Tribology of confined Fomblin-Z perfluoropolyalkylethers: molecular weight dependence and comparison between unfunctionalized and telechelic chains
Tribology of confined Fomblin-Z perfluoropolyalkylethers: molecular weight dependence and comparison between unfunctionalized and telechelic chains
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受限 Fomblin-Z 全氟聚烷基醚的摩擦学：分子量依赖性以及非官能化链和遥爪链之间的比较
DOI：
10.1023/a:1019137824102
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发表时间：
1999
影响因子：
3.2
通讯作者：
S. Granick
中科院分区：
文献类型：
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作者：
M. Ruths;S. Granick
本文研究了数均相对分子质量为Mn≈3000−4000 g，−-1的未官能化和端官能化(遥螺旋)Fomblin-Z全氟聚烷基醚熔体在1和3 Mpa下剪切速率为10~(-2)s~(-1)时的分子薄膜的动态剪切性能。将剪切响应与相同化学组成但相对分子质量较低的末端官能化聚合物的测量结果进行了比较，Mn≈为2000g，mo1-1。非官能化聚合物Fomblin Z03的约束膜的主要弹性响应和高剪切模数表明，它形成的结构很可能在低压下就已经固化。它的润滑性能不如羟基(DOL)和胡椒基封端的Fomblin-Z(AM2001，AM3001)，后者的缔合分子形成的结构在限制下不易凝固。末端官能化聚合物的压缩膜厚度随相对分子质量的增加比AsMn0.5的增加更明显。剪切模数越大，分子量越大，松弛越慢。在3 Mpa的常压下，这些薄膜像在1 Mpa的Z03薄膜中已经看到的那样，固化并表现出粘滑。未官能化的Z03、σ和GT；3 Mpa的极限剪应力超过所有末端官能化聚合物的极限剪应力一个数量级。羟基封端聚合物的极限剪切应力大于胡椒基封端聚合物。
The dynamic shear properties of molecularly-thin films of unfunctionalized and end-functionalized (telechelic) Fomblin-Z perfluoropolyalkylether (PFPAE) melts with number-average molecular weightMn≈ 3000−4000 g,mol-1have been studied at shear rates of 10-2−105s-1at normal pressures of 1 and 3 MPa. The shear responses are compared to measurements on end-functionalized polymers of the same chemical composition but lower molecular weight,Mn≈ 2000 g,mol-1. The predominantly elastic response and high shear moduli of the confined film of unfunctionalized polymer, Fomblin Z03, suggest that it forms a structure likely to solidify already at low pressure. Its lubricating properties are less favorable than the ones found for hydroxyl- (DOL) and piperonyl-terminated Fomblin-Z (AM2001, AM3001), where associated molecules form a structure less prone to solidification under confinement. The thickness of the compressed films of the end-functionalized polymers increased more strongly with molecular weight than asMn0.5. The shear moduli were found to be larger, the higher the molecular weight, indicating slower relaxations. At a normal pressure of 3 MPa, these films solidified and displayed stick–slip as seen already at 1 MPa in the Z03 film. The limiting shear stress of the unfunctionalized Z03, σ > 3 MPa, exceeded by an order of magnitude the limiting shear stress of all of the end-functionalized polymers. The limiting shear stress of the hydroxyl-terminated polymer was larger than that of the piperonyl-terminated polymer.
W.Gasser：“二氧化硅的准单层沉积”固体薄膜。
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