含磷聚酰亚胺纤维的制备及其力学与阻燃性能

采用廉价的三苯基氧膦和混酸合成了一种含磷二胺单体,二（3-氨基苯基）苯基膦氧(DAPPO)。在4,4′-二胺基二苯醚（ODA）、3,3′,4,4′-联苯四酸二酐（BPDA）和均苯四酸二酐（PMDA）聚合体系中引入该单体,制备含磷聚酰亚胺纤维。热失重分析（TGA）结果表明,聚酰亚胺纤维的热稳定性随含磷量的增加而明显提高。当n（DAPPO）：n（ODA）为7：93时,纤维的极限氧指数达到了43,说明纤维的阻燃性能显著提高。     

AO-resistant properties of polyimide fibers containing phosphorous groups in main chains

A series of polyimide fibers containing phosphorus element derived from (3-aminophenyl) methyl phosphine oxide (DAMPO) diamine was exposed to an artificial atomic oxygen environment which simulated the space environment in low earth orbit (LEO). The mass loss, surface morphology, chemical composition, and mechanical properties of the fibers before and after atomic oxygen (AO) exposure were compared in detail with a blank sample. Results showed that the phosphor-containing fibers demonstrated lower mass change and less tensile strength reduction. SEM results showed that the fibers with phosphorous element had relatively dense surface after AO exposure. Meanwhile, XPS results indicated that a passivated phosphate layer, which could protect the following under-layer from attacking by AO, was formed on the surface of the fibers. These results indicated that the incorporation of diamine (DAMPO) into the main chains could protect the fibers for avoiding further erosion from AO exposure. Hence, the phosphor-containing PI fibers exhibits potential application in space fields.     

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR*

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm~(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.     

新型手性联萘酚硅氧烷衍生物的合成与表征

手性联萘酚;氯丙基三乙氧基硅烷;Williamson成醚反应;结构表征     

含嘧啶聚酰亚胺的制备及其粘结性能

综合2,5-二氨苯基嘧啶(PRM)的刚性结构特征和配位化学特征以及二苯醚二胺(ODA)的柔性结构特征,制备出一系列性能可控的含嘧啶聚酰亚胺.含嘧啶聚酰亚胺的玻璃化转变温度、热稳定性、拉伸强度和模量等,均随聚酰亚胺中PRM比例的升高而增加.但热膨胀系数却随PRM比例的增加而降低,当PRM和ODA的比例为1∶1时,热膨胀系数为17×10-6K-1,与铜箔的热膨胀系数一致,可与铜箔形成尺寸稳定的无胶挠性覆铜板;同时,这一比例的含嘧啶聚酰亚胺与铜箔的粘结强度也达到最高(17.3 N·cm-1).这种含嘧啶聚酰亚胺的性能可以满足无胶挠性印制电路对基底膜材料的尺寸稳定性和粘结性能的要求.     

碳纤维三向织物/环氧树脂复合材料的制备与力学性能

选择不同纱线间距[即二经(纬)纱之间的中心距]尺寸的碳纤维三向织物, 采用热压成型技术制备了碳纤维三向织物/环氧树脂复合材料. 研究了纱线间距及样品裁剪角度等对力学性能的影响, 并与碳纤维二向织物/环氧树脂复合材料的力学性能进行对比. 结果表明, 随着纱线间距尺寸从2 mm增加到6 mm, 0°方向断裂强度从221.7 MPa下降到148.1 MPa, 撕裂强力从1000 N下降到600 N; 90°方向断裂强度从50.0 MPa下降到22.1 MPa, 撕裂强力从330 N下降到100 N; 顶破强力从424 N下降到216 N. 这些力学性能的逐渐降低是单位面积的碳纤维增强体含量减少和织物的孔洞增大共同作用的结果. 纱线间距为2 mm的碳纤维三向织物复合材料在0°(以纬纱为基准), 30°, 45°, 60°和90°方向的断裂强度分别为221.7, 48.5, 44.3, 227.7和50.0 MPa, 即断裂强度在0°和60°方向大于在30°, 45°及90°方向. 由三向织物的编织原理可知, 0°与60°方向完全相同, 因此其断裂强度相似, 且样品中有一组纱线与外加载荷平行, 对形变破坏具有一定的约束作用, 而30°, 45°和90°方向样品中三组纱线所在的方向均和外加载荷存在一定的夹角, 有效分散外加载荷的能力减弱. 对比碳纤维三向织物/环氧树脂复合材料与碳纤维二向织物/环氧树脂复合材料的断裂强度、 撕裂强力和顶破强力发现, 前者的综合性能明显优于后者, 碳纤维三向织物/环氧树脂复合材料的断裂强度、 撕裂强力、 顶破强力分别为221.7 MPa, 1000 N和424 N, 三向织物的优势得到凸显, 为后续制备多种类型的碳纤维三向织物复合材料及应用奠定了基础.     

二甲基苯二胺芳香聚酰胺的结构与性能

利用ＩＲ，ＷＡＸＤ，ＤＳＣ及ＴＧ等表明了多取代芳香族聚酰胺的结构与性能。     

Mechanical properties of polyimide/multi-walled carbon nanotube composite fibers

A series of polyimide (PI)/multi-walled carbon nanotube (MWCNT) composite fibers were prepared by copolymerizing a mixture of monomers and carboxylic-functionalized MWCNTs, followed by dry-jet wet spinning, thermal imidization, and hot-drawing process. The content of the carboxylic groups of MWCNTs significantly increased when treated with mixed acid, whereas their length decreased with treatment time. Both the carboxylic content and length of MWCNTs influenced the mechanical properties of the composite fibers. Fiber added with 0.1 wt% MWCNTs treated for 4 h exhibited the best mechanical properties, i.e., 1.4 GPa tensile strength and 14.30% elongation at break, which were 51% and 32% higher than those of pure PI fibers, respectively. These results indicated that a suitable MWCNT content strengthened and toughened the resultant PI composite fibers, simultaneously. Moreover, raising draw ratio resulted in the increase of tensile strength and tensile modulus of the composite fibers.     

Comparison of different methods for determining the imidization degree of polyimide fibers

In this study, polyimide fibers at different stages of imidization were characterized by TGA, DSC, and FTIR. The imidization degree(ID) calculated by TGA was based on the weight loss of each sample, which was caused by the imidization of residual amic acid groups. The results of TGA showed good regularity with the thermal treatment temperature of the PI fibers. For DSC, the ID was calculated based on the area of endothermal peak of each sample. Compared with TGA, DSC showed a relatively higher value because the endothermal peak was reduced by the exothermic re-formation of polyamic acid which may be partially degraded during thermal treatment. The IDs obtained by the FTIR spectra generally showed poorer regularities than those obtained by both TGA and DSC, especially for the results calculated using the 730 cm-1 band. Based on the 1350 cm-1 band, the obtained IDs showed better agreement with the TGA or DSC results. The results obtained by these three methods were compared and analyzed. The ID obtained by TGA showed much more reliability among these three methods.     

联吡啶还原合成吡啶基四氢吡啶和吡啶基六氢吡啶

吡啶基四氢吡啶衍生物(Ⅰ)和吡啶基六氢吡啶衍生物(Ⅱ)是α受体和HT1A受体类似物的结构组成部分,应用在药物合成中[1].Ⅰ和Ⅱ可通过环化反应、烷基化反应或联吡啶还原合成[2].环化反应或烷基化反应路线较长,且易形成含不饱和哌啶基吡啶的混合物,需要进一步的还原或纯化[2a];用Ni合金还原联吡啶只能直接合成吡啶基六氢吡啶,且反应时间长,收率低[2d];N-氧化联吡啶还原合成吡啶基六氢吡啶收率低,不适用于大量合成[2e].