Thesis
Investigation of novel methods for manufacturing polyimide aerogel stock shape
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16652
- Person Identifier (Local)
- 201982848
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Polyimide aerogels have excellent thermal and mechanical properties that make them suitable for a wide range of applications, especially in insulation. They can be fabricated in powder-based, film-based and monolithic forms. However, conventional methods for producing monolithic aerogel can be time-consuming and expensive, especially given the lengthy process required for solvent exchange and drying. Polyimide aerogel in the form of powder particles has therefore attracted significant attention relating to its wide variety of applicable properties, including its high mass diffusion rate and thermomechanical properties, especially as compared with monolithic shapes. Although this project’s industrial partner, Blueshift International Materials, currently manufactures polyimide aerogel in the form of film and stock shape; but there is a desire to further reduce the costs for their stock shape products. Therefore, it is necessary to develop and modify this method to increase its viability. This PhD project comprises two main work packages to address needs relating to this process. Firstly, the polyimide aerogel particles are synthesised using three different methods: dry milling, wet gel grinding, and emulsion in ambient pressure drying; secondly, the stock shape form is fabricated by consolidating synthesised particles. Although polyimide aerogel particles can be used directly as a finished product, it is nevertheless desirable to develop a cost-effective process in order to convert polyimide aerogel particles into stock shape. To the best of our knowledge, such an attempt has not been reported within any existing literature on polyimide aerogel. This study details the development of an alternative technique (adding epoxy and dimethyl sulfoxide solvent) to obtain polyimide aerogel stock shape by consolidating polyimide aerogel particles. Using this technique, the solvent exchange is performed on the powdered form (in less than 3 h), and this results in a significant reduction in the solvent exchange step compared to the stock shape form (144 h). This approach also reduces the cycle time involved in processing polyimide stock shape aerogel by nearly 60%, which has a clear potential for reducing production costs. In order to produce particles of a variety of sizes, dimethyl sulfoxide was added in different concentrations to dilute it. Microscopic properties of interest, including skeletal and porous structure, microparticle size and assembly, were then examined using nitrogen sorption, mercury intrusion porosimetry and SEM. Macroscopic properties, such as thermal stabilities (up to 500 ℃) and conductivities, were also compared and correlated with other parameters, such as densities and dilution ratios. These methods involved using produced particles with diameter sizes between 4 and 20 μm and porosities as high as 94%. The stock shape samples obtained from particle consolidation were characterised by mercury intrusion porosimetry, nitrogen sorption, thermogravimetric analysis and compression testing. Compared with the stock shape made using the existing method, the powder-to stock shape samples with epoxy addition are promising in terms of appearance and mechanical properties. Compression tests also showed that the addition of epoxy improves the mechanical properties and compressive strength at 10% strain by 18%. In the same context, the samples made using dimethyl sulfoxide as the solvent exhibited higher thermal stability and porosity than stock shapes made using traditional methods. These results suggest that a range of useful thermal and mechanical properties can be obtained for PI aerogel stock shape prepared using particles.
- Advisor / supervisor
- Fletcher, Ashleigh
- Yang, Liu
- Resource Type
- DOI
关系
项目
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PDF of thesis T16652 | 2023-07-19 | 公开 | 下载 |