梯度结构纳米纤维吸音气凝胶的可控构筑及其声能耗散机制研究

The current fibrous sound absorption materials can not satisfy the urgent requirements of transportation equipment for high performance sound absorption materials with lightweight due to the poor sound absorption performance at low frequency and high density. Herein, we will investigate the fabrication and structure regulation of the gradient structured nanofibrous aerogels for sound absorption, and reveal the collaborative optimization mechanism of the materials’ structures and sound absorption performance, finally, obtain a lightweight material with high sound absorption performance at low frequency. Recently, we have preliminarily prepared gradient structured nanofibrous aerogels. However, the sound absorption performance and mechanical properties of these aerogels could not satisfy the requirements of practical applications due to their fewer gradient grade and poor structure stability. Therefore, we will carry out the controllable fabrication and performance optimization of the gradient structured nanofibrous aerogels for sound absorption, establish the critical forming condition of the gradient structure, and illuminate the regulating rule of the gradient structure during the bonding process of fibers. Moreover, we will find out the relationship between the bonding structure and mechanical properties, and establish the numerical model of acoustic energy dissipation for the gradient structured fibrous aerogels. Finally, we will explore the optimized structure of the fibrous aerogels for sound absorption, and achieve the materials with the highest gradient grade of 6, density ≤ 10 mg/cm3, and sound absorption coefficient at low frequency ≥ 0.56, which could realize the practical applications in the prevention and control of traffic noise.

当前纤维类吸音材料普遍存在低频吸音性能差、重量大的问题，难以满足交通运输装备对高效轻质吸音材料的迫切需求。本项目拟研究梯度网络纳米纤维吸音气凝胶的成型及结构调控规律，揭示材料本体结构与吸音性能的协同优化机制，获得具有低频段高效吸音性能的轻质纤维材料。近期申请者初步制备出具有梯度网络结构的纳米纤维气凝胶，但该材料的梯度级数较低且结构稳定性较差，导致其吸音及力学性能仍未达到实际应用要求。本项目将开展梯度纤维气凝胶的可控构筑及其吸音性能优化研究，确立气凝胶梯度网络结构成型的边界条件，明晰纤维粘结交联过程中梯度结构稳定性的调控规律，阐明纤维框架粘结结构与材料力学性能的本构关联，建立适用于梯度纤维气凝胶的声能耗散预测模型，确立材料达到最佳吸音性能时的本体结构特征，实现其梯度级数最高为6级/cm、体积密度＜10mg/cm3、低频段最大吸声系数≥0.56的目标，以满足其在交通噪声控制领域的应用要求。

本课题“梯度结构纳米纤维吸音气凝胶的可控构筑及其声能耗散机制研究”旨在明确纤维气凝胶梯度网络结构成型的边界条件及其调控规律，揭示纤维粘结交联过程中梯度结构稳定性的调控机制，实现低频段下高吸声系数的梯度结构纤维气凝胶的可控制备及其在交通噪声控制领域的应用。从2019年初到2022年底，开展了大量的实验研究工作。我们分析了纤维均质分散液形成的边界条件，并研究了冷冻-干燥参数对纤维气凝胶成型过程的影响规律，确立了纤维分散液冷冻过程中纤维网络框架的成型机制，掌握了气凝胶梯度网络结构调控的科学方法。进一步考察了纤维搭接点在粘结交联过程中物理熔接及化学交联的动态演变过程，研究了原位粘结交联反应对纤维集合体本体结构和力学性能的影响规律，掌握了梯度结构纳米纤维气凝胶结构稳定性调控的科学方法。在上述研究的基础上，制备了三明治梯度结构纳米纤维气凝胶、梯度网络结构纳米纤维气凝胶等吸音材料，通过研究材料结构与其吸音性能间的内在关联，确立了纳米纤维气凝胶具有优异吸音性能时的本体结构特征。经过四年的研究，我们顺利完成了任务书中规定的任务，制备的纳米纤维吸音气凝胶实现了梯度级数最高为6级/cm、体积密度<10mg/cm3、低频段最大吸声系数≥0.56的目标。项目执行期间共培养博士4名，硕士5名。发表学术论文13篇，申请发明专利5项，其中授权专利4项。本课题的完成对探究梯度结构纤维气凝胶的成型机制、实现其在交通噪声控制领域的应用具有重要意义。