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The ~1H and ~(13)C NMR spectra of polyether-polyurethancs (A) based on 4, 4'-diphenylmethanediisocyanate (MDI), N-methyl diethanolamine (MDEA), and polytetramethyleneoxide (PTMO)and the zwitterionomers derived from A with various degree of ionization was assigned by comparingwith model compounds. Phase separation of the samples was visualized through pulsed NMR investigations. The FIDsignals of these multiphase elastomers were recorded and decomposed by non-linear least squaresregression into fast Gaussian and slow exponential components assodated with the hard, the soft andthe interface respectively. Thus pulsed NMR gives both qualitative and quantitative informationabout the existence of multiphases and the relative amounts of materials in each phase. 相似文献
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利用碱脲溶剂低温溶解纤维素,在该体系中掺杂一定比例的全硫化羧基丁苯弹性纳米粒子,制备了纤维素/全硫化弹性纳米粒子复合膜.通过透射电镜、扫描电镜、WAXD、固体核磁共振、热分析和力学性能测试等对该复合膜的结构和性能进行了表征.结果表明,全硫化羧基丁苯弹性纳米粒子(CSB ENP)均匀的分散在具有微纳孔洞结构的纤维素基体中.CSB ENP的引入对纤维素再生过程中的结晶性影响不大.纤维素/全硫化弹性纳米粒子复合膜具有良好的透光性,并且热稳定性也有所提高.加入少量的CSB ENP可以增韧纤维素膜,且能保持良好的力学性能.当CSB ENP的含量为5 wt%时复合膜的断裂拉伸强度和断裂伸长率同时得到了提高. 相似文献
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利用原位变温核磁共振氢谱(1H NMR)、核磁共振氟谱(19F NMR)和核磁共振磷谱(31P NMR)等NMR技术研究特定温度下离子液体的热分解机理.在温度低至80℃时,1-丁基-3-甲基咪唑阳离子(C4mim+)和六氟磷酸根阴离子(PF5-)组成的离子液体[C4mim][PF5]呈现1个缓慢但明显的分解过程.无水[C4mim][PF5]在温度高于80℃时开始分解,生成少量的五氟化磷(PF5)和氟化氢(HF),氟化氢中的氢原子来自于1-丁基-3-甲基咪唑环2位上的氢原子.在丢掉这个氢原子后,阳离子成环形成一个卡宾,并与PF5形成卡宾/PF5复合物.定量NMR分析显示在分解反应达到平衡状态时,自由态PF5和卡宾/PF5复合物的比例为7∶3. 相似文献
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