用双筒毛细管流变仪和旋转流变仪研究了两种商用聚合物熔体--聚甲基乙烯基硅氧烷(PMVS)和线型低密度聚乙烯(LLDPE)的壁滑行为.通过剪切速率扫描的方法发两种聚合物熔体均发生粘滑转变,而且发生粘滑转变的临界剪切应力随温度线性增加,这与Brochard和de Gennes提出壁滑的解缠机理一致.用壁滑外推长度表征壁滑程度,发现两种熔体在温度为60℃～210℃范围内的壁滑外推长度均为0.05mm～O.06mm.结果表明,对于线形链高分子如PMVS,LLDPE和高密度聚乙烯(HDPE)等在剪切应力达到临界值时均发生同一类粘滑转变.
Wall slip behavior of two commercial polymer melts: a polymethylvinylsiloxane(PMVS) and a linear low-density polyethylene(LLDPE) were studied experimentally by using a capillary rheometer with twin bores at different temperatures and a rotational rhemeter.It was found that a stick-slip transition was observed for PMVS and LLDPE as the shear rate sweep was done in an increased order.The critical shear stress for the onset of stick-slip transition increased linearly with temperature for both the two melts, which accords with the disentanglement mechanism proposed by Brochard and de Gennes.While the extrapolation length used to quantify the magnitude of the transition remains about 0.05 mm～0.06 mm for PMVS and LLDPE at 60 ℃～210 ℃.The result shows that a similar slip-stick transition can occur for linear polymer melts such as PMVS, LLDPE and high density polyethylene (HDPE) at a critical shear stress.
参考文献
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| [2] | Wang SQ.;Drda PA. .SUPERFLUID-LIKE STICK-SLIP TRANSITION IN CAPILLARY FLOW OF LINEAR POLYETHYLENE MELTS .1. GENERAL FEATURES[J].Macromolecules,1996(7):2627-2632. |
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