Hindered phenols remarkably enhance the sound attenuation and vibration damping of acrylic polymers. However, this novel damping material suffers from gradual degradation during long-term use because of potential self-aggregation and crystallization of small molecules. In this work, the effects of small molecule size, hydrogen bonding strength, and mobility of the pendant group of acrylic matrices on the long-term damping stability were investigated. The results were correlated to the hierarchical relaxation of acrylic mixtures. We were surprised by the findings that the damping degradation dynamics appears to be governed by β_fast relaxation instead of α and/or β_JG relaxation of the polymer matrix. Further experiments revealed that the long-distance diffusion of small molecules to self-aggregation and subsequent crystallization is regulated by β_JG relaxation, but dissociation of the intermolecular hydrogen bonding between the hydroxyl group of phenols and the carboxyl group of acrylates during physical aging plays the decisive role in damping degradation. We supposed that the small molecule’s fluctuation-induced dissociation of hydrogen bonding is limited within a sub-Å amplitude and therefore couples with the cage-breaking motion of β_fast relaxation. These results clarify the mechanism of small-molecule-enhanced damping and provide a strategy for the rapid evaluation of the service life of novel damping materials and a thermodynamic criterion k₀ for the future design of small molecules and long-term stable damping materials.

中文翻译：

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β_快速松弛控制丙烯酸聚合物/受阻酚杂化物的阻尼稳定性

受阻酚显着增强了丙烯酸聚合物的声音衰减和减振效果。然而，由于潜在的小分子自聚集和结晶，这种新型的阻尼材料在长期使用中会逐渐降解。在这项工作中，研究了小分子尺寸，氢键强度和丙烯酸酯基侧基的迁移率对长期阻尼稳定性的影响。结果与丙烯酸类混合物的分层松弛相关。我们对以下发现感到惊讶：阻尼衰减动力学似乎受β_快速弛豫而不是α和/或_{βJG的支配}聚合物基质的松弛。进一步的实验表明，小分子的长距离扩散至自聚集和随后的结晶受_βJG弛豫的调节，但是在物理老化过程中，酚的羟基与丙烯酸酯的羧基之间的分子间氢键的解离作用在抑制降解方面起决定性作用。我们假定氢键的小分子的波动引起的解离子埃振幅内限制，因此与耦合β的笼破运动_快速放松。这些结果阐明了小分子增强阻尼的机理，并为快速评估新型阻尼材料的使用寿命和热力学判据提供了策略。k ₀用于将来设计小分子和长期稳定的阻尼材料。