Increase of Long‐chain Branching by Thermo‐oxidative Treatment of LDPE
Increase of Long‐chain Branching by Thermo‐oxidative Treatment of LDPE
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DOI：
10.1063/1.3604477
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
V. H. Rolón-Garrido;Jinji Luo;M. Wagner
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文献类型：
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作者：
V. H. Rolón-Garrido;Jinji Luo;M. Wagner
低密度聚乙烯（LDPE）在170°C下进行热处理和热氧化处理，随后通过线性粘弹性测量和单轴拉伸进行表征。采用分子应力函数（MSF）模型对所测拉伸粘度进行量化。对于热处理过的样品，暴露时间在2到6小时之间。长链分支（LCB）的形成只发生在热处理的前两个小时。在较长的暴露时间下，没有观察到应变硬化水平的差异。这是通过使用MSF模型来量化的：非线性参数fmax2从原始样品的fmax2 = 14增加到经过2到6小时热处理的样品的fmax2 = 22。对于在热处理期间暴露在空气中30至90分钟的热氧化处理样品，随着暴露时间从30至75分钟的增加，应变硬化水平急剧增加，达到fmax2 = 55，因为……
Low‐density polyethylene (LDPE) was exposed to thermal and thermo‐oxidative treatment at 170 °C, and subsequently characterized by linear‐viscoelastic measurements and in uniaxial extension. The Molecular Stress Function (MSF) model was used to quantify the elongational viscosities measured. For the thermally treated samples, exposure times between 2 and 6 hours were applied. Formation of long‐chain branching (LCB) was found to occur only during the first two hours of thermal treatment. At longer exposure times, no difference in the level of strain hardening was observed. This was quantified by use of the MSF model: the nonlinear parameter fmax2 increased from fmax2 = 14 for the virgin sample to fmax2 = 22 for the samples thermally treated between 2 and 6 hours. For the thermo‐oxidatively treated samples, which were exposed to air during thermal treatment between 30 and 90 minutes, the level of strain hardening increases drastically up to fmax2 = 55 with increasing exposure times from 30 up to 75 min due ...