科研之友
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摘要
The PP alloy was synthesized directly in the reactor with a 4(th) generation Ziegler-Natta catalyst. it is very different from mechanically blended PP alloys, its properties, especially its impact strength,are superior to those of the latter. However,so far the studies on the stucture of this kind of PP alloys have not been reported. The microstructure of a PP alloy was characterized by IR,DSC,and C-13-NMR. The sample was first fractionated and 8 fractions were obtained. The IR analysis showed that the ethylene content of each fraction is different. Except for the first fraction,which is an elastomer, the others are all hard powders at room temperature. Therefore, the fractions above 50 degreesC perhaps are all composed of ethylene-propylene block copolymers. DSC analysis showed that the melting curve of the PP alloy became broadened compared with that of i-PP,and a small peak appeared at 120 degreesC. The extracts of PP alloy in boiling heptane and every fractions of PP alloy all exhibited many small peaks. These peaks demonstrated that the macromolecular chains in PP alloy are composed of ethylene-propylene blocks,whose sequence length are very different. The C-13-NMR spectrum of fraction at 90 degreesC, similar to other fractions at 50 similar to 100 degreesC,also indicated that there are long ethylene sequences in macromolecualr chains of PP alloy. According to the above analysis,a conclusion was reached that the E-P copolymer in PP alloy is composed of EPR and E-P blocks,with different ethylene sequence length. This polydispersity structure in PP alloy made it possess very high impact property.
- 出版日期2000-12
- 单位浙江大学; 洛阳理工学院
