The biomarkers of 2,6,10,15, 19-pentamethylicosenes and their carbon isotopic composition in the sediments from the Gulf of Mexico

The methanogenic archaea and sulfate reduction bacteria are flourishing in the sediments associated with gas venting and gas hydrate settings on the sea floor, where the anaerobic oxidation of methane (AOM) me-diated by these bacteria is the dominant path…     

聚间苯二甲酰间苯二胺溶液的动态流变特性

研究用低温溶液缩聚法制备的聚间苯二甲酰间苯二胺（PMIA）溶液的动态流变特性,讨论PMIA溶液质量分数、温度和相对分子质量对动态流变特性的影响,G′和G″的交点可得到的Gc和ωc可表征PMIA的相对分子质量分布宽度,结果是随着相对分子质量的增大其分布宽度增加,并用Modified-Carreau模型求得不同相对分子质量的PMIA溶液的粘流活化能为31.7~18.5kJ/mol,并随着相对分子质量的增大而增大.     

Pyrolysis Process in Aramid Fibers Investigated by Py-GC/MS & TGA-DTA/MS

Poly(m-phenylene isophthalamine) (PMIA) and Poly( p-phenylene terphthalamine) (PPTA) are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis coupled with mass spectrometry ( TGA-DTA/MS ). The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis. At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization appens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.     

叔胺作为HCl吸收剂对间苯二胺与间苯二甲酰氯缩聚反应的影响

研究了各种叔胺作为聚间苯二甲酰间苯二胺（PMIA）合成反应中HCl的吸收剂对PMIA分子量的影响。结果表明，在PMIA树脂合成中加入添加剂α－甲基吡啶，对提高PMIA分子量作用明显，探索了高分子量PMIA树脂稳定的生产工艺，并用红外光普、热失重分析对PMIA进行表征。     

Pyrolysis Process in Aramid Fibers Investigated by Py-GC/MS ＆ TGADTA/MS

Poly （ m-phenylene isophthalamine） （PMIA） and Poly（ p-phenylene terphthalamine） （PPTA） are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS） and thermogravimetric analysis coupled with mass spectrometry （ TGA-DTA/MS ）. The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis, At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization happens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.     

聚芳酰胺多孔膜的制备及其介电性能研究

以间苯二胺和间苯二甲酰氯为单体,2-甲基吡啶为缚酸剂,N,N-二甲基乙酰胺为溶剂,用低温溶液缩聚法合成了间位聚芳酰胺（PMIA）;然后以乙醇为非溶剂,用非溶剂致相分离法成功制备了不同孔结构的聚芳酰胺多孔膜.采用核磁及红外等手段对所合成聚芳酰胺的结构进行了表征,考察了聚芳酰胺溶液浓度对多孔膜孔结构及介电性能的影响.结果表明:当聚芳酰胺的浓度为21%,17%和15%时,都可以得到孔结构规整的多孔膜,它们在1 MHz频率的介电常数分别为2.31,2.07和1.89,与聚芳酰胺标准膜的介电常数6.22相比分别降低了63%,67%和70%.