While there is great interest in polymer nanofibers due to their high strength, methods to measure their time-temperature superposition (TTS) curves are lacking. The objective of this work is to demonstrate one such method and thereby to predict room temperature creep compliance over many decades of time. A complimentary measurement is also presented to estimate the associated activation energy. The experimental method is demonstrated for polyacrylonitrile (PAN) nanofibers using an on-chip surface micromachined stepper motor actuator. It is first shown that the method yields good agreement with previous room temperature measurements. Subsequently, data up to 95 °C, near the glass transition temperature, is presented. Time-temperature superposition master curves are then constructed, and activation energies for two narrow diameter ranges (221 ± 27 nm and 150 ± 9 nm) are determined. The activation energy of the 221 nm fiber agrees well with the bulk PAN value, while the 150 nm fiber is 50% larger, indicating the importance of higher chain packing and reduced chain mobility in thinner fibers. TTS curves spanning 7 (221 nm) and 9 (150 nm) decades are presented. Over this time span the creep compliance increases by a factor of approximately 10 for each. This work demonstrates a viable method to measure polymer nanofiber TTS curves from which quantitative activation energy can be determined, and from which creep compliance values over time can be predicted.

中文翻译：

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单个电纺聚合物纳米纤维的尺寸相关蠕变主曲线

虽然由于聚合物纳米纤维的高强度而引起人们对它们的极大兴趣，但缺乏测量其时间-温度叠加 (TTS) 曲线的方法。这项工作的目的是展示一种这样的方法，从而预测几十年的室温蠕变柔量。还提供了一个补充测量来估计相关的活化能。该实验方法使用片上表面微加工步进电机致动器对聚丙烯腈 (PAN) 纳米纤维进行了演示。首先表明该方法与之前的室温测量结果非常吻合。随后，提供高达 95 °C（接近玻璃化转变温度）的数据。然后构建时间-温度叠加主曲线，确定了两个窄直径范围（221 ± 27 nm 和 150 ± 9 nm）的活化能。221 nm 纤维的活化能与散装 PAN 值非常吻合，而 150 nm 纤维大 50%，表明在更细的纤维中更高的链堆积和降低链迁移率的重要性。呈现跨越 7 (221 nm) 和 9 (150 nm) 十进制的 TTS 曲线。在这段时间内，蠕变柔量增加了大约 10 倍。这项工作展示了一种测量聚合物纳米纤维 TTS 曲线的可行方法，从中可以确定定量活化能，并且可以预测随时间推移的蠕变柔量值。表明在更细的纤维中更高的链堆积和降低链流动性的重要性。呈现跨越 7 (221 nm) 和 9 (150 nm) 十进制的 TTS 曲线。在这段时间内，蠕变柔量增加了大约 10 倍。这项工作展示了一种测量聚合物纳米纤维 TTS 曲线的可行方法，从中可以确定定量活化能，并且可以预测随时间推移的蠕变柔量值。表明在更细的纤维中更高的链堆积和降低链流动性的重要性。呈现跨越 7 (221 nm) 和 9 (150 nm) 十进制的 TTS 曲线。在这段时间内，蠕变柔量增加了大约 10 倍。这项工作展示了一种测量聚合物纳米纤维 TTS 曲线的可行方法，从中可以确定定量活化能，并且可以预测随时间推移的蠕变柔量值。