Influence of polyfunctional monomer on melt strength and rheology of long‐chain branched polypropylene by reactive extrusion
Influence of polyfunctional monomer on melt strength and rheology of long‐chain branched polypropylene by reactive extrusion
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DOI：
10.1002/app.31738
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发表时间：
2010-06
影响因子：
3
通讯作者：
Fenghua Su;Hanxiong Huang
中科院分区：
文献类型：
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作者：
Fenghua Su;Hanxiong Huang
在选择的多官能单体（PFMs）和过氧化物过氧化二苯甲酰（BPO）的存在下，使用反应挤出将长链支化（LCB）添加到线性聚丙烯（PP）中。傅立叶变换红外光谱（FTIR）直接证实了反应挤出过程中发生的接枝反应。通过粘度曲线、储能模量曲线、Cole-Cole曲线、Van-Gurp曲线等流变曲线的分析，证实了改性PP在改性后的骨架中引入了LCB结构。与直链PP相比，支化PP的熔体强度更高，熔体流动指数更低，结晶温度更高。改性PP中的LCB含量及其熔体强度受所用PFM类型的影响，并可通过PFM的性质和结构来控制。沸点较低的PFMs，如1，4-丁二醇二丙烯酸酯（BDDA），不能在改性PP骨架中形成LCB结构。分子链较短的双官能单体，如1，6-己二醇二丙烯酸酯（HDDA），如果它们的沸点高于最高挤出温度，则有利于支化反应。而PFM分子中的羟基等极性基团对支化反应有不利影响，这可能是由于基团的极性对PFM在PP基体中的分散不利。
Long chain branching (LCB) were added to linear polypropylene (PP) using reactive extrusion in the presence of selected polyfunctional monomers (PFMs) and a peroxide of dibenzoyl peroxide (BPO). Fourier Transformed Infrared spectra (FTIR) directly confirmed the grafting reaction occurred during the reactive extrusion process. Various rheological plots including viscosity curve, storage modulus, Cole-Cole plot, and Van-Gurp plots, confirmed that the LCB structure were introduced into modified PPs skeleton after modification. In comparison with linear PP, the branched samples exhibited higher melt strength, lower melt flow index, and the enhancement of crystallization temperature. The LCB level in modified PPs and their melt strength were affected by the type of PFM used and could be controlled by the PFM properties and structure. PFMs with lower boiling points, such as 1, 4-butanediol diacrylate (BDDA), could not produce LCB structure in modified PP skeleton. The shorter molecular chain bifunctional monomers, such as 1,6-hexanediol diacrylate (HDDA), favored the branching reaction if their boiling points were above the highest extrusion temperature. And some polar groups, such as hydroxyl, in the molecule of PFM were harmful to the branching reaction, which might be attributed to the harm of the polarity of groups to the dispersion of PFM in PP matrix.