Molecular structure and shear rheology of long chain branched polypropylene formed by light cross-linking of a linear precursor with 1,3-benzenedisulfonyl azide
Molecular structure and shear rheology of long chain branched polypropylene formed by light cross-linking of a linear precursor with 1,3-benzenedisulfonyl azide
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DOI：
10.1002/app.26674
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发表时间：
2007-10
影响因子：
3
通讯作者：
J. K. Jørgensen;K. Redford;E. Ommundsen;A. Stori
中科院分区：
文献类型：
--
作者：
J. K. Jørgensen;K. Redford;E. Ommundsen;A. Stori
线性等规茂金属基聚丙烯（Mw = 125,000 g/mol, Mn = 61,000 g/mol）经少量1,3-苯二磺酰叠氮化物轻微交联形成长链分支（LCB）。在小型挤出机中，在200℃条件下进行反应挤出交联。在加工温度下，两个叠氮基团分解成亚硝基，作为PP的交联剂。交联反应主要是通过将单线态亚硝基插入CH键而发生的。1,3-苯二磺酰叠氮化物的浓度分别为518、806、1029和2038 PPM。SEC显示形成了高分子量的LCB组分。SEC没有观察到降解现象。LCB的引入引起了LCB典型的流变行为，即零剪切粘度增加，剪切变薄，流动活化能增加和相角平台。然而，与早期的PE研究相比，观察到的流变影响和交联效率是有限的。讨论了可能的原因。©2007 Wiley期刊公司高分子学报，2007
Linear isotactic metallocene based polypropylene (Mw = 125,000 g/mol, Mn = 61,000 g/mol) was lightly crosslinked by small amounts of 1,3-benzenedisulfonyl azide to form long chain branches (LCB). Crosslinking was carried out by reactive extrusion at 200°C in a small scale extruder. At the processing temperature, the two azide groups decompose to nitrenes that work as crosslinkers for PP. The crosslinking reaction occurs primarily by insertion of singlet nitrenes into CH bonds. 1,3-benzenedisulfonyl azide concentrations of, respectively, 518, 806, 1029, and 2038 ppm were used. SEC revealed formation of a high molecular weight LCB fraction. No degradation was observed by SEC. The introduction of LCB gave rise to rheological behavior typical of LCB as increased zero shear viscosity, accompanied by increased shear thinning, increased flow activation energy and a phase angle plateau. However, the rheological impact and crosslinking efficiency observed were limited compared to earlier studies on PE. Possible reasons for this are discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007