Huang Ying, Gohs Uwe, Müller Michael Thomas, Zschech Carsten, Wießner Sven
Department of Reactive Processing, Institute of Polymer Materials, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden, Germany.
Institute of Materials Science, Technische Universität, Dresden D-01069 Dresden, Germany.
Polymers (Basel). 2019 Jul 31;11(8):1279. doi: 10.3390/polym11081279.
In this work, natural rubber (NR) was masticated using an internal mixer to fit the requirements of reactive blending with polylactide and characterized by size exclusion chromatography (SEC), Fourier-transform infrared (FT-IR) spectroscopy and dynamic rheology measurements. Subsequently, the effect of elevated temperatures (25 °C, 80 °C, and 170 °C) on the electron beam (EB) induced crosslinking and degradation of masticated natural rubber (mNR) in a nitrogen atmosphere without adding crosslinking agents has been investigated. The sol gel investigation showed that the gel dose of mNR slightly increased with increasing irradiation temperature, which is also confirmed by the swelling test. The chain scission to crosslinking ratio (/) was found to be less than 1 for irradiated mNR at 25 °C and 80 °C, suggesting a dominating crosslinking behavior of mNR. However, a significant increase of ratio (~1.12) was observed for mNR irradiated at 170 °C due to the enhanced thermal degradation behavior at high temperature. A remarkably improved elasticity (higher complex viscosity, higher storage modulus, and longer relaxation time) for EB modified mNR was demonstrated by dynamic rheological analysis. Particularly, the samples modified at higher temperatures represented more pronounced elasticity behavior which resulted from the higher number of branches and/or the longer branched chains.
在本工作中，使用密炼机对天然橡胶（NR）进行塑炼，以满足与聚乳酸反应共混的要求，并通过尺寸排阻色谱法（SEC）、傅里叶变换红外（FT-IR）光谱和动态流变学测量对其进行表征。随后，研究了在不添加交联剂的氮气气氛中，高温（25℃、80℃和170℃）对电子束（EB）诱导的塑炼天然橡胶（mNR）交联和降解的影响。溶胶-凝胶研究表明，mNR的凝胶剂量随辐照温度的升高而略有增加，溶胀试验也证实了这一点。发现在25℃和80℃下辐照的mNR的断链与交联比（/）小于1，这表明mNR具有主要的交联行为。然而，由于在高温下热降解行为增强，在170℃下辐照的mNR的 比显著增加（约为1.12）。动态流变学分析表明，EB改性mNR的弹性显著提高（复数粘度更高、储能模量更高、松弛时间更长）。特别是，在较高温度下改性的样品表现出更明显的弹性行为，这是由于支链数量更多和/或支链更长所致。
