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jilifu007木虫 (小有名气)
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| 由于超支化聚合物具有低粘度的特性，把HBPSi加入到CE树脂中以后,树脂的粘度下降,且相容性很好。对所制备的浇铸体进行冲击强度测试，结果如图6所示。从图6可以看出冲击强度随着HBPSi百分含量的增加而增强，即随着超支化聚硅氧烷含量的增加,冲击强度越来越高,韧性越来越大，特别是当HBPSi的含量在4%左右,冲击强度的提高幅度最大。体系的冲击强度由纯氰酸酯的9.78KJ/m2提高到16wt%的20.38KJ/m2，增加了108.4%。这主要有两方面的原因：首先，CE单体聚合后的交联密度大，加上分子中三嗪环（triazine rings）结构高度对称，造成CE固化后较脆。加入HBPSi后，HBPSi的环氧基团可使三嗪环转化为异氰脲酸酯，异氰脲酸酯进而与环氧基反应生成噁唑啉酮（oxazolidinone rings)(见示意式1a),降低了树脂网络的刚性。此外,环氧基也会直接与CE进行反应(见示意式1b)，使树脂的交联点间分子链长度距越来越大, 降低了树脂的交联度，在一定意义上增加了链的柔性，从而使CE的韧性增加；第二，由于超支化聚合物的特有的高度支化分子的空腔结构和分子链中柔性的硅氧链段的存在，对冲击能量的吸收也起了至关重要的作用。 |
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maxuedong
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| As the hyperbranched polymer with a low-viscosity characteristics, HBPSi to join the CE in resin, the resin viscosity decrease, and good compatibility. Prepared for the carried-casting impact strength tests, the results shown in Figure 6. Figure 6 from the impact strength can be seen as HBPSi increase in the percentage increased, along with that of over-polysiloxane content increases, more and more high-impact strength, increasing toughness, especially when the HBPSi 4% in the content, impact strength of the largest increases. The impact by the intensity of the pure isocyanate 9.78KJ/m2 to 16wt% of 20.38KJ/m2, an increase of 108.4 percent. It has two main reasons: First of all, CE monomer polymerization after the cross-linking density, coupled with triazines elements in the ring (triazine rings) structure of the high degree of symmetry, resulting in more brittle after curing CE. HBPSi to join after, HBPSi of epoxy groups can triazine ring into isocyanuric acid ester, isocyanuric acid ester and then with epoxy to form one oxazoline (oxazolidinone rings) (see signal-1a), To reduce the stiffness of the resin network. In addition, the epoxy will be carried out directly with the CE (see signal-1b), so that the resin cross-linking point between the molecular chain length of the growing distance, reducing the resin cross-linking, in a sense, an increase of chain The flexible, so that the CE of the increase in toughness; Secondly, because of cost overruns of the polymer unique to a high degree of support elements of the cavity structure and molecular chain of soft silica segment of the existence of the impact energy absorption also played a A crucial role. |
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3楼2009-01-12 10:18:01