Sunil ChandraKant Joshi
Nanyang Technological University, Singapore
Sunil ChandraKant Joshi is a faculty in the School of Mechanical and Aerospace Engineering of Nanyang Technological University Singapore. He received his PhD from Monash University, Australia, for his work on composites manufacturing processes. His research includes aerospace composites and structures, multifunctional composites, numerical simulation composites manufacturing processes, autoclave molding, fi lament winding, microwave curing, braided composites, environmental effects and engineered composites. The silica aerogel composite technology, mentioned in this talk, has resulted in a US patent (No. 9, 764, 301,19th Sep, 2017) and been licensed to a company for thermal and acoustic insulation market. He has successfully supervised over 150 project students (including 8 PhDs) and has about 200 publications and reports to his credit.
Silica aerogels are synthetically-produced, ultra-light-weight, insulating materials. Th ese are available in, either granular or wrapped-in blanket forms. In these forms, however, the material is either fragile or sheds dust particles during handling and site use. Another novel form, recently developed, is a composite of the silica aerogel granules bound together using a non-toxic,
non-hazardous, water-soluble binding agent. Th ese composites are equally light-weight, good heat insulators, sound reducers and water-resistant. Th is paper presents our study on these eco-friendly silica aerogel composites carried out to enhance their processing, manufacturability, dimensional accuracy and mechanical performance. Appropriate close mold designs were conceptualized and built to avoid out-of-plane deformations or warping of the composite blocks during the fabrication process. Th e samples produced using these new molds are perfectly fl at. Th is is a step forward such that any conforming shape now can be produced. In addition, the new mold design is compact and facilitates simultaneous fabrication of more samples. Th e silica aerogel composites are generally rigid. Investigations were conducted using specifi c fi llers and reinforcement to enhance the fl exibility of these composites. Solid and liquid additives, namely fumed silica, carbon nanotubes and methyltrimethoxysilane (MTMS) were tried. Th eir eff ects were studied using 3-point bending and cyclic compression tests. Additionally, a physical reinforcement in the form of the woven thermoplastic mesh and the glass woven fabric was studied. Th e impact of these was examined using the standard mechanical properties tests. It was observed that fumed silica helped enhance compression behavior while the glass fi ber reinforcement provided better fl exibility. Th e mechanical performance was found enhanced by two-fold. Th e proposed talk will touch upon the concept developments, mold design, reinforcing procedures, test results and accomplishments and the underlying reasons.