Structural Recovery and Physical Aging in Plasticizing Environments

通过玻璃化转变，增塑剂跳跃对聚合物玻璃中异常体积恢复的发现将通过三种新的实验进行探索。首先，将研究结构恢复过程中质量吸收的动力学。其次，将进行增塑剂跳变后的第一次焓恢复实验，以确定在玻璃结构的焓部分是否也存在观察到的体积异常。这将需要在PI实验室为Calvet量热计开发一种独特的压力电池。第三，将开发一种非共振介质孔燃烧光谱（NSHB）技术，以确定增塑剂跳变和t跳变制造的玻璃的动态非均质性。实验结果将在玻璃成型材料的能量景观范式中进行解释。这项工作将提供第一套完整的数据，用于构建宏观变量（体积、焓和浓度）的全范围，并将它们与玻璃结构演变或物理老化过程中材料的微观性质（NSHB）的测量联系起来。最后，在德克萨斯理工大学开发的NSHB能力将是美国第一个这样的设备。研究生和博士后研究员将在项目负责人的直接指导下进行拟议的研究。这项工作有望为研究生和博士后在前沿研究方面提供良好的培训。作为培训的一部分，研究生和博士后将参加国家或地区会议并展示他们的研究成果。除了为学生提供良好的培训外，项目的成果将在可行的范围内纳入PI教授的本科和研究生课程。由于该研究是跨学科的，包含高分子材料科学（玻璃成型材料的结构恢复和塑化）和量热学以及基础凝聚态物理（非共振光谱孔燃烧）的多个方面，为研究生和博士后提供了难得的教育机会。他们将被要求熟悉项目的各个方面。此外，这项工作还涉及两项重要的仪器设计和建造任务（量热计压力容器和介电NSHB仪器），这对实验科学家的教育具有重要意义。＊＊＊

The discovery of anomalous volume recovery in polymer glasses subjected to plasticizer-jumps through the glass transition will be explored using three new classes of experiment. First, the kinetics of mass absorption during structural recovery will be investigated. Second, the first enthalpy recovery experiments after plasticizer-jumps will be performed to determine if the observed volume anomalies are also found in the enthalpy part of the glassy structure. This will require development of a unique pressure cell for the Calvet calorimeter in the laboratories of the PI. Third, a non-resonant dielectric hole burning spectroscopy (NSHB) technique will be developed to establish how dynamic heterogeneity of the plasticizer-jump and T-jump created glasses compares. The experimental results will be interpreted within the energy landscape paradigm for glass-forming materials. The work will provide the first complete set of data that constructs the full range of macroscopic variables (volume, enthalpy and concentration) and relates them to a measure of the microscopic nature of the material (NSHB) during the evolution of glassy structure or physical aging. Finally, the development of the NSHB capabilities at Texas Tech University will be the first such apparatus in the United States.%%%The graduate students and post-doctoral researcher will perform the proposed research under the direct supervision of the PI. The proposed work is expected to provide excellent training for the graduate student and post-doctoral associate in cutting edge research. As part of their training, the graduate student and post-doc will attend and present their research results at national or regional meetings. In addition to providing good training for students, the results of the project will be incorporated to the extent feasible in both undergraduate and graduate courses taught by the PI. Because the research is interdisciplinary, containing multiple aspects of polymer materials science (structural recovery and plasticization of glass forming materials) and calorimetry as well as fundamental condensed matter physics (non-resonant spectral hole burning) the work provides a rare educational opportunity for the graduate student and post-doc. They will be expected to be familiar with all aspects of the program. In addition, the work involves two significant instrument design and construction tasks (pressure vessel for calorimeter and dielectric NSHB apparatus) that are important in the education of experimental scientists. ***