性环氧树脂.产物经红外、核磁表征其结构.用膨胀剂跟踪测定阳离子引发膨胀单体开环聚合体积膨胀率为3.16%,考察预聚体改性环氧树脂体积膨胀率的变化,为1.194%.