Université Côte d'Azur, Institut de Chimie de Nice, UMR CNRS 7272, 06100 Nice, France.
Université Côte d'Azur, Institut de Physique de Nice, UMR CNRS 7010, 06100 Nice, France.
Molecules. 2019 May 9;24(9):1797. doi: 10.3390/molecules24091797.
Polytetrafluoroethylene (PTFE) is a polymer that displays exceptional properties. This synthetic fluoropolymer is also known to crystallize very fast upon cooling. The present work highlights for the first time the influence of nanosilica clusters on PTFE crystallization at fast cooling rates (up to 5000 K·s). The silica was synthesized from aqueous silicate solution and the surface modification was performed using TriEthoxyFluoroSilane (TEFS). In order to understand the crystallization behavior of PTFE/silica nanocomposite at a fast cooling rate, the measurements were carried out by Fast Scanning Calorimetry (FSC). The data were consequently combined with the measurements performed by conventional Differential Scanning Calorimetry (DSC). Interestingly, the results displayed variation of the crystallization behavior for the nanocomposite at fast cooling rates compared to slow cooling rates. The differences in crystal morphologies were then observed by Scanning Electron Microscopy (SEM) after slow and fast cooling rates. Finally, the effective activation energies () obtained from the crystallization under various cooling rates were combined in order to obtain one set of Hoffman-Lauritzen parameters. This procedure allowed us to show that the crystallization of PTFE in the presence of silica is promoted or hampered according to the cooling rates employed.
聚四氟乙烯（PTFE）是一种具有特殊性能的聚合物。这种合成氟聚合物在冷却时也非常快地结晶。本工作首次强调了纳米二氧化硅簇在快速冷却速率（高达 5000 K·s）下对 PTFE 结晶的影响。硅溶胶合成，并用三乙氧基氟硅烷（TEFS）进行表面改性。为了了解快速冷却速率下 PTFE/二氧化硅纳米复合材料的结晶行为，通过快速扫描量热法（FSC）进行了测量。随后，将数据与常规差示扫描量热法（DSC）的测量结果相结合。有趣的是，与缓慢冷却速率相比，快速冷却速率下纳米复合材料的结晶行为显示出变化。然后通过扫描电子显微镜（SEM）观察了缓慢和快速冷却速率后的晶体形态差异。最后，将在不同冷却速率下结晶获得的有效活化能（）组合在一起，以获得一组 Hoffman-Lauritzen 参数。该程序使我们能够表明，在存在二氧化硅的情况下，PTFE 的结晶根据所采用的冷却速率得到促进或阻碍。
